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Pilot Operated Vs Direct Acting Pressure Reducing Valves

Pilot Operated Vs Direct Acting Pressure Reducing Valves

Pilot Operated Vs Direct Acting Pressure Reducing Valves

(OP)
Anybody knows the typical droop for both?  Want to know this as would like to know if I am presented with both options,  whne should I pick either or?

Been readind thru books and they only give qualitative criterias and not quantitative.

Thanks.

RE: Pilot Operated Vs Direct Acting Pressure Reducing Valves

In general, direct acting valves have more droop than pilot operated.  As a matter of fact, I have not seen droop associated with the pilot operated valves, as the Cv and flow for the valve is normally reported without ANY droop. For example, Spence regulators report a 1 psi accuracy at 95% of rated flow.

For direct acting valves, each manufacturer rates thier own valves, so there is no typical.  In most cases, they have a different rated Cv's for the valve according to the amount of droop that is acceptable to the end user.

For example the valves I am familiar with are the Leslie GPK.  for a 3" valve they report a Cv of 55.8 with 2 psi min. droop and a Cv of 84.6 for a 3.5 psi min. droop.

It is similar with Cashco direct acting where they report an entire chart of Cv's with 10%, 20%, and 30% droop.

I don't know if this helps...

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