Yes, as you throttle down a pump, you have less water going through it, but
the motor is still pumping in power -- not as much as when you are letting
water flow and doing work on it, but still significant. The difference
between the power in, and the power put into the water by pumping it is
transformed to heat, raising the temperature of the water. This can cause
cavitation under some conditions, when you get to a suction pressure less
thant the vapor pressure of the fluid.
Bill Schertz
----- Original Message -----
From: <echristley@nc.rr.com>


> Forgive me for being slow here, but there are quite a few more lines on
this graph than I'm used to.  Does this graph say that as the head pressure
rises to 100ft, it raises the water temp by about 40 degree,and yet uses
nearly 10HP to do it?
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