2 identical pumps in parallel - same efficiency? 2

[paracetamol]

Hi all,

If one pump has a hydraulic efficiency of 85% at BEP, do two of the same pumps running in parallel also have an 85% efficiency?

Now say the two pumps are each running at 120% of the BEP flow, how do I find the resulting efficiency?

Any help is appreciated.

 

[LittleInch]

If they are doing the same flow rate they Yes.
When running two centrifugal pumps instead of one, you rarely get double the flow. Hence you won't be at BEP.
No flow data so can't say.

To find the efficiency you look at the pump curve. If say BEP is 80%, at 120% of BEP I would expect somewhere between 65 to 75% efficiency.

Each pump is different.

PS - What's with the purple text? It's giving me a head ache...

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

 

[paracetamol]

Thank you for your reply Sorry about the purple text, trying the forum's features.

So is there a relationship between the %BEP flow and the efficiency?

So if BEP is 2000 m3/h and BEP efficiency = 80%. Is there a formula to approximate the efficiency for running the pump at 2400 m3/h (120% of BEP)?

Edit: Looking at the pump curve to find the efficiency no need for a formula.

 

[LittleInch]

Yup, No formula. Just curves.

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

 

[EdStainless]

The pump curve is half of your story.
It will give you head vs flow, eff, and power.
Then you need your system curve to figure out where the pump(s) will actually be operating.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[TenPenny]

It's a safe starting assumption that two pumps will be the same efficiency, but it will be affected by the pump condition / wear, etc, and also the motors. It really depends on what you are looking for, but as others have said, you really need to start with the pump curve, it will have the efficiencies on it.