Transmitter-1: -40 mmwc
Transmitter-2: -130 mmwc (slowly deviated to more negative reading)
Transmitter-3: -35 mmwc

Where as no leakage in anywhere in Transmitter-2.
it's LRV-)1050 & URV+)0 mmwc (as like others.)

I have drained the drain lines & transmitter also.
But still problem is persisting.

Please give some tips.

 

Hello,

What type of transmitters are you using? Are they HART smart? Did this problem just start or has it always been an issue?

 

Is this problem persisting since commissioning or appeared later on? if it is there since commissioning then check the elevation of HP and LP impulse piping. There may be problem of varying elevation. If it is developing later on then only one reason i can find is that someone must have performed zero calibration of sensor. This you can verify by isolating and draining the transmitter and check the output current at zero pressure. If this is the case you have no other option except for changing all the three transmitters.