Large Air Receiver

Medium Air Receiver

80 PSI Supply Air

Manifold

Muffler

Exhaust Valve (demand)

Transmitter

I2P4-20 ma

Foxboro743cbDigital

Controller4-20 ma

Pressure Station

LevelColumn

Pump

I2PConverter

S

0%

100%

1+ 1+ 1+1- 1- 1-

3+ 3+3-3- 2-

2+

2AI-I2V

2AP+A5

2AO-V2I

A/M Station

Level Station

Drain

NIA02 Loop Calibration, Control & NIA02 Loop Calibration, Control & TroubleshootingTroubleshooting

20092009

Given the necessary tools, equipment and references the I&C technician will calibrate and troubleshoot

instrumentation loops. Mastery will be demonstrated by successful completion of all in class exercises,

Laboratory Practical Evaluations and scoring 80% or better on an end of course exam.

Course Terminal Objective:

Topics:

• Isolating & Restoring Instruments• Foxboro coding refresher• Loop Calibration (calibration principles)• Loop Control (loop tuning)• Loop Troubleshooting• Industry Events

– 40 hour class– 7 labs- CBT exam

3 valve manifold section

• How many ways are there to valve out a transmitter?

• How many ways to put one back into service?

• How many are acceptable?

• What are we trying to prevent?

• What if the transmitter in question has a dry reference leg? How does this change valving it in or out?

Six ways.

Six ways.

What do we NOT want to happen when isolating & restoring an instrument

• Full system pressure on one side of a transmitter and atmospheric on the other side

• System flow through the 3-valve manifold• Loss of wet reference legs• Water in dry reference legs• Leaving instruments out of configuration• Disturbing other instruments on shared

sensing lines

Possible ways to valve out a transmitter

First Second Third ResultsShut high Open equalizer Shut low This is the recommended

correct method

Shut high Shut low Open equalizer disadvantage:temporarily locks pressure

into both sides of manifold and transmitter

Open equalizer Shut high Shut low Flow through manifold !!!

Open equalizer Shut low Shut high Flow through manifold !!!

Shut low Open equalizer Shut high Not so bad

shut low Shut high Open equalizer disadvantage:temporarily locks pressure

into both sides of manifold and transmitter

Equalizing Valve

Process High Pressure tap

Process Low Pressure tap

Instrument Low Pressure tap

Instrument High Pressure tap

HighSideIsolation

LowSideIsolation

High Pressure test tap

Low Pressure test tap

Typical Dragon Three-Valve Manifold

Low SideIsolation

High SideIsolation

Instrument Root Valves

Equalizer

Process

Flow

HP LP Flow through 3-valve manifold

Possible Sequences for returning a transmitter to service

First Second Third ResultsOpen Low Shut Equalizer Open High This is the recommended

correct method

Open Low Open High Shut Equalizer Flow through manifold !!!

Open High Shut Equalizer Open Low Not so bad.

Open High Open Low Shut equalizer Flow through manifold !!!

Shut equalizer Open High Open Low Hammers Transmitter with full system

pressure on only one side

Shut Equalizer Open Low Open High Hammers Transmitter with full system

pressure on only one side

Instrument Root Valves

High SideIsolation

Low SideIsolation

Equalizer

Process

Flow

HP LP

Out of service, root valves shut

Instrument Root Valves

High SideIsolation

Low SideIsolation

Equalizer

Process

Flow

HP LP

Open Root valves

Low SideIsolation

High SideIsolation

Instrument Root Valves

Equalizer

Process

Flow

HP LPCheck equalizer open, then open low side isolation

Low SideIsolation

High SideIsolation

Instrument Root Valves

Equalizer

Process

Flow

HP LP

Shut equalizer

Low SideIsolation

High SideIsolation

Instrument Root Valves

Equalizer

Process

Flow

HP LP

Shut equalizer valve

Low SideIsolation

High SideIsolation

Instrument Root Valves

Equalizer

Process

Flow

HP LPOpen High Side Isolation

Low SideIsolation

High SideIsolation

Instrument Root Valves

Equalizer

Process

Flow

HP LPTransmitter in service

On to SPEC 200 Coding