Control Valve Sizing Parameters.

[Weegie]

Our control valve data sheets show (limited) process data as follows:-
Temperature - norm/max
Inlet press - norm/max
Min. flow @ DP
Norm. Flow @ DP
Max. Flow @ DP
My question is, what pressure & temperature numbers should be used to calculate the valve cv ?
For min flow cv, I would use normal press/temp values
For normal flow cv, I would use normal press/temp values
For max flow cv, would I use max press/temp values ??

Thanks.

 

[roydm]

It's hard to be sure without knowing your process but usually the DP is the lowest when the flow is highest because pressure drops at other points in the line.

Hope this helps
Roy

 

[prayogi]

Is the dP constant?. As I know the Cv is only depend on flow, dP and SG. You will need P inlet to calculate the maximum allowable dP accross the valve. From this dP allowed, you will find whether your valve is away from caviation or not.

But we need to know your process. what is the process fluid?