Absolute Pressure Transmitter Calibration

F

Thread Starter

F. De Souza

We have an Absolute Pressure transmitter:
Range 0 to 1500mbara (4 to 20mA O/P).

The transmitter allows me to calibrate either:

0 mbara = 4mA or
1500mbara = 20mA or
0 = 4mA and 1500mbara=20mA.
(Ref:ATM pressure=1005.

Please, help me with the calibration procedure.

Thanks,
F. De Souza
 
H
Since this is smart device , you need HART protocol device like the HART COMMUNICATOR.
In this case, you need tp put tha parameters of the transmitter apprppriately including your desired seting values
or
You can implore the use work bench callibrator like the dead weight tester with gauge range 0-2000mBar and pneamatic regulator and a multimeter.
 
You cannot use dead weight tester for this range. Calibrate wityh HART communicator is OK. But will not varify the real life measurements. You need a stangard gauge/precision calibrator of 0~1500mbarA or suitable range. You can set up with a vaccum pump and some valves to get the same thing.

skrishna_raj @ hotmail. com
 
M

Michael B. Musico

Good day guys, here's another one

PT range is 135mbara-1351mbara

reference zero is 105mbara

4mA = 135mbara..... etc...

Our calibrator injected 0.135barg & TX output is 135mbara & so on...

(please note that the calibrator injected Gauge pressure)

What's your conclusions please.. is it a faulty TX.. some kind explanations please...
 
An absolute pressure transmitter with a reference zero of 0 mbara will act as a barometer. Comparing an absolute pressure transmitter's measurement (with its pressure port open to the atmosphere) with the local weather station's barometric pressure is a way of determining whether the transmitter is functional.

Somehow, your transmitter has a 135mbara zero, so a comparison with the weather station's barometric pressure should reveal that your transmitter reads approx 135mbara lower than the weather station.

When a gauge pressure is applied to an absolute pressure transmitter and the absolute pressure value is the same (or very close) to the gauge pressure value, then the effective 'zero' is not absolute zero (0 mbara) or even 135mbara; the effective zero is close to the atmospheric pressure at that location (elevation above or below sea level and weather affect the reading)

Someone probably 'calibrated' the zero without an applied vacuum. In my opinion, such performance makes an absolute pressure transmitter useless for its purpose, which is measuring an applied pressure referenced to near-absolute zero pressure.
 
An absolute pressure transmitter with a reference zero of 0 mbara will act as a barometer. Comparing an absolute pressure transmitter's measurement (with its pressure port open to the atmosphere) with the local weather station's barometric pressure is a way of determining whether the transmitter is functional.

Somehow, your transmitter has a 135mbara zero, so a comparison with the weather station's barometric pressure should reveal that your transmitter reads approx 135mbara lower than the weather station.

When a gauge pressure is applied to an absolute pressure transmitter and the absolute pressure value is the same (or very close) to the gauge pressure value, then the effective 'zero' is not absolute zero (0 mbara) or even 135mbara; the effective zero is close to the atmospheric pressure at that location (elevation above or below sea level and weather affect the reading)

Someone probably 'calibrated' the zero without an applied vacuum. In my opinion, such performance makes an absolute pressure transmitter useless for its purpose, which is measuring an applied pressure referenced to near-absolute zero pressure.
With a transmitter135 mbara zero would a comparison with the weather stations barometric pressure read approximately 135 mbara higher than the weather station, rather than lower as stated?
 
Yes, my mistake. Oops, yes, a 'zero' value of 135mBara would report a value 135mbara higher than the local weather station barometric pressure when the transmitter is open to atmosphere.
 
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