Regarding the selection of range for pressure measuring instruments
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This post was last edited by The project’s progress on 2022-2-9 at 22:33. I’d like to discuss a basic issue with everyone. The guidelines for selecting chemical process instruments state that when measuring stable pressures, the normal operating pressure should fall within the range of 1/3 to 2/3 of the instrument’s range. When measuring the pressure of pulsating media, such as the pressure at the pump outlet, the normal operating pressure should be within the range of 1/3 to 1/2 of the instrument’s range. By \"operating pressure,\" I believe it refers to the pressure under normal operating conditions; am I correct in understanding this? When looking up information online, it says that this refers to the maximum pressure, which is a bit confusing. Another question: if the process pressure at the pump outlet is increased by 0.32 MPa, how should the measurement ranges of the pressure gauge and the pressure transmitter be chosen? Should the pressure gauge be set to 0–0.6 or 0–1? ； Should the transmitter be chosen from these two? The process specification also mentions a parameter; the normal value at the pump outlet is given as 0.22, while the maximum value is 0.4. Should 0.6 be used or 1?
Since the pump outlet pressure is pulsatory, a range of 0~1 should be used; the range of the pressure transmitter can be set to match that of the pressure gauge. I’ll wait for the responses from other seniors
Well, choosing 1 is less than 1/3, while choosing 0.6 is higher than 1/2. I think it’s better to have lower precision rather than having incorrect values. There’s another issue: can the pump outlet pressure generally be considered the maximum value?
Normally, the maximum operating pressure is around 60% of the range!
What about the normal operating value? Is it within the specified range?
The normal value at the pump outlet is 0.22, with a maximum value of 0.4. Using a gauge with a range of 0.6, the normal operating condition falls within 1/3 of the gauge’s range, while the maximum value occurs at 2/3 of the range. Do you think this meets the requirements?