Pump Capacity

[aida2011]

Hi all

I am wondering, if a pump is rated at 250 m3/h (40 m head, 40 kW motor), can it actually deliver 250 m3/h?

Thanks very much

Miss Aida Hanani
Plant Engineer

 

[JohnGP]

If a pump is rated by a manufacturer at 250m3/h at 40m head then it should be able to deliver 250m3/h. A 40kW motor seems feasible, but power requirement depends on the fluid being pumped and the pump efficiency at the operating point. You would need the applicable pump curve to check what the pump is actually capable of achieving.
Cheers,
John

 

[Artisi]

Yes, that is why it is rated as 250m3/h, providing the 250m3/h rating is at 40m total head, higher head will mean reduced flow while lower head will increase flow which is ok provided you don't exceed available motor capability and is within NPSHr requirements.
Why didn't you post a pump performance curve - removes all guess work.

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.)

 

[BigInch]

Yes. 40 kW rated motor power, allowing for 68% pump efficiency, will lift 250 m3/h of water to 40 meters.

I hate Windowz 8!!!!

 

[LittleInch]

Why are wondering? Do you have a pump which is not doing 250m3/hr?

As my learned other posters note above if everything is as it should be then yes it will pump / deliver 250m3/hr.

However a presumably centrifugal pump is a very flexible beast and in reality could pump anywhere from approx. 100 to 400m3/hr if the downstream system provides a different system curve compared to what it was designed to do. Centrifugal pumps are not fixed units of flow - the duty point or name plate is just the point at which the pump is close to its best efficiency point (BEP) and not much else.

My motto: Learn something new every day

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

 

[1gibson]

Only when installed in a system that allows it.

If system resistance is higher than 40m, then it will deliver less flow.
If system resistance is lower than 40m, it will deliver more flow.

The pump "can" deliver any flow on the curve. They system resistance determines the flow that the pump "may" deliver at any point in time.