Conversion method for wedge flow meters
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After taking the square root of the differential pressure transmitter, the milliampere signal is sent to the DCS. According to the formula: differential pressure = constant * flow rate squared * density. But the actual density is 1.2, not 1.5, which is the density specified in the transmitter formula. If the square root of 1.5/1.2 equals a constant, then is the actual flow rate that constant multiple of the flow rate displayed by the DCS? If not, what is the actual volumetric flow rate?
This post was last edited by wxz_9999 on 2010-12-15 at 15:50. Without temperature and pressure compensation, the value displayed on your DCS corresponds to the flow rate based on the pressure and temperature values given in the orifice plate calculation sheet; in other words, it represents the volume at a density of 1.5. You can find the corresponding temperature and pressure for a density of 1.2 using a density table, and then perform the conversion using the formula P1V1/T1=P2V2/T2. I think when calculating volumetric flow rate, it should not be related to density, but rather to temperature and pressure.
Reply to 2# wxz_9999: But the formula provided by the manufacturer is related to density; it refers to the flow rate of a liquid that is quite viscous.