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# Back pressure valve

## Back pressure valve

(OP)
Hello,
I'm new here in this forum, and i find it amazing
I'm working on a bench test for testing check valves. I found some examples of this test where a back pressure is used at the outlet ( to the tank). I don't really understand what a back pressure valve does. Does it help maintain the pressure in a system? for example, if i connect my pump to it directly ( pump-> Back PV=> Tank), Would it help to rise the pressure in order for the circuit to function?
What are some of its characteristic that i need to design one.

Thank you for your time and help.

### RE: Back pressure valve

A backpressure valve is simply a variable restriction in a FLOWING LINE that changes its flow area to try to maintain upstream pressure at a pre-set value. It only does anything at all while fluids are flowing in the line since they do not provide a bubble-tight seal. They consist of a way to sense upstream pressure, and a way to adjust the flow area in response to changes in the sensed pressure.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

### RE: Back pressure valve

(OP)
So from whay you said. it's a variable restriction changing flow to maintain to inlet pressure. Does the formula for flow in function of drop pressure apply to it? : ( Q=C.S.sqrt(drop pressure/density))) .

Thank you again

### RE: Back pressure valve

Not so much. Ever valve as a cv, but the flow area is irregular so the cv is a function of the valve open percent. The manufacturers of these valves do a lot of bench testing in various fluids to be able to provide reasonable equations (and factors) for their valves.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

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