Barometric Pressure Transmitter Calibration

Historically to confirm the accuracy of the Gas Turbine barometric pressure transmitters, we installed a high accuracy Rosemount Barometric Pressure Transmitter and would just compare the readings. If the 2 Gas Turbine Barometers and the additional Rosemount Transmitter read within +/- .05 inhg of each other, we would call it good.... Now we need traceability of calibration.

Originally we planned to send out the Rosemount for NIST calibration and use that as the standard to calibrate the Gas Turbine transmitters. But since the newer Rosemount is permanently installed, we are thinking of getting a more mobile/hand held unit that is easier to send out and use that as the standard. With a known standard (as the present barometric pressure), we could then pump up and down from there. I was just wondering what others do. How do you calibrate your barometric pressure transmitters?
 
How do you calibrate your barometric pressure transmitters?

Could you not just compare it to a mercury manometer after all isn't that the standard, inches Hg? If you don't have a good vacuum pump tap, the manometer into the impulse tube and do it in-situ.

It should also read the barometric pressure at zero no?

I must admit I have never had to check one, just my thoughts.
 
There is always question as to the correct way to determine BP. If you use the local internet for the BP it is in relative BP meaning it is corrected for altitude. I'm no expert but do calibrate BP transmitters on a regular basis. Best way is to use a mercury manometer for your starting point as they are a standard. Second and available is to get the current local BP off of the internet which is relative BP, correct it for altitude ( 1" hg for every 1000 ft of elevation) ie. 3600 ft elevation would be 3.6" of mercury subtracted from relative BP. So, 29.9" hg - 3.6" for altitude correction would be 26.3" hg. If I'm wrong please correct me.
 
You can purchase a hand held "absolute pressure" monitor that will work for a calibration check. Most turbins only look at a narrow range between 28 and 32 "hg. Transcat sells a handheld pump that does positive and a vacuum that will pull down pretty far.
Historically to confirm the accuracy of the Gas Turbine barometric pressure transmitters, we installed a high accuracy Rosemount Barometric Pressure Transmitter and would just compare the readings. If the 2 Gas Turbine Barometers and the additional Rosemount Transmitter read within +/- .05 inhg of each other, we would call it good.... Now we need traceability of calibration.

Originally we planned to send out the Rosemount for NIST calibration and use that as the standard to calibrate the Gas Turbine transmitters. But since the newer Rosemount is permanently installed, we are thinking of getting a more mobile/hand held unit that is easier to send out and use that as the standard. With a known standard (as the present barometric pressure), we could then pump up and down from there. I was just wondering what others do. How do you calibrate your barometric pressure transmitters?
 
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