Calculation of orifice plates for liquid flow restriction

The value of the Cv for the orifice plate is used to determine whether flow restriction is possible; if it is too high, flow restriction cannot be achieved, while only when it is low enough can flow restriction take place. The formula for calculating the Cv value is as follows: Cv = V [G / (P1 – P2)] 1/2, where V represents the maximum flow rate (gallons per minute in the US and Canada), P1 is the pressure on the inlet side (pounds per square inch), P2 is the pressure on the outlet side (pounds per square inch), and G is the specific gravity of the fluid flowing through the valve (water has a value of 1)

Is this the calculation of the flow coefficient for a control valve? Does it mean to use this as a reference for calculating the orifice plate?

I understand that for flow control or pressure control using orifice plates, the calculation formula essentially relates flow rate, the pressure before and after the plate, and the orifice diameter; knowing two of these values allows one to calculate the third, usually the orifice diameter. Firstly, there are requirements for flow or pressure limitation in terms of process considerations; for example, a flow-limiting orifice plate is used. The flow rate that is limited by this plate corresponds to the flow rate specified in the calculation formula. The pressure before the plate is known, and the pressure after the plate is also determined by process requirements, so it can be considered known as well. Thus, the orifice diameter can be calculated using the formula ； Conversely, for a pressure-reducing orifice plate, since the pressures before and after the plate are known, and given the requirements of the flow process, it is possible to determine the orifice diameter. For gases, the adiabatic index has an impact, while for liquids only the flow parameters matter; therefore, it is sufficient to look up a flow coefficient. For the orifice plate itself, it serves both to limit flow and to regulate pressure

It seems to be the case, but there are doubts regarding the specifications. Since the standards provide a criterion for determining that flow rate stops increasing when the pressure difference before and after the gas reaches a certain level, why isn’t there a similar criterion for liquids? Perhaps my understanding of the standards is incorrect.

I understand that this same judgment criterion applies to liquids as well; it’s just that the volume of liquids is less affected by pressure, so the formula used for judgment is relatively simple. When calculating orifice plates for flow restriction, the first step is to determine the number of plates required. There are methods for determining this in the case of multi-plate orifice plates, and these methods apply both to gases and liquids. The judgment formula you mentioned is used to quickly determine whether a single plate is sufficient for gases, while for liquids, you can consider a value of 2.5×10E6 Pa – this value is actually included in the formula used to calculate the number of plates required for liquids