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# Swing Check Valve velocity

## Swing Check Valve velocity

(OP)
I have seen in some specifications that for a swing check valve the maximum velocity is 2.5 m/s. The client is stating in their specification that pumping station piping can have a maximum of 3 m/s.

This is a water pumping station and the non-return valves are 800mm diameter.

Why would a valve supplier put a 2.5 m/s limit on the velocity for a non return valve?

Regards

John

### RE: Swing Check Valve velocity

My understanding for large swing checks is that at high velocities they kind of bounce or skim off the liquid and the flapper starts hitting the top of the valve then falling back into the liquid, then hitting the valve.... - kind of like a skimming stone on a pond.

Usually swing checks like to hang down into the flow at an angle of 10-20 degrees from the horizontal( assuming flow is horizontal).

Might be wrong - ask the vendor if it's a guide velocity or one they have actually tested / calculated.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

### RE: Swing Check Valve velocity

That s close to the maximum fluid velocity that would be expected in normal water systems. Setting a limit also sets the maximum force that the valve has to handle. F = ma.

### RE: Swing Check Valve velocity

Check if the criterion stated at the bottom of page 3 of this doc applies to your check valve

https://www.flowserve.com/sites/default/files/2016...

This essentially implies the min velocity permissible is approx 1.0m/sec for swing checks in water service.

### RE: Swing Check Valve velocity

I'd say the max limit would be around the value obtained when the constant in that formula on page 3 is between 150 and 200 - you may hit some total pressure drop limit long before this.

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