Centrifugal Pump Design

No. The pump doesn't care. You wouldn't be able to measure any difference in output between the two speeds anyway.

What's the tolerance of the procurement specification?

Yes. In this case, the pump will rotate at 2960 RMM's not the slightly higher speed specified.

Define "difference". Did you mean different flow rate, pressure, head, speed, cost, convenience?

Look at the pump curve.

You look at the pump curve. Then tell me how you could possibly tell the difference in any performance value at 2960 and 2980 RPM. You can't!

It doesn't matter. It's 20 RPM, not 200.

Please read the question.

Don't order me to look at the pump curve. I don't have it. Yell at the OP if you nmeed to badger someone.

He asked whether there was a "difference". Obviously there is one. However, such difference may be insignificant depending on which of the many parameters are ranked.

whatever

The pump will operate at a lower pump curve, though the difference is only slight. If the process can tolerate the minor drop-off of performance, and if it can't then it isn't robust enough to the effects of minor process variations, then it doesn't matter a jot.

The small difference in speed would not normally be considered significant, at least so far as pump operation is concerned. However, this difference in speed may be associated with the efficiency of the motor. In that case, one of the motors might meet some efficiency criterion whereas the other might not.

1.337% drop in head developed. 2 % less hydraulic power. Not terribly significant in pump terms.

Refer to affinity law Q1/Q2 = N1/N2 and H1^2/H2^2 = N1^2/N2^2 and P1^2/P262 =N1^3/N2^3 Q is flow rate H is the head P is the power hope this will be helpful

regards

sorry i made a mistake so the equation regarding the head and power should be as the following H1/H2 = N2^2/N2^2 and P1/P2 = N1^3/N2^3

Technically "yes" is the answer.

The pump (for this matter centrifugal fan also) will follow affinity law which states

C is proportional to N,

H is proportional to N^2

P is proportional to N^3.

In your case C = (2960/2980) x Rated Capacity,

H = (2960/2980)^2 x Rated Head,

P = (2960/2980)^3 x Rated Power,

The ratio (2960/2980) = 0.9932 and hence reduction in the Capacity will be 1 - (0.9932) = 0.0067 and in terms of percentage it is 0.67% very negligible. In the same way you can calculate reduction in Head and Power demand.

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