MSA Customer Training Gas Detection Principles.pdf

© MSA 2007

Gas DetectionGas Detection

© MSA 2007

Measuring, why?Measuring, why?

To take care of workers health and life - prevent dangerous situations

To protect the inventory for damage

To fulfill local / national laws or regulations

© MSA 2007

Measuring, what?Measuring, what?

Ex(Vol%)(%LEL)(%UEG)

Ox(Vol%)

Tox(ppm)

(ml/m3)(mg/m3)

HazardousGases or vapors

© MSA 2007

Combustion

Oxygen

Fuel

Ignition

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What is Combustion?What is Combustion?

Combustion = reaction between flammable gas and OxygenCombustion without Oxygen = impossibleFor combustion right ratio between combustible gas and Oxygen is neededSufficient ignition-energy will increase the temperature and a reaction will take place

© MSA 2007

DefinitionsDefinitions

Combustible Gases

Ex Explosive (measuring range)Comb CombustibleLEL Lower Explosive LimitUEL Upper Explosive LimitVol% Volume Per cent

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LEL AND UEL

• Below Lower Explosive Limitnot enough fuel to ignite

• Above Upper Explosive Limitnot enough oxygen

• Between LEL and UEL

Atmosphere is Explosive *VALUES ACCORDING TO NATIONAL ELECTRIC CODE (NEC)

© MSA 2007

METHANE

5 15

LowerFlammableLimit

UpperFlammableLimit

GAS BY VOLUME

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4 75GAS BY VOLUME

HYDROGEN

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Acetone 2.5% by volume

Acetylene 2.5% by volume

Benzene 1.2% by volume

Butane 1.9% by volume

Butyl Alcohol (Butanol) 1.4% by volum

Diethyl Ether 1.9% by volume

Ethane 3.0% by volume

Ethyl Alcohol (Ethanol) 3.3% by volume

Ethylene 2.7% by volume

Ethylene Oxide 2.7% by volume

Hexane 1.1% by volume

Hydrogen 4.0% by volume

Isopropyl Alcohol (Isopropanol) 2.0% by volume

Methane 5.0% by volume

Methyl Alcohol (Methanol) 6.0% by volume

Methyl Ethyl Ketone 1.4% by volume

n-Pentane 1.4% by volume

Propane 2.1% by volume

Propylene 2.0% by volume

Styrene 0.9% by volume

Toluene 1.1% by volume

Xylene 1.1% by volume

*VALUES ACCORDING TO NATIONAL ELECTRIC CODE (NEC)

© MSA 2007

Ignition energyIgnition energy

Minimum energy (in mJ) required to ignite a combustible vapor/gas in air

Example:Hydrogen: 0,01 mJMethane: 0,28 mJHexane: 0,24 mJAmmonia: 680,00 mJ

© MSA 2007

Vapor PressureVapor Pressure

The vapor pressure is expressed in mbar at a given temperatureSubstances with a boiling point of > 350o C have a negligible value (almost no vaporization)

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Flash PointFlash Point

Liquid classification related to flash point

< 21o Celsius≥ 21o Celsius en ≤ 55o Celsius> 55o Celsius en < 100o Celsius≥ 100o Celsius

© MSA 2007

Flash Point

© MSA 2007

Measuring Methods CombustiblesMeasuring Methods Combustibles0-100% LEL range

Catalytic Oxidizing (also leak)Semi Conductor (also leak)IR FID (leak)PID

0-100 Vol% / %GasThermal ConductivitySemi ConductorIR

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Platinum thread

The PelementHuman Hair

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Ceramic bead

The MSA Pelement

Catalytic material (Palladium)

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CatalystCatalyst

A (chemical) substance which starts a process and/or accelerates it and ends up unchanged

Example: Burned ashes in combination with sugar

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The MSA PelementNeedle

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Glass coating on passive pelement(compensator)

The MSA Pelement

No gas entryPossible!

© MSA 2007

Wheatstone Bridge

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Wheatstone BridgeWheatstone Bridge

Used by catalytic, and the thermal conductivity measuring methodsAlteration of the electrical resistance, due to changing of the temperature The unbalance is electronically amplified and displayed as a value corresponding with the gas concentration

© MSA 2007

The Catalytic SensorThe Catalytic Sensor

♦ Operating temperature 450° C or higher

♦ Detection sensor (D) is catalytic active

♦ Compensation sensor (K) is catalytic inactive

D-Sensor C-Sensor

18 LEL

© MSA 2007

Variety Types of Instruments available with Catalytic LEL Sensor

Variety Types of Instruments available with Catalytic LEL Sensor

© MSA 2007

MonitoringMonitoring

Observe:DensityAir flowTemperature

CHCH44

CC44HH1010

HH22SS

CHCH44COCO

© MSA 2007

1009080706050403020100

0 10 20 30 40 50 60 70 80 90 100

METERREADING

% LEL

2 to 1RATIO

METHANE

100 % LEL METHANE = 5 % BY VOLUME

PENTANE

100 % LEL PENTANE = 1.5 % BY VOLUME

© MSA 2007

1009080706050403020100

0 10 20 30 40 50 60 70 80 90 100

PENTANE

METERREADING

% LEL

2 to 1RATIO

100 % LEL METHANE = 5 % BY VOLUME

100 % LEL PENTANE = 1.5 % BY VOLUME

METHANE CALI BRATED TO THE SAFE SIDE

C2H2H2

GASOLINE

NH3

CH4 CO

© MSA 2007

Catalytic Detector

Requires 9% for accurate readings

Minimum 4% required for explosion

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Sensor Poisoning

Responds only to combustible gases

Poisons (H2S, silicons, Freons, Fluorinated Hydrocarbons) can decrease the sensitivity

© MSA 2007

Thermal Conductivity PrincipleThermal Conductivity Principle

Sample of the gas creates an unbalance in temperature, due to exchange or admission of heatThe unbalance is electronically amplified and displayed as a value corresponding with the gas concentration

© MSA 2007

Thermal conductivity SensorThermal conductivity Sensor

♦ Operating temperature 450° C or higher

♦ Sensors are catalytic inactive

♦ Resistor change due to heat exchange 26

© MSA 2007

INFRARED SENSORSINFRARED SENSORSThe IR sensors uses the gases property to absorb infrared radiation at different wave lengths.

© MSA 2007

HC-LEL, CO2, CO

Refrigerants / Toxic gases

3-5.5 μ 8-15 μ

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IR SensorIR Sensor

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Open Path IR SensorOpen Path IR Sensor

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LEL Meter (1)LEL Meter (1)

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LEL Meter (2)LEL Meter (2)

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Catalytic x IRCatalytic IR

Implantation cost

Low High

Maintenance cost

High Low

Life 2 to 3,5 years 5 to 10 yearsMonthly Biannual - AnnualZero + Span Zero (usually)

Detects almost any combustible gas

Don’t detect diatomic gases (H2)

Sensible to poisoning substances

Don’t affected by other compounds interference

Lack of sensibility with the continuous gas exposure

Sensibility don’t changes with the continuous gas exposure

Simple Maintenance Maintenance on the manufacturer

Needs Oxygen Works on inert atmospheres

Limitations

Calibration

© MSA 2007

Measuring Methods ToxMeasuring Methods Tox

Electro ChemicalDetector Tubes (Reagents)Semi Conductor

PID Photo Ionization DetectorFID Flame Ionization DetectorIR Infra Red

© MSA 2007

DefinitionsDefinitions

PPM Part Per Million (0,000.1 vol%)

PPB Part Per Billion (0,000.000.1 vol%)

TLV Treshold Limit Value

TWA Time Weighted Average (8 hrs)

LTEL Long Term Exposure Level (8 hrs)

STEL Short Term Exposure Level (15 min)

T90 Response Time

© MSA 2007

T90 Response Time

100 -

80 -

60 -

40 -

20 -

0 -

%%

90

2,5 T

63,2

1T

95

3T

98,2

4T

99,34

5T

99,76

6T

99,9

7T

100

8T2T

86,5

Time = n x T (seconds)= % of end value

© MSA 2007

Effects of low OxygenEffects of low Oxygen

Above 19,5% Necessary for normal life

14 - 19,5 %Threatening danger, don’t enter the room, use independent breathing protection (SCBA)

12 - 14 %Deep breathing, higher pulse rate, worsecoordination

10 - 12 %Faster and superficial breathing, dizzy, bad judgement, blue lips

8 - 10 % Nausea, vomit, unconscious, pale6 minutes = 50% fatal, 8 minutes = 100% fatal

4%Coma in 40 seconds, spasm, breathing stops, death

0% Unconscious, death in 10 seconds

EFFECTS OF LOW OXYGEN

© MSA 2007

Electrochemical O2 SensorElectrochemical O2 SensorMembraneCounter Electrode

OXYGEN

Membrane

Signal7-15 mV

Sensing ElectrodeElectrolyte10% KOH

Reaction at Sensing Electrode O2+2H2O+4e => 4OH

Reaction at Counter Electrode 2Pb+4OH => 2PbO+2H2O+4e

Nett reaction 2Pb+O2 => 2PbO

LED is being consumed!

Pb

Au

© MSA 2007

Measuring CO2 by O2displacement?Measuring CO2 by O2displacement?

CO2 is heavier than OxygenTWA value = 5000 ppm (0.5% Vol)0.5% CO2 displacement = 0.1% O2

O2 Alarm = 19.5%19.5% O2 = 8% CO2

Answer is NO!!

© MSA 2007

CO2 in relation to O2

25 -

20 -

15 -

10 -

5 -

0 -0,5

20,83

2,0

20,53

8,0

19,3320,93

0,03

Vol%

O2

Vol% CarbonVol% Carbon DioxideDioxide

© MSA 2007

Effects of CO2Effects of CO2

4-6 Vol% 40.000-60.000 ppmchanges of bleeding in veinsin the brain, head aches, dizziness

6-8 Vol% 60.000-80.000 ppmparalyzing as if curare has been used

8-10 Vol% 80.000-100.000 ppm

extinguishing of a burning candle, spasm, fast unconsciousness, death

20 Vol% 200.000 ppmDeadly within a few seconds

0.5% Vol 5000 ppm TWA Value

Effects of CO2

© MSA 2007

Effects of COEffects of CO

PPM Vol% Effect25 0.0025 TWA value, safe during 8hrs

200 0.02 Headache, discomfort

800 0.08 Dizziness, nausea, unconsciousness within 2 hrs

1600 0.16 Lethal within 1 hour

Effect of Carbon Monoxide on People

© MSA 2007

PhysiologicalPhysiological

PPM Vol% Effect0.1 0.00001 Dirty smell (rotten eggs)10 0.001 TLV value, safe during 8 hrs

100 0.01Paralyzing smelling nerves in 3-15 min. Irritation on eyes and throat. Life danger after exposure of 8-48 hrs

200 0.02Smelling nerves immediately paralyzed, Irritation on eyes and throat. Life danger after exposure of 4-8 hrs

500 0.05

Disturbance of balance, paralyzing of respiration in 30-45 min. Immediate need for artificial respiration, lethal after exposure of 30-60 minutes

700 0.07Fast unconscious (max. 15 min), respiration stops, lethal after exposure of 2-15 minutes

1000 0.1Immediately unconscious, brain damage, lethal after 3 minutes

Effect of Hydrogen Sulfide on People

© MSA 2007

Important Properties of H2SImportant Properties of H2S

Relative gas density: 1.2Heavier then air, may accumulate at ground level in dips or holes

Highly water solubleWater can contain large amounts of H2S which may evaporate quickly at temperature or pressure changesIs absorbed if tubing used for sampling or calibration is wet. It has to made sure that they are absolutely dry.

© MSA 2007

Electrochemical H2S SensorElectrochemical H2S Sensor

Reaction at Sensing Electrode H2S+4H2O =>Pt=> CO2+H2SO4+8H+8e

Reaction at Counter Electrode 2O2+8H+8e =>Au=> 4H2O

Nett reaction H2S +2O2 => O2+ H2SO4

CounterElectrode

Membrane

Membrane

OP

Ref. Electrode

Sensing Electrode

Electrolyte

6N H2SO4Ref. Voltage

Signal

HYDROGEN SULFIDE

OP

Au

Pt

Au

© MSA 2007

RH

ISOBUTEN

0,0 ppm⏐⏐⏐⏐⏐⏐

RH

e-

RH+

h x v

13.4

The gas sample is transferred into the measuring chamber of the PID.

One part of the sample is ionized by UV-light.

The electrical charged particles formed move to the oppositely charged electrode and get discharged

The electrical current is proportional to the concentration of the component(s)

+

-

PIDPID PPhoto hoto IIonization onization How does it work?How does it work?

DDetectoretector

© MSA 2007

PIDPID

Most substances can be ionizedSome easier than others, depends on their ionization potential

Measured on an eV [electron volt] scale

From 7 to about 16

© MSA 2007

Ionize - Convert into “+” charged ionsIon - An electrically charged particle or group of atomsPotential - Ability to be ionizedIP is measured in Electron Volts [eV]

PID [ Ionisation Potential ]PID [ Ionisation Potential Ionisation Potential ]

© MSA 2007

Enough energy to Enough energy to ionize any compound ionize any compound less than 9.6 eVless than 9.6 eV

Enough energy to Enough energy to ionize any ionize any compound less than compound less than 10.6 10.6 eVeV

•Toluene 8.83 eV

•Benzene 9.25 eV

•Styrene 8.47 eV

•Propy alcohol 10.20 eV

•Phosphine 9.87 eV

•Vinyl chloride 10.00 eV

Enough energy to Enough energy to ionize any compound ionize any compound less than 11.7 less than 11.7 eVeV

•Methylene chloride 11.32 eV

•Chloroform 11.37 eV

Lamps Come in Different EnergiesLamps Come in Different Energies

PID [ eV Scale ]PID [ eV Scale eV Scale ]

© MSA 2007

PID [Why not 11.7eV as standard?]PID [Why not 11.7eV as standard?Why not 11.7eV as standard?]

The window is made up of lithium fluoride

Very hydroscopic = absorbs water vaporDecrease the transmission of the photons!Over time you lose the ionization energy!!

© MSA 2007

What is a VOCVOC?

VVolatile - Compounds in the vapor state at a low temperature

OOrganic - Compounds containing carbon atoms

CCompound - Composed of two or more elements

© MSA 2007

Examples of VOCs

BenzeneHexaneAcetoneTolueneXyleneVinyl Chloride

ButadieneCumeneEthyleneStyreneMethyl Ethyl Ketone

Hundreds of others !!Hundreds of others !!

© MSA 2007

ApplicationsApplications

Leak detection from process equipmentValvesFlanges and other connectionsPump or compressor sealsPressure relief devicesProcess drainsOpen-ended lines Degassing & vessel vents

© MSA 2007

Variety of Instruments available with Sensors for Toxic gases

Variety of Instruments available with Sensors for Toxic gases

© MSA 2007

Selection Criteria for InstrumentsSelection Criteria for InstrumentsApplication

Portable or PermanentWhich GasesSingle or Multi GasPumped or Diffusion

ApprovalsEx ApprovalPerformance approvalVerification of most critical Properties by independent test house

Supplier CompetenceSupplier Availability

© MSA 2007

What is a Confined Space(OSHA 29CFR 1910.146)What is a Confined Space(OSHA 29CFR 1910.146)

Confined spaces exist in many settings. In any area:Not intended or designed primarily as a place of workIs large enough for a worker to enter and perform workHas limited or restricted means for entry or exitIs not designed for continuous human occupancy

© MSA 2007

What is a Confined Space(OSHA 29CFR 1910.146)What is a Confined Space(OSHA 29CFR 1910.146)

Where the potential for engulfement,inadequate ventilation, a contaminated atmosphere or Oxygen deficient atmosphere may exist

© MSA 2007

What must be done before entering a confined spaceWhat must be done before entering a confined space

Obtain an entry permit from the employerTest for a safe Oxygen levelTest for Toxic gases, vapours or fumesTest for flammable gases or vapoursVentilate and cleanEnsure a stand-by person is present (with PPE)Wear appropriate PPE as necessary

© MSA 2007

Continuous TestingContinuous TestingContinuous Testing meansleaving the instruments on during the entire time that workers occupy the confinedspace. Through continuous monitoring, workers are alerted immediately to any atmospheric changes in the confined space

© MSA 2007

VAPOR DENSITYVAPOR DENSITYWhere to detect the gas hazard:Take samples at the top, middle and bottom of a confined space

© MSA 2007

SAFETY TIPSSAFETY TIPS

Never entry a confined space without an entry permitTest for hazards-know how to use the equipment and interpret the resultsLeave immediately if you experience dizziness,headedness or difficultiesStay alert at all times-do not take your safety as granted

© MSA 2007

CalibrationCalibration

OSHA guidelinesNIOSH standard for confined spacesNFPA 306 for control of gas hazards on sea vesselAll of these standards recommend calibration checks prior to each use.Use a known concentration of test gas.Do not use self-contrived techniques whichcan lead to misleading conclusions about instrument’s ability to detect gases

© MSA 2007

Calibration StandardCalibration Standard

The National Institute of Occupational Safety & Health’s ( NIOSH ) Confined Workplaces Training Resources Manual says the only way to be sure an instrument is performing properly is to check the calibration on a daily basis

© MSA 2007

Built-in boot

Lithium Ion battertechnology

Best in class triple alarm system

Missing sensor alarm

SOLARIS

© MSA 2007

Detection of combustible gases, O2, H2S, CO, NH3, Cl2, NO2, HCN, O3, COCl2, PH3, SO2, CO2, ClO2

Very largeeasy to read graphicdisplay for quickdata viewing

Robust,easy to gripdesign

Simple one handoperation

Clear andintuitive to use

IR – Sensor Technologyfor CO2, HC, CH4

ORIONplusplus Compact. Durable. Ingenious.Compact. Durable. Ingenious.[ The handiest 5 gas detector under the starsThe handiest 5 gas detector under the stars ]

© MSA 2007

Detection of combustible gases, Oxygen, Hydrogen Sulfideand Carbon monoxide

Very largeeasy to read graphicdisplay for quickdata viewing

Robust,easy to gripdesign

Simple one handoperation

Extremely loud horn

PID – Sensor Technologyfor VOC like Benzene,JP8

SIRIUSSIRIUS®® [Compact and Versatile Compact and Versatile ––for all your needsfor all your needs]

© MSA 2007

Audible alarm 95dB at 30cm

Easy to read displayshows gas concentration

Broad range of sensors:Detection of either O2, H2S, CO, Cl2, HCN, ClO2, SO2, NO2, NH3 and PH3with replaceable sensors

Replaceable battery

Bump test check-mark displayed for 24 hours

Battery life indicator

Simple one buttonoperation

Highly visible LEDs

ALTAIR PRO [Main Features]ALTAIR PRO [Main Features]

Robust, easy to grip design

© MSA 2007

High-end Single-Gas Detectormeasures and displays gas concentrationcan be turned on and off

Available for:O2CO, CO Fire, CO SteelH2SNH3Cl2ClO2HCNNO2PH3SO2

ALTAIR PRO [Product Description]ALTAIR PRO [Product Description]

© MSA 2007

Economical bump test stationDesigned for use with ALTAIR and ALTAIR PROManual and automatic versions available

ALTAIR PRO [ALTAIR QuickCheck]ALTAIR PRO [ALTAIR QuickCheck]

Instrument cradle

Powered by AC power supply

Easy to read LEDs

Connection to gas cylinder

© MSA 2007

GALAXY [ Overview ]GALAXY [ OverviewOverview ]

Standalone StationBump check stationCalibration stationCharging station

Multiple Bump check & calibration System for SOLARIS, SIRIUS & ORIONSOLARIS, SIRIUS & ORION

© MSA 2007

GALAXY [ Overview ]GALAXY [ Overview Overview ]

Protectivesystem door

Connection for multiple system

Easy-to-understand visual and audible indicators

OPTIONAL: Wired orwirelessnetworkinterfacemodule,batterypack, orprotectiveend cap

© MSA 2007

GALAXY [ Operating Instructions ]GALAXY [ OperatingOperating Instructions Instructions ]

Open the doorInsert the instrumentClose the door

MSA Customer Training Gas Detection Principles.pdf

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Transcript of MSA Customer Training Gas Detection Principles.pdf