Centrifugal Pump Questions

[Critt27]

Hello Everyone

I have a customer that has 2 7.5HP motors with centrifugal pumps connected to each. We have noticed that the flow rates have been not what we expected (lower). The one pump had a broken seal and upon fixing this we found the impeller was sized for a 5 HP motor. I would like to change the impellers of both pumps to 7.5 HP size but the customer is worried about the increase in the water taking ability may collapse the water intake that runs into a lake.

Is there anything I should be worried about?

 

[Artisi]

How did you establish that the impellers are for 5hp?

 

[chicopee]

get the manufacturer's pump performance curve to answer your questions. I am assuming that you have negative suction with a negative suction head of 24'(at best), so if you have steel piping with schedule 40,it is very unlikely you will collapse the pipe unless it is badly corroded.

 

[Critt27]

The pump guy that looked at the broken seal told me this... (I figured he measured and checked the curve??) he also thought it was very unlikely that we could collapse the pipe....this is a Low lift Pump which is pumping from the lake into a holding pond.

 

[Artisi]

Are you using steel pipe on the inlet?

 

[BigInch]

Are you looking for more flow or higher head?

You can change the impellers and still run at the same flow with a higher differential head, if you control the flowrate or the discharge pressure.

Find the new operating point to understand the significance of any changes you think you want to make.

"I think it would be a good idea."
- Mahatma Gandhi (1869-1948),
when asked about Western civilization