Faulty non return valve on pump

[WilliamTz]

Hi

I got 4 x Condenser water pumps in parallel....2 new and 2 old.... non return valves on each

Occasionally I loose condenser water flow through the chiller when running of the new pumps

I did notice water flow noise coming from the two old the condenser water pumps, when they were off off. It was a hissing noise as if there was flow. The fan on the motor was not turning as I thought it would if the non return was not functioning. Anyway I closed the discharge valves on each of the old pumps and the hissing sound immediately stopped.

My question is; can water run backwards through the pump with out the impeller necessarily rotating if the non return is not sitting right?

BQ

 

[Valvecrazy]

Yes. The check valve is just not leaking back enough to spin the pump.

 

[LittleInch]

Agree, The flow needs to be quite reasonable to overcome the static friction. A hissing sound implies quite low quantities. A gurgling sound would be higher flow.

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

 

[gerhardl]

Apart from the answers above (agree!) it is a separate question why the two old checkvalves are failing.

This could be caused by a multitude of reasons, one or several in combination. Two failing at the same time could indicate an imbalance in flow/capacity (layout or dimension), but not necessarily.

 

[Artisi]

Is this tied in with your previous posts about cavitation and other problems reported?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[WilliamTz]

Artist
Yes. The non return valves passing is not the issue. The chiller cuts out on low condenser water flow every 24-48 hours approx. Head wrecing trying to find the reason

I arrive at the chiller. Valves on chiller n towers closed and pump off. Alarm on the chiller.
Could air be getting in ?
B