How do I calibrate this differential pressure transmitter, it is used to measure steam and we are not going to take it out of the process
In order to do the calibration, force its value from DCS, then isolate it and remove it, install the spare one, and normalize it, after its reading and mA are stable on its display and on HART, Normalize it from DCS as well, now the system is running smoothly, calibrate the removed transmitter on the test bench
If the DP transmitter has a 3 or 5 valve manifold then you can isolate the transmitterr from the process and then apply pressure from a calibration source to the transmitter while the transmitter is isolated from the process.
The 5 valve manifolds have ports for 4th and 5th valves that allow you to apply pressure from a calibration source through those ports to the transmitter.
A 3 valve manifold requires the use of the threaded ports on the ‘backside’ of the DP transmitter’s process heads, on the opposite side of where the manifold valve assembly connects. Those backside ports in the process heads either have a plug or a vent valve. When the transmitter is isolated from the process, then the vent valve can be used to release pressure. It’s more difficult to release pressure with a plug and it might be worth replacing the plug with a vent plug if this is more than a one time calibration. Then apply pressure from a calibration source.