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Suction Specific Speed

Suction Specific Speed

Suction Specific Speed

(OP)
Hello,
The suction specific speed of centrifugal pump with 3560 rpm constant speed, with below operating condition is app. 12370 which is high. what would be the effect of this and what is your recommendation to decrease it?
1000 gpm, npshr: 19ft, 3560 rpm, 150hp, Sp.Gr. 0.8

RE: Suction Specific Speed

Most likely NPSH problems and cavitation = high maintenance costs.

--Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

RE: Suction Specific Speed

Buy a different pump?

I don't really understand the issues here?

What is the required duty of the pump?
got flow, but head required?
NPSHR is not the operating point.

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

RE: Suction Specific Speed

"what would be the effect of this and what is your recommendation to decrease it?"

Isn't Nss a function of the pump/impeller design? If you want to change it, you'd have to change the pump / impeller design.

RE: Suction Specific Speed

Yes, From pierres note that sort of Nss is more akin to a low head, high flow axial pump.

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

RE: Suction Specific Speed

seems like a text book question to me (wo all the details)

--- Best regards, Morten Andersen

RE: Suction Specific Speed

(OP)
Thank you all for your responses, this pump is currently under operation and we have lots of issue and maintenance works. I suspect high NSS can cause all of this issue.

RE: Suction Specific Speed

Think you might find having the wrong pump for the duty is the real cause....

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

RE: Suction Specific Speed

(OP)
any suggestion on straight run after discharge flange? how can this affect pump performance?
There is a elbow bolting on the discharge flange?
discharge nozzle size is 6".

RE: Suction Specific Speed

High maintenance could be due many problems. Chief amongst which is solids in the feed that block process fluid coolant circulation to the shaft bearings and seals. Bearing overheat and seize up. Nothing to do with Nss.

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