Damper Pot

For us non-metric guys, the cited range is approximately -2.0"w.c to 0.20" w.c.

Transmitters in this range are sometimes referred to as draft range transmitters.

The DP readings at this low range can be affected by moving air on the reference side, either as direct pressure on impulse tubing or as a venturi effect across the opening of a impulse tube.

I suspect that a damping pot is a chamber designed to damp air movement in the reference side impulse tubing that would otherwise be misinterpreted by the transmitter as pressure changes.

I've seen scintered filters on the end of impulse tubing or capillary tubing used for impulse tubing in order to damp reference side pressure fluctuations.