Can anyone tell me the correct elevation of pressure transmitter in liquid service against the process pipe tapping point?
The discussion is whether the pressure transmitter sensing module or the whole pressure transmitter is required to be below the process pipe tapping point.
In liquid service you want to keep the impulse line and transmitter filled with the process fluid and for any entraped gas to rise out of the line. Therefore a downward slope and/or a vertical drop to the transmitter which is below the pressure tap. You will have to zero out the head of the impulse line if the elevation difference is significant.
In gas service you do not want any fluids or condensates to plug the impulse line or accumulate to offset the measurement. Therefore, a sloping impulse line from the transmitter above the pressure tap.
Steam service is different with the transmitter still above the pressure tap but with a condensing loop to trap some condensate at the pressure transmitter to prevent the steam from overheating the transmitter.
How is the sensing module separate from the transmitter?
Or do you mean the wetted part of the transmitter vs the top works?
The elevation of the wetted part is all that matters.