analogue outputs
analogue outputs
(OP)
I need your help on setting analogue outputs.
The output is +/-5Vdc. The units are absolute pressure.
If the pressure transducer is calibrated to gauge pressure 0-10bars and output settings are 500mV/bar and offset 1bar what voltage should be read at -5V, 0V, +5V.
I understand that the 0V = 1bar and +5V should read 11bars. What about -5Vdc=??
I appreciate your advice.
The output is +/-5Vdc. The units are absolute pressure.
If the pressure transducer is calibrated to gauge pressure 0-10bars and output settings are 500mV/bar and offset 1bar what voltage should be read at -5V, 0V, +5V.
I understand that the 0V = 1bar and +5V should read 11bars. What about -5Vdc=??
I appreciate your advice.





RE: analogue outputs
When an absolute pressure transmitter is 'calibrated' for 0V = 0barg, then it will evidence a ± shift around 0V as the atmospheric barometric pressure changes. It will only read 0V at the same barometric pressure as was applied when the device was calibrated.
An 'interesting' way to use an absolute pressure transmitter . . .
>I understand that the 0V = 1bar and +5V should read 11bars.
the statement requires some notation indicating absolute pressure:
0V = 1barA and +5V should read 11barA
With calibration to gauge pressure, a 0-10 barg span with a 1 barg offset over -5Vdc to +5Vdc output scale could be:
0 bara = ~-500mV
~1 bar a = 0 barg = 0 V (at sea level)
~2 bar a = 1 barg = 500mV
~3 bar a = 2 barg = 1V
~4 bar a = 3 barg = 1.5V
~5 bar a = 4 barg = 2.0V
~6 bar a = 5 barg = 2.5V
~7 bar a = 6 barg = 3.0
~8 bar a = 7 barg = 3.5V
~9 bar a = 8 barg = 4.0V
~10 bar a = 9 barg = 4.5V
~11 bar a = 10 barg = 5.0V
RE: analogue outputs
Your calibration probably needs to be -5v=-15psig, 0v= ambient pressure, +5v=+15psig
RE: analogue outputs
Thanks again!!
RE: analogue outputs
Make sure that the customer knows that 'absolute' does not mean absolute in this case; that the pressure readings are only approximately (~) absolute, since the transmitter was cal'd to gauge pressure, with gauge pressure's inherent reference to the atmospheric barometric pressure at time of calibration.
It isn't just open-to-atmosphere that's off, all pressure readings are off by the difference between whatever the barometric pressure was when cal took place and standardardized 1 bar absolute.
RE: analogue outputs