I reinstalled the 6" pulley and set up the flow system to pump through

my

evaporator cores plumbed in parallel.  Pictures are attached.

I borrowed a optical digital tach to measure the actual pump rpm,

however

this created an unusual opportunity.  It works by counting pulses, and

the

flourescent lights give a reading of 3600 rpm due to the 60 cycle

current.

Therefore to measure the rpm, I had to run it in total darkness with a
flashlight illuminating the pulley.  I used two strips of foil on the

pulley

to reflect light pulses back to the tach.  The pump rpm with a 6" pulley

on

the 3450 rpm motor was 5160 RPM.

I then plumbed my evaporator cores in parallel as shown in "Parallel

cores"

photo.  These were hooked to the pump outlet, and full flow tests were
performed.

Motor RPM = 3450
Pump RPM = 5160
Pressure generated at no flow = ~20 psi
Pressure generated at full flow, no evaporator cores in line = 2.5 psi
Pressure with cores in place = 8 psi
Time to fill 5.8 gallons = 14-15 seconds (flowing through rads) = 23-25
gallons per minute.
Current on ammeter = 13 amps = 1560 watts

2.1 HP in ? Are you sure you have that amp meter set right?

Interestingly, the current on the motor with no load (i.e. only spinning
itself) was ~10 amps, which I don't understand. Can someone who knows

more

about motors help expain that?

Bill Schertz
KIS Cruiser #4045

Bill - you are doing great work in this pump testing (but what else would
I expect). Power measurements on a ac motor with current and voltage
is frequently very misleading because of "power factor" effects
ie phase shift due to the inductive nature of the motor. You will
almost always compute higher than actual. If you could get an
actual wattmeter it would be better, but they are not too common.
A DC motor would be a good option - actually many saw and most
router motors can be run on DC (just do not stall them or
they will quickly burn up) - Vance

An old starter motor would be a good choice with up to 300 amps for
short periods of time. 11 volts at 300 amps 3300 watts 4.4 HP.

The problem is getting the power out. I'll machine a hub for 
a V belt pulley Bill if you come up with a starter motor.
With all that torque available something like a two to one 
drive might be fine.

Paul Lamar
 
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