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Suction pressure less than vapor pressure

Suction pressure less than vapor pressure

(OP)
Hi guys,
we are looking to buy a new horizontal overhung centrifugal pump and one of the suppliers have sent us the datasheet of a pump which puts the suction pressure at 0.30 barg, maximum suction pressure at 0.8 barg, and the vapor pressure of the liquid at 0.6 barg.
Now we know that if the suction pressure is less than the vapor pressure of the liquid being pumped then it would cause cavitation in the pump. So that means that there will be cavitation issues in the pump unless I am overlooking something???. I just wanted to confirm before I write back to the manufacturer.

Thanks guys.

RE: Suction pressure less than vapor pressure

What is the liquid being pumped and at what temperature?

RE: Suction pressure less than vapor pressure

check that the units are actually all barg (vapour pressure might be bara), but if you are buying the pump, what did YOU ask for on YOUR data sheet that you sent to the pump vendor??

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

RE: Suction pressure less than vapor pressure

Could it be a mistake from this pump supplier?
What are the suction pressures on the pump design from other suppliers?

RE: Suction pressure less than vapor pressure

"suction pressure at 0.30 barg, maximum suction pressure at 0.8 barg, and the vapor pressure of the liquid at 0.6 barg."
I don't understand this.
What is suction pressure and what is "maximum" suction pressure? have you given a range of suction pressure to the mfr.?
also why are we not talking "NPSHa; NPSHr" at the location and the point of service where the criteria for cavitation effectively applies?

RE: Suction pressure less than vapor pressure

Please cross check it and look for the NPSHr, and check the temperature of liquid being pumped..

RE: Suction pressure less than vapor pressure

Vapor pressure would almost never be given in units of barg, but rather bara. Big difference (about 14.7 psi).

RE: Suction pressure less than vapor pressure

Suction pressure, maximum suction pressure, and vapor pressure are all items that the CUSTOMER specifies to the pump vendor. It's not up to the pump vendor to decide what you are pumping and how.

I suggest you review whatever data was supplied to the vendor in the first place.

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