Pump shop performance test

[qualitypro]

I have a question on a suppliers shop test performed. The order called for a electric driven firewater pump with a 125 HP/1765 RPM motor to meet the design conditions. The supplier states that he used a 200HP/3500 RPM motor to test the pump in the shop and that it passed the performance test without giving any further information other than the pump curves. Is it possible to perform such a test with an overdesigned motor rating? how good is the pump after this testing?

 

[ScottyUK]

If the pump was tested at twice rated speed then I can't imagine that the test is meaningful, and it's surprising that the 200 HP motor was big enough to drive the pump at twice normal speed unless the 125 HP motor is ludicrously over-sized. While it would be possible to use a VSD to lower the speed of the 200 HP motor to 1765 rpm, the motor won't deliver 125 HP at that speed (or it won't for long, ha-ha) - it will de-rated to 100 HP at 1750 rpm.

The information reported to you is at best incomplete. At worst, well...

 

[waross]

A pump that takes 125 HP at 1765 RPM will require 500 HP at 3530 RPM.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

It isn't possible that he ran the pump to 3500rpm using a 200hp, 3500rpm motor. So, his 200hp motor was either capable of running it at 1765rpm or he ran it up to the limit of the motor (some speed below 1765rpm) and extrapolated the curve to the rated pump speed. So, ask him what he did exactly.

 

[qualitypro]

Thanks ScottyUK, Waross & LionelHutz. The supplier was questioned on more details on the test performed and came back with a correction that the lab report provided by his sub was incorrect and that a 200HP motor was not used as stated before. The motor used during performance test was 500 hp, 3/60/460V, 1782 RPM. The hp was controlled by a variable frequency drive during the test. This is just confusing.