What is the purpose of wet leg in DP type level transmitter

Field Instrumentation
1

Explain the need for wet-leg in DP type level transmitter

2
  • It would prevent the process from directly acting on the transmitter diaphragm
  • if process condition change due to ambient temperature then use wet leg
  • Prevent the transmitter diaphragm from chemical or stem process
  • If the wet leg is elevated then no matter density the measured valve will be accurate
3

I’m not exactly what the claim is. It sounds like a claim that a wet can compensate for process medium density in the vessel.

Elevation just adds or subtracts a fixed constant from wet leg pressure side.

A wet leg does offer a fixed reference level/pressure isolated from the process, as long as the process does not merge/mix with the fill fluid and and in so doing, change the wet leg fill density.

But even an unpolluted wet leg with a known density can not compensate for density changes in the vessel under measurement.