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I just want to ask on how does 3000 rpm and 1700 rpm make a big difference in overall performance of pump motors?

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RPM isn't the main factor in noise, really. A Dremel can spin at 30,000 RPM and make less noise than my angle grinder at 8,000rpm. What really matters is the bearing types, the motor type (brushless? stepper?) and what the load is. For pumps, the impeller style might be different. In any case, we'll need more details. Do you have two products you're comparing? –  kavisiegel Dec 6 '13 at 9:43
    
You're asking two different questions here... Do you care about noise, or performance? –  Tester101 Dec 6 '13 at 14:37
    
In relation to what kind of pump? Big low RPM large diameter single impeller jet pump sitting topside isn't the same as a smaller diameter high RPM multi-impeller submersible intended to sit in the well casing 150' down. –  Fiasco Labs Jan 6 at 1:05

1 Answer 1

I think what you're really asking is, "how do I compare pumps"?

Pumps will have ratings, listed on the specifications sheet. I don't know what you're using this pump for, so I cannot steer you toward any specific product. However, I can tell you what I'd look for.

  1. Flow. There should be a flow or throughput measurement. In the United States, this is usually described in gallons per minute. Basically, it tells you how much water goes through the pump. For a well pump, this site recommends at least 10GPM for residential and 20GPM for light commercial buildings.

  2. Pressure. There will also be a pressure measurement. The US standard is pounds per square inch, or psi. Home plumbing systems need pressure of at least 10psi to successfully run a dishwasher or washing machine. You'll need higher pressure for other applications (for example, 40-60psi for residential sprinkler systems).

  3. Loudness. This is measured in decibels (dBA). These measures are relative; this chart shows some comparisons: 20 dBA is the volume of leaves rustling; 60 dBA for normal conversation; 110 dBA for a car horn; 140 dBA for fireworks. A lower decibel rating will mean a quieter pump.


As an aside, many times it is possible to build an insulated housing around a pump to lessen the noise produced. Just make sure you still have adequate ventilation so it does not overheat.

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Another consideration is that with higher RPM, a pump can start having cavitation problems in the impeller, leading to erosion of the materials. The higher RPM will probably be seen in submersible pumps that have smaller diameter impellers to keep the rim velocity down. –  Fiasco Labs Jan 6 at 1:03

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