Gas flow metering
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In Dcs, the orifice plate measures the gas flow rate under actual operating conditions; the reading displayed on the controller is in standard cubic units. How is this standard cubic value obtained? And how is the design range of the display controller determined?
In calculations, orifice plates can be used in standard cubic units; if calculations are done based on operating conditions, they can be converted to standard cubic units using gas equations in a computer.
Based on the gas equation, temperature and pressure compensation is applied to the flow rate data under actual operating conditions to obtain the flow rate data under standard conditions. There should be a dedicated flow calculation module in DCS.
I guess you are referring to the standard cubic flow rate of differential pressure flow meters. My understanding is that the orifice plate manufacturers calculate the density under the operating conditions specified by the design institute; they then multiply the volumetric flow rate by this operating density to obtain the mass flow rate, and finally divide by the standard density to get the standard cubic flow rate