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what if pump shut off head is come in negative??

what if pump shut off head is come in negative??

what if pump shut off head is come in negative??

(OP)
I am running the pump at different RPM using VFD but at one condition my pump shut off head comes in negative how i can increase my pump shut off head??

RE: what if pump shut off head is come in negative??

Negative to what exactly? Can you sketch the pump curve? Why not just increase speed? I'm sorry but the question needs figures and data for it to make sense to a stranger.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

RE: what if pump shut off head is come in negative??

So you're drawing a vacuum with the discharge valve shut??

RE: what if pump shut off head is come in negative??

Perhaps like a water well pump that loses prime when suction flow is stopped.

Independent events are seldomly independent.

RE: what if pump shut off head is come in negative??

Aha, yes, a suction lift service. If so, then the problem is on the suction side (where most puzzling pump problems originate), and usharma007 needs to address NPSH issue or just don't slow down the pump to that point.

Of course a little bit of input from usharma007 would go a long way in solving the mystery.

RE: what if pump shut off head is come in negative??

Yes. Also maybe not enough suction flow to keep velocities high enough to sweep ingested air bubbles along, producing a vapor lock in the suction piping at a high point. At this point the possibilities are endless.

What's going on there usharma?

Independent events are seldomly independent.

RE: what if pump shut off head is come in negative??

Crystal balls a bit hazy today?

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.)

RE: what if pump shut off head is come in negative??

Weekend. Everything is a bit hazy today.

Independent events are seldomly independent.

RE: what if pump shut off head is come in negative??

I stand corrected....most pump problems don't originate on the suction side, they originate on the INLET side.....

RE: what if pump shut off head is come in negative??

Yes it is a bit hard to get away from suction side, suction lift, suction flow etc, of course this doesn't create any problems to those who understand what is meant not what is said.

Dictionaries don't seem to help - for interest just checked my "bible" of English language and guess what - "if something sucks a liquid, gas or object in a particular direction, it draws it there with a powerful force." seems we are losing on all fronts. Now considering an email to the publishers pointing out that the description could be / should be changed to correct the misinformation.

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.)

RE: what if pump shut off head is come in negative??

Why do you run pump at different speed?
What is your reason to do that?

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