CV value and applicable flow rate of the pressure relief valve
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As we all know, pressure regulators are characterized by their KV or CV values to indicate their flow capacity; there are other ways of expressing this as well, but I won’t go into those here. I would like to ask whether, for a given model of pressure regulator, there is a suitable flow range under different required pressure differences. If so, what is the relationship between this suitable range and the CV value? The CV value is defined as the number of gallons per minute of water at 60°F (15.6°C) that can flow through the valve when it is fully open and the pressure difference remains at 1 lpsi (1 lbf/in2). For example, for a given model of pressure regulator with a pressure of 5 bar before the valve, if the desired pressure after the valve is 3 bar or 2 bar respectively, is there a maximum flow limit for this valve under these different operating conditions? Otherwise, it might lead to unstable valve control or similar issues.
The pressure difference before and after the valve, as well as the degree of opening, have a direct impact on the flow rate; for the same flow rate, the greater the pressure difference, the smaller the degree of opening, and the faster the flow velocity
Linear comparison is difficult to achieve; it depends on your requirements for the traffic curve
I’m not sure what the effects would be if the selected value for CV is greater than the calculated value
The stability of valve control has no direct relation to flow rate; what affects stability are the valve core, spring, and diaphragm. Under the same operating conditions, a decrease in outlet pressure will also lead to a decrease in flow rate. This issue is a bit complicated – whether there is a flow limit under different operating conditions can be determined by the CV value. However, the CV value is relative rather than absolute, so the flow rate varies for different fluids under the same conditions, as the specific gravity of these fluids differs.