GC955 600-ENG vs 6 feb 2011 · Manual for the Syntech Spectras GC955 series 400 , 600 and 800...

GC955

MANUAL

JUNHO 2013

SYNTECH SYNTECH SYNTECH SYNTECH SPECTRAS Analyser GC955Analyser GC955Analyser GC955Analyser GC955

Manual for the Syntech Spectras GC955Manual for the Syntech Spectras GC955Manual for the Syntech Spectras GC955Manual for the Syntech Spectras GC955----seriesseriesseriesseries

Version 6 February 2011

Synspec b.v.

De Deimten 1

9747 AV Groningen

Nederland

[email protected]

Manual for the Syntech Spectras GC955 series 400 , 600 and 800 single/double 29-1-2013 2


Contents overview

Chapter 1 Technical instrument dateChapter 1 Technical instrument dateChapter 1 Technical instrument dateChapter 1 Technical instrument date ________________________________________________________________________________________________________________________________________________________________________ 5555

1.1 Technical- and order specification _________________________________________ 5

1.2 Quality control __________________________________________________________ 5

Chapter 2 Installation of the equipmentChapter 2 Installation of the equipmentChapter 2 Installation of the equipmentChapter 2 Installation of the equipment ________________________________________________________________________________________________________________________________________________________________ 7777

2.0 Safety notice _________________________________________________________ 8

2.1 General requirements __________________________________________________ 9

2.2 Explanation of the requirements _________________________________________ 9

2.3 Preparing the instrument for the first run _________________________________ 12

2.4 Switching off the equipment: ___________________________________________ 13

2.5 Overview of the instrument ____________________________________________ 14

Chapter 3 Description of functionChapter 3 Description of functionChapter 3 Description of functionChapter 3 Description of functionssss ____________________________________________________________________________________________________________________________________________________________________________ 19191919

3.1 Gas chromatographic principles of the GC955 ___________________________ 21

3.2 Detector options and separation effectiveness ____________________________ 26

3.3 Electronics and software ______________________________________________ 29

Chapter 4 Getting started with the GC955Chapter 4 Getting started with the GC955Chapter 4 Getting started with the GC955Chapter 4 Getting started with the GC955 ____________________________________________________________________________________________________________________________________________________ 35353535

4.0 Introduction _________________________________________________________ 36

4.1 Preparing the instrument and the environment ____________________________ 36

4.2 The first normal measurements_________________________________________ 38

4.3 Calibration and registration of the calibration _____________________________ 43

4.4 Automatic measurements _____________________________________________ 48

4.5 Data registration and data handling _____________________________________ 50

4.6 IO-state ____________________________________________________________ 54

4.7 Remote control ______________________________________________________ 55

4.8 Alarm functions ______________________________________________________ 55

4.9 Password ___________________________________________________________ 56


Chapter 5 Program adjustment and optional featuresChapter 5 Program adjustment and optional featuresChapter 5 Program adjustment and optional featuresChapter 5 Program adjustment and optional features ________________________________________________________________________________________________________________ 57575757

5.0 Introduction _________________________________________________________ 58

5.1 Program edit menu overview ___________________________________________ 58

5.2 Chromatogram adjustment ____________________________________________ 59

5.3 Temperature and flow programming ____________________________________ 61

5.4 Sensitivity adjustment _________________________________________________ 64

5.5 Run settings ________________________________________________________ 67

5.6 Communication ______________________________________________________ 68

5.7 Alarm and password settings __________________________________________ 72

5.8 Advanced calibration options __________________________________________ 73

5.9 Improving peak identification by retention time lock________________________ 82

5.10 Settings of the identification file GC955id.txt ______________________________ 83

Chapter 6 Service and maintenanceChapter 6 Service and maintenanceChapter 6 Service and maintenanceChapter 6 Service and maintenance ____________________________________________________________________________________________________________________________________________________________________ 85858585

6.0 Introduction _________________________________________________________ 86

6.1 Photo ionisation detector ______________________________________________ 93

6.2 Cleaning the FID _____________________________________________________ 97

6.3 Pneumatics _________________________________________________________ 98

6.4 Gas chromatography ________________________________________________ 104

6.5 Computer maintenance ______________________________________________ 111

6.6 Installing an auto-validation valve ______________________________________ 118

Chapter 7 Stream selChapter 7 Stream selChapter 7 Stream selChapter 7 Stream selectorectorectorector ________________________________________________________________________________________________________________________________________________________________________________________________ 121121121121

7.1 Introduction ________________________________________________________ 122

7.2 Programming the stream selector _____________________________________ 122

7.3 Data output ________________________________________________________ 125

7.4 Errors occurring with the stream selector valve __________________________ 129

INDEXINDEXINDEXINDEX ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 131131131131


Chapter 1 TechChapter 1 TechChapter 1 TechChapter 1 Technical instrument datenical instrument datenical instrument datenical instrument date ( if applicable)

1.1 Technical1.1 Technical1.1 Technical1.1 Technical---- and order specificationand order specificationand order specificationand order specification

1.2 Quality control1.2 Quality control1.2 Quality control1.2 Quality control

Depending on instrument series and application. See AED.


Chapter 2 Installation of the equipmentChapter 2 Installation of the equipmentChapter 2 Installation of the equipmentChapter 2 Installation of the equipment

2.0 Safety notice _________________________________________________________ 8

2.1 General requirements __________________________________________________ 9

2.2 Explanation of the requirements _________________________________________ 9 2.2.12.2.12.2.12.2.1 Power demandPower demandPower demandPower demand ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 9999 2.2.22.2.22.2.22.2.2 Room temperatureRoom temperatureRoom temperatureRoom temperature ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 9999 2.2.32.2.32.2.32.2.3 RelaRelaRelaRelative humiditytive humiditytive humiditytive humidity ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 10101010 2.2.42.2.42.2.42.2.4 DimensionsDimensionsDimensionsDimensions ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 10101010 2.2.52.2.52.2.52.2.5 Gas fittingsGas fittingsGas fittingsGas fittings ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 10101010 2.2.62.2.62.2.62.2.6 Carrier gasCarrier gasCarrier gasCarrier gas ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 10101010 2.2.72.2.72.2.72.2.7 Extra gases for the detectorsExtra gases for the detectorsExtra gases for the detectorsExtra gases for the detectors ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 11111111 2.2.82.2.82.2.82.2.8 Sample filteringSample filteringSample filteringSample filtering ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 11111111 2.2.92.2.92.2.92.2.9 Sample tubingSample tubingSample tubingSample tubing ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 11111111 2.2.102.2.102.2.102.2.10 Calibrating equipmentCalibrating equipmentCalibrating equipmentCalibrating equipment ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 11111111

2.3 Preparing the instrument for the first run _________________________________ 12 2.3.12.3.12.3.12.3.1 Visual inspectionVisual inspectionVisual inspectionVisual inspection ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 12121212 2.3.22.3.22.3.22.3.2 Connecting the gas supply and the sample tubingConnecting the gas supply and the sample tubingConnecting the gas supply and the sample tubingConnecting the gas supply and the sample tubing ________________________________________________________________________________________________________________________________________________________________________________ 12121212 2.3.32.3.32.3.32.3.3 Start and stop of a PDECDStart and stop of a PDECDStart and stop of a PDECDStart and stop of a PDECD ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 12121212

2.4 Switching off the equipment: ___________________________________________ 13

2.5 Overview of the instrument ____________________________________________ 14


2.02.02.02.0 Safety noticeSafety noticeSafety noticeSafety notice

This manual for the Syntech Spectras introduces you to the installation, the running and simple This manual for the Syntech Spectras introduces you to the installation, the running and simple This manual for the Syntech Spectras introduces you to the installation, the running and simple This manual for the Syntech Spectras introduces you to the installation, the running and simple maintenancmaintenancmaintenancmaintenance of the Syntech Spectras gas chromatographs.e of the Syntech Spectras gas chromatographs.e of the Syntech Spectras gas chromatographs.e of the Syntech Spectras gas chromatographs.

The instrument has been built for semi-continuous measurement of hydrocarbons in air and other gases.

WARNING:WARNING:WARNING:WARNING:

The instrument is to be used only by trained personnel.

Please note that the following risks have to be considered when working with the instrument:

• A relevant selection of the gases nitrogen, helium, hydrogen and air at a pressure from 0.5 to 5 bar will

be connected to the instrument. Personnel must be schooled in working safely with these gases.

• The instrument works with a 220VAC power supply. Inside the instrument there is a high voltage supply of

2 kV in a protective housing.

• The pre concentration unit will be at a temperature of 100 to 260 °C during desorption.

The instrument has been tested for accordance to the EMCdirective 89/336/EMC, test specification EN 50081-1:

1991 and EN 50082-2: 1994.

There is a warranty on the instrument of one year after delivery. The warranty does not include filters, pre

concentration tubes and capillary columns. For a PID lamp there is a two-year warranty.

WARNING: If you do not copy your data in a regular cycle, loss of data is at your own risk! Of WARNING: If you do not copy your data in a regular cycle, loss of data is at your own risk! Of WARNING: If you do not copy your data in a regular cycle, loss of data is at your own risk! Of WARNING: If you do not copy your data in a regular cycle, loss of data is at your own risk! Of

course the hard disk itself is replaced under warranty! We expect the life span of your hard disk course the hard disk itself is replaced under warranty! We expect the life span of your hard disk course the hard disk itself is replaced under warranty! We expect the life span of your hard disk course the hard disk itself is replaced under warranty! We expect the life span of your hard disk

tttto be about 5 years!o be about 5 years!o be about 5 years!o be about 5 years!

NOTICE:NOTICE:NOTICE:NOTICE:

• Please inspect the instrument for transport damage after receiving it. In case of damage we ask you to

contact your supplier within 8 days after receiving the instrument.

• Be sure to read chapter 2 before installing the instrument, and chapter 3 and 4 before switching the

instrument on.

• If you have questions about running the instrument, please contact your supplier or Synspec. (Tel. +31

50 526 6454, fax +31 50 525 6540, e-mail [email protected])

• Always disconnect the gas and power supply before opening the instrument

• Do not move the instrument when the internal computer is working to avoid damage to the hard disk.

• Beware of electrostatic shocks to the internal computer: do not drop metal parts in it, take care to use

appropriate equipment.


2.12.12.12.1 General requirementsGeneral requirementsGeneral requirementsGeneral requirements

power demand 220 V AC, mean 100 VA, start-up 600 VA

room temperature

requirements

5 - 35 °C

relative humidity

requirements

20 - 90 %

dimensions 19” rack, 5 Standard Height Units, depth 37.2 cm net

gas couplings all gas-connections to the instrument with 1/8” Swagelok-compatible couplings.

Pressure regulators must be of gas chromatographic quality

carrier gas Nitrogen: quality N 5.0, 4 bar connection to the instrument demand 5 ml/min.Nitrogen: quality N 5.0, 4 bar connection to the instrument demand 5 ml/min.Nitrogen: quality N 5.0, 4 bar connection to the instrument demand 5 ml/min.Nitrogen: quality N 5.0, 4 bar connection to the instrument demand 5 ml/min.

extra gases for an FID-detector:

-hydrogen, quality 5.0 consumption ca 20 ml/min. From a bottle or a

hydrogen generator.

-zero air, quality 5.0, 250 ml/min.

sample filtering inert microfilter 5 µ at the entrance is advised

sample tubing tubing must be clean and inert (stainless steel, Teflon or FEP). Replace tubing

when sooty!

calibrating equipment must be present to calibrate at least a zero and span concentration every month

2.22.22.22.2 Explanation of the requirementsExplanation of the requirementsExplanation of the requirementsExplanation of the requirements

2.2.1 Power demand

Standard 220 VAC (210 - 230 VAC), we recommend 600 VA, however for normal start-up the maximum demand

is about 300 VA, at continuous use the demand is about 90 VA. (A 110VAC, 60Hz version is avaliable)

2.2.2 Room temperature

For standard applications, unless otherwise stated, room temperature may vary between 5 and 35 °C . However, it

is not advised to use a room temperature regulation that results in temperature changes of more than 5 oCper

hour. In this case stable retention times are not reached.


2.2.3 Relative humidity

Must be 20 - 90%.

2.2.4 Dimensions

The instrument is built for a 19” rack. We advise to give the instrument a ventilation space of 1 standard HU at the

bottom and top. Mounting on a rail is advised. If the GC is placed on a metal or wooden board, please pay

attention to good ventilation at the bottom: either by using a ventilated housing or by using a perforated board.

Do not forget to reserve a place for keyboard and mouse, preferably a board on slides, which can be 10 to 50 cm

below the GC.

2.2.5 Gas fittings

All fittings to the instrument must be 1/8” Swagelok-compatible, for the gas supply in brass, for the sample in

stainless steel (this also prevents confusion).

Pressure regulators must be of gas chromatographic qualitygas chromatographic qualitygas chromatographic qualitygas chromatographic quality, i.e. must be dust free and may not absorb or emit

hydrocarbons.

As regulators and the connections to bottles are not standardized, the best idea is to get advice from a good gas

supplier in your country. Explain what you want to do with the equipment before ordering. Never order pressure

regulators in another country, this is simply a waste of money!

For the carrier gas nitrogen, gas chromatographic quality means: use a nickel-plated bronze regulator with steel

membrane, range 0 - 4 or 0 - 10 bar. Use bottles with a maximal pressure of 200 bar.

For calibrating gases a stainless steel regulator with high quality steel membrane is preferred.

2.2.6 Carrier gas

Nitrogen of GC-quality (quality 5.0 or higher, i.e. 99.999% pure) must be used, unless otherwise specified. It

should be connected by a 1/8” FEP or Teflon tube, maximum length 2 m, to the carrier gas port. The pressure at

the port should be between 2.5 bar and 4 bar.


2.2.7 Extra gases for the detectors

Two of our detectors use no other gases besides the carrier gas: the PID and the TCD.

To generate the signal the FID has a hydrogen flame, which uses hydrogen and air. For hydrogen, bottles

or a generator can be used. In a lab a bottle is a good solution, provided it can be stored well. For a

mobile station we think generators are superior: this way the user has no responsibility for transporting

and storing bottles in a field situation.

A hydrogen generator is expensive. But, considering its lifetime, in the end it is not more expensive than

bottles.

The PDECD uses very pure helium to generate a strong UV-light, which is used to ionise xenon. Xenon is

dosed as a 3% xenon in helium mixture.

Both gases must be provided in quality 6.0. The helium must also have an extra catalytic purifying step.

All materials in connection with the gases must be ultrapure and must all be stainless steel.

2.2.8 Sample filtering

The internal diameter of the inside tubing is mostly 0.5 to 1.0mm. So the sample has to be filtered. We advise a

Teflon filter membrane of 5 micron, preferably in a 1/8” housing, alternatively in a 6 mm or 1/4” housing with good

connections to the 1/8” tubing. Alternatively disposable nylon filters with glass frit or Teflon filters can be used.

2.2.9 Sample tubing

Clean inert tubing at the sample-port is essential for obtaining good results.

Use only PTFE (Teflon), FEP or stainless steel, even for short connecting pieces. Do not use other plastics or

bronze.

Do not use the same tubing for taking ambient air samples and calibration samples. Use two tubing systems, that

are only connected the last 5-15 cm before the sampling port.

Of course the tubing can be connected to central sampling systems with a large volume pump. Contact us if you

have doubt about the GC ‘s position within a larger sampling system.

2.2.10 Calibrating equipment

We advise a daily span check. If these checks are stable, a basic calibration is only needed one to three months.

Without an automatic daily check a manual span check is advised every two weeks at least until the instrument is

stable, where after a monthly check is the minimum.

See chapter 4 for more details about the calibration.


2.32.32.32.3 Preparing the instrument for the first runPreparing the instrument for the first runPreparing the instrument for the first runPreparing the instrument for the first run

All the above mentioned supplies must be present

2.3.1 Visual inspection

Before the GC is switched on after disuse it should be inspected. After normal transport it may be presumed that

the instrument will function correctly.

The instrument should be inspected for loose parts, as they can do much harm in the oven ventilator and the

computer.

After transport it is useful to check

- the correct position of the computer’s boards in the connections, this is simply done by pressing the boards

down into their connectors.

2.3.2 Connecting the gas supply and the sample tubing

The gas lines of the instrument have been closed for transport. Remove the metal plugs at the backside, keep

them to use when the instrument has to be moved without gas lines connected to it. The ends of the two sample

gas lines are also protected for some columns: with a plastic plug at the back (sample outlet) and a similar

plastic plug in the computer compartment at the front protecting the end of the detector output.

See the scheme of the rear side: connect carrier gas to carrier gas port. The stainless steel Tee that is delivered

for the sample tubing must be connected to port 4 and 5; then the sample tubing must be connected to it. Place

the sample filter in the last piece of tubing before the sample Tee.

For an FID: Clean, dry compressed air must be connected to the AIR-port, pressure at the port at least 3.0 bar

but less than 4.0 bar. Hydrogen must be connected to the hydrogen port, pressure at the port 2.5 bar.

Test for leaks!!

2.3.3 Start and stop of a PDECD

PDECD Gas supply:PDECD Gas supply:PDECD Gas supply:PDECD Gas supply:

Helium and 3% xenon in helium must be connected to the system.

1. First connect the pressure reducers to the bottle and flush these 6 times. Then connect the two

purifiers to the gas, flush these for 15 minutes.

Only after this the purifiers may be switched on.

2. Helium must be placed in the GC on the back of the PDECD, xenon at the entry “dopant inlet”.

3. Check all connections with a helium leaktester!

Once the unit has been used, preferably leave the entire gas system as it is while removing the GC, just

shut off all inputs that are set free. The system is leakproof and should remain so under pressure.


Turn on:Turn on:Turn on:Turn on:

1. GC and PDECD can be started independently. The best thing is first to start the PDECD and then the

GC.

2. Put the switches of the PDECD in the following position:

Temperature 100 °C

Mode: at PDECD

Range: at 1

Power:-

Amplification (Attenuation) at 1

3. First of all switch the power supply of the PDECD on.

4. Wait until the detector temperature is stable (for 5 to 10 minutes), then put the discharge at ‘on’.

5. As the lamp starts, the background will fall from 200 to circa 1-10 mA.

6. Start the gas chromatograph.

If the helium has been disconnected this can take up to circa 1.5 hour. Otherwise circa 5 minutes.

2.42.42.42.4 Switching off the equipmentSwitching off the equipmentSwitching off the equipmentSwitching off the equipment::::

When the analyser will not be used for a longer time, the choice are :

• To let it run on without doing anything with the results: this will enable you to start up in minutes,

the only problem is that it consumes power and gas.

• Stopping the run and leaving it ready for restart: this is generally better. There is less

consumption of gas and power, but still a very quick restart. Not advised with cold traps, as

condensation may give problems in the trap when it is not heated out frequently.

• Switching it off completely: in this case take care that no dust or humidity comes in.

A special case is the PDECD, which is the most difficult to turn on.

1. In case of a PDECD detector: during short interruptions its the best option is to let the gas supply

run normally and keep the PDECD switched on.

2. If the PDECD must be switched off, first switch off the discharge.

3. Then disconnect the current of the PDECD unit.

4. During lengthy interruptions disconnect the power of the purifiers and close off the gas bottles.

This will prolong the startup time to circa 2 hours.


2.52.52.52.5 Overview of the instrumentOverview of the instrumentOverview of the instrumentOverview of the instrument

Figure 2.1: Front view

1 LCD-screen

2 Error LED

3 Idle/Running indication LED

4 Power switch


1111

2222

3333 4444

5555

6666 7777

8888

9999

10101010

Figure 2.2: Rear view

1 Carrier gas

2 Output pump

3 Sample inlet

4 Stripper outlet

5 External connectors

6 Digital input and output connectors

7 Analogue input and output connectors

8 Oven ventilation

9 Instrument ventilation with filter

10 Power, 220 V


1111

2222

3333

5555

4444

7777

8

9

6

Figure 2.3: Top

1 Oven

2 Lamp /detector

3 10-port valve

4 Computer

5 Gas regulation cabinet

6 Hard disk

7 High Voltage board and computer power supply. DDDDangerangerangeranger: high voltagehigh voltagehigh voltagehigh voltage

8 Power supply

9 Flow sensor

10 Hard disk


2

6

7

8

3

1

12

5

11

4

9

10

Figure 2.4: Some details of the GC’s downside open

1 Connection mouse and keyboard

2 Power supply print

3 Power connection

4 MX Print (main GC electronics)

5 Analogue and digital Connections

6 Valve bracket

7 Mass flow controller

8 pre concentration tube

9 Gasflowregulation

10 Bypass pump

11 Ventilation motor

12 Piston with optosensor


Figure 2.5 Connections to a stream selector with calibrator

Mains 220 V 50 Hz

Strippe r out Sample in

Carrier gas AIR

10 p-valve Samplepump

SAMPLE PUMP OUT

LPT1 COM 2

Stream selector 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

dig.in dig.out Relais 1 2 3 4 5 6

Analog out

1 (spangas) 2 3 4 5

6 7 8 9 10 (Zero - air)

Fuse 1,5 A

A1 A2 A3

Exhaust

Sample out Purge

Compressor

Dryer

air

helium cylinder

Calibration gas bottle

GC 855 combined with stream selector and complete gas supply system for automatic validation


Chapter 3 Description of functionsChapter 3 Description of functionsChapter 3 Description of functionsChapter 3 Description of functions

3.0 Introduction _________________________________________________________ 20 3.0.13.0.13.0.13.0.1 Overview of the options for the Syntech Spectras GC955 seriesOverview of the options for the Syntech Spectras GC955 seriesOverview of the options for the Syntech Spectras GC955 seriesOverview of the options for the Syntech Spectras GC955 series ________________________________________________________________________________________________________________________________ 20202020

3.1 Gas chromatographic principles of the GC955 ___________________________ 21 3.1.13.1.13.1.13.1.1 SamplingSamplingSamplingSampling ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 23232323 3.1.23.1.23.1.23.1.2 Pre concentrationPre concentrationPre concentrationPre concentration ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 23232323 3.1.33.1.33.1.33.1.3 Desorption and strippingDesorption and strippingDesorption and strippingDesorption and stripping ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 23232323 3.1.43.1.43.1.43.1.4 SeparationSeparationSeparationSeparation ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 24242424 3.1.53.1.53.1.53.1.5 Temperature regulationTemperature regulationTemperature regulationTemperature regulation ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 25252525 3.1.63.1.63.1.63.1.6 Cycle timeCycle timeCycle timeCycle time ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 25252525 3.1.73.1.73.1.73.1.7 Cleaning of the systemCleaning of the systemCleaning of the systemCleaning of the system ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 25252525

3.2 Detector options and separation effectiveness ____________________________ 26 3.2.13.2.13.2.13.2.1 Detector optionsDetector optionsDetector optionsDetector options ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 26262626 3.2.23.2.23.2.23.2.2 PIDPIDPIDPID ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 26262626 3.2.33.2.33.2.33.2.3 FIDFIDFIDFID ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 27272727 3.2.43.2.43.2.43.2.4 TCDTCDTCDTCD________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 28282828 3.2.53.2.53.2.53.2.5 PDECDPDECDPDECDPDECD ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 28282828 3.2.63.2.63.2.63.2.6 Separation effectiSeparation effectiSeparation effectiSeparation effectivenessvenessvenessveness ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 29292929

3.3 Electronics and software ______________________________________________ 29 3.3.13.3.13.3.13.3.1 Electronics in the instrumentElectronics in the instrumentElectronics in the instrumentElectronics in the instrument ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 29292929 3.3.23.3.23.3.23.3.2 Program controlProgram controlProgram controlProgram control ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 30303030 3.3.33.3.33.3.33.3.3 Menu structure of the softwaMenu structure of the softwaMenu structure of the softwaMenu structure of the software programre programre programre program ____________________________________________________________________________________________________________________________________________________________________________________________________________ 30303030 3.3.43.3.43.3.43.3.4 Data handlingData handlingData handlingData handling ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 31313131 3.3.53.3.53.3.53.3.5 Communication with external equipment Communication with external equipment Communication with external equipment Communication with external equipment ---- remote controlremote controlremote controlremote control ____________________________________________________________________________________________________________________________________________________ 32323232 3.3.63.3.63.3.63.3.6 Alarm functions and passwordAlarm functions and passwordAlarm functions and passwordAlarm functions and password ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 33333333


3.0 Introduction

In section 3.1 the operating principles of the gas chromatograph are explained: sampling, separation and

analysis. Section 3.2 gives an overview of the detection and separation possibilities, section 3.3 of the

electronics, software and the data handling

3.0.1 Overview of the options for the Syntech Spectras GC955 series

The gas chromatograph GC955 is produced in 7 different types, adapted to the different requirements of

the compounds that have to be measured, the field conditions and the different uses by the customers.

Generally instruments are sold adapted to the requirements of the customer and calibrated for the

compounds that will be measured.

The basic GC955 includes:

(1) rack mounted 19" instrument, 5 standard Height Units

(2) built-in industrial computer

(3) detector

(4) sampling and injection unit for gaseous samples: with a sample loop; or with a pre concentration

unit, which can either be used at room temperature or cooled to 5 °C

(5) column: a packed column up to 5 M; or a capillary column up to 30 M at ID 0.53 MM or 60 M at

ID 0.32 MM

(6) temperature regulation: isothermal at a range from 40 to 100 °C ; or temperature programmed at

a range of 40 to 120 °C


The different combinations of the options in points (4) to (6) lead to 7 different series.

The instrument can also be supplied without an LCD screen.

For sampling from up to 10 different points a stream selector can be added.

series sample

loop

preconcen-

tration

cooled

preconcen-

tration

Packed

column

capillary

column

isothermal

oven

temperture

programmed

oven

100 √√√√ √√√√ √√√√

200 √√√√ √√√√ √√√√

300 √√√√ √√√√ √√√√

400 √√√√ √√√√ √√√√

500 √√√√ √√√√ √√√√

600 √√√√ √√√√ √√√√

800 √√√√ √√√√ √√√√

This manual is written for the series 200, 400 , 600 and 800, as they all have pre concentration. Although

column type, temperature regulation and detector which are used may be quite different, the gas flow

schemes are quite similar.

3.13.13.13.1 Gas chromatographic principles of the GC955Gas chromatographic principles of the GC955Gas chromatographic principles of the GC955Gas chromatographic principles of the GC955

A gas chromatograph for the automatic measurement of air samples and other gases has a special

method to take a sample: not by injection, but by leading the sample through a loop. Either the sample is

pumped, or the sample flows in under a slight overpressure. By switching a valve the sample is

introduced into a gas chromatographic column where it is separated. Then the separated compounds

are measured in the detector. The flow of carrier gas and sample through the system is complicated. By

way of a sophisticated 10-port valve, which is switched between two modes -position 03 and 04 - they

are sent in the right directions. Figure 3.1 and 3.2 give an overview of the gas lines in both modes of the

valve.


Fig. 3.1 Diagram of the GC955 injection mode

Fig. 3.2 Diagram of the GC955 analyzing/sampling mode


3.1.1 Sampling

Each cycle, the gas chromatograph takes a fresh sample of the air or gas that is to be analysed into a

sample loop. This is done by a small membrane pump in the instrument. The capacity of the pump is 1.5

l/min. Depending on the distance of the instrument from the source the pump can be switched on from

10 seconds to several minutes.

The dimensions of the sample loop depend on the concentration of the compounds that have to be

analysed: from 75 microliters for the high ppm range to 3 ml for the low ppb range.

3.1.2 Pre concentration

The machine works semi-continuously: the first step is flushing the sample tubing by drawing air (or

sample gas) through it with a pump. Then the pump is switched off and with the help of an indirect piston

system a volume of 35 ml sample gas is preconcentrated on a Tenax® or Carbograph column. This

procedure can be repeated until enough sample material has been drawn. Before each sampling the

pump can be switched on again for a short time. The pre concentration tube can be purged with carrier

gas to remove oxygen and water if desired.

Fig. 3.3: principle of pre concentration: the dark arrows show the airflow for emptying the piston, the white arrows show the

backflush, during which the sample is sucked through the pre concentration tube

For hydrocarbons with boiling points below 20 °C the absorption capacity of the medium can be a

problem, because the compounds can break through during sampling: in this case they are not trapped

completely and in the time between trapping and desorption they may evaporate. Enhancement of the

capacity is possible by cooling the pre concentration tube during absorption. Bij 3.1.2

The pre concentration tube can be cooled by radiation. To do this, the pre concentration tube is

embedded in an aluminium block. This block is cooled on both sides by Peltier elements. To avoid

freezing or condensation in the system, drying of most samples will be needed. The lowest temperature

that can be reached in practice is – 5 oC.

3.1.3 Desorption and stripping

The sample is desorbed in a short time by heating the pre concentration tube quickly, while flushing it

with carrier gas. By way of the 10-port valve in position 03 the sample is brought on the separation

column. (See the diagram 3.1)


The separation column consists of two parts : a stripper column and an analysis column. These are

usually two identical columns, with different lengths. The goal is to prevent a prolonged analysis, which is

normally caused by the necessity of waiting for elution of the highest boiling compound. Therefore the

time is set for the slowest eluting compound of interest to get through the column. After this time the flow

in the stripper column is reversed by switching the 10-port-valve.

Figure 3.4: Gas chromatographic separation with a sample loop and stripper/analysis column: the air is pumped into the loop, after

which the whole sample is brought onto the stripper column. After the passing of the desired compounds the rest is flushed back.

The earlier compounds are separated on the analysis column.

3.1.4 Separation

The rest of the analysis is performed with the 10-way valve in position 04. ( See the diagram 3.2 ) The

compounds which already passed through the stripper column continue their way through the analysis

column to the detector. (see 3.2) The gases, which already were seperated somewhat in the stripper

column, are seperated as far as possible in the analysis column .


3.1.5 Temperature regulation

The analysis can be done at a constant temperature or with a temperature program. With a cyclic

changing temperature compounds with more differing boiling points can be separated and determined

within an acceptable cycle time. During separation the oven is heated, usually 15 - 60 °C above the basic

temperature. After the heating phase cooling down has to take place before the next cycle can start. This

takes a few minutes.

3.1.6 Cycle time

The cycle time depends on the following factors:

1 difference in boiling point of the compounds to be determined

2 flow velocity and column ID/coating quotient

3 basic temperature

During each cycle the sampling for the next cycle is performed.

3.1.7 Cleaning of the system

For automatic measurements with the GC the cleaning of the system is essential to prevent deterioration

of the column, which would result in detoriation of the peaks. The backflush column is flushed every cycle

for some minutes separately from the analysis column in the reversed direction. To clean the analysis

column each cycle has to last until no more signals are detected.

The time setting for cleaning is done for normal ambient air. In a very dirty atmosphere a longer time may

have to be set for to clean the stripper.


3.23.23.23.2 Detector options and separation effectivenessDetector options and separation effectivenessDetector options and separation effectivenessDetector options and separation effectiveness

3.2.1 Detector options

The GC955 can be supplied with the following detectors:

* Photo Ionisation Detector (PID)

* Thermal Conductivity Detector (TCD)

* Flame Ionisation Detector (FID)

* Pulsed Discharge Electron Capture Detector (PDECD)

A combination of two detectors is possible. This is not always possible in the standard housing, ask for

special offer.

3.2.2 PID

Standardly the instrument will be provided with a Photo Ionisation Detector, 10.6 eV, with a measuring

cell of 50 µl.

This detector will achieve a high resolution and allow the measurement of very low concentrations: for

aromatic hydrocarbons, alkadienes and sulfur compounds down to 150 ppt, i.e. 0,4 µg/m3.

Photo ionisation is the process by which a photo excited electron absorbs enough radiant energy to be

ejected from the atom or molecule. Photo ionisation is initiated by the absorption of a 10.6 eV photon by

the molecule. If the molecule has an ionisation potential equal to or less than 10.0 eV, the following

process occur.

R + hv -----> R+ + e-

where hv is a photon with approximately 10.6 eV and R is the species of interest. Molecules with

ionisation potentials greater than 10.6 eV will yield a lesser response

The detector source is a low pressure discharge lamp filled with noble gas. It provides a stable

monochromatic source of high energy photons suitable for ionisation of the various components in gas

chromatography.

The UV source is contained in a vacuum-tight envelope with a UV grade magnesium fluoride window

maintaining isolation of the UV source from the gas chromatograph's carrier gas. The lamp’s output is

approximately 100 microwatts of 10.6 eV photons contained in a beam 6 degrees wide.

The PID-signal is amplified, the signals are then stored as a value of 0 - 10 V. On the LCD-screen the

chromatogram can be followed. Peak height and peak area can be quantified and stored for those peaks

that are of interest.


Figure 3.5: An analysis of an airsample loaded with paint residues as a result of painting activities one day before

The PID has a low sensitivity for saturated hydrocarbons. This detector is however specifically sensitive

for aromatic hydrocarbons, unsaturated compounds and heterogeneous hydocarbons like sulphur

compounds. Because of this, a group of interesting substances in the fields of environmental pollution,

process monitoring and industrial hygiene can be assessed.

The photo ionisation detector is ideally suited for continuous monitoring with a gas chromatograph: it is a

stable, sensitive detector, requiring no special gases.

The selective sensitivity makes possible monitoring of a range of (eco) toxics in the ppt to ppm-range.

Nitrogen or helium can be used as a carrier gas.

3.2.3 FID

The flame ionisation detector is the almost universal detector for the gas chromatograph, often used in

the laboratory.

Its sensitivity makes it suitable for the low ppb to ppm range. Needing a hydrogen flame and pure air as

a source of oxygen, the running cost of this detector is higher than for a PID. Hydrogen is shut off when

the flame does not burn, the flame temperature is monitored for this. Nitrogen or helium can be used as a

carrier gas.

The combination of a PID and an FID gives the opportunity to monitor complex mixtures satisfactorily.


Principle of flame ionisation: in a flame of oxygen and a burning compound ions are formed. When other

molecules than hydrogen pass through a hydrogen flame, these will also burn and increase the amount

of ions formed compared to pure hydrogen.

The ions and electrons generated by the ionisation are attracted to the positive and negative side of an

electrical field in the detector cell. The electrical current in the detector cell changes, and this change is

measured.

Fig. 3.6 With a double detector system, combining an FID with a PID or a TCD, the flow scheme for a system 600

will be as follows:

Preconcentration tube

Stripper column Analysis column

first detector,TCD or PID,

only carrier gas flows through

second detector,FID

Pure air

HydrogenCarrier gas Carrier gas

Gas supply to a double detector system with PID or TCD and FID

3.2.4 TCD

The thermal conductivity detector is the oldest detector in gas chromatography. Its sensitivity is less than

for the PID’s or the FID’s, which means the TCD is suitable to monitor compounds in the low ppm to %

range.

However, the TCD can measure compounds not detected by the other two (see section 5). The carrier

gas is usually helium.

Principle: The temperature of a conductive material wire influences the resistance. A gas flowing through

a heated chamber cools the wire.

Depending on the molecules in the gas the uptake of heat changes, this factor is called the thermal

conductivity. Changes in the conductivity of the wire are measured.

3.2.5 PDECD

The newest detector in this range is the Pulsed Discharge Electron Capture Detector. It is very sensitive

to those compounds that can trap electrons easily and not sensitive to others.

This means in practice that the PDECD is sensitive in the ppb-range to hydrocarbons containing chlorine,

bromine, fluorine . This detector needs a steady supply of purified helium and of a dopant gas.

Principle: helium is ionised by a pulsed discharge. High energy photons are emitted in this ionisation.

The photons in their turn ionise the dopant, which is Xenon. This results in a Xenon ion and an electron.


The electrons give a standing current, which is diminished when they are captured by the sensitive

compounds. The pulsed discharge principle is an electron source without the conventional radioactive

Ni-element. Users do not need training in handling radiation risks.

With the combination PID/PDECD a range of interesting environmental and toxic compounds can be

measured and identified.

Fig. 3.7 A flow scheme for a system with sample dryer looks as follows:

Sample dryer Preconcentration tube

Stripper column Analysis column

first detector,PID,only carrier gas flows through

second detector,PDECD

Helium3% Xenon in Helium

Carrier gas

Gas supply to a double detector system with PID and ECD

3.2.6 Separation effectiveness

The separation is determined by the column, the basic temperature, the programmed temperature rise

and the flow velocity of the carrier gas. The separation capacity of a column is determined by its length,

the type of coating and the quotient of the coating thickness and the inner diameter.

All commercially obtainable packing materials can be used in stainless steel columns of 2.1 mm ID up to

5 meters long and in fused silica or steel capillary columns of up to 60 m ( at I.D. 0,32 mm) and up to 30

m (at ID 0.53 mm.)

By choosing the column material and the temperature area, many different mixtures can be separated.

3.33.33.33.3 ElectronicElectronicElectronicElectronics and softwares and softwares and softwares and software

3.3.1 Electronics in the instrument

The GC955 uses an industrial Pentium computer. The electronics boards specially made for the

instrument are the power supply and the central function and signal control board. The instrument is

EMC-compatible . The power supply and the central board are situated at the underside.

The instrument has electronic sensors to measure the flow of the carrier gas and the pressure of the

valve switching gas. For sampling there are sensors for the sample pressure and temperature, to enable

correction for outdoor temperature and outdoor air pressure of the sample volume. An optosensor

checks the functioning of the piston.


3.3.2 Program control

The control of the cycle program is done by a user-friendly program under Windows 98. In a menu the

present cycle can be followed, or a stored chromatogram can be reloaded and settings of the cycle

program can be changed.

The GC955 is delivered with settings, which are adapted to the application as specified.

Changes in the program can easily be made in a bar diagram, in which is visible directly, what the

consequences of the proposed changes would be for the program.

Of course it is also possible to change the program for the determination of other compound mixtures.

The software has its own help function.

The software has the following menu structure:

3.3.3 Menu structure of the software program

View mode: Actual runActual runActual runActual run

File

Printer options

Print view

Print actual run

Options

Select screenelements

Adjust detector Y axis offset

Filecomments

Set calibrationmode

Edit sample concentrations

Open zerogas valve

Open span gas valve

Alarmstatus

Disable samplepump

Password protection

Activate autovalidation

Column flow

Restart FID

Maintenance active

View mode: File dataFile dataFile dataFile data

Options

Select view items

Select screenelements

Adjust detector Y-axis offset

Edit peakwindows

Filecomments

Reprocess data

Edit sample concentrations

Retention time lock 1

Retention time lock 2


Animate data

Data selection

Animate the

Stop animation

View mode: Program editProgram editProgram editProgram edit

Settings

Instrument settings

Run settings

Rundata output text format

Analog output

Analog input settings

Digital outputs

Automatic validation

Alarm settings

Communication

Change password

Change instrumentpanel

View mode: Calibration curveCalibration curveCalibration curveCalibration curve

Options

Dataselection calibration files

Calculate calibrationline

Settings

View mode: GraphGraphGraphGraphs

Settings

Select components

Scale

View mode: Autolinearisation Autolinearisation Autolinearisation Autolinearisation

Options

Start auto-validation

Auto-validation files

3.3.4 Data handling

The measured values are saved on the instrument’s hard disk. Measured cycles can be restored on the

LCD - screen, but also at the same time on another connected PC-screen (in a network, or on a

connected workstation).

Height and area of measured peaks are calculated for selected areas of interest in every cycle, for

instance for methylmercaptane and ethylmercaptane. The program has a default setting for integration:

start and end of peaks are determined by calculating and evaluating the first and second derivatives of

the detector-signal. If desired, the setting can be adjusted for each individual signal.

These values are saved as value per cycle on the hard disk. Besides this the values are passed on via

the RS232-port in the datastructure as specified by the customer


The measured raw data can also be read out directly via three analogue ports at the backside of the

GC955.

Calibration data can be entered through a separate menu. With these calibration values a calibration line

is calculated. In this way the measured data can be read out and stored as concentration values.

The raw data and the calculated concentrations may both be stored to allow for later corrections.

3.3.5 Communication with external equipment - remote control

Communication is possible via the digital and analogue in- and outputs, via the RS232-connectors,USB

and ethernet. Several functions of the GC are checked continuously; if there are problems an error

message is given. Status information can be sent to and from the instrument .

Digital input and output connectors

The GC955 has seven digital output ports, and 4 digital inputs. These are freely programmable and can

be used for the linking up of external equipment (external integrator or calibrator) or to react to external

signals, like a remote start or a pressure switch.

RS232-port

The same messages can be send over the RS232-ports and a modem connection towards a control

station. By online control further information about the problem can be obtained, errors in the setting of

the program can be fixed, or other optional changes can also be made by modem communication. GC’s

with connected equipment for calibration can also be calibrated in this way.

Remote control of the instrument is best done with a Windows based remote control program. Synspec

recommends the use of Symantec's PC-anywhere (version 8.0 or higher). The remote control can in this

case take place over modem, or over a ethernet-LAN.

With a normal LAN connection, a shared disk can be obtained, to retrieve ASCI-data from the GC.

The USB ports are used to connect external (zip)drives, CD-reader and writers etc.

Overview of data transfer and of communication options: for each option the useful elements are

explained, if an option does not fulfill a task it is labeled “no”.

Data transfer Status information Instrument control

Analogue outputs Concentration values will be transmitted

No no

Analogue inputs Can be used to read in data from other instruments

no no

Digital outputs no Yes, all set parameters in

the digital communication protocol will be transmitted.

Limited: some actions, like runstart, or start calibration can be set.

RS-232-

communication

Concentration values will be transmitted

Yes, all set parameters in the communication protocol will be transmitted.

Limited: some actions, like runstart, or start calibration can be set.


RS-232 modem

and PC Anywhere

Yes, all data can be copied. Speed depends on modem and phone line

Yes, as the GC screen can be seen

Can be used to change settings and then activate them. Only possible if phone line is stable.

Ethernet

connection

yes no Not directly

Can be used to check on remote PC measurements and then to copy back improved programs.

USB connection Can be used to copy data from the hard disk to zip drive, memory stick, CD-writeable etc.

no no

3.3.6 Alarm functions and password

The GC955 is adapted for use as early-warning system for toxic compounds. Levels for low and high

alarm can be set. Alarms can be given over modem, or over digital outputs. The GC can also be

provided with a buzzer or lamp for an alarm on site.

The GC955 can be protected by password.


Chapter 4 Getting started with the GC955Chapter 4 Getting started with the GC955Chapter 4 Getting started with the GC955Chapter 4 Getting started with the GC955

4.0 Introduction _________________________________________________________ 36

4.1 Preparing the instrument and the environment ____________________________ 36 4.1.14.1.14.1.14.1.1 Gas supplyGas supplyGas supplyGas supply ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 36363636 4.1.24.1.24.1.24.1.2 Sample tubingSample tubingSample tubingSample tubing ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 37373737 4.1.34.1.34.1.34.1.3 Backlight of the LCDBacklight of the LCDBacklight of the LCDBacklight of the LCD----screenscreenscreenscreen ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 37373737 4.1.44.1.44.1.44.1.4 Instrument identificationInstrument identificationInstrument identificationInstrument identification ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 37373737

4.2 The first normal measurements_________________________________________ 38 4.2.14.2.14.2.14.2.1 Switching on the electrical powerSwitching on the electrical powerSwitching on the electrical powerSwitching on the electrical power ________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 38383838 4.2.24.2.24.2.24.2.2 Starting the first runStarting the first runStarting the first runStarting the first run ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 38383838 4.2.34.2.34.2.34.2.3 Actual runActual runActual runActual run ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 40404040 4.2.44.2.44.2.44.2.4 Data fileData fileData fileData file ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 40404040 4.2.54.2.54.2.54.2.5 Stopping the progStopping the progStopping the progStopping the programramramram ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 42424242 4.2.64.2.64.2.64.2.6 Overview of activities in normal runsOverview of activities in normal runsOverview of activities in normal runsOverview of activities in normal runs ________________________________________________________________________________________________________________________________________________________________________________________________________________________ 42424242

4.3 Calibration and registration of the calibration _____________________________ 43 4.3.14.3.14.3.14.3.1 The principle of calibrationThe principle of calibrationThe principle of calibrationThe principle of calibration ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 43434343 4.3.24.3.24.3.24.3.2 Measuring calibration mixturesMeasuring calibration mixturesMeasuring calibration mixturesMeasuring calibration mixtures ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 44444444 4.3.34.3.34.3.34.3.3 Calculating the conversion factorCalculating the conversion factorCalculating the conversion factorCalculating the conversion factor ________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 45454545 4.3.44.3.44.3.44.3.4 Calibration gas mixturesCalibration gas mixturesCalibration gas mixturesCalibration gas mixtures ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 46464646 4.3.54.3.54.3.54.3.5 Calibration overviewCalibration overviewCalibration overviewCalibration overview ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 47474747 4.3.64.3.64.3.64.3.6 Adding a quality control pointAdding a quality control pointAdding a quality control pointAdding a quality control point ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 47474747

4.4 Automatic measurements _____________________________________________ 48 4.4.14.4.14.4.14.4.1 Adjusting the integration method.Adjusting the integration method.Adjusting the integration method.Adjusting the integration method. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 48484848 4.4.24.4.24.4.24.4.2 Overview of preparations for automatOverview of preparations for automatOverview of preparations for automatOverview of preparations for automatic measurementsic measurementsic measurementsic measurements ____________________________________________________________________________________________________________________________________________________________ 50505050

4.5 Data registration and data handling _____________________________________ 50 4.5.14.5.14.5.14.5.1 Data registrationData registrationData registrationData registration ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 50505050 4.5.24.5.24.5.24.5.2 Data handlingData handlingData handlingData handling ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 52525252 4.5.34.5.34.5.34.5.3 AnimationAnimationAnimationAnimation ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 52525252 4.5.44.5.44.5.44.5.4 GraphsGraphsGraphsGraphs ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 53535353 4.5.54.5.54.5.54.5.5 Reprocessing data filesReprocessing data filesReprocessing data filesReprocessing data files ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 53535353

4.6 IO-state ____________________________________________________________ 54

4.7 Remote control ______________________________________________________ 55

4.8 Alarm functions ______________________________________________________ 55

4.9 Password ___________________________________________________________ 56


4.04.04.04.0 IntroductionIntroductionIntroductionIntroduction

The GC955 is a gas chromatograph for automatic measurements of compounds in air and other gas

mixtures. In this chapter the normal functioning of the instrument is explained: the handling of the gas

chromatograph, the calibration and the data handling. At the end of several sections there is a

summarizing table.

There are a lot of possibilities to change the instrument’s program. Data handling and communication

can be set to adapt to all sorts of protocols. All this is covered in chapter 5. For normal use these

parameters are set for the customer and do not have to be changed.

4.14.14.14.1 Preparing the instrument and the environmentPreparing the instrument and the environmentPreparing the instrument and the environmentPreparing the instrument and the environment

Visual inspection

Before the GC is switched on after disuse, it should be inspected. After a normal transport it may be

presumed that the instrument will function correctly. The instrument should also be inspected for loose

parts, as they can do much harm in the oven ventilator and the computer.

After transport it is useful also to check the flow of the stripper column with a flow meter.

4.1.1 Gas supply

The gas supply must be connected to the instrument:

1. Nitrogen (PID, FID) or Helium (TCD, PDECD) of GC-quality must be connected to the carrier gas

port, pressure at the port at least 2.5 bar, but below 4.5 bar.

2. For an FID: Hydrogen must be connected to the hydrogen connection port, clean air to the air

connection port. Pressure for both at least 2.5 bar, but below 4.5 bar.

You may read out the internal pressure of the carrier gas from manometers on the top of the GC after

taking off the lid. If the pressure on the outside ports is correct, the internal pressure should reach the

preset value: carrier gas, depending on the application, should be between 2 and 3.5 bar. The setting of

these values must not be changed without consultation with your dealer.

Take Care : the pressure drop over the internal pressure reducer should be .5 Bar at least, else the

reducer will not function correctly.

Special instrument types:

For the FID: connect clean air and hydrogen to the connections above the ventilator. Always test the

hydrogen supply carefully for leaks! Preferably use a hydrogen generator that shuts off in case of sudden

leakage!

For the PDECD: start by connecting helium to the purifier and connect the purifier at the outlet to the 30

ml/min. restrictor, flush for 15 min. and then connect the purifier to the power supply. The same for the

dopant gas to its purifier and the 3.5 ml/min. outlet. Let this run for 15 min and then connect to the back

of the gas chromatograph.


Connect helium via a purifier to the inlet on the top of the detector, helium doped with xenon via the other

purifier to the dopant inlet. Please do not open the inlets until just before connecting them, and only open

the bottles when they are connected.

4.1.2 Sample tubing

Clean inert tubing at the sample-port is essential to obtain good results.

1. Use only PTFE (Teflon), FEP or stainless steel, even for short connecting pieces. Do not use other

plastics or bronze.

2. Do not use the same tubing for taking ambient air samples and calibration samples. Use two tubing

systems, that are only connected the last 5-15 cm before the sampling port.

3. Always use an inert micro filter (10 micron) at the sampling port.

4.1.3 Backlight of the LCD-screen

To lengthen the lifetime of the LCD-screen’s backlight the Windows screensaver is activated. This means

that the screen will go dark if mouse and keyboard are not used for longer than 30 minutes. Under the

Windows 98 Main panel\Settings\Control panel\Desktop\Power saving features this setting can be

changed.

4.1.4 Instrument identification

1. Chapter 1 identifies a lot of manufactured parts in the instrument. Many of these are delivered with

instruction leaflets about use and maintenance. As far as they are useful to the customer they are

supplied with the manual.

2. The GC comes with a range of settings which are saved in the GC955id.txt. These are, for each serial

number individually, the calibrations of the following sensors: flow sensor, pressure sensor for pneumatic

air, and pressure sensor for the outdoor air-pressure. There is also a list of 10 names of compounds that

can be selected. The factors for conversion from ppb to µg/m3 are also set here, as they differ from

country to country. When sensors are replaced or other compounds must be measured, this file has to

be corrected..

3. The application as ordered is saved as one or more run-programs. These work with a flow setting that is

noted in the technical instrument data (chapter 1).


4.24.24.24.2 The first normal measurementsThe first normal measurementsThe first normal measurementsThe first normal measurements

4.2.1 Switching on the electrical power

The instrument can be switched on once the gases are connected and the filter is in place. The GC must

be connected to a mouse and a keyboard. The oven cover must be closed. The L-shaped cover must be

put on.

For a TFor a TFor a TFor a TCDCDCDCD: always make sure that the supply of carrier gas is sufficient.

For an FIDFor an FIDFor an FIDFor an FID: the instrument will not start up completely if the flame does not start; so check the

supply of air and hydrogen.

For a PDECDFor a PDECDFor a PDECDFor a PDECD: see to it that the switches are set in the following way:

Temperature : 100 °C

Mode: on PDECD

Range: on 1

Current: -

Attenuation: 1

First, switch on the power supply of the PDECD. Wait until the detector temperature is stable (5-

10 min.) then switch on the pulsed discharge. When the lamp starts the background current

drops from 200 to ca 1 - 10 mA. If the helium has been disconnected the lamp may take up to 1.5

hour to start. Otherwise it takes 5-10 min. When the lamp has started, start the gas

chromatograph itself.

4.2.2 Starting the first run

After starting the GC the Windows 98 program starts and the 955 screen appears. A self-test is

performed on electronics and PID lamp and the oven is heated to the base temperature of your default

application program. Then the PID lamp is started.

For an FIDFor an FIDFor an FIDFor an FID: the instrument will not start up completely if the flame does not start: so check the supply of

air and hydrogen. When starting, the hydrogen valve is opened. With newly connected lines, the

hydrogen flow limits the burning, and the instrument will not start in the first run. For safety the hydrogen

valve shuts after 10 seconds if the flame does not burn. This process is repeated 6 times, then an error

message will appear. Close the program. Start anew until the flame burns. After transport this may take 3

to 4 repeats of the procedure. The burning can be checked by holding a mirror to the FID-exhaust at the

rear of the instrument. If the connections have been left in place, generally the instrument will start

quickly.

If the instrument is set to start automatically after power failure, this will also work. This somewhat long

procedure is designed to guarantee a safe start.

If the instrument was working, a new start can only begin after the flame has been exhausted: until then

you will see the message: “reset state not low”.


If you have taken off the hydrogen or air on a working instrument, the hydrogen safety valve will close. To

restart the FID, click options\actual run\restart FID.

The carrier gas flow through the capillary column should be between 1.0 and 5.0 ml/min., through the

packed column between 12 and 25 ml/min. This will be set by the mass flow controller. Checking for

leaks or obstructions is advised after long transports, or after working without adequate filters. The flow is

set for the application.

A pressure sensor is used to check if the pressure to switch the diaphragm valve is correct.

Figure 4.1: The data file-mode

The program contains seven different functions: actual run, data file, program edit, calibration, graphs,

autoliniarisation and IO-state diaphragm. See also the overview of the program structure in Chapter 3.

In the view mode pop-up-menu you can select the desired mode.

1. In actual run the present measurement is shown on screen with the measured values below.

2. In the data file mode you can recall all measured chromatograms to the screen to compare them.

(See a data-file in figure 4.1)The hard disk (>3 GB) has a large capacity to store chromatograms.

3. The program edit menu enables you to change the program, (chapter 5),

4. the calibration program is used for calibrating (4.3).

5. The graph is used for a quick view of the measured compounds.

6. The option autolinearisation can be used for a multi-point calibration (chapter 5)

7. The IO-state diagram shows the instrument’s present state of functioning.


4.2.3 Actual run

The default mode is actual run. After an automatic check of the settings, the program is standby for run.

The oven must reach the desired starting temperature before the first cycle is started by clicking start run

with the mouse. Now the background zero adjust signal is set, then the program starts. The detectors

need some time to stabilize, so the first reset may take a minute. (In automatic mode it will start either

immediately or as soon as synchronization is reached.)

The measured values can be seen on the chromatogram.

In the status lines below the chromatogram information is given : clock time, cycle time, the actual

measured value for the detectors, ambient temperature, oven temperature.

Further extra sensor signals, from left to right: pressure of valve switching air, flow of carrier gas.

The ambient temperature is measured on the underside of the instrument.

The base line is normally set at about 10 mm above the edge of the chromatogram window. This can be

changed under actual run\options\adjust detector Y-offset.

With two detectors it is most practical to keep one on offset zero and the other one at 30. With unstable

baselines you may want to put it even higher.

Timing

The sample that is analyzed is always the sample that has been preconcentrated in the last run.

Each application has its own cycle time. There are two possibilities: either the next cycle starts

automatically after the end of the last run, or the instrument measures synchronously. See section 5.5 for

details. If you want to stop measuring click with the mouse on stop run.

4.2.4 Data file

Choose view mode, then data file in the pop-up menu to recall files for comparison with the present

measurements. Choose the directory for the correct month (for instance d_9505 for May 1995)

The chromatograms are saved in month-directories, with day-subdirectories, with a filename derived from

the measurement time in days, hours, minutes, prefixed by an m: e.g. m_281435.bin.

The chromatogram appears if you double-click a file. The scale in the x-axis and the y-axis is the same as

in the chromatogram that is being measured, to make a comparison simpler. You can move freely

between the modes actual run and data file.

Setting peak windows for integration

The sample analyzed in the first run is the sample that is in the pre concentration trap or sample loop . If

you want to know the chromatogram of the present ambient air, you have to wait for the second run.

Click stop run during the second run.

After the end of this run go to data file , load the just measured chromatogram and study this

chromatogram to determine the retention times of the peaks of interest, which you want to determine

quantitatively. Within a window the highest peak is integrated (default setting).


Fig. 4.2: The peak window editor

For automatic measurements of these peaks in coming runs, you must set the peak windows.

1. Click options, then edit peak windows and set the windows you want to determine. Edit peak

windows allows you to choose from a list of compounds and to set the window time in seconds.

2. The effect can be seen after clicking select screen elements under options and then checking the

box show peak windows. With each peak window can also be shown: the retention time of the

measured peak, the integrated area and the calculated concentration. See chapter 4.4, automatic

measurements, for the finer points of peak window setting.

3. To use these windows in the following runs, return to actual run and click start run.

Fig. 4.3: The window select screen elements


4.2.5 Stopping the program

There are three ways to stop the program:

1. The correct way is to click the button: stop run, then the program stops at the end of the present run

and this run is still saved normally. After this you can either start again after making changes or you

can stop the instrument: do this by clicking in the upper left corner of the window and then clicking on

close.

2. If you must break off in between for some reason, click abort run: now the program stops immediately

and you can switch off the power. After this, go back to Windows and close the program. The next run

of the GC may be contaminated by rests of the aborted run.

3. The last way is for emergencies: just switch off the power. The last run is not saved and this way of

stopping the GC is only advised in emergencies, as the computer has no way to save open files

correctly.

Independently of the way used to stop the program the machine makes a reset of all set parameters to

the position needed for a restart. This also happens in case of any power failure.

4.2.6 Overview of activities in normal runs

no.no.no.no. ActionActionActionAction dialog to usedialog to usedialog to usedialog to use optionaloptionaloptionaloptional

1 Switch on power - -

2 do first run by click start run view mode \ actual run check temperatures, PID

lampfunctioning, attenuation

3 check peak windows view mode \ data file \ edit screen

elements and edit peak windows

wait for second run after start to

get actual chromatogram

4 stop program view mode \ actual run - stop run click abort run in emergencies,

close the program GC955 by

clicking the left top pull down

menu.


4.34.34.34.3 Calibration and registration of the caliCalibration and registration of the caliCalibration and registration of the caliCalibration and registration of the calibrationbrationbrationbration

4.3.1 The principle of calibration

Fig. 4.4: A calibration line for benzene from a permeation tube source, diluted to a range from 1.2 to 11 ppb

A calibration is used to determine the conversion factor for automatic calculation of concentrations from

area values. It is also used to check the correct functioning of the instrument.

The frequency of calibrations, the number of points determined and the number of repetitions per point

depend on your quality control scheme. For calibration we provide several facilities, see 4.3.4..

The calibration is divided in two parts:

Firstly, the measurementmeasurementmeasurementmeasurement of a calibration gas in the desired dilutions with the required amount of

repetitions for each set of concentrations. These are performed as calibration runs, after the calibration

has been set active under options in actual run. Please observe: normally during each cycle the analyzed

sample has been sampled in the cycle before the present one. This saves time, but is confusing, alas.

(During the first cycle after you started calibration the analyzed air will still be the last ambient air sample

and so on.)

Secondly, after the calibration the conversion factorconversion factorconversion factorconversion factor is determined and from then on the values on screen

and on the analogue outputs are given as ppb-values. The raw integrated data can still be recorded to

make later data correction possible.


4.3.2 Measuring calibration mixtures

Before starting the calibration you should set the peak windows (see 4.2.2), this must be done on the

peaks of a file in data file.

Fig. 4.5: The window calibration under actual run, used to start or stop the calibration mode

Start sampling the calibration gas during the next actual run. The following run the calibration gas mixture

will be analyzed, to use this for your calibration curve you must click set calibration active under options

in actual run.

There are three choices: start new calibration, add data to current calibration and add quality control point.

If you click start new calibration the present calibration is no longer active. To prevent mistakes this

choice must be confirmed before it is activated. Add data to current calibration can be used if a

calibration had to be discontinued for some reason. A calibration must still be completed within 24 hours.

A validation point can be made with add quality control point, if for quality control the validity of a

calibration has to be checked. (See 4.3.5)

The calibration-runs will be registered as files named c_”dayhourminute”.bin (like c_281435.bin) in a

separate directory, ‘calibdat’ under GC955.

During the run you should preferably notate the concentration values of your calibrating mixture in the

dialog window edit sample concentrations under options in actual run. Values can be given as mg/m3 or

µg/m3 ,as vppm or vppb. This is also the default format in which your measuring data will then be

calculated and registered afterwards.

If concentrations are repeated you do not have to enter the values every time.

After calibration, the tubing must be rearranged for taking outdoor air samples: either by hand or

automatically by switching a solenoid.

Then the automatic measuring and registration of the results can start again. Again click set calibration

active under options in actual run and choose normal data mode.


4.3.3 Calculating the conversion factor

The measured calibration values are used to make a calibration line. The correlation coefficient of the line

will be calculated, to indicate the linearity.

Fig 4.6: Calibration selection dialog, used to select the files which will be used to calculate the calibration line

This is done in the calibration mode of view mode.

1. Go to the dialog box in calibration curve, click to accept the calibration files you want to use. If there are

concentration values forgotten or entered wrongly, this can be corrected by going in data file mode,

loading the chromatogram and correcting the concentration under options\edit sample concentrations.

After closing data files which are changed, you are asked to confirm the changes.

2. You may remove files from the calculation set, but of course this should not be done to reach a higher

“correlation coefficient” but only because there are plausible reasons to reject these measurements for

the calibration curve.

3. From the measured values in mV the concentrations in ppb or µg/m3 are calculated.

4. Under calibration\options\settings now the unit in which the concentration is calculated can be set. The

default unit is the one used when entering the calibration concentrations. But now, optionally another one

can be used: from the measured values in mV the concentrations in ppb or µg/m3 can be calculated.

Fig. 4.7: Settings for calibration: choose the unit in which the data are to be saved


5. The calculation of the calibration line can be done in three ways. For normal use the linear regression with

fixed base point is the best. For measurements where the very low range and high range of higher boiling

compounds are important (i.e. with toluene below 0.5 ppb and above 50 ppb) the non-linear regression is

better as there is with higher boiling compounds a slight deviation from linearity in the higher range.

6. After this calculation has been done, this calibration is used to calculate concentrations out of raw

measured data until the next time that start new calibration is activated.

4.3.4 Calibration gas mixtures

Three kinds of calibrations can be done:

• a basic calibration, to determine the functioning of the instrument. Synspec or your distributor

normally provides the instrument with a calibration of at least 5 points.

• a basic calibration by the customer with his own calibration gas: here zero air and at least two,

but preferably three different concentrations of the calibration gas should be determined for a

basic calibration. For every concentration at least two (preferably three) samples should be

analyzed.

• a control calibration to check if the instrument’s sensitivity is stable. Here one concentration

(span) and zero gas can be determined.

To calibrate the GC a calibration mixture is needed, that contains at least the components of interest, for

instance benzene, toluene and a xylene isomer for the environmental BTX-measurements. Zero air is

needed as well, to determine the zero-point and to dilute the calibration mixture.

The highest concentration should be in the region where the maximum concentration is expected. The

other concentrations should be in the normal air range. Deviation of linearity mostly occurs in the upper

and lower range of a usable concentration range. Adapt your calibration range as far as possible to the

concentrations that are essential later: so if the threshold for an alarm is 100 ppm, do not calibrate with

50 ppb.

We advise a daily span and zero check. If these are stable, a basic calibration is only needed every

month up to three months. Without an automatic daily check, it is advised to do a manual span and zero

check at least every two weeks.

To obtain low calibration concentrations, normally diluting of commercially obtainable calibration gas with

zero-air is needed.

To save calibration gas you can switch off the sample pump during calibration by clicking disable sample

pump under options in actual run


4.3.5 Calibration overview

No.No.No.No. actionactionactionaction dialog to usedialog to usedialog to usedialog to use optionaloptionaloptionaloptional

1. calibration start - start the diluting system,

connect calibration gas to GC

2. check peak windows view mode\data file\show peak

windows and edit peak windows

3. take first calibration sample use actual run

4. first calibration run after start of run set calibration active

under options \ set calibration active

5. notate concentrations use actual run \options \edit sample

concentrations

if concentrations are not yet

known, wait for curve calculation

6. repeat 4 and 5 concentration data are copied

into next file if you don’t change

them

7. end of calibration reconnect ambient air sampling during

the last calibration run, click actual run\

option\set calibration mode and select

normal data mode after last run

8. select runs for calibration curve use dialog box in view mode\calibrate\

calibration curve

check the concentrations,

remove runs of bad quality

9. calculate curve click calibration curve in dialog box check the line for linearity,

correlation

10.set calibration factor active after acceptance of the calibration

curve this is active until the next

calibration.

4.3.6 Adding a quality control point

The quality control system often requires a regular calibration check. For this you should enter a

calibration sample during maximally half an hour. How many runs this is, depends on your program. If

the option add quality control point (under actual run\ options\set calibration mode) is chosen, these

values will be drawn on the calibration line. The calibration itself will not change.

There is also an option to automatically make a quality control point at regular frequencies. For this

please contact Synspec or your distributor about the details of the program we must prepare. When you

use this option the calibration gas has to be switched on automatically and the way this is done will vary

with the customers’ own choice of equipment.

The program is already prepared to set the time for a validation run. See for this chapter 5.


4.44.44.44.4 Automatic measurementsAutomatic measurementsAutomatic measurementsAutomatic measurements

A well adjusted instrument will run for two to four weeks without needing attention. Of course, the gas

supply must be sufficient and calibrations should be made following the quality standard.

It is advised to set the program for automatic restart after power failure and for synchronization of cycle

time with clock time, see 5.5, run settings. However, you can always leave this mode by clicking stop run.

Now the machine stays standby until start run is clicked again.

In the auto-mode the peaks in the windows are determined. The setting of these windows must be done

carefully. this is done under: options\edit peak windows, where you can choose the windows you want to

adjust:

1. They should not be too broad, to prevent interference from other components. However, they

can be narrower than the real peak, as the program calculates beginning and end .

2. A few seconds extra must be taken, because of small variations in retention time depending on

variations in the room temperature.

3. You should not determine these details on the data measured in the first cycle after starting the

instrument because the temperature in the first run differs slightly from later runs.

To check the current setting, a sample is taken (preferably a low concentration calibration gas-mixture,

an ambient air mixture is also possible) and this is checked with the temperature program and the

window setting.

To do this, choose view mode\data file and go to options\select view items, and there are the boxes oven

temperature and oven temperature (set point).

Follow the compliance of the measured temperature with the set point: if this is not correct yet, then wait

for another run, until the temperature is stable.

Follow the signal from the detectors on screen::

The exact times depend on: temperature, column type, and flow of the carrier gas. The window timing is

determined for each individual column, carrier gas flow, and temperature program. After adjustment of

your GC, these times do not change very much, so normally the application program should give the

expected peaks in the expected windows.

The oven temperature should be as programmed.

4.4.1 Adjusting the integration method.

In case of complicated chromatograms, it may be difficult to set a satisfying window for the start and end

of each peak. Adjustment of the integration method may help in some cases.

In data file, under options\edit peak windows there is a button attributes.

There is a default setting for integration, which is applied to each peak window if you do not click the

attribute button in the listing. Start and end of peaks are determined by calculating and evaluating the first

and second derivatives of the detector signal.


The area under the peak, with a start and end within the given time setting of the peak window is

calculated. Typical area values for small peaks just above the instrument noise are under 500.

An advanced integration option is the use of retention time locking. By locking the chromatogram on an

always identified peak, like Butane for C2C6 or toluene for C6C10, all shifts due to temperature or flow

differences will be corrected. See 5.9 for more information.

For special cases the setting can be adjusted for each individual signal. Typical problems are:

incomplete separation leading to ‘shoulders’, or even to two maximums in one peak, and baseline

changes in a peak window. Settings are:

1. Integration result is 2x first half of peak area: this helps quite well if the peak to be determined is

only disturbed by a later peak.

2. Integrate with [forced] horizontal baseline from start of peak: in this case a strict horizontal

baseline is integrated, independent of possible drift.

3. Include possible shoulders: this is useful in the presence of small peaks under the main peak.

4. Integrate down to detector values = 0 [virtual baseline]: this can be used if there is an peak in

front of the peak of interest and the detector signal had not yet gone down to baseline before the

start of the peak

5. Integrate highest peak in window: this prevents smaller peaks nearer to the center of the window

to be mistaken for the peak of interest. If this is not active, then the peak with the lowest hit rate,

i.e. the peak nearest to the center of the window, is integrated.

6. Integrate the complete window: this causes an integration of the whole area>PID=0 to be

integrated from start to end of the window.

Integrate with [forced] horizontal baseline from end of peak: in this case a strict horizontal baseline is

integrated, independent of possible drift.

1 2 4

Fig 4.8: The normal integration and method 1, 2 and 4


The attributes may help to integrate as well as possible. Of course, a better way is to change the

chromatogram by changing flow, temperature or perhaps even the column type. Do not hesitate to ask

Synspec or your distributor in case of separation problems.

Changes in the attributes have to be made before a calibration is started. As the described problems

mostly only occur with the sample air and not with the calibration sample, decision to use one of the

alternative attributes has to be made beforebeforebeforebefore a calibration is made.

4.4.2 Overview of preparations for automatic measurements

No.No.No.No. actionactionactionaction dialog to usedialog to usedialog to usedialog to use optionaloptionaloptionaloptional

1. Start the instrument see 4.2

2. do a calibration see 4.3

3. check the peak windows use view mode \ data file \

options \ select screen elements

4. check the gas supply

5. check the temperature regulation use view mode \ data file \

options \ view items

6. check the remote control

connections

7. remove old data from hard disk

4.54.54.54.5 Data registration and data handlingData registration and data handlingData registration and data handlingData registration and data handling

4.5.1 Data registration

In a normal series of measurements selected peaks are integrated and after a calibration the

concentrations are calculated.

These values are saved in the file rundata.txt. To select the desired data format click view mode, program

edit, options, run data output text format. In the window that appears choose between the saving of either

or both of raw data and of measured retention times together with the concentration values. Also choose

the desired delimiter between the data.

On the following page you see an overview of the data registration of the measured chromatograms:

there are three kinds of saved files: the normal measurements of sample air, the measurements of

calibrating gas and the measurement of validation points: they are saved as respectively m-, c- and v-

files. They are bin-files, binary in type. (See figure 4.9 for an overview of the data structure)

For each kind, a directory is made, with monthly directories and daily subdirectories.


In the chromatograms all information is saved, and they can be viewed the same way as actual run. Even

reintegration of windows is possible.

GC955 (root)

D_yymm

D_yymmdd

M_ddhhss

M_ddhhss

M_ddhhss

Datafiles

1 day-datafiles

D_yymmdd

M_ddhhss Datafiles

1 day-datafiles

1month-datafiles

GC955 directory structure GC955 directory structure GC955 directory structure GC955 directory structure

CALIBDAT

C_yymmdd

C_ddhhss

C_ddhhss

Calibration datafiles (measurements)

1 complete calibration

rundata.txt

format:DateTime ; IntVal-1 ;Conc-1 ;IntVal-2 ;Conc-2 ; IntVal-3 ;Conc-3 ; Comment

09-07-9519:53 ;46232 ;7.9 ;30302 ;9.9 ; 512031 ; 3.0 ;This is a testrun

C_yymmdd

C_ddhhss

C_ddhhss


1 complete calibration

VALIDAT

V_ddhhss

V_ddhhss


series of daily validations

GC85 5 (root)

D _yymm D_yym mddM_ddh hssM_ddh hssM_ddh hss Datafiles1 day- datafiles

D_yym mddM_ddh hss Datafiles1 day- datafiles1mon th-datafiles

GC 855 di rectory struc ture GC 855 di rectory struc ture

C ALIBDAT

C_yym mddC_ddhh ssC_ddhh ss Calibration da tafiles (measuremen ts)1 complete ca librationC_yym mdd

C_ddhh ssC_ddhh ss Calibration da tafiles (measuremen ts)1 complete ca librationVALIDAT

Figure 4.9: Data structure of measured data in the directory GC955


4.5.2 Data handling

At present the hard disk has >6.000 MB space, of which >5000 MB can be used to save data. Regular

data transfer is advised. This can be done by copying the rundata.txt, to obtain the measured values.

WARNING: we are not able to guarantee the life span of your hard disk! If you do not copy your data in a WARNING: we are not able to guarantee the life span of your hard disk! If you do not copy your data in a WARNING: we are not able to guarantee the life span of your hard disk! If you do not copy your data in a WARNING: we are not able to guarantee the life span of your hard disk! If you do not copy your data in a

regular cycle, loss regular cycle, loss regular cycle, loss regular cycle, loss of data is your own risk! Of course the hard disk itself is replaced under warranty!of data is your own risk! Of course the hard disk itself is replaced under warranty!of data is your own risk! Of course the hard disk itself is replaced under warranty!of data is your own risk! Of course the hard disk itself is replaced under warranty!

To transfer chromatograms, copy the bin-files unto diskettes, a ZIP drive or a recordable CD.

These can be connected via the USB connectors.

The easiest way to do this, is using Windows Explorer. Data can also be transferred by remote control

(see 4.7).

After transferring the data you should do probability checks on the integrated values and the

concentration values.

It is useful to look at the chromatograms to check the following:

• unexpected extra peaks

• unstable baseline

• shifting retention times

• changes in the set parameters for temperature, pressure and flow

This can be done at another PC after loading the GC demo-version. It can also be done in the animation

mode. If there have been changes that made the measured data unusable, by reprocessing the original

data files often a better result can be obtained. This is done under reprocess data files (4.5.5).

After checking a data series the chromatograms should be deleted from the GC’s hard disk, again using

Explorer. The rundata.txt can be left as it is, and will just grow longer. If you wish to start a new

rundata.txt, then rename or delete the present one (after saving the data on a diskette).

4.5.3 Animation

A time series of chromatograms, played as an animation is one of the simplest ways to make the above

checks. A series of BIN-files is displayed as a film, making it possible to view a week of data in just a few

minutes.

Copy the BIN files you want to animate to the directory C:\GC955\ANIMATE. Be sure that no other BIN

files are in this directory.

Choose the desired attenuation of the y-axis and the scale of the x-axis before starting. These are then

fixed during the animation.

Click on view mode\data file\ animate data\ data selection. Now, the data have been loaded for the film.

This takes time, as each file is loaded and processed. When ready, the animation can be viewed by

selecting view mode, data file, animate data, Animate them .


The animation appears and starts when you press the button start. Speed can be adjusted with the

speed bar. To stop the film press stop.

Leave animation by pressing view mode\data file\animate data\stop animation.

An animation can be saved under a separate filename, and therefore it can be copied. The extension

should be .ADF.

4.5.4 Graphs

For simple evaluation of the measured concentrations the graph mode can be used. After clicking view

mode\graph a simple graph of the measured concentrations against time appears on screen. This

should only be used as a quick check, as it does not have the scope of normal data validation programs.

4.5.5 Reprocessing data files

Why use reprocessing?

The data files are in fact chromatograms, i.e. detector-output data. During the actual run, the instrument

settings, like peak windows and calibration are used to interpretinterpretinterpretinterpret the chromatogram.

The results of this interpretation, like peak labeling, retention times, and concentration, are saved in

RUNDATA.TXT. This data is not saved with the data file (*.BIN-file).

Fig 4.10: Dialog to edit the reprocessing of data

This makes it possible to reinterpret (reprocess) the data, without changing the original data files.

For instance: a peak arises in the chromatogram, which could only be assigned after the measuring

period had finished. Reprocessing makes it possible to give accurate information on this newly identified

peak, even though it is not appearing in the original RUNDATA.TXT.

To do a reprocessing, the data files must be transferred to a PC.

WARNING: do not use any name in the path of all main- and subdirectories that has more than 8

characters.


In the PC-version of the GC955 program, the Help file contains an extended explanation of reprocessing.

The names and path of the data files, which are to be reprocessed, are placed in a text file.

The program starts loading the first data file and re-integrates this file with the current settings.

The data files themselves remain unchanged.

The following list is an overview of settings, which are important in reprocessing:

• Peak window settings

• Integration attributes

• Calibration

A simulation of a calibration can be done on the PC.

The results of the reprocessing are placed in an output file. The format of this file is like RUNDATA.TXT’s.

As an option, there is a possibility also to generate a report file for each chromatogram. In this file all

found peaks are described, with areas, labels (if known) retention times etc.

These report files can be used in other statistical software for peak identification and pattern recognition.

As soon as a valid input filename is entered the data processing can be started by pressing the start

button. The status line indicates the total number of files to be processed and the number of the actual

processed file, giving an idea on how long the processing will take.

It is possible to stop the processing by pressing the stop button.

All output files are placed in the directory GRAPHDAT, a subdirectory of the directory where GC955.EXE

is located.

4.64.64.64.6 IOIOIOIO----statestatestatestate

A new feature in the GC955 is the view mode IO state.

Here, you can follow the switching of the valves, the pump and the sampling piston, in real time. You can

also see the action of the heating regulation, both for the oven and for the pre concentration.

If you click on the ‘i’ of the sampling piston, you can check its functioning. A running piston is shown on

the upper line, with the counter and the present pressure. At the end of each stroke the final pressure and

temperature are saved, together with the total counts corrected for the pressure drop. These are shown

on the lines below. If the counts for different strokes are quite different, something is obstructing the

smooth running of the piston. In this case, please contact Synspec or your distributor.


WarningWarningWarningWarning: the IO diagram is designed for the standard instruments with one valve and a PID/FID detector

combination. If you have a special instrument, we will not incorporate the details of this in the diagram.

So, you may miss important things, like your TCD, or your second valve. For these instruments, we refer

to the manual for the diagram.

Figure 4.11 IO-state diagram

4.74.74.74.7 Remote controlRemote controlRemote controlRemote control

The remote control of the instrument works with the program Symantec (Norton) PC Anywhere. If you

want to use this, the following components are needed:

• The program PC-Anywhere for Windows 98 (version 8.0 or higher)

• A modem (or, if you make a direct connection, a null-modem cable.)

• Follow the instructions in the manual of PC_Anywhere.

Alternatively, the connection can be made via the ether net connector, over a LAN network.

4.84.84.84.8 Alarm functionsAlarm functionsAlarm functionsAlarm functions

For use in environments where an alarm signal is desired whenever concentrations of toxic compounds

rise too high, an alarm function is added. It is possible to attach a buzzer or a lamp to an output port at

the backside. For low alarm, high alarm, and status alarm, the signals are all different.


Fig. 4.12: The alarm status window

The compounds of interest should be calibrated at first. Then a low and a high alarm level can be set

under program edit\settings\alarm setting. (As an alternative area levels can be set, but this is less

exact.) If concentrations exceed the set levels the word alarm appears on the screen. In alarm status

under actual run\options, the cause for the alarm can be found. By clicking on accept alarm, you show

that the alarm has been seen: the buzzer or light is switched off. The word onscreen disappears as soon

as safe values have been measured again.

By clicking reset, the alarm function is reactivated.

If there is malfunctioning of the apparatus, the words “system alarm” will appear on the screen. Most

times the instrument will continue to function.

The alarm will also be noted in the log-file.

4.94.94.94.9 PasswordPasswordPasswordPassword

The GC955 can be secured against influence from outsiders by the use of a password. Under actual run

the password can be activated, for this you must click on options\password protection. The password

can be changed in program edit mode. (See chapter 5).


Chapter 5 Program adjustment and optional featurChapter 5 Program adjustment and optional featurChapter 5 Program adjustment and optional featurChapter 5 Program adjustment and optional featureseseses

5.0 Introduction _________________________________________________________ 58

5.1 Program edit menu overview ___________________________________________ 58

5.2 Chromatogram adjustment ____________________________________________ 59 5.2.15.2.15.2.15.2.1 Gas flow settingsGas flow settingsGas flow settingsGas flow settings ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 60606060 5.2.25.2.25.2.25.2.2 Programs for sampling unstable compounds or small sample volumesPrograms for sampling unstable compounds or small sample volumesPrograms for sampling unstable compounds or small sample volumesPrograms for sampling unstable compounds or small sample volumes ________________________________________________________________________________________________________ 60606060

5.3 Temperature and flow programming ____________________________________ 61 5.3.15.3.15.3.15.3.1 Isothermal ovensIsothermal ovensIsothermal ovensIsothermal ovens ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 61616161 5.3.25.3.25.3.25.3.2 Temperature programTemperature programTemperature programTemperature programmed ovensmed ovensmed ovensmed ovens ________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 62626262 5.3.35.3.35.3.35.3.3 Flow programmingFlow programmingFlow programmingFlow programming ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 62626262 5.3.45.3.45.3.45.3.4 Pre concentrationPre concentrationPre concentrationPre concentration heatingheatingheatingheating ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 63636363 5.3.55.3.55.3.55.3.5 Cooled Cooled Cooled Cooled pre concentrationpre concentrationpre concentrationpre concentration ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 63636363

5.4 Sensitivity adjustment _________________________________________________ 64 5.4.15.4.15.4.15.4.1 Sample strokesSample strokesSample strokesSample strokes____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 64646464 5.4.25.4.25.4.25.4.2 Adjustment of the samplingAdjustment of the samplingAdjustment of the samplingAdjustment of the sampling ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 64646464 5.4.35.4.35.4.35.4.3 Instrument settingsInstrument settingsInstrument settingsInstrument settings ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 66666666

5.5 Run settings ________________________________________________________ 67 5.5.5.5.5.5.5.5.1111 Changing the instrument panelChanging the instrument panelChanging the instrument panelChanging the instrument panel ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 67676767

5.6 Communication ______________________________________________________ 68 5.6.15.6.15.6.15.6.1 Analogue outputsAnalogue outputsAnalogue outputsAnalogue outputs ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 68686868 5.6.25.6.25.6.25.6.2 Extended 16 channel RS232 analogue output multiplexerExtended 16 channel RS232 analogue output multiplexerExtended 16 channel RS232 analogue output multiplexerExtended 16 channel RS232 analogue output multiplexer ____________________________________________________________________________________________________________________________________________________ 69696969 5.6.35.6.35.6.35.6.3 Digital outputsDigital outputsDigital outputsDigital outputs ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 70707070 5.6.45.6.45.6.45.6.4 RS232 Communication settingsRS232 Communication settingsRS232 Communication settingsRS232 Communication settings ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 70707070 5.6.55.6.55.6.55.6.5 Analogue inputsAnalogue inputsAnalogue inputsAnalogue inputs ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 72727272

5.7 Alarm and password settings __________________________________________ 72 5.7.15.7.15.7.15.7.1 AlarmAlarmAlarmAlarm settingssettingssettingssettings ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 72727272 5.7.25.7.25.7.25.7.2 Changing the passwordChanging the passwordChanging the passwordChanging the password ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 72727272

5.8 Advanced calibration options __________________________________________ 73 5.8.15.8.15.8.15.8.1 Automatic validationAutomatic validationAutomatic validationAutomatic validation ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 73737373 5.8.25.8.25.8.25.8.2 AutoAutoAutoAuto----validation with a 6validation with a 6validation with a 6validation with a 6----port Vici valveport Vici valveport Vici valveport Vici valve ____________________________________________________________________________________________________________________________________________________________________________________________________________________ 75757575 5.8.35.8.35.8.35.8.3 Setting the digital outputs for the automatic validation with a 6Setting the digital outputs for the automatic validation with a 6Setting the digital outputs for the automatic validation with a 6Setting the digital outputs for the automatic validation with a 6----port Viciport Viciport Viciport Vici----valve.valve.valve.valve. ____________________________________________________________________________________ 75757575 5.8.45.8.45.8.45.8.4 Calibration by using autoCalibration by using autoCalibration by using autoCalibration by using auto----validationvalidationvalidationvalidation ____________________________________________________________________________________________________________________________________________________________________________________________________________________________ 76767676 5.8.55.8.55.8.55.8.5 AutoAutoAutoAuto----validation with two 3/2 magnetic valvesvalidation with two 3/2 magnetic valvesvalidation with two 3/2 magnetic valvesvalidation with two 3/2 magnetic valves ____________________________________________________________________________________________________________________________________________________________________________________________ 76767676 5.8.65.8.65.8.65.8.6 AutolinearisationAutolinearisationAutolinearisationAutolinearisation ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 78787878 5.8.75.8.75.8.75.8.7 Calibrate for all components with a single component calibration mixtureCalibrate for all components with a single component calibration mixtureCalibrate for all components with a single component calibration mixtureCalibrate for all components with a single component calibration mixture ________________________________________________________________________________________________ 79797979

5.9 Improving peak identification by retention time lock________________________ 82 5.9.15.9.15.9.15.9.1 IntroductionIntroductionIntroductionIntroduction ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 82828282 5.9.25.9.25.9.25.9.2 Setting the retention time lockSetting the retention time lockSetting the retention time lockSetting the retention time lock ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 83838383

5.10 Settings of the identification file GC955id.txt ______________________________ 83



There are a lot of options to change the instrument’s program. Data handling and communication can be

set to adapt to all sorts of protocols. All this is covered in chapter 5. For normal use these parameters are

set for the customer and do not have to be changed.

The beginner is advised to read through the parts 5.1 to 5.5. The setting of communication, alarms and

auto-validation is more advanced work. (Section 5.6 to 5.9)

5.15.15.15.1 Program editProgram editProgram editProgram edit menu overviewmenu overviewmenu overviewmenu overview

By clicking the program edit menu under view mode you get access to a whole range of ways to change

the program settings.

The easy way to do this, is to load a program file: click file, load program file, select a program by

double-clicking.

The program is loaded in the program edit menu, where you can edit it if you wish. To activate a program

change for the next actual run, click stop run, and click start run after the end of the run.

Fig 5.1: the program edit menu

Before making your own programs you should have a good understanding of how gas chromatography

works. If you are still unsure how to effect certain changes in the measurements, please contact your

dealer or Syntech Spectras and we shall send you the desired program, or give you instructions how to

make minor adjustments.


Changing the program yourself is very easy once you understand something about chromatography. As

long as the programs are saved under different names, nothing can go wrong: returning to the old

program is always possible.

The central part of the program is represented by the seven bars on the program edit screen. (See figure

5.1) Together they build the most important functions of the program: cycle time, injection time, pre

concentration heating, purge time, sample pump, sample strokes, oven temperature.

To change bars, click on them, and then move the pointers with the mouse. The cycle time determines

which elements are used: if they are outside of the cycle time bar, they will not be in use, as the next

cycle starts before they are reached.

Any change as described in the sections 5.2Any change as described in the sections 5.2Any change as described in the sections 5.2Any change as described in the sections 5.2----5.5 is not activated, unless the program is stopped and then 5.5 is not activated, unless the program is stopped and then 5.5 is not activated, unless the program is stopped and then 5.5 is not activated, unless the program is stopped and then

restarted.restarted.restarted.restarted.

5.25.25.25.2 Chromatogram adjustmentChromatogram adjustmentChromatogram adjustmentChromatogram adjustment

The time needed to separate the compounds in a sample depends on their boiling points, their

absorption on the column material, the temperature and the carrier gas flow. The injection time is set as

the time, which the slowest compound you want to measure needs to pass through the stripper column.

The cycle time is the time this compound needs to pass through the stripper and the analysis column

plus time needed to bring the system back to the state needed for the start of the next run.

Without temperature programming, the time a compound needs to pass through stripper column and

analysis column is relative to the length of the two columns. So if you make the cycle time longer, you

must also lengthen the injection time by the same factor.

When you use temperature programming, these time settings cannot be calculated, but are made

experimentally, as described below.

To try out the settings for new compounds, use a long cycle time and a relatively long injection time for

instance:

For a 2 M stripper, and a 13 M analysis column: start with the injection time ¼ of the total cycle time.

Make sure all compounds you want to measure are out of the analysis column before the end of the

cycle time with an isothermal program, and before cooling down with a temperature programmed

instrument.

Adjust the cycle time to whole minutes minus 15 seconds; this makes the planning of continuous

measurements easier.

(See for the planning of automatic measurements also 5.5, run settings) Now you can shorten the

injection time by steps of 5 seconds until a peak of interest disappears. Then set the time 5 seconds

longer again.


5.2.1 Gas flow settings

The gas flow is one of the factors that determine the separation and the cycle time. By setting the flow

higher, the cycle becomes shorter, but the separation is decreased.

Only change the flow when making separations of new mixtures. This is done by going to actual run

\options \change column flow. Here you can type the column flow in ml/min. The flow is regulated by a

mass flow controller, and will change within a few seconds. See 7.3.3 for flow programming.

5.2.2 Programs for sampling unstable compounds or small sample volumes

Long sampling times are useful if a mean concentration has to be calculated over longer time spans, e.g.

1-hour means. For this we deliver many instruments with cycle times from 10 minutes up to 45 minutes

The pre concentration then is charged during many sample strokes. This is not advisable with unstable

compounds: they can react with oxygen, water or other compounds, and the adsorbing medium may

even act like a catalyst.

A solution can be, to use a system with cooled pre concentration: a system of the series 800. (See 5.3.4

and chapter 7). The other option is to take only 1 or 2 sample strokes at the start of a cycle and to inject

into the column immediately after this.

It is advised to purge especially with these unstable compounds: this removes water and oxygen, and so

prevents reaction with these during desorption. However, it does take time, during which desorption and

reaction may occur.

In the program, there must be at least 20 seconds between purging and injecting. (Purging influences the

pressure conditions in the system, which must have time to readjust before injection.)

If the sample amount is small, for instance when Tedlar bags are analyzed, the internal pump is not used

in the program. It is advised to test, how many sample strokes are needed with the system used, to

reach a sufficient sensitivity.


An example of a program:

Figure 5.2: 2 sample strokes to preconcentrate, and then a short purging, before injection. Used for

unstable compounds.

5.35.35.35.3 Temperature and flow programmingTemperature and flow programmingTemperature and flow programmingTemperature and flow programming

5.3.1 Isothermal ovens

The oven can be used isothermally or with a temperature program.

With an isothermal oven, the separation of compounds with boiling point differences of more than 30 o C

takes a lot of time and produces broad peaks. However, the process is easy to use.

To change the base oven temperature click instrument settings under program edit\settings : there is an

item for adjusting the base oven temperature. Drag the temperature list box to select the temperature.

The highest temperature for isothermal measurements is 100 o C. The lowest temperature depends on

the room conditions: as there is no forced cooling in the isothermal oven, you must account for at least

10 o C above expected maximum room temperature to reach a stably regulated temperature.


5.3.2 Temperature programmed ovens

The temperature programmed oven allows you to make quicker analysis with less peak broadening of

compounds with greater boiling point differences.

To change the temperature programming, click oven temperature under program edit.

The temperature program appears as a graph of temperature against time. To change the settings, click

on a corner and drag this in the desired direction. The base temperature, however, must be changed as

described under isothermal ovens. The following limitations must be observed:

• Start temperature and end temperature must be the same.

• Heating velocity can be set from 0 o C to 20 o C per minute. You cannot drag a slope to heat

more than 20 o C per minute.

• Cooling down is done by forced ventilation and depends on the room temperature. After cooling

down the oven is closed again and after 20 sec. the heating up to oven base temperature is

made.

• The last peak of interest must have left the column before cooling down, else this last peak will

be split up.

Before the next cycle is started, the stable temperature must be held for minimally 30 seconds.

With differences of more than 30 o C in the cycle it should be checked that the cooling down part of the

temperature program functions by following at least three cycles. Check the compliance with the real

temperature with the set temperature on the data file under view mode, choose under options the view

items oven temperature set and programmed and check if your program leaves enough time for

temperature stabilisation. If not, use a longer cycle.

5.3.3 Flow programming

Temperature and flow largely determine the components’ retention time. With the new electronic mass

flow controller, you can use a combination of temperature and flow programming in the GC955.

At the moment, the flow programming is not made in the window program edit, but in the file GC955id.txt.

Enter the following parameters:

Startflow = (in ml/min. multiplied by 10)

Endflow = (in ml/min. multiplied by 10)

Flowrampstart = (in seconds multiplied by 5, so 5 minutes is 5x60x5 = 1500)

Flowrampend = (in seconds multiplied by 5, so 10 minutes is 5x60x10 = 3000)

A good start flow is in the range of 1 to 2.5 ml/min. For the standard mass flow controller we use, the

maximum end flow is 10 ml/min.

The flow starts to increase after flowrampstart and reaches its highest point at flowrampend. It stays at

that level until one minute before the end of the cycle.


5.3.4 Pre concentration heating

On the pre concentration tube the hydrocarbons from the sample are absorbed. With quick thermal

desorption, these are evaporated. The pre set value for heating is 30 seconds, with a start 3-6 seconds

before injection. The tube is normally cleaned in 30 seconds. The heating time can be adjusted by

clicking and dragging the pre concentration heating bar. Do not heat longer than the injection time.

Check after changing this time if the pre concentration is cooled down before the sampling starts. This

can be done in data file, choose pre concentration temperature under options\select view items .

The temperature can also be adjusted under program edit\settings\instrument settings. The standard

temperature of 180 o C is too high for compounds that polymerize or decompose easily. Choose a lower

temperature, like 100 o C. You must, however, heat for a longer period to clean the tube completely.

Fig. 5.3: checking the cooling of the pre concentration before a new sample is taken

5.3.5 Cooled pre concentration

With low-boiling and unstable compounds the results can improve with a cooled pre concentration. For

normal pre concentration, the temperature is in the range of 25 to 45 °C , depending on the internal

temperature of the instrument. Of course, this also depends on the room temperature.

The pre concentration system can be cooled by radiation. For this the pre concentration tube is

embedded in an aluminum block. This block is cooled on both sides by Peltier elements. After startup of

the GC, the block needs a few minutes to reach the correct temperature. The minimum that can be

reached by the present version is –5 °C. To obtain this in continuous mode, the room temperature around

the instrument should be around 20 °C, else the minimum will be higher. However, under most

conditions, a temperature of +5 °C will be possible.


To avoid freezing or condensation in the system, drying of most samples will be needed. Synspec

advises the use of a Perma Pure dryer, based on Nafion. (Please be aware of the limitations of this and

other types of drying system, when trying to measure water soluble hydrocarbons: they will tend to go

with the water.)

Adjustment of the pre concentration temperature can be done by changing the value precontemp in the

file GC955id.txt. This value can be set from –5 to +30.

5.45.45.45.4 Sensitivity adjustmentSensitivity adjustmentSensitivity adjustmentSensitivity adjustment

The sensitivity may be adjusted in two ways:

by changing the sample strokes,

by changing the ionization voltage, also under instrument settings.

These changes of the GC-settings make a new calibration unavoidable. So, you should not change them

after a complete calibration.

5.4.1 Sample strokes

The amount of sample strokes determines the amount of air that is pre concentrated and thus the

sensitivity. Each sample stroke has a volume of 35 ml.

The pre concentration material should not be saturated. If you are in doubt, please ask your distributor or

Syntech Spectras about the capacity for your compounds. You can also check the saturation yourself, by

running a series with a constant concentration of a calibrating gas, adding an extra sample stroke each

time. For the materials Tenax and Carbopack, saturation data are available for many compounds,

however, these data are not complete.

5.4.2 Adjustment of the sampling

In the GC955, the sampling can be adjusted in the following ways:

1. stroke frequency

2. stroke length

3. sampling speed

4. minimum sampling pressure.

By moving stroke points in and out of the cycle time you can adjust the total sampled volume.By moving stroke points in and out of the cycle time you can adjust the total sampled volume.By moving stroke points in and out of the cycle time you can adjust the total sampled volume.By moving stroke points in and out of the cycle time you can adjust the total sampled volume.


Fig. 5.4: diagram of sample piston

If you want to sample frequently, at a high concentration, it is possible to make the stroke length shorter.

The maximum is 1500 steps, by changing the stroke length in the file GC955id.txt you can make this

shorter. Type: samplestrokemax = (a count between 250 and 1500). The sampling speed can be

decreased in case only a few strokes are desired, by changing the sampling step frequency in the file

GC955id.txt you can decrease this speed. Type: samplespeedmax = (a count between 200: maximum

speed, and 40: minimum speed).

Depending on the type of filling in the pre concentration tube, the pressure will drop during sampling.

Normally, this will result in a pressure between 750 and 850 mBar. For low boiling hydrocarbons, this will

already lead to a less effective sampling. To prevent evaporation due to low pressure, you can adjust the

minimum pressure in the file GC955id.txt. Type: samppressmin = (type in a value between 650 and 950,

which is the value in mBar).

In data files, the sampling information can be visualized by selecting the menu item options\select view

items in data mode and clicking sample.

Warning: a sample must be completed, before you start the next one. Else, the correction for temperature

and sample is incorrect. If only one stroke is used, and this one stroke is not completed, a fatal program

error occurs.

fig. 5.5: options for view items


Figure 5.6: first half of a 30 minute program with 9 sample strokes

5.4.3 Instrument settings

The sensitivity of the instrument can be set by changing the ionization voltage.

This is done under settings\instrument settings.

Fig. 5.7: Instrument settings

The ionization voltage can be adjusted from -600 (very insensitive) to -5000 mV (very sensitive).


5.55.55.55.5 Run settingsRun settingsRun settingsRun settings

Depending on your measuring program, it is possible to make as many measurements as possible, or to

make them according to a standard time scheme.

This is done under settings, run settings. Choose either a time scheme according to your cycle time at a

discrete time schedule, e.g. 15 minutes, or choose restart immediately after end of run.

Fig. 5.8: Run settings

In the first case the machine will wait with starting the next measurement until the computer clock reaches

the right minute to synchronize the cycle time. If you use a synchronized cycle of 10 minutes, then you

must set the cycle time just under 10 minutes, for instance 15 seconds shorter. This is done, to allow for

data saving and zero-adjustment before the next cycle begins.

In the second case, the machine will always start immediately after you click on the start run button, and

it will start the next run, after a run has ended.

The instrument can be set for automatic restart after power up. If this button is not activated, the program

is loaded up to the point where the button start run has to be clicked.

5.5.1 Changing the instrument panel

Under settings\change instrument panel, you can change the look of the area below the chromatograms

on the LCD. The screen is preset for your instrument. Do not activate this item, unless you exchange

detectors, or exchange the trap for a loop or a cooled trap.

By clicking on the symbol, the instrument panel screen opens up:

You now can change the elements shown on the bottom line, their units, the names or abbreviations

shown.


Fig. 5.9 instrument panel configuration for the setting of the indications on the lower part of the LCD

As long as the screen is active, you can also reorganize the placement of the elements.

To save and get out, again click on change instrument panel.

If you have messed it up completely, you can get back to a standard setting by clicking on Default.

These settings are saved in the configuration file (.CFG).

5.65.65.65.6 CommunicationCommunicationCommunicationCommunication

5.6.1 Analogue outputs

At the rear of the instrument is the analogue output connector with four pins. These can be attached to

the Phoenix female connector provided with the instrument.

The outputs are 1 - 10V, maximal current 1 mA.

The first three analogue outputs are dedicated to the first three peak windows. If you want other peaks to

appear at the analogue outputs, change the order in edit peak windows, under data file \settings.

The range can be set.

The last pin is dedicated to the detector output signal.


Figure 5.10: Analogue output dialog

5.6.2 Extended 16 channel RS232 analogue output multiplexer

The 4 analogue outputs can only transfer the data from 4 peaks. For systems analyzing many peaks, like

the ozone precursor application and many others, this is only a fraction of the complete information. For

such applications, we advise you to use the RS232 communication protocols, as they are much more

flexible. Alternatively, collect the data by copying the rundata.txt file.

However, sometimes the need exists for more than 4 peaks over analogue output. For this, we provide

an option to multiply the peaks over an RS232 connection.

Warning: for some systems, all RS232 ports are already needed for other functions, like calibration

valves, second GCs etc. In this case the multiplexer cannot be used.

Installing the box is very easy:

1. Connect the multiplexer with a normal (not crossed) rs232cable to the GC to serial port no. n,

where n=1, 2, or 3.

2. Connect the power cable and switch it on.

3. On the GC, open the file GC955_ID.TXT.

4. Add a line <RS232ANAOUT = TRUE>.

5. Add a Line <AOCOMPORT = n> (where n is the no from point 1).

6. Close and save the file.

7. Copy the new software onto the GC’s hard disk (back up the previous GC955_1.EXE). It might be

necessary to delete the file ACT_LIN.DAT.

8. restart the GC program.

9. The first 14 windows of the peak window editor will be visible on the multiplexer. The output scale

is the same as in the GC, under Program\options\ analogue output.

Only calibrated component windows will be seen, non-calibrated component windows will be set at zero.

The original 4 analogue outputs on the GC are still active and the window as described in 5.6.1 will not

change.


5.6.3 Digital outputs

The connection for digital signals is also at the rear of the GC. It is a 16-pin connector with 7 digital TTL-

outputs. They are activated over the digital output dialog under settings in program edit

Fig 5.11: The digital outputs

The buttons c1 up to c4 can be set as combinations of two sensors or functions, to make even more

data available over the digital outputs.

Fig. 5.12: Defining combinations of readings of sensors and settings to combinated digital outputs

5.6.4 RS232 Communication settings

Over the RS232-connection, through a modem, communication with another PC is possible, by using

PC-Anywhere.


Using specially designed communication programs, communication with central data logging systems is

also possible. As these systems are not at all standardised, adaptations will often be necessary.

However, the basic programming is already included. Please ask Synspec or your distributor for

adaptations that will work on your system.

A choice between several optional settings can be made under communications in settings under

program edit:

Fig. 5.13: Choice for communication systems

Optionally, the German Hessen-Bayern and the Gesytec protocol can be activated. The ASCI-terminal is

more common . The RS232-settings must be deactivated before PC-Anywhere can work.

If changes are made, the program should be saved, then it should be activated by starting a new run,

and then the computer must be restarted, as the settings are activated as soon as the computer starts.

Over the RS-232 status protocols similar to those of the digital outputs can be set:

Fig. 5.14: Example of an error status protocol, for the Hessen-Bayern protocol system.


5.6.5 Analogue inputs

The GC’s PC can, of course, also be used as a data logger for other instruments. As this is not used

regularly, it is disabled by default. If you are interested in using a running GC to function as a data logger

for analogue signals from other equipment, please contact Synspec or your local distributor.

5.75.75.75.7 Alarm and password settingsAlarm and password settingsAlarm and password settingsAlarm and password settings

5.7.1 Alarm settings

The alarm function must be programmed under program edit\settings\alarm settings. Here, low and high

threshold values can be set for up to 10 compounds. For each channel the values must be set

individually. Before this is effective, a calibration must be done. Optionally, area values can be entered,

but this is not advised. The system alarm has its own settings.

Figure 5.15: Alarm settings window

Once data have been entered in this window, and the “active” boxes are checked, the system will give

alarm warnings on screen, optionally over a buzzer or warning lamp, when the value is higher than the

threshold. The alarm is also automatically noted in the GC955-logfile. If the low and/or high component

alarms are activated, the alarm is also set in the digital output window.

5.7.2 Changing the password

The default password is GC955 (use capitals). To change this password, go to program

edit\settings\change password. Now, the present password must be entered, to get access to the

change option. The new password must be entered and confirmed, after that, it is active.


5.85.85.85.8 Advanced calibration optionsAdvanced calibration optionsAdvanced calibration optionsAdvanced calibration options

WarningWarningWarningWarning: in section 5.8, several options for automatic validation are explained. These all include the

connection of a calibration gas source to the GC. Several different switching systems are introduced.

The following two remarks concerning the gas source must be observed:

1. In all cases the calibration gas must be at ambient pressure: from 900 to 1050 millibar. If the

pressure is outside this range, a proper correction of pressure cannot be calculated. If the pressure

is above 1.5 bar, the GC may be damaged.

2. The flow of the calibration gas from an undiluted bottle must be restricted to a flow of cir. 25 ml/min.

Synspec can provide you with a simple critical orifice. Synspec takes no responsibility for bottles that

are emptied due to a lack of restrictors.

5.8.1 Automatic validation

A periodical automatic validation of the calibration can be set with the menu option automatic validation.

When this is switched on, the system will not save the new values as measured samples, but save them

in the validation directory. In the rundata.txt they are prefixed with v.

The cycle can be set from 23 up to 168 hours (7 days).

Figure 5.16: Auto-validation editing window

This feature is very flexible in design. The system returns to the set frequency per week if you enter a

preferred day. The system indicates the time of the next validation. Up to 5 runs can be set, for zero air or

span gas. However, the system does not switch on the validation gas.

There is an option to attach a switching valve to the GC, in this case the providing of the gas can also be

directed from the GC.

Under Under Under Under edit concentrationsedit concentrationsedit concentrationsedit concentrations you can enter in the concentration of the span gas. (see figure 5.13you can enter in the concentration of the span gas. (see figure 5.13you can enter in the concentration of the span gas. (see figure 5.13you can enter in the concentration of the span gas. (see figure 5.13))))

Under Under Under Under edit conditionsedit conditionsedit conditionsedit conditions the following is possible:the following is possible:the following is possible:the following is possible:


1. Toggle auto-calibration if the deviation is greater than set range: this means that your old calibration

is deactivated, so do this only with span gas of exactly known concentration!

2. If possible, skip the first values: this gives a greater accuracy, but needs a longer calibration cycle.

3. Use relative factors to calibrate missing compounds: it is possible to calibrate other compounds with

known relative sensitivity for one compound, for instance nonane and decane relative to octane.

4. Alarm function: for the span gas a deviation in concentration is given, for zero gas an area value

greater than a set value can be chosen.

Figure 5.17: Auto-validation conditions

Figure 5.18: Auto-validation concentrations


5.8.2 Auto-validation with a 6-port Vici valve

The Syntech Spectras GC can be provided with a 6-port Vici electrical valve for switching between the

sample and a calibration gas. See chapter 6, for the connections that have to be made to the gas system

and to the green digital connector. In this section, the programming is treated. In the auto-validation

menu set the following:

1. use only span gas, no zero gas.

2. set the timing and the amount of cycles according to the instructions in 5.8.0.

3. in edit conditions activate disable sample pump if span gas active.

4. in edit concentrations set the concentrations and activate use.

Figure 5.19: Auto-validation conditions for the Vici 6-port valve

The valve will now be switched by the GC, provided the digital settingdigital settingdigital settingdigital setting is ok.

5.8.3 Setting the digital outputs for the automatic validation with a 6-port Vici-valve.

To set the digital outputs correctly select the following settings in the menu digital outputs:

under program edit\settings, select digital outputs.


Figure 5.20: Settings for the Vici 6-port valve

This corresponds with the pins as shown:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

dig.indig.outRelais

1 2 3 4 5 6

Analog out

5.8.4 Calibration by using auto-validation

Auto-validation is normally used to check the validity of an existing calibration. However, it can also be

used to calibrate. In the item edit concentrations the actual concentrations of all components that must

be calibrated must be added and in edit conditions the conditions for the switching of calibration valves

from the GC etc.

Then add a line in the file GC955id.txt:

AUTOVALMENU = TRUE.

After restart of the program GC955 an extra item is added in actual run\options: activate auto-validation.

If you click on this a calibration will be performed automatically. An alarm will appear if the values deviate

more than the set condition. After a power failure an automatic validation will start up also.

5.8.5 Auto-validation with two 3/2 magnetic valves

For some applications a combination of two 3/2 magnetic valves can be used as an alternative to the

high quality Vici 6-port valve.

We provide this as an extra option. While the inertness of the Vici system is guaranteed, this is not the

case for the 3/2 magnetic valves. The customer should test for himself whether his calibration gas does

not deteriorate when lead over this system.


The system looks like this:

Fig. 5.22 switchbox external view

Fig. 5.23 Switchbox digital connections

The system can also be mounted afterwards by the supplier or customer, with a special installation

leaflet.

The system will be connected and activated by the digital input pins. The valve’s settings will already be

prepared by Synspec.


The digital settingsdigital settingsdigital settingsdigital settings will be:

Figure 5.24: Settings for the 3/2 magnetic valves

This corresponds with the pins in the diagram:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

dig.indig.outRelais

1 2 3 4 5 6

Analog out

Fig. 5.25 digital configuration for switchbox

5.8.6 Autolinearisation

The instrument has an option to test the linearity without using more than one concentratThe instrument has an option to test the linearity without using more than one concentratThe instrument has an option to test the linearity without using more than one concentratThe instrument has an option to test the linearity without using more than one concentration of calibration ion of calibration ion of calibration ion of calibration

gas. This is only possible for instruments with a gas. This is only possible for instruments with a gas. This is only possible for instruments with a gas. This is only possible for instruments with a pre concentrationpre concentrationpre concentrationpre concentration tube.tube.tube.tube.

The mode: autolinearisation is loaded from view mode \autolinearisation. Click options and then start

autolinearisation. The instrument now pops up the request to connect the calibration gas. Choose a

stable concentration, and leave it on the instrument for 7 hours.

The instrument will now run 12 cycles, with 9 to 1 complete strokes and 3 partial strokes of the sampling

piston. Set the instrument to actual run and wait until the end of the autolinearisation before doing other

things with the computer: the calculation uses most of the processor capacity.

The second order regression is calculated and shown afterwards in the mode autolinearisation. The

parameters calculated can be used to improve the linearity of the instrument.


If the instrument is still non-linear, two actions should be undertaken: first of all, tubing and rotor must be

cleaned. Also, the detector sensitivity should be increased. This can be done by cleaning the lamp and

the detector. If this does not improve the detector signal, a new lamp may be needed.

If you do not want to use the calculated parameter in your data processing, it is easy to return to the

original setting: close the program GC955, delete the file autolinS3.dat in the directory GC955 and restart

the program. Now the original program is in use again.

5.8.7 Calibrate for all components with a single component calibration mixture

This procedure describes the use of one gas to calibrate several others. This option can well be used for

C8-aromates. The error will be <2% as the sensitivity is identical. Also it is possible to do it for the C6-C8

aromates with only benzene. Here, the error will be in the same range. In any case, these errors are

systematic and will not change with time.

Please note: this method can only be used for calibrating hydrocarbons that have physically similar

properties in their behaviour in the detector and have boiling points that differ less than 100 °C. You

should be certain of the peak identification.

Procedure:

Have the analyser running for at least one hour, and then run 2-3 times with the calibration mixture. The

chromatogram will look like this:

Fig. 5.26: Chromatogram with calibration gas and correct setting of windows

You must know the retention times for all components you want to calibrate, so all is integrated in the

ambient air.


Now you must add the concentrations in the window:

Fig. 5.27 Concentration of p-xylene used for all xylene-isomers

Give all C8 peaks the concentration of para-xylene and save the file.

Do this for all peaks you want to calibrate.

If you do this when the system is still running, the calibration for benzene, toluene and p-xylene will be ok,

but for o-xylene and ethylbenzene the result will be wrong.

Calibration for o-xylene and ethylbenzene:

Stop the program. Make a note of the retention times for all C8 components:

Fig. 5.28 Original peak window setting for the xylene peaks

Now the tricky part: the peak window of first ethylbenzene and then o-xylene are shifted to the place of

the p-xylene window,and the system then is calibrated in this position.


So: first exchange the retention times of ethylbenzene and p-xylene:

Fig. 5.29: windows exchanged for the calibration of Ethylbenzene

fig. 5.30: Window of Ethylbenzene over the p-Xylene peak

You see that now, the window for ethylbenzene is on the place of the p-xylene window.

Go to the window calibration\options\data selection calibration files.

Now when you select ethylbenzene, you will see some points made during the running calibration,

without ethylbenzene in it. This means that the area was low. These points must first be removed by

clicking on remove file until all points have disappeared.

Now you must reload them in the setting with ethylbenzene over the para-xylene. Load them anew by

clicking on the files in add file.


Fig. 31: calibration line for Ethylbenzene

In this way you have calibrated ethylbenzene.

Repeat the procedure for o-xylene.

After this, set the windows in the original position and start a new run.

5.95.95.95.9 Improving peak identification by retention time lockImproving peak identification by retention time lockImproving peak identification by retention time lockImproving peak identification by retention time lock

5.9.1 Introduction

Retention time locking is a method to keep peak windows centered over the peak, even if the retention

times are shifting.

This is done by selecting a peak, which can always be identified (this limits the applicability). This peak

will be the reference peak.

When a chromatogram is recorded, the retention time of the reference peak is compared with the

retention time of the reference peak in the original chromatogram where the peak windows were set (the

reference chromatogram).

All peak widonws (including the reference peak) are now recalculated.

With these new calculated peak window settings, the chromatogram is integrated.

To show the user that retention time lock is active, there will be a message in the screen.

Also, the file data will be flagged accordingly.


5.9.2 Setting the retention time lock

First of all, load (or record) a file containing all relevant peaks in the view menu data file. Center the peak

windows exactly to the middle of the peaks. Make sure that the window over the peak you want to make

the reference peak is broad (say 30 seconds).

The windows over the other peaks can be smaller than you would normally set them.

In data file select the dialog retention time lock.

Fig. 5.32: Retention time lock window

Press set to make the actually loaded chromatogram the reference chromatogram.

Select the reference peak in the list.

Press lock now, to lock on the reference peak.

With retention time lock active you can switch between active and not active.

If you want to recheck the retention time lock file, click load, then it will be loaded in the editor.

5.105.105.105.10 Settings of the identification fileSettings of the identification fileSettings of the identification fileSettings of the identification file GC955id.txtGC955id.txtGC955id.txtGC955id.txt

Every instrument has its own identification file, named GC955.txt. In this file specific settings for the

applications ordered by the customer are activated. They influence the data communication protocol

used, the alarm settings, the temperature regulations, the integration method, etc.

In the table in the appendix you will find an overview of the options.

Notice:Notice:Notice:Notice:

Normally these settings are not to be changedNormally these settings are not to be changedNormally these settings are not to be changedNormally these settings are not to be changed by the customer without consulting with the supplier or with by the customer without consulting with the supplier or with by the customer without consulting with the supplier or with by the customer without consulting with the supplier or with

Synspec, even if you have two Syntech Spectras GC955s with different settings.Synspec, even if you have two Syntech Spectras GC955s with different settings.Synspec, even if you have two Syntech Spectras GC955s with different settings.Synspec, even if you have two Syntech Spectras GC955s with different settings.


Chapter 6 Service and maintenanceChapter 6 Service and maintenanceChapter 6 Service and maintenanceChapter 6 Service and maintenance

Chapter 6 Service and mainteChapter 6 Service and mainteChapter 6 Service and mainteChapter 6 Service and maintenancenancenancenance ____________________________________________________________________________________________________________________________________________________________________ 85858585

6.0 Introduction _________________________________________________________ 86

6.0.16.0.16.0.16.0.1 Troubleshooting and maintenance schemeTroubleshooting and maintenance schemeTroubleshooting and maintenance schemeTroubleshooting and maintenance scheme ________________________________________________________________________________________________________________________________________________________________________________________________________ 86868686

6.0.26.0.26.0.26.0.2 Troubleshooting schemeTroubleshooting schemeTroubleshooting schemeTroubleshooting scheme ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 87878787

6.0.36.0.36.0.36.0.3 MaintenanMaintenanMaintenanMaintenance schemece schemece schemece scheme ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 92929292

6.1 Photo ionisation detector ______________________________________________ 93

6.1.16.1.16.1.16.1.1 InstallationInstallationInstallationInstallation ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 93939393

6.1.26.1.26.1.26.1.2 MaintenanceMaintenanceMaintenanceMaintenance ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 93939393

6.2 Cleaning the FID _____________________________________________________ 97

6.3 Pneumatics _________________________________________________________ 98

6.3.16.3.16.3.16.3.1 Maintenance of the diaphragm valveMaintenance of the diaphragm valveMaintenance of the diaphragm valveMaintenance of the diaphragm valve ________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 99999999

6.3.26.3.26.3.26.3.2 Opening the left compartment of the instrumentOpening the left compartment of the instrumentOpening the left compartment of the instrumentOpening the left compartment of the instrument ________________________________________________________________________________________________________________________________________________________________________________________ 101101101101

6.3.36.3.36.3.36.3.3 PumpPumpPumpPump ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 103103103103

6.4 Gas chromatography ________________________________________________ 104

6.4.16.4.16.4.16.4.1 Carrier gas supplyCarrier gas supplyCarrier gas supplyCarrier gas supply ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 104104104104

6.4.26.4.26.4.26.4.2 Pre concentration tubePre concentration tubePre concentration tubePre concentration tube ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 101010105555

6.4.36.4.36.4.36.4.3 Cooled pre concentration trap mainCooled pre concentration trap mainCooled pre concentration trap mainCooled pre concentration trap maintenancetenancetenancetenance ____________________________________________________________________________________________________________________________________________________________________________________________________ 105105105105

6.4.46.4.46.4.46.4.4 Correct functioning of the cooled pre concentration trapCorrect functioning of the cooled pre concentration trapCorrect functioning of the cooled pre concentration trapCorrect functioning of the cooled pre concentration trap ____________________________________________________________________________________________________________________________________________________________ 105105105105

6.4.56.4.56.4.56.4.5 Replacement of the cooled pre concentration trapReplacement of the cooled pre concentration trapReplacement of the cooled pre concentration trapReplacement of the cooled pre concentration trap ________________________________________________________________________________________________________________________________________________________________________________ 107107107107

6.4.66.4.66.4.66.4.6 10101010----port vaport vaport vaport valve lve lve lve ---- gas chromatographygas chromatographygas chromatographygas chromatography ____________________________________________________________________________________________________________________________________________________________________________________________________________________________ 108108108108

6.4.76.4.76.4.76.4.7 Capillary columnsCapillary columnsCapillary columnsCapillary columns ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 108108108108

6.4.86.4.86.4.86.4.8 Packed columnsPacked columnsPacked columnsPacked columns ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 110110110110

6.4.96.4.96.4.96.4.9 Replacement of carrier gas filtersReplacement of carrier gas filtersReplacement of carrier gas filtersReplacement of carrier gas filters ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 111111111111

6.5 Computer maintenance ______________________________________________ 111

6.5.16.5.16.5.16.5.1 Loading strange software: not advisedLoading strange software: not advisedLoading strange software: not advisedLoading strange software: not advised ____________________________________________________________________________________________________________________________________________________________________________________________________________________ 111111111111

6.5.26.5.26.5.26.5.2 Data communication with external data loggers and other PCsData communication with external data loggers and other PCsData communication with external data loggers and other PCsData communication with external data loggers and other PCs ____________________________________________________________________________________________________________________________________ 112112112112

6.5.46.5.46.5.46.5.4 Computer conditionsComputer conditionsComputer conditionsComputer conditions ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 113113113113

6.5.56.5.56.5.56.5.5 Correct setup for the GC955Correct setup for the GC955Correct setup for the GC955Correct setup for the GC955 ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 114114114114

6.5.66.5.66.5.66.5.6 GC955 Digital outputsGC955 Digital outputsGC955 Digital outputsGC955 Digital outputs ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 115115115115

6.6 Installing an auto-validation valve ______________________________________ 118

6.6.16.6.16.6.16.6.1 Installing a Vici 6Installing a Vici 6Installing a Vici 6Installing a Vici 6----port electronic valve for automatic validationport electronic valve for automatic validationport electronic valve for automatic validationport electronic valve for automatic validation ________________________________________________________________________________________________________________________________________ 118118118118

6.6.26.6.26.6.26.6.2 Mounting the valveMounting the valveMounting the valveMounting the valve ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 118118118118

6.6.36.6.36.6.36.6.3 Configuring GC955 digital outputsConfiguring GC955 digital outputsConfiguring GC955 digital outputsConfiguring GC955 digital outputs ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 119119119119



The service and maintenance chapter is intended for trained service personnel. Do not start working

before reading the whole text and contact Synspec or your distributor if you are unsure about the exact

way to proceed.

If yoIf yoIf yoIf you must open the instrument, always shut off the gas supply and the electrical power before starting. u must open the instrument, always shut off the gas supply and the electrical power before starting. u must open the instrument, always shut off the gas supply and the electrical power before starting. u must open the instrument, always shut off the gas supply and the electrical power before starting.

Take care of closing the gas supplies, especially the hydrogen supply. After repair, always check the Take care of closing the gas supplies, especially the hydrogen supply. After repair, always check the Take care of closing the gas supplies, especially the hydrogen supply. After repair, always check the Take care of closing the gas supplies, especially the hydrogen supply. After repair, always check the

hydrogen connection for leaks!!hydrogen connection for leaks!!hydrogen connection for leaks!!hydrogen connection for leaks!!

If you have to work If you have to work If you have to work If you have to work in the oven compartment, be sure to discharge the high voltagein the oven compartment, be sure to discharge the high voltagein the oven compartment, be sure to discharge the high voltagein the oven compartment, be sure to discharge the high voltage on the lamp. (See on the lamp. (See on the lamp. (See on the lamp. (See

section 6.1.2) section 6.1.2) section 6.1.2) section 6.1.2) If you have to test pneumatics, ventilation, or the PID, only pull out oven’s own power

supply. (See illustration 6.5)

6.0.1 Troubleshooting and maintenance scheme

Troubleshooting and maintenance is a task, which should be shared between distributor and client depending on

their experience, budget, and the required speed of repairs.

Where only the distributor should work, this is marked as ‘D’. Where distributor and client can share the work or

cooperate, this is indicated as ‘C’. In some cases the client can identify the problem, but not make a repair, there

it is indicated as ‘C/D’.

The following points will be covered in the troubleshooting list:

1. Instrument will not start up

2. Leak in gas supply

3. Pressure alarm

4. Flow alarm

5. Retention times are unstable

6. Peaks have bad shape

7. Integration is impossible

8. No peaks in data file

9. Calibration is not linear

10. Big change in sensitivity

11. Program stops at end of cycle

12. Data cannot be copied on floppy disk

13. Bad reproducibility

14. Measuring is not continuous

15. Baseline unstable


6.0.2 Troubleshooting scheme

problem C/D cause Details of problem analysis/ repair

instrument will

not start up

C Loose connectors Check if the connections in the computer compartment are in place:

they can get loose during transport. Beware of electrostatic shocks to

the system!

C/D blown fuse replace fuse at entrance by spare one, check at next start-up what

happens: there may be an electrical problem in the instrument.

C/D failure of computer

board

check if the connectors are in place, check if the processor ventilator is

connected to the processor

C Wrong comport Check in the file GC955id.txt the setting for the MX port. For an internal

connector it must be Mccomport 4. For an external comport it can be 1,

2 or 3. Check the comport, and fill in the number of the port that is used

in the file GC955id.txt. Restart the GC program

C/D hard disk failure check if the pc can make contact to the hard disk at start up: if not

contact your supplier about a new hard disk

C/D bad contact in

detector

see below

C/D fault detected at

start-up

check the error messages, correct for them, shut down the GC955.exe

and restart

C Instrument is very

cold

Two problems: water condensing on electronics and leading to general

errors, and water condensing on lamp and leading to PID lamp fault

message. Both problems will disappear if the instrument is heated to the

temperature of the environment before start.

C Error message oven

temperature or pre

concentration

temperature at start

up

Instrument is very cold and the heating of the oven or the pre

concentration uses more energy than the safety settings of the

instrument allow. Please raise the environmental temperature or set the

program to a start temp for the oven of 45oC and for the pre

concentration of 180 °C

C Error on FID Check hydrogen and air supply and the pressures of these gases: after

a shut down the hydrogen line contains only air, so it will take time to

reach the analyser. Check also if the hydrogen line contains droplets of

water (wet scrubbers), this will blow out the flame when it ignites

C Error on FID A cold FID lights slowly, have patience and try 3 times

C Error on FID To start up the system it is often useful to set the hydrogen pressure a

bit higher.

leak in gas

supply

D Bad connection on

carrier gas system

The connections of the carrier gas system come from the carrier gas

connection at the rear, lead through the left compartment to the

pressure and flow controllers with the carrier gas filters and then to the

oven compartment. Small leaks are often found in the oven

compartment, big leaks in the left compartment. Check of the oven


compartment: The machine is first checked in the analysis mode with

leak tester soap: switch the machine off, Check all Vici type

connections. Then test the injection mode: First switch off the oven

heating (see ch 6.1), then check again for leaks.

If you find a leak here, tighten the connection about half a turn and

check again.

C/D Broken column A broken column appears at two moments: either directly after a

transport , or a few hours later. In the first case the glass has broken, in

the second case the polymer protection has been scratched off; After

start-up the column may still hold for a time and then break during

heating up or cooling of the tubing. Proceed as described in ch. 6.4

D leaking tubing The steel tubing is quite strong. The FEP-tubing we use on other parts

can only be damaged by bad handling. Replace tubing by identical

pieces, contact Synspec.

D leak in valve

switching parts

Big leaks can occur in the left compartment or on the 10-port valve

panel if the tubing has come out of the quick insert fittings. Take out the

tube completely by pressing down the small black or blue ring. Then

push in completely. If this does not help, then the fitting will have to be

replaced.

A leak on the 10-port valve panel needs a trained person for repair, as

the panel holds 10-port valve and detector, and these are essential

parts. First take off the bottom cover. Loosen the valve and the detector,

loosen the panel by unscrewing it and take it out. Check the

connections to the four valves and also to the pressure sensor. If the

pressure sensor is leaking put in a new one.

D leak in carrier gas in

left compartment

leaks on the pressure or flow regulator or on the carrier gas filters are

also best detected with leak test fluid. The connections on the pressure

regulator are not so easily reached, take you time to inspect and tighten

them. The straight and bended tubing unions in this compartment

should always be tightened by using two wrenches: be sure to hold one

part still while turning the other, in order not to bend the tube instead of

tightening the connection.

Pressure alarm C Pressure of valve

switching air too low

or too high

Set pressure to 3 to 4.5bar.

Check the dimension and length of the supply tubes.

Check for leaks.

D Pressure sensor or

calibration

malfunctioning

Each sensor is calibrated individually. Do not exchange GC955id.txt.

If defect, exchange sensor on valve bracket.

flow alarm C pressure of carrier

gas too low

increase pressure to about 3.5 to 4.5 bar.

C/D problem in mass

flow controller

If the cause for flow alarm is the mass flow controller, it can block the

system or swing. If it swings, you must increase the carrier gas pressure.


If it is blocked, contact your distributor.

C/D broken column flow will be zero in either injection position (break in stripper column) or

in both positions (break in analysis column). See ch 6.5

D leak in carrier gas

system

see problem: leak in carrier gas supply.

retention times

are unstable

C/D problem in mass

flow controller

see problem: flow alarm, cause: problem in mass flow controller.

C long connection line

for carrier gas and

low pressure on

carrier gas

The pressure drops over the separating column: if the supply is too

small, there is almost no pressure at the end of the column, this leads to

instability: for 0.53 mm columns it must be at least 2 bars, for 0.32

columns at least 2.2 bars, getting higher with longer columns.

C room temperature

has a variation of

>5 °C per hour

See to it that the change stays below this, or at least place the

instrument away from the airflow of air conditioners, especially the left

side compartment should be protected!

D bad or difficult type

of column

Water sensitive and packed columns are more sensitive than the

standard silicone column. Either choose another column, or see to it,

that carrier gas always stays on the column, and that the sample is dry.

Contact Synspec for advise on optimising.

D defective

thermocouple in the

oven

Check the temperature if you are in doubt with a different temperature

sensor and compare with the reading on the GC955-screen.

PID peaks have

bad shape

C/D bad connection in

the PID

check the blue and yellow connector on the PID for the electrical

contact. Take off the top of the PID and check inner and outer side of

the electrode for the connection. Tighten all screws.

integration is

impossible

C long cycle time change minimum peak height, see ch.6, as the system is seeing more

then 100 peaks

C two peaks are

coeluting

change setting of integration: choose integrate 2 x first half of peak for

the first of the two

C two peaks are

coeluting

choose the setting: start integration at PID-value is 0 for the second

peak

C two peaks are

coeluting

use a different column

C peak is very broad change setting for minimum slope change ( see ch 6)

C/D peaks are broad

because column is

malfunctioning

heat out the column at 25 °C above the normal temperature

C Peak is split up into

many small peaks

Check if the peak appears at the moment the oven shutter is opening: in

this case the peak is split up in the column.

contact Synspec about better choice for measuring this compound


no peaks in

data file

C setting of peak

windows has not

been saved

set peak windows on a chromatogram, stop run and start run after end

of cycle. Save the settings also by saving the program under its own

name (like btx5.prg ) in the program edit mode. Do this any time you

have changed the window settings.

calibration is

not linear

C use of wrong

settings

Use the GC955id.txt and the autolin.dat which belong to the instrument.

Linearity of calibration depends on the type of detector cell used: you

should never copy the GC955id.txt from another version.

D New

autolinearisation

required

After major changes in the equipment (new lamp, column, valve or

changes of components measured) a new autolinearisation should be

done. See chapter 5.

C/D Instrument out of

linear range

The linear range of the instrument is 1 x 10^4, e.g. from 0.1 ppb to 1

ppm. If you get a wider range and want to measure over all of it, use

non-linear multipoint calibration

C/D absorption effects

in internal or

external tubing

clean out or change external tubing. If this does not help, clean out

internal tubing and 10-port valve with diluted ammonia and distilled

water. Dry well and reinstall.

D reaction effects in

internal or external

tubing

reactive hydrocarbons may react with and on metal and polymer

surfaces. With which of these they react, depends on the compound.

Contact you supplier or Synspec if you have problems with linearity in

calibration

big change in

sensitivity on

PID

C/D lamp failure if a change of more then 20% within 24 hours occurs, it is possible that

the lamp is leaking

C instable calibration

gas or unsuitable

pressure reducer,

leading to gradual

decline

check the stability by keeping the bottle at stable temperature. Flush the

pressure reducer well before calibrating

C no dust filter on

sample inlet

fine dust will coat the lamp window. Clean the lamp by wiping it with

lamp tissue

big change in

sensitivity on

FID

C Pressure of air or

hydrogen has

changed

Reset to original pressures

C FID is dirty Clean FID

program stops

at end of cycle

C cycle time too near

to synchronising

time

set for at least 10 seconds between end of cycle and synchronising.

With 30 min. cycle at least 15 seconds.

C bad contact in

detector

see below

C synchronising time check the synchronising time set under program edit\settings\run


incorrect settings: if you run a 5 min. cycle synchronised to 30 min. etc. the

program will wait after each cycle for the correct time. Stop the program

at the end of the run. Set the timing at the desired frequency, save the

program under its own name and restart.

bad

reproducibility

C Leak in sampling

system

Check for this by putting a cap at the sample entrance: the piston

strokes should now not be completed. If the piston moves smoothly

despite closing the sample entrance, you have a leak. Contact the

distributor

D Leak in 10-port

valve or column

system

Check the connections and the column

C Dirty sampling lines In this case the concentrations at calibration will rise for a long time.

Change tubing.

measuring is

not continuous

C Stop run has been

clicked

Click start run

C Problem with

computer leading to

missed

chromatograms

and blue screen

errors

Check log file to look for an automatic restart. Observe system to watch

for appearance of sudden stop. Check hard disk, computer board,

processor

C Error messages in

program without

real reason

Messages generated by bad communication between electronics of GC

and computer board. Contact your distributor for possible update of ICs

on the electronics board.

C Problem with tasks

for Windows 98

Windows 98 can be set for multitasking. However, especially network

connections can interfere a lot. Contact Synspec for improvement of

task settings.

C Problem with writing

of files

Check the size of the log file and of data files. Make back-up and

remove the original.

Defragment the hard disk after this.

Ethernet

connections

interfere

Ask your network manager how new files are handled. If each new file is

immediately backed-up as a standard on your network, it is not possible

to connect a GC to it.

baseline

unstable with

PID

C Bad contact in

detector

Remove detector and check all electrical contacts

Baseline

unstable with

FID

C FID is dirty Clean FID

C Hydrogen supply is This gives sharp noise peaks on the chromatogram: exchange


wet dryers and relight the FID.

C Air pressure is not

stable

This gives waves on the FID. Install a different pressure control

system on the air supply.

6.0.3 Maintenance scheme

Below is an overview of the advised frequency for maintenance work on a continuously used Syntech Spectras

GC955 series 600 and 800.

D/

C

Time in

hours

Work Frequency manual

at

needed

C 0.5-3 Calibration 1 x every 2

weeks to 1 x

every month

4.3 Calibration gas, automated settings in

automatic validation advised to promote

quick calibration

C 0.1 Replacement of micro

dust filter for sample

1x every 2

Months

4.1.3 Teflon filter

C 0.1 Remove dust from

ventilator

1x every 2

Months

6.5

C 1 Clean the lamp 1x every Year 6.1.2 Lamp tissues, lamp cleaning powder

C/

D

1 Clean the FID 1 x every year 6 Fine brush

C 0.5 Change of carrier gas

filters

1x every Year 6.2.5 2 Filters

D 2 Cleaning of diaphragm 1 x every year By distributor only

C 1 Renew external sample

tubing

1x every Year 4.1.3 FEP or Teflon tubing

C/

D

0.5 Replacement of Pre

concentration Tenax

tube

1 x every Year 6.3.1 Pre concentration tube

D 1 Replacement of cooled

Pre concentration trap

1 x every Year 6.3.1 Cooled trap, resend to distributor for

refund

C 1 Optimise hard disk 1 x every year 4

D 2 Clean internal

Gastubing

1x every 2

Years

6.3.3

C 1 Clean lamphouse 1x every 2

Years

6.1.2


6.16.16.16.1 Photo ionisation detector Photo ionisation detector Photo ionisation detector Photo ionisation detector

The photo ionisation detector UV lamp, High Voltage Power Supply and amplifier are constructed of the

present state of art devices to assure optimum operation. The overall detector dimensions are 8 cm by 4

cm with 1/16 inch stainless steel inlet and outlet fittings and a reaction chamber volume of 50 microliters.

Electrical connections to the high voltage supply and electrometer amplifier are plug-in.

6.1.1 Installation

The PID detector is mounted in the oven near the 10-way-valve. This reduces condensation within the

detector and provides an overall stable temperature. The maximum operating temperature is about 100°

C. Due to the oven design, a column temperature up to 150° C can be used.

The PID has a cable connection to the High Voltage Supply passing through the oven wall (the red and

black one). On the High voltage supply the inner core (red) must be connected to the positive side of the

supply, which has been marked. Also, the blue and yellow signal cable can be seen, which is plugged

into the amplifier board.

An overview of the connecting cables is seen in figure 6.1 and 6.2, side and upper views of the detector.

Operating

After connecting the power and gas lines the background signal from the PID is automatically checked

and compensated. Due to column bleed and the supplied ionisation voltage a background ionisation will

exist. By reducing the background signal electrically before entering the detector amplifier the output of

this amplifier is almost zero and the whole dynamic range can be used for PID detector signal

amplification.

6.1.2 Maintenance

Once a year with a capillary column or once every month with packed column the lamp window should

be cleaned with a light-source cleaning material.

Once every two years all other components should be cleaned as well.

Switch off the power of both the PID electronic unit and the gas chromatograph. Discharge the HV Discharge the HV Discharge the HV Discharge the HV

output by shortening the + and output by shortening the + and output by shortening the + and output by shortening the + and ---- connectors of the HV at the lamp connectors of the HV at the lamp connectors of the HV at the lamp connectors of the HV at the lamp ---- see figure 6.2 and 6.3.see figure 6.2 and 6.3.see figure 6.2 and 6.3.see figure 6.2 and 6.3. Disconnect

gas inlet and outlet lines of the PID detector, remove the high voltage supply cable and signal /ionisation

cable.


High Voltage pos1/16" Vici detector outlet

ionisation voltage

signal

to amplifier board

to HV supply

1/16" Vici detector inlet

red

black

blue

yellow

Figure 6.1: PID-Detector side view

High Voltage ground

High Voltage pos

1/16" Vici detector outlet

ionisation voltagesignal

to amplifier board

to HV supply

1/16" Vici detector inlet

red

black

blueyellow

High Voltage ground

Figure 6.2: PID-Detector upper view


Disassembling

1. For the position of the parts, see figures 6.3 and 6.4: views of the detector when assembled and

when disassembled.

2. First remove the Vici-connectors from the detector. Loosen the input connection at the oven wall

separator, not at the detector.

3. Remove the electrodes by pulling them carefully from their connectors. The connection for the

ionisation voltage and the ground of the High Voltage supply is done in the same way.

4. Loose the three long hex-screws from the upper part of the detector and take off the upper part.

5. Loose the three smaller hex-screws from the clamp-ring and take off the three parts of the clamp

ring.

6. The peek detector housing, inner electrode, in and outlet connectors can be cleaned in a mild

ammonia solution using an ultrasonic bath.

7. Rinse several times with hot water, dry by using clean air and put the parts in a 100°C stove for half

an hour.

8. The lamp is sealed to the detector house with an O ring in the outer grove of the lamp. Carefully, take

the O-ring out with a small sharp screwdriver, be careful to point away from the lamp window to

prevent scratching.

9. Clean the window of the lamp with a light-source cleaning material. Use lens tissue to prevent

scratching the surface. In most cases the use of a cleaning material is not necessary, and the stain

on the window may be removed using lens tissue only.

Assembling

1. Take care not to touch the lamp window and inner electrode with your fingers.

2. Fit the spring and the lamp with the O-ring into the aluminium housing and the three clamp ring

parts. The spring must ascertain the contact of the lamp house to the outer ring of the lamp.

Observe the position for the High Voltage-connector in respect to the other parts.

3. Assemble the lamp and lamp house with the three short fixing hex screws. Pay attention that the

distance between the clamp ring and the detector house must be less than 1 mm when pushed

together by hand, if not the gasket for the lamp might be too thick or not correct in place.

4. Mount the detector with the three long hex-screws. Take care that it is mounted with the connectors

in the correct position.

5. Install the inlet and outlet Vici-connectors.

6. Connect the electrodes according to the scheme in figure 6.1 and 6.2.


DETECTOR HOUSING

LAMP CLAMP RING

LAMP HOUSING

OUT

Figure 6.3: PHOTO IONISATION DETECTOR ASSEMBLY

out

in

ionisation

voltage

signal

out

HV positive

HV neg

conn like

others

situated at this

position


Fig. 6.4: PID (right) and FID (left , below 10-port valve) in the detector compartment.

6.26.26.26.2 Cleaning the FIDCleaning the FIDCleaning the FIDCleaning the FID

The main maintenance on the FID is the cleaning, 1 to 2 times per year, of accumulated soot. Take apart

the FID. Then clean the chimney with a brush. Clean carefully the other parts on the FID itself with a small

brush. Take care with the thin wire: this material should not be touched. The FID is mounted deep in the

instrument: take time to remove the connections and to remount them.

Procedure:

1. Switch off the system, remove the gas connections. Be careful with the hydrogen.

2. Take out the T on top of the FID.

3. Take out the tubing to the FID.

4. Carefully take the FID out of its socket.

5. Gently move it up and backwards in the same movement and take the chimney out of the hole.

6. Remove the spring and lay it aside.

7. Gently take off the metal part from the ceramic part. To make this a bit easier, warm it up to hand’s

warmth before starting to turn.

8. Clean the chimney with a brush. Remove any contaminations from the rest of the FID with a brush.

9. The solderings on the FID and the little spiraled wire should be left untouched.

10. Remount all parts. Push the tubing as deep as possible in the Teflon sockets.


Figure 6.5: FID in place

Figure 6.6: FID taken apart

6.36.36.36.3 PneumaticsPneumaticsPneumaticsPneumatics

Safety notice: within the following sections procedures are described, where the power has to be

switched on, while the oven is open. To prevent heating to take place, it is advised to loosen the

connector to the oven heating. To do this, take off the bottom plate by loosening the screws. On the

underside two large electronic prints are visible: the central MX board and the power supply. Take off the

connector for the oven power supply - see figure 6.5. Do not forget to remount them before closing the

underside.

By pneumatics the following elements are switched:

10-port valve

oven ventilation

pump


Print MX

Power supply

Valve cabinet

Detector

10-port valve

Power supply oven and preconcentration

Thermo-couple oven and preconcentration

solenoids actuator and oven

Figure 6.7: Opened underside view

front rear

6.3.1 Maintenance of the diaphragm valve

The diaphragm valve can get blocked if dust comes in, or if the column bleeds.

Symptoms: at first, sampling only goes slowly and is not complete. Alarms are given, if no sampling stroke is

complete. Once it is completely blocked no peaks are seen, only a flat line. This changes from one run to the

next.

Prevention: always use a sample filter, and use columns with low bleed. If you are uncertain, contact Synspec or

your distributor for advice on filters and columns.

The valve can easily be opened and replaced. However, caution must be taken, and the whole procedure must

be followed exactly.

Maintenance is done by opening the valve, cleaning the top part and mostly replacing the diaphragm itself. You

need the following: ¼” key, 5/15” key, 9/64” hexagonal key (essential part, without this it is impossible), long

Phillips (cross-headed) screwdriver, ultrasonic bath, neutral soap, ammonia, distilled water, small pincer.


Procedure:

1. Switch off and disconnect the system.

2. Place it on a dust free workspace with enough room to place a lot of small parts that you remove from

the GC.

3. Remove the GC column: loosen the nuts and take the column out. Leave the nuts in place.

4. Disconnect the 4 connectors on the detector side of the oven wall

5. Take out the oven wall by removing the two screws fixing it to the oven bottom.

6. When it is out, take out nuts and the special column ferrules.

7. Remove all connectors to the diaphragm valve. This takes experienced people 3 minutes, count on 15

minutes for the first time you do it. The diaphragm has numbers, please put each tube that you take out

on a piece of paper with this number on it. Three tubes are not taken out of the instrument. Take care: the

unions are long, and the tubing coming out of it must not be bended when taking it out, else it will be

difficult to place back. Always start by removing the tubes that you can reach easily, those on the right

side. Carefully remove the two that go to the rear of the GC. Now, on the side to the pre concentration,

the two that go to the pre concentration are the most difficult: carefully loosen them at both ends and

take them out without bending.

8. When all connectors are out, open up the valve by removing the central hex screw with the 9/64” key. If it

is too tight, increase your force by using combination pliers. Remove the screw, and take off the top of

the valve.

9. Inspect the top part and the diaphragm. If the top is dirty between 4 and 5, there is column bleed. If it is

dirty between 1,10,9 and 8, the sampling is the problem. It there are many particles, the sample has to be

filtered better.

10. The top must be cleaned in the ultrasonic bath, until it is clean as a mirror. Afterwards, a last treatment

with distilled water, and then dry it in an oven at 90 ºC.

11. Normally, the diaphragm cannot be cleaned like that, but has to be replaced. Take it off with a pincer.

12. Put on a new one with TOP on top. It fits on the two pins.

13. Carefully put back the dried top part of the diaphragm, with nr. 2 in the direction of the rear wall. Fix it with

the hex screw.

14. Remount all connectors in counter direction. Be careful, not to bend the tubes and to tighten all

connections. Not too tight!

15. Then remount the oven wall and reconnect the tubing on the detector side.

16. Last of all, put the column back in place.


Fig. 6.8: The diaphragm valve

6.3.2 Opening the left compartment of the instrument

Introduction

Opening a left panel of a GC955 is shown here on an example where a transformer has to be modified from 220

to 110 V settings.

However, for exchanging other elements, like sample piston and mass flow controller, the same procedure is

valid.

Fig. 6.9: Loosen the 4 brass nuts connecting to the tubing on the right side.


Take off the LCD cover by taking out the four little screws.

Fig. 6.10 Then take out the 2 screws on the photo.

Fig. 6.11 Then take out the screws indicated on this photo connecting the flow regulation panel to the middle wall.

At the rear panel 3 screws have to be taken out connecting the side to the back panel.

Take out the two attachments on a cooled precon if present (by unscrewing the 2 holders at the left panel

completely)

Then take the 2 screws out of the sample pump so it gets disconnected from the left panel.

Now the left panel can be turned to the side (90 degrees), and the transformer I is freely accessible.


Fig. 6.12 The left panel removed from the GC

The picture is of a system without a cooler, but will be the same concerning the transformer.

Now resolder the wires on the transformer as indicated on the next photograph.

Fig. 6.13 Pre concentration trafo

Now reassemble all, by carrying out all steps in reverse order.

Check all the work you’ve done, before applying the main lead and powering the system up.

6.3.3 Pump

The KNF-pump is used to pump the sample air up to the entrance. With inadequate filtering dust may

gather in the unit and the membranes of the pump get blocked.

If the pump does not function, it can be demounted from the left side of the instrument: unscrew the two

bumpers and lift off the pump (See figure 6.8). Open the four screws and clean the square and the two

small round membranes with clean tissue. Mount them again and try to start the pump.

If this does not help, contact your supplier.


6.46.46.46.4 Gas chromatographyGas chromatographyGas chromatographyGas chromatography

Problems may occur in the following sections gas chromatography parts:

• carrier gas supply

• 10-port valve

• column

• carrier gas filters

• pre concentration tube

• cooled pre concentration trap

6.4.1 Carrier gas supply

The flow of the analysis column and the flow of the stripper column should be checked during

maintenance: they should stay the same between services.

Check them in both configurations of the 10-port valve, take care not to measure at the moments the

oven door is opened and shut, as the flow will then shortly vary.

If the flow decreases sharply, a leak has occurred. This mostly occurs at the fixation points of the

columns.

However, because of vibrations caused by pumps or by transport movements, other unions in the

system may start to leak.

For leaks at the columns see section 6.3.4.

At other places leaks may be sought by using Soppy soap. Retighten the union and check again.

With serious leaks it will also be apparent that the carrier gas consumption has increased. If leak free, the

GC’s Nitrogen pressure should drop only after 30 seconds after shutdown of the Nitrogen supply.


6.4.2 Pre concentration tube

Because of the continuous heating and cooling down of the pre concentration tube loaded with the total

spectrum of ambient air hydrocarbons the pre concentration tube filling will change. Replacement of the

tube after a year is advised.

1. First, shut off gas supply and power, and then remove the bottom cover.

2. New tubes are supplied with their thermocouple attached. Be careful with the connection of the wire

to the tube: it can break off with rough handling, this cannot be repaired.

3. Loosen the two poles of the thermocouple from the MX-print (brown on + , blue on - ). (See figure

6.7)

4. Pull the wire through the valve cabinet, and up to the pre concentration tube. Remove the tie wrap.

To loosen the tube, first unscrew the couplings to the bulkheads.

5. Remove the 1/8” FEP-tubing with the nut and ferrule and carefully push it up to the connectors on

the new pre concentration tube. The end of the FEP-tubing must project about 1 mm, to function as

insulation.

6. Put in the new pre concentration tube and fasten the tubing carefully.

7. Then push the thermocouple wire to the underside, push it through the opening in the valve cabinet

and refasten the poles at the correct configuration.

8. Finally, fasten the thermocouple wire under the one elbow union with a tie wrap.

6.4.3 Cooled pre concentration trap maintenance

Maintenance of the cooled pre concentration trap treats the following: how to check if it is working

correctly and how to replace it.

As the trap is expensive due to the elements used for the cooling, we give you the option to exchange the

trap for a new one. We take it apart at Synspec, and reuse all parts except for the inside trap. You cannot

replace the internal trap yourself, as this is a very specialised job.

6.4.4 Correct functioning of the cooled pre concentration trap

First of all, look at the bottom line on the screen of a running instrument, see the item precontemp. During

the cooling phase, this temperature should be in the range of the temperature set in the file GC955id.txt.

Then load a data file, look under options\select view items and activate pre concentration temperature.

The red line should look like this at enlargement 25% or 10%: the rise must be very steep, the decline to

cold should be gradual. But, before the sampling starts again, it should be at base temperature again.

Normally you will see the action of the Peltier cooler: it is switched on only every 2 seconds, so you see a

rise and dip.


Fig. 6.14 Peltier cooler cooling every 2 seconds

Fig. 6.15: Heating the cold trap with Peltier cooling afterwards

Errors:

• Trap is not cooling. Usually this means the thermocouple has broken: especially with the –5 to +

300 temperature difference the strain on this soldering is heavy and it sometimes breaks.

However, you must check if the Peltier coolers are warm on the outside. If they are, then they

work. If they’re not warm, they don’t work, and they cause the error.

• Sometimes, the temperature rise is slow and does not go to set-point. This may happen if the

system has been standing idle for a long time, during which it was cooling. Very slowly ice will be

formed inside of the foam isolation. Please contact us, we have a method to try to dry the cooler

out again. Please be aware that this is very much a strain on the thermocouple: it is better to turn

the analyser off instead of having it for a long time on hold.

• Also, compare the sample strokes with an original chromatogram: if the system needs much

longer to complete a stroke, or if the strokes are not finished before the next one starts, the

system is blocked. This may be caused by very fine dust, coming through the external filter, or

because a filter has not been used.


If all functions check out ok and the linearity and reproducibility of the system is ok, there is no reason to

replace the trap.

6.4.5 Replacement of the cooled pre concentration trap

Order a new one at Synspec giving the serial no. of the instrument and at the same time indicate if you

will be returning the old trap. Fillings for the different applications are not identical, we must produce the

same trap according to our instrument data.

Replacement procedure:

Disconnect all power and gas, place the instrument on a clean surface and open the bottom cover. Place

the instrument on its right side.

The trap is connected at : the left side panel with two mechanical holders, to the sampling system by two

Vici 1/8” connectors on the middle panel, to the transformer by a fixed electrical connection, to the MX

electronics board by a thermocouple, to the sample piston electronics by two connectors.

Easy: take out by hand the connectors on the sample piston electronics board, unscrew the connectors

on the MX board with a no. 0 screwdriver.

The mechanical fixation on the left side panel is not always identical, as the Peltier cooler ventilators

sometimes differ. But, if possible, we use two brass holders. Take out the very small hexagon screws on

the holders and the two screws on the left side panel.

The best way to get room is to take out the two screws fixing the pump on the left side panel. Take care:

on the inside two o-rings are used.

The connection to the transformer is special for this type of trap: two small hexagon screws must be

loosened, then the connector can be taken off the pin. For the top connector this is easily done with a 1.5

mm hexagon wrench. For the one on the bottom, it is best to use an hexagon wrench with a 90º angle.

Now, the last connection is with the Vici nuts. Unscrew these and then carefully take out the unit to the

top. Please return to Synspec for refund of money.

Remounting the system is essentially in the counter direction. Be careful with the tubing on the Vici

connector: it is thin tubing and bends easily, after which it would no longer fit correctly. Also take care

that the electrical isolation in the form of the two pieces of FEP tubing is not displaced, as this would

result in a shortcut of the electrical circuit.

Remounting the transformer again is difficult.

After that, reconnect the thermocouple in the same way as the one for the oven thermocouple.

As last steps remount the pump and put back the special holders of the pre concentration. Set them at

such length, that the trap is vertical, else the lower Vici connector may start to leak.


6.4.6 10-port valve - gas chromatography

The 10-port valve has an all-important function for the whole gas system. At the correct actuator pressure

and protected by adequate filters at sample and carrier gas inlet it is guaranteed for 1.000.000 turnings.

When changing tubes or columns, care should be taken to work in a dust free atmosphere, as damage

from dust will most likely occur in the 10-port valve.

The valve is easily blocked by dust or small metal particles. In this case from one run to the next you will

have a straight baseline and no flow during injection.

Opening the 10 port diaphragm valve should only be done by trained technicians.

The procedure is as follows:

1. Remove the column and remove the wall in the oven. For this you have to unscrew the four Vici

connectors to it and two screws at the bottom of the valve compartment.

2. Now you have a good access to the 10 connectors on the 10 port. Unscrew them carefully,

taking care not to bend the tubing.

3. With an hexagon key 9/64” you can easily open the top of the valve. Remove it carefully.

4. Now you see the diaphragm lying on the small pistons, and in your hand you have the polished

surface of the other side. Any dust is normally found on top of the diaphragm or on the polished

surface. Clean with optical tissues.

5. The diaphragm sometimes deteriorates and gets bubbles around the piston ring. In this case it

can be replaced by a new one. Contact Synspec for that.

6. Replace all, now your system should be ok again.

6.4.7 Capillary columns

The instrument comes provided with a stripper column and a analysis column. These are precut and

installed. The stripper column is marked with short, the analysis with long sleeves of PTFE-tubing.

The column is made of fused silica and will not break easily.

However, in the bulkheads in the oven wall, breakage may occur for two reasons: heavy shocks to the

instrument, and too strong tightening.


Fig. 6.16 Capillary column in the oven

Tightening of the column iTightening of the column iTightening of the column iTightening of the column in the bulkheadsn the bulkheadsn the bulkheadsn the bulkheads: the correct procedure is:

1. slide the nut over the column, then the fused silica-adapter: with the 0.53 column this goes

easily.

2. Then slide the fs-adapter carefully into the bulkhead.

3. Screw the nut carefully until finger tight. Now the column can still be slightly moved inside the

adapter as the adapter is a polymer that has to be tightened to clamp the column.

4. Tighten with the 1/4” wrench about 10º, check if the column can still be moved. Repeat this until

the column is fastened: this is enough.

Do not screw any further: in principle it is possible to pulverise the column end without much force!

Leaks in these bulkheads are not so easily detected with “Soppy”, because of the low pressure.

However, the decrease in flow can be measured.

In case of leaks caused by a break in the union, the column can easily be reinstalled correctly:

1. Shut off gas supply and power.

2. With a 1/4” wrench open the unions on the bulkheads.

3. First, remove the two unions at the rear; pull out the columns, mostly the fused silica adapters stay in

the union. Remove the nut from the columns, tilt the instrument and catch the fs-adapters with your

other hand. If they do not come out this way, pull them out with a needle.

4. Inspect the ends of the column: if they are broken, cut off 0.5 cm with the ceramic column cutter that

is supplied with the instrument. To cut off a piece just make one medium light stroke with the side of

the cutter and break the column backwards. Inspect under a good lamp, if there is a square cut.

5. Also clean out the fs-adapter, preferably with a very small drill, else with thin wire.

6. Remount these two column ends by following the procedure for fastening a column as described

above. Then proceed with the two at the front.


Normally, there should be enough spare column to cut 0.5 cm from each end. Else it is possible to

rewind the column to allow for more room.

When other separations are desired or when the column deteriorates after several years, Synspec or

your distributor supplies precut columns as a replacement.

1. Remove the unions two by two as described above, then bend the ends of the column into the

bracket, to prevent them getting stuck during removal.

2. Now the column can be pulled out: first lift the column at the front side, then slowly pull it out.

3. When putting in the new column, follow the reversed procedure. Try to avoid scraping of the column

at the oven wall cut-outs at the rearside: scratches on the silica may lead to breaks.

4. The column case is just large enough to give a good grip at the oven walls.

5. Install the column in the bulkheads: the column with the long PTFE-sleeve at the a-, with the short

sleeve at the s-marked bulkhead.

6. Test for the correct flow at both analysis and stripper column.

6.4.8 Packed columns

The instrument comes provided with a stripper column and a analysis column. The lengths are usually

0.4 and 1.6 M, the internal diameter is 2.1 mm. The packings are chosen for their stability, if possible we

use a polymer type without coatings. However, for some analysis the only solution is to use a solid

support, mostly a kind of inorganic material with a coating.

The problems that occur with packed columns are:

• High boiling compounds absorb so well on them, that they are not removed from the stripper

column at the normal temperature. The column becomes saturated, and peaks get broader.

From time to time the column has to be heated for several hours while backflushing. For this you

should set the temperature at 100 °C (see Chapter 5). After cooling down, the peaks should

again be sharper.

• The column slowly looses its coating after several months of use and retention times get shorter.

Here, the solution is either to readjust flows, or to put in a new column.

• The column material breaks, the column gets more and more blocked: this occurs mostly with

carbon packings, which are fragile. The retention time gets longer. Here the solution is to put the

flow somewhat higher.

• Replacing a packed column set is easy: with a ½” key take out the present set and replace it by

a new one. To take it out, first unscrew the connectors on the inside, then those on the side of

the walls.

• The polyimide fittings are flexible and must not be screwed too tightly. Best first screw them on

by hand as far as possible, then tighten them, with only a light pressure of the key. Check

afterwards with leak test soap.


6.4.9 Replacement of carrier gas filters

The commercially available Nitrogen of quality 5.0 contains up to 1 ppm hydrocarbons (the next quality,

6.0 may still contain 0.5 ppm hydrocarbons).

To prevent pollution of the system the carrier gas is filtered with activated charcoal (mesh 60/80) in two

filters: one on the analysis and one on the stripper system.

It is advised to replace them after a year, or to replace them when the background ionisation signal

becomes high.

Procedure:

Stop the system and close off the gas supply.

Open the filter holder in the left compartment.

Only filters no. 1 and 2 have to be replaced, no. 3 filters the possible backflush from the sample piston

and has a life time of over 10 years. Loosen the connections of filters 1 and 2 with a ¼” key.

Remove them and replace with cleaned, activated coal filters.

It is quite feasible to reuse the filters: put them in an oven for a night, at 200 ºC, while flushing them

through with Nitrogen. (Heating without flushing does not work).

If then the reactivated filters are capped, they can be reused the next time filters have to be replaced.

6.56.56.56.5 Computer maintenanceComputer maintenanceComputer maintenanceComputer maintenance

The Syntech Spectra GC955 has a built-in industrial PC. The system is dedicated to the control of one or

two GCs with all their functions.

Also all the data saving and data communication is handled by the PC.

As an option analogue and digital data logging from other instruments is possible.

6.5.1 Loading strange software: not advised

This PC can of course be used for other things, like word processing, spread sheet evaluation, playing

games, etc. Over the different ports you can load any software. However, in that case we do not

guarantee correct functioning of the system. If Synspec has to repair systems with software problems,

and we find strange software on the system, we charge you for all costs involved.


6.5.2 Data communication with external data loggers and other PCs

Several versions of data logging are available from our side. Also ethernet connection is possible.

A problem most frequently occurs in three cases:

1 With data loggers: only at the end of a cycle a new value will be transmitted through the RS232

port. This is different from many other instruments that may be present at the same site. So, in many

cases, the RS232 port is frequently approached by the customers’ data logger. If this occurs with

instruments that are set to transmit many parameters of measured peaks or of status settings, the

system may become very slow or fail. Please set the data logger frequency to the lowest value you can,

preferably to once every cycle. If you use a modem for data logging, it should have a speed of at least 54

kBps.

2 Some types of data logging programs, like the bus programs, have many subtle variations. The

GC can in principle be set to communicate, but we need detailed information of the data logging

software protocol. We will be pleased to contact the software department of the customer to exchange

information.

3 An ethernet connection enables quick data transfer. We do not advise to log on to an office

network with a central backup. This will mean that each time a new file is saved or a file is changed, a

copy will be made over the network. For a standard GC this means that at the end of each cycle the bin-

file and the rundata.txt must be copied. At the end of a month this may be too much for the system,

which would produce an error message. Because of this message, a line would be added to the file

GC955.log. Therefore GC955.log would also be backed up, which creates another error, and so on, and

the system would get stuck. So, logging onSo, logging onSo, logging onSo, logging on to a central network is only possible if you can avoid to a central network is only possible if you can avoid to a central network is only possible if you can avoid to a central network is only possible if you can avoid

automatic backupautomatic backupautomatic backupautomatic backup.


Hard disk maintenance

Hard disk capacity gets bigger every year. Nowadays, it’s hard to believe that we started this system in

1995 with a hard disk of 140 MB. Still, the hard disk will fill up, especially if you have short analysis cycles

or a double system.

You should make a backup frequently, and do a clean up at least every 6 months. The most essential

thing to copy is always the rundata.txt or the rundatamonth.txt, as this contains the ASCII file with the

results of each measurement.

Actions at a 6-monthly maintenance session:

• Copy all rundata.txt or the rundatamonth.txt and all the data files (*.bin files of the measurements

in the monthly subdirectories) by the USB-port, the Ethernet connector or the RS232-connector

to another medium, like a laptop, a ZIP disk, or a memory key. Then, delete these files from the

hard disk to make space.

• If the GC955.log is larger than 0.5 MB, rename it or copy it to another medium and delete. A new

log file will be generated.

• Make a safety backup of the calibration files and the functioning essentials (GC955.exe,

act_run.prg, act_calib.dat, GC955id,txt) to store together with the bin-files for later reference.

• When all this has been finished, run scandisk and if you have time also defragment the disk.

Start ScanDisk by clicking StartStartStartStart, pointing to ProgramsProgramsProgramsPrograms, pointing to AccessoriesAccessoriesAccessoriesAccessories, pointing to

System ToolsSystem ToolsSystem ToolsSystem Tools, and then clicking ScanDiskScanDiskScanDiskScanDisk. Start Disk Defragmenter by clicking StartStartStartStart, pointing to

ProgramsProgramsProgramsPrograms, pointing to AccessoriesAccessoriesAccessoriesAccessories, pointing to System ToolsSystem ToolsSystem ToolsSystem Tools, and then clicking Disk Disk Disk Disk

DefragmenterDefragmenterDefragmenterDefragmenter.

6.5.4 Computer conditions

Optimal conditions for the PC are: steady power supply, no vibrations, temperature 5-30 °C, humidity

below 80%. But: if necessary, systems can run up to 45 °C, power failures are not so terrible, and good

hard disks can bear a lot of humidity.

Beware of the following:

An extra ventilator for the computer compartment is provided in the L-shaped lid of the GC. When you

open the lid, take it off slowly and take of the connector on the computer board. When you close the lid

first reconnect.

If the temperature indicator of ambient temperature is above 45 °C , you should take measures to lower

it: improve ventilation, look for a different place to set the system.

With high humidity and high temperature the hard disk is at risk when the system is stopped. On cooling,

down the internal pressure will be lowered and humid air can be sucked in. This will lead to rust formation

inside the hard disk.

Vibration from pumps is bad for the hard disk.


During transport, sometimes the processor ventilator becomes unstuck. Try to fix it again, but if it is

broken, you can buy standard ventilators for Pentium processors in most countries without a problem.

6.5.5 Correct setup for the GC955

Customers sometimes change the set-up of Windows on their own. However, it is essential that this

should be as it was originally. Here are the correct settings:

Fig 6.17 Correct settings for Windows 98


6.5.6 GC955 Digital outputs

Configuring the outputs is described here more extensively than in Chapter 5. If you want to use the

digital outputs please check if the following text helps you any further, else contact Synspec for more

help on your desired settings:

Under programview\options select Digital outputs..., the following dialog will appear :

Fig. 6.18 Digital settings

On the left side you find the digital output no (1..7) with its corresponding PIN-no at the backside of the

GC.

Digital output no 5 is active at pin 9, but also on the relay-output, pin no 2,3 and 4.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

dig.indig.outRelais

1 2 3 4 5 6

Analog out

Fig. 6.19 Connections on digital outputs

Every digital output can be linked to an internal state of the GC, or to a combination of internal states.


Here is an overview of the different states which can be used:

Logical name Description/meaning

Running State Start button has been pressed, amber LED is burning

Calibration mode GC is in calibration mode (also on screen)

Span gas valve open two possibilities :

1. Menu item Actual run\Open span gas valve is checked (also on

screen)

2. Autocalibration is active and Span gas valve open is checked (also

on screen)

Zero gas valve open Autocalibration is active and Zerogas valve open is checked and a zero run

is active

Span gas-data at analogue output The previous run was a run with span gas (span gas valve open)

Zero-air-data at analogue output The previous run was a run with zero gas

Calibration data at anologue output The previous run was a calibration run

New run start During the first half of the run, this state is high, it toggles to low state

Span gas value out of range Span gas value was higher than the alarm setting in program

edit\settings\auto-validation\conditions

Zero-air value out of range Zero gas value was higher than the alarm setting in program

edit\options\auto-validation\conditions

High component alarm One of the components reached a level higher than defined high level in the

dialog program edit\settings\alarm settings....,

and the active checkbox for this component was checked

Low componentalarm One of the components reached a level higher than defined low level in the

dialog program edit\settings\alarm settings....,

and the active checkbox for this component was checked

High system alarm One of the following situations occurred:

1. The column flow has been below the alarm level defined in GC955-

ID.TXT (default 1 ml/min.) for more than 10 seconds

2. The column flow was more than 10 seconds higher than the alarm

level defined in GC955-ID.TXT (default 4 ml/min.)

3. The air pressure was below 2.0 Bar

4. The air pressure was above 4.0 Bar

5. The hard disk space is below 10 MB

Low system alarm The hard disk space came below 30 MB

Flow too low The column flow was more than 10 seconds below the alarm level defined in

GC955-ID.TXT (default 1 ml/min.)

Air pressure too low The air pressure was below 2.0 Bar

Waiting for remote start Run is waiting to start until digital input 1 is high.

Waiting for time synchronisation Run is waiting for real time synchronization.

External sample pump active

Purge stream selector


Cooling pre concentration Pre concentration trap is cooled.

Equalizing valve open

Digital input 1 (#12) high

Oven cooling active Oven is cooled to start next run at base temperature



Acoustic alarm (intermitting) Systems can be provided with acoustic alarm. Is active here.

Combined alarm

Oven temperature error

Data at output not valid (flagged)

Combination 1

Combination 2

Combination 3

Combination 4

Using combinations :Using combinations :Using combinations :Using combinations :

After selecting one of the buttons C1 to C4 in the dialog above, a new dialog will appear like this :

Fig. 6.20Combinations can be given a name. They may be fully nested.


6.66.66.66.6 Installing an autoInstalling an autoInstalling an autoInstalling an auto----validation valvevalidation valvevalidation valvevalidation valve

6.6.1 Installing a Vici 6-port electronic valve for automatic validation

To install a Vici valve after delivery to the customer, the valve must be mounted on the rear of the

instrument, the stainless steel tubing must be adapted and the digital connector for the GC must be

connected.

6.6.2 Mounting the valve

Mounting of the valve: with the valve you will receive a mould to bore two holes in the aluminium wall.

Bore the holes at this places, screw on the holder of the valve and mount the valve as tight as possible

on the holder. This is important, else the valve will work itself loose.

The T that connects the 10-port entrance and the pump at the instrument must be removed and the

tubing that is supplied with the valve must be installed. Use for this the ½” and 7/8” wrenches that are

supplied with the GC.

If the calibration gas comes from a gas diluting system, please see to it that the flow is between 1 and 4

l/min. In this case the pump can also function during automatic validation.

If the calibration gas comes undiluted from a bottle, install a restriction between the bottle and the 6-port

valve. Set the pressure in such a way, that the flow is ca. 20 to 40 ml/min.: this is enough, provided the

pump is switched off during calibration.

To check the working of the valve, you can use the manual switch button that is supplied with the valve.

However, normally the valve is meant to be switched automatically from the GC itself. Store the manual

switch after testing, for possible rechecking in case of malfunctioning.

The electrical connection from the valve to the GC must be made as follows:

• Connect the TTL switching signals to the digital outputs of the GC (terminal 5 Pos A, Terminal 6 Pos

B, terminal 16 Ground), using the Green 16 pole Phoenix connector.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

dig.indig.outRelais

1 2 3 4 5 6

Analog out

Fig. 6.21 digital outputs with a Vici valve


WARNING:WARNING:WARNING:WARNING:

After a power failure, it may happen that the valve is opened half when the power comesAfter a power failure, it may happen that the valve is opened half when the power comesAfter a power failure, it may happen that the valve is opened half when the power comesAfter a power failure, it may happen that the valve is opened half when the power comes on again.on again.on again.on again.

To be sure that everything functions normally, check the result of the auto-validation that always starts

automatically after power failure. Check that after this auto-validation the external sample is measured.

If not, switch the valve a few times manually in actual run\options\switch validation valve and again test

that the external sample is on.

If the valve is connected to an undiluted bottle and the flow of this bottle is not restricted, it may empty If the valve is connected to an undiluted bottle and the flow of this bottle is not restricted, it may empty If the valve is connected to an undiluted bottle and the flow of this bottle is not restricted, it may empty If the valve is connected to an undiluted bottle and the flow of this bottle is not restricted, it may empty

very quickly! Synspec gives no refund overy quickly! Synspec gives no refund overy quickly! Synspec gives no refund overy quickly! Synspec gives no refund on emptied bottles if the auton emptied bottles if the auton emptied bottles if the auton emptied bottles if the auto----validation valve is not checked after validation valve is not checked after validation valve is not checked after validation valve is not checked after

power failure.power failure.power failure.power failure.

6.6.3 Configuring GC955 digital outputs

In the file GC955_ID.TXT add the line

AUTOVALMENU = TRUE,

in actual run\options a new item will be visible, called "Activate auto-validation"

To switch the valve properly, the signal for Valve Position A must always be the inverse of Valve Position

B. If one is high, the other one is low and vice versa.

So, in the digital output dialog, press the button C1 to define a combination.

Figure 6.22: Digital output dialog

Select for both items "Span gas valve open", check the two boxes NOT, and the radio button "OR". Give it

a name like "No Span gas". The combination gives TRUE, if the span gas valve is not opened.


In the end it looks like this:

Fig. 6.23: Digital output dialog

Now, in the digital output dialog select span gas valve open for output 5, and for output 6 Combination 1

No Span gas.

The edited dialog looks like this :

Figure 6.24: Digital output dialog

If you press the OK button, the settings will be saved to disk.

To check the proper switching of the valve, use the item open validation gas valve under actual

run\options.

If the valve switches in the wrong way, either switch the connections at terminals 5 and 6, or exchange

the commands entered the digital output dialog.

Of course, if the procedure described above is followed, the valve can also be operated from other

output channels.


Chapter 7 Stream selectorChapter 7 Stream selectorChapter 7 Stream selectorChapter 7 Stream selector

7.1 Introduction ________________________________________________________ 122 7.1.17.1.17.1.17.1.1 InstallationInstallationInstallationInstallation ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 122122122122

7.2 Programming the stream selector _____________________________________ 122 7.2.17.2.17.2.17.2.1 Pump and channel step switchingPump and channel step switchingPump and channel step switchingPump and channel step switching ________________________________________________________________________________________________________________________________________________________________________________________________________________________ 122122122122 7.2.27.2.27.2.27.2.2 Channel namesChannel namesChannel namesChannel names ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 123123123123 7.2.37.2.37.2.37.2.3 Programming the time sequenceProgramming the time sequenceProgramming the time sequenceProgramming the time sequence ____________________________________________________________________________________________________________________________________________________________________________________________________________________________ 124124124124 7.2.47.2.47.2.47.2.4 Activating the digital connectionsActivating the digital connectionsActivating the digital connectionsActivating the digital connections ____________________________________________________________________________________________________________________________________________________________________________________________________________________________ 124124124124 7.2.57.2.57.2.57.2.5 Alarm levelsAlarm levelsAlarm levelsAlarm levels ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 125125125125

7.3 Data output ________________________________________________________ 125 7.37.37.37.3.1.1.1.1 GraphsGraphsGraphsGraphs ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ 125125125125 7.3.27.3.27.3.27.3.2 Time weighted averages with a stream selectorTime weighted averages with a stream selectorTime weighted averages with a stream selectorTime weighted averages with a stream selector ________________________________________________________________________________________________________________________________________________________________________________ 127127127127

7.4 Errors occurring with the stream selector valve __________________________ 129



Any Syntech Spectras GC can be equipped with a multi-stream selector.

With a stream selector, it is possible to sample from up to 15 different streams with one GC. The streams

are measured one after another. The GC’s software controls the stream selector. This software makes it

possible to program the time sequence in which the channels are to be measured. A sequence of 20

steps (for 15 channels) makes it possible to measure some channels more frequently than others.

7.1.1 Installation

The stream selector is normally mounted on top of the GC .

The provided RS232 (zero modem) cable is attached, and the sample line from the GC is attached to the

Sample-out connector of the stream selector.

From the backside of the stream selector comes a two-wire cable. The blue lead is connected to pin 16

(ground) of the digital output, the orange lead is connected to a free digital output (pin 5 to 11).

If ordered directly with an instrument the stream selector is already connected to the 16 pin plug, with the

orange lead on digital output 1 (pin 5).

To configure the GC for a stream selector:

In order to enable the stream selector software add the following line to the file GC955_ID.TXT :

STREAMSELECTOR = TRUE

After a new start of the GC, the software will be active with the stream selector.

Changes will be activated in the program edit menu and a new item is added under view mode: the item

stream selector. For this, see section 7.2

The digital connections must be activated in the program unit: digital outputs. For this, see section 7.3

7.27.27.27.2 Programming the stream selectorProgramming the stream selectorProgramming the stream selectorProgramming the stream selector

7.2.1 Pump and channel step switching

In this part, a few remarks are made about programming. These are based on knowledge of the chapter

5, which treats the subject deeper. Please read chapter 5.1 to 5.4 before changing the program by

yourself.

In the view mode Program edit two extra bars will appear, one for the external sample pump (located in

the stream selector), and one for setting the channel-step-signal. This is the moment in the run, when the

stream selector switches to the next channel. Of course, this moment must fit with the sampling settings Of course, this moment must fit with the sampling settings Of course, this moment must fit with the sampling settings Of course, this moment must fit with the sampling settings

of the GC program.of the GC program.of the GC program.of the GC program.

Make the adjustments for the step signal step and the external sample pump and restart the program.

For an example see figure 7.1.


Figure 7.1: New bars in Program edit, External sample pump and step signal

7.2.2 Channel names

Before programming the sequence of the stream selector the channels can be named after the location

they are connected to i.e. "Storage" or "Lab first floor".

This is done in the view mode stream selector under options\edit channel names.

Here you can edit up to 16 different channel names. The names are saved by clicking on ok.

To activate them in the program, click stop run and start run as described in section 5.1.

Figure 7.2: Edit channel names


7.2.3 Programming the time sequence

With the menu-item stream selector\edit stream selector cycle it is possible to program a 20-step duty

cycle for the stream selector.

The GC starts measuring with the first step and continues until an entry “ Restart cycle” is reached or until

step 20 is reached. Then the cycle restarts at step 1.

Figure 7.3: Edit stream selector dutycycle program

7.2.4 Activating the digital connections

Please first read chapter 5, section 5.6.2

The external sample pump is switched by the digital-output with the orange lead.

To activate this output, select the dialog program edit\digital outputs.

On the list box, select external sample pump active, and press OK.

Figure 7.4: Assign digital output to external sample pump


7.2.5 Alarm levels

The stream selector alarm levels can be set for each channel per component. This is important to cover

an area, where the risks are different concerning the acceptable levels and the components that might

cause the problems. However, calibration is only done once.

Figure 7.5: Setting individual alarm settings per channel

7.37.37.37.3 Data outputData outputData outputData output

In the ASCII-file RUNDATA.TXT, for each line the channel number will be inserted.

To save the channel data in separate files, add the following line to GC955_ID.TXT:

PERCHANNEL = TRUE

The filenames will be RUNDATA.Cxx where xx is the channel number.

To store the data in separate files each month, add the following line to GC955_ID.TXT:

RUNDATAMONTH = TRUE

The filenames for each channel will then be RDmmyyyy.Cxx, where mm is the month and yyyy is the year

of the saved data.

7.3.1 Graphs

The graph-mode is very useful for the stream selector.

The view will be as follows:


Figure 7.6: Stream selector view

In the submenu stream selector graph, settings parameters for the view can be set: time scale,

concentration range and channels to be pictured.

Figure 7.7: Adjustment of parameters

Alternatively, the values can be viewed as a table.


Figure 7.8: Table that will contain measured values

7.3.2 Time weighted averages with a stream selector

Stream selector can be used for the calculation and saving of time weighted averages.

Many industrial applications are intended to meet of the workers’ safety regulations, which

usually require the data to be saved as time weighted averages.

A new software feature of the Syntech Spectras, is the calculation per channel of TWA and the setting of

alarms not on last measured value but on the TWA.

This option only works on one component.

To use this option you must have an instrument with a stream selector and the new version of the

software. First the instrument has to be set up and calibrated.

After this, open the window: TWA settings. Channel by channel you can now activate the TWA function.

This means that you are able to set different alarm levels and that the TWA will only be used for those

channels that are in function.

You can choose the time span to be averaged, and name it. Of course, the most well known setting is for

an 8-hour mean.

If you want to use only one setting, you just set it for the first channel and copy it to all other channels.

Fig. 7.9 setting TWA values

After you start measuring, the best window to open on the GC is the following window:


Fig. 7.10 The TWA screen

This will also become the default window after start-up.

The channels will be displayed, with the actual value and two TWA values.

In between a bar shows the trend: if green, below alarm, if orange low alarm, if red high alarm.

This colouring enables monitoring personnel to get an impression of the status of the concentration at

some distance of the screen.


7.47.47.47.4 Errors occurring with the stream selectoErrors occurring with the stream selectoErrors occurring with the stream selectoErrors occurring with the stream selector valver valver valver valve

The VICI multi position valve is operated by the GC over RS232.

The comport used for GC955 is standard COM2.

As soon as in the GC955_ID.TXT "STREAMSELECTOR = TRUE" is found, the COM2 will be initialised,

and the commands Go1, Go2 etc will be sent to the stream selector.

A few errors can occur:

The stream selector channel numbers should change when the program switches to the next channel. If

they do not change, the following errors can be the reason:

1) The VICI valve hardware is locked up.

For this it is best to check by hand:

• Open the stream selector top.

• Take out the multicolour flatcable of the controller, and connect the handset to the valve.

• Use the buttons to steer the valve to position 1, test the other positions.

• If ok, reconnect the multicolor cable and test the GC operation.

The hardware may lock up due to a weak point in the electronic lay out. Contact Synspec or your

distributor.

2) The comport does not work or is occupied.

In the GC955.LOG file in the directory GC955, a line will appear during startup of the GC:

'Opening comport VICI valve'

If an error occurs during intialisation another line will be added:

'Error opening comport VICI valve'

If this last warning comes, the COM2 was not OK. There might be a hardware failure,

or the port was occupied, for instance by another device. So, try to reinstall the comports in the correct

way. Call us if you have problems here.

3) If no error occurs during initialisation, and the stream selector does not react on commands of the GC,

the following has to be checked:

a. the RS232-connection cable between stream selector and GC might not be correctly fitted. In this

case, the pump can still work, as it is directed over the digital connector, but the valve movement cannot

function.

b. If the connection seems to be ok, then a test with the Windows terminal program is used to

check the proper working of the valve. Start up a terminal program (Hyperterminal under Accessories in

Windows 98) select com2, 9600,n,8,1. Type GO2<enter>, the valve should switch to position 2. If it does

not, contact Synspec.


INDEXINDEXINDEXINDEX

10-port valve, 23, 111

abort run, 40

accept alarm, 56

activate a programchange, 58

actual run, 37

add data to current calibration, 43

Adjustment of the sampling, 64

alarm settings, 72

alarm signal, 55

ambient temperature, 38

Analog inputs, 32, 72

analog output connector, 68

Analog outputs, 32

analysis column, 23

animation, 52

aromatic hydrocarbons, 26

ASCI-terminal, 71

attributes, 48

Autolinearisation, 80

automatic restart, 47, 67

autovalidation, 78

Autovalidation, 76

background zero adjust, 38

base oven temperature, 61

baseline changes, 48

base-temperature, 36

bulkheads, 108

Calculating

the conversion factor, 44

calibration, 37

Calibration data, 31

calibration facilities, 42

calibration line, 31

calibration mixture, 45

carrier gas consumption, 107

carriergas, 34

carriergas filters, 114

channel names, 127

chromatograms, 50

cleaning of the system, 24

combinated digital outputs, 70

computer, 28

Computer, 116

constant temperature, 24

conversion from ppb to µg/m3, 35

cooled pre concentration, 60, 63

cooling down, 59

Cooling down, 62

cycle time, 24, 59

data registration, 50

data transfer, 52

datafile, 37, 39

detector housing, 98

diaphragm valve, 111

digital in- and/or output ports, 31

digital output, 118

Digital outputs, 32

digital TTL-outputs, 70

discharge the high voltagedischarge the high voltagedischarge the high voltagedischarge the high voltage, 88

discrete time-schedule, 67

ECD, 9, 27

edit sample concentrations, 43

electronic boards, 28

elution, 23

Ethernet connection, 32

external data loggers, 115

FEP, 35

FID, 9, 26, 36

FID-, 7

flow programming, 62

flowsensor, 37

forced cooling, 61

fs-adapter, 112

fused silica, 28, 111

gas flow, 60

Gesytec, 71

graph of temperature

against time, 62

graph of the measured

concentrations, 53

graphs, 37

hard disk, 116

heating power supply, 101

Heating velocity, 62

Hessen-Bayern, 71

heterogeneous hydocarbons, 26

high voltage supply cable, 96

identification file, 85

Identification file, 35

in stainless steel-columns, 28

incomplete separation, 48

inert microfilter, 35

injection time, 59

install a Vici valve, 121

instrument panel, 67

Integrate highest peak, 48

integration, 31

integration method, 48

internal pump, 60

IO diagram, 55

lamp window, 96

leaks, 107

Loading of strange software, 115

machine stays standby, 47

Maintenance of the cooled pre

concentration, 108

maintenance on the FID, 100

maintenance work, 95

manometers, 34

measured raw data, 31

menu structure, 29

modem connection, 31

O ring, 98

original datafiles, 54

oven temperature, 38, 59

password, 56, 73

PC-Anywhere, 55

PDECD, 27

periodical automatic validation, 74

photoionisation detector, 96

PID, 25

PID-signal, 25

piston, 22


pointers, 59

pre concentration heating, 59

pre concentration temperature, 63

pre concentrationtube, 22

precut columns as replacement, 113

pressure sensor, 37

program edit, 37, 58

programfile, 58

PTFE, 35

Pulsed Discharge Electron Capture

Detector, 27

pump, 22, 106

purge time, 59

quality control point, 47

raw data, 50

Rear view, 13

reference chromatogram, 84

reference peak, 84

remote control, 55

reprocessing, 53

reset the alarm, 56

resolution, 25

restart immediately after end of run, 67

retention time lock, 84

retention times, 50

RS232 analog output multiplexer, 69

RS-232 modem and PC Anywhere, 32

RS-232-communication, 32

RS232-connection, 71

rundata.txt, 50

Sample filtering, 9

sample pump, 59

sample strokes, 59, 64

Sample tubing, 35

saturated hydrocarbons, 26

screensaver, 35

self-test, 36

sensor signals, 38

sensors, 35

separation, 23, 28

separation column, 23

Setting peak windows, 38

shoulders, 48

signal / ionisation, 96

software, 29

Start and stop of a PDECD, 10

start new calibration, 43

start run, 38, 39

stepsignal step, 127

stop run, 39, 40

stream selector alarm levels, 129

streamselector, 126

Switching off the equipment, 11

synchronisation, 47

systemalarm, 56

TCD, 9, 27

temperature stabilisation, 62

temperatureprogram, 24

Tenax®, 22

thermal conductivity detector, 27

thermal desorbtion, 63

thermocouple, 108

time, 38

time weighted averages, 131

Turning off the equipment, 11

unsaturated compounds, 26

unstable compounds, 60

Upper side, 14

USB connection, 32

view items, 62

warranty, 6

Contactos/Contacts:

Comercial/Commercial:

Luís Ferreira da Costa

e-mail: luiscosta@bhb,pt

Tel: (+351) 21 843 64 00

Fax: (+351) 21 843 64 07

Assistência/Service:

Joaquim Picante

e-mail: [email protected]

Tel: (+351) 21 843 64 00

24 Horas: (+351) 96 523 73 93

Note:

SYNSPEC b.v., the owner of this document, reserves the right to make technical changes or modify the contents of this document without prior notice. With regard to purchase orders, the agreed particulars shall prevail. SYNSPEC b.v. does not accept any responsibility whatsoever for potential errors or possible lack of information in this document.

Copyright© 2011

SYNSPEC b.v. All rights reserved

GC955 600-ENG vs 6 feb 2011 · Manual for the Syntech Spectras GC955 series 400 , 600 and 800...

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Transcript of GC955 600-ENG vs 6 feb 2011 · Manual for the Syntech Spectras GC955 series 400 , 600 and 800...