dummy valve in hydraulic calculations

[honche725]

hello everyone! how and when do you use a dummy valve in hydraulic calculations such as pump sizing? should or should it not have a pressure drop value? thanks.

 

[BigInch]

I've used a dummy valve to set a particular pressure in a line segment that I needed to have in order to continue with further study. Generally large openings with very small pressure drops allow releasing volume quickly enough that you don't have to wait too long to get there. Use fast closing times when you can't stop the simulation, close the valve, then continue.

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[MortenA]

Ahhh now i get it - for calculation purposes in a simulation software - e.g. "pressurizing" a section in steady state but not allowing flow once the evnt you want to invettigate starts?

I agree with biginch - use large diameter and low (but not zero) loss coefficient. This will in most cases not cause "numeric disturbance" later on.

Best regards

Morten