Issues regarding the selection of absolute pressure transmitters
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1. Problem description: The operating pressure is 22 kPaA. Currently, an absolute pressure transmitter is being used, with a set range of 0–60 KPa and an output signal of 4–20 mA in standard format. There shouldn’t be any doubts about this part! 2. Question: In my operating conditions, when there are issues with the system, I require the operating pressure to be set above atmospheric pressure (10 KPaG). In that case, isn’t the range of the transmitter selected above inappropriate? ----------------Hope an expert can give a brief answer! Thank you so much! !
I think it’s unreasonable! Because the upper measurement limit of the transmitter is 60 kPa(A), while atmospheric pressure is approximately 100 kPa(A).
It has exceeded the range of the instruments and DCS, so of course it’s unreasonable. At this point, the DCS may display something like “60kPa?” ”data. There are often posts asking experts to provide answers; when I see those, I don’t know whether to reply or not – in such cases, it’s better just to skip it.
Experts are like professionals; the word itself is good, but it’s been overused! The Chinese language is so rich – why worry about it? Help out if you can; everyone has times when they need help, right, expert?
Pressure measurement points are installed for process monitoring; if the measured parameters cannot be seen when the process conditions change, then having such sensors is pointless. Therefore, I personally believe that the range should be set at 100 KPa or above, to facilitate process monitoring； Generally, absolute pressure gauges can measure values above 100 Kpa without any issues ；
Reply to 5# cnooczhouyx: Choose a transmitter with a range of 0–130 Kpa(A); such transmitters are available in this range
Reply to 6# hzyhyb: It’s not a big problem
This post was last edited and replied to by 9shanghai on 2010-7-28 at 17:25. Reply 1# zwmgood83: 1. Problem description: The operating pressure is 22 kPaA. Now an absolute pressure transmitter is selected, with a range set to 0–60 KPa, and the output signal is a standard 4–20 mA signal. There shouldn’t be any doubts about this part! 2. Question: In my operating conditions, when there are issues with the system, I require the operating pressure to be set above atmospheric pressure (10 KPaG). In that case, isn’t the range of the transmitter selected above inappropriate? The unit for absolute pressure should be kPa.abs, right? If 1 atmosphere equals 103 kPa.abs, then the pressure in this case should be 113 kPa.abs. The set range of the transmitter is 0～120 KPa.abs; the corresponding output signal is a 4～20 mA standard signal, and the display shows values from 0～120 KPa. This should make it clear to the process team as well.
If the transmitter’s range is sufficient, change the range. If the transmitter’s own range is insufficient, then replace it with one that has an appropriate range. Generally, as long as the range of the gauge is appropriate, the range of the transmitter should match the range set in the DCS. Then there’s no problem