We discuss about Foundation Fieldbus Transmitter Loop Checks Procedure. This involves Fieldbus loop checks, FF loop checks, Transmitter loop checks and DCS loop checks.
Fieldbus Transmitter Loop Checks Procedure -
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For FF device commission FF segment prior to loop testing by measuring resistance and DC voltage of segment conductor if all devices are connected otherwise only resistance will be recorded and voltage will be measured after all devices are connected and compare the result with FF segment checkout forms.
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Check and verify the DCS configuration for applicable points. Reference drawings will be P&ID and ISS.
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Apply the pressure for all (Analog / Digital) smart transmitters by using test equipment (Hand Pump) for 0%, 25%, 50%, 75% and 100% simulation to check the transmitter response at DCS. This method shall be used for all smart transmitters.
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Verify the corresponding reading in the DCS / Integral indicator and at remote indicator if applicable.
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For non-smart transmitters case Hand Pump shall be used for simulation or when required (4-20mA) ma source to be used for simulation purpose instead of hand pump.
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Alarms function (in DCS) shall be checked by simulating / verifying the required signal using communicator or hand pump using latest P&ID.
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For displacement type LT Hydraulic pump will be used with hosepipe and transparent tube with liquid (water).
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Normally Transmitter loop test should be performed after completion of the impulse line works including pressure test. In some case loop test can be executed without impulse tubing being connected if piping is not completed.
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In case of impulse line not installed and tested then this exception item to be mentioned in the loop test exception log sheet prior to signing the loop folder.