Jeff Spitzer wrote:

In many cases of water pump power you will find that it's hard to make the
numbers add up.  I'll tell you why.  Most of the horsepower goes into the
bearings and seals.  If you do the math you find that 35-40 GPM at 15 psi
or whatever you think the loop drop is amounts to only fractional
horsepower.  Now take the pump in your hand and estimate the frictional
torque of the seals.  Now multiply that torque times 10K RPM or whatever
the pump is spinning.  You'll find that it amounts to more power.  If I had
to guess I'd say the pump itself uses around 1 hp and the seals and
bearings accounts for a couple more.

Jeff Spitzer

 
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