Pressure differential transmitter issue

Hello All.

I am in an industrial facility where we had an issue with a pressure differential transmitter. the transmitter is installed on a combustion air re-heater. the transmitter was doing well until we have experienced a trip. after the trip the transmitter starting to give low readings compared to before the trip. we have already tested the transmitter and flushed all its sensor tubes. however the readings were not enhanced.

Does anyone has an idea about what is exactly the root cause?

Snapshot of the readings:

Pressure differential transmitter issue

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Honestly it looks like your reading has cleaned up a good deal. Does the meter track through a calibration? If it does track through a 5 point calibration I would say that it is a real reading and you’ve got what you got.

Other things you could try if you aren’t happy with it verify you have a good zero on the meter.

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Cross-check with other pressure transmitters, if any available on the same line.

Do calibration and re-validate the transmitter functionality.

Also, check process conditions, it may happening really in the field.

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Maybe you need to calibrate

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; Is it suitable to perform a Zero trim on Absolute pressure transmitter? If the atmospheric pressure is 14.6 PSI,

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If you know the barometric pressure and do the math you could trim it out if need be. Fluke also makes absolute modules in their 750 series. On the other hand you could open your low leg to atmosphere and supply 14.7 PSIg with your pump and you should show 4 mA if not run a pressure zero trim. I think that makes sense, someone else correct me if I’m off on that.

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Maybe a vacuum though lol. Because with your calibration equipment you would be going from G to A

Hi guys firstly you need to understand what pressure dp it is whether its absolute or gauage pressure. Secondly if both hp and lp legs are clear then isolate the transmitter do a zero check if gauage. If thats fine do a 5 point calibration check by pumping the hp and venting the lp leg and observe the output. By the looks of this trend the meter was erratic after the trip its response has improved this could have resulted in it been partially plugged. Or signal interference do simulate loop

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Oh if zero out, vent both legs and do a zero trim