For differential pressure flow meters, is it necessary to take the square root of the percentage of differential pressure (the ratio of differential pressure to total differential pressure)?
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I have a question for all the marine professionals here: For differential pressure flow meters, whether the flow rate value displayed on the DCS screen is expressed in terms of volume flow rate in units of m3/h or L/h, or in terms of mass flow rate in units of kg/h or t/h, is it necessary to take the square root of the percentage of differential pressure (the ratio of the differential pressure to the total differential pressure)? {Because: The instantaneous flow rate of a secondary meter = square root of (differential pressure/transmitter range) * flow rate range of the secondary meter.} Thank you to all my fellow sailors{:1_90:}
The flow rate is proportional to the square root of the pressure difference; therefore, taking the square root is necessary. It can be squared at the transmitter, or it can be squared at the DCS.
What was said on the 2nd floor is correct, but generally, squaring is done on the control system side to ensure that the value output by the differential pressure transmitter better matches the accuracy of the transmitter
You, the original poster, have already posted a third thread regarding the issue of taking the square root in differential pressure flow meters. You keep focusing on this problem of taking the square root; have you mixed up the differential pressure transmitter or flow transmitter used in conjunction with throttling devices (that is, the √△P transmitter)? The differential pressure transmitter outputs a differential pressure signal, which needs to have its value taken as the square root in a display unit or DCS – it is only after this step that we get the flow signal. The √△P transmitter outputs a flow signal that has been squared (the squaring is done within the transmitter). It is recommended that you look into the working principle of differential pressure flow meters and the relevant calculation formulas, and then the issue of taking square roots will become clear.
The flow rate is proportional to the square root of the pressure difference; therefore, a square root operation is required. Generally, this square root function is selected during DCS configuration, so that the output from the field gauges remains linear, and selecting the square root option ensures an appropriate display on the field gauges；