William wrote:
Shouldnt the stand pipe be on the suction side of the pump?
Bill
Why?
Went back today after the RTV pump gasket had a chance to cure.
I changed to a lower ratio on the mill step pulley system and wonders
of wonders the pump ran at 4200 RPM without blowing the circuit breaker.
Exactly the same pump RPM with the higher ratio. Apparently
the mill motor was overloaded and slowed down by that much.
I could now shut off the system completely. 4200 RPM
GPM
Flow Press psi Valve
0 3 closed
25 1
35 0
45 0
55 0
65 0
75 0
off scale 0 wide open
I have no idea what the negative pressure was on the inlet side
of the pump as the gage was bottomed out. Will get a +/-
gage next week and rerun this test.
I then pressurize the system to 15 psi using the air compressor.
GPM
Flow Press psi Valve
0 18_17_6 closed
25 18_16_6
35 17_15_6
45 15_13_6
55 15_13_6
65 15_13_6
75 15_13_6
off scale 15_13_6 wide open.
Stoped: 14_14_14 psi. wide open.
Pressures are in order: pump outlet, after flow meter,
inlet side of the pump.
As you can see in a closed loop system at high flow rates
restrictors hardly affect the pressure at all. What is STRONGLY
affected is the flow rate.
There is a about a 6 to 8 psi pressure differential
across the pump however. I'll know more next week when
I get the +/- pressure gage for the inlet side.
BTW the pump got almost too hot to touch.
Paul Lamar
Paul,
On your pressurized system, it looks like the inlet guage stayed positive,
so the deltaP across the pump was about 12 psi at 4200 rpm.
I got about 8.5-9 psi at zero flow at 3730 rpm so these numbers seem to
correlate pretty good.
Be interesting to try a run at about 2500 rpm (2450) and see what the
delta-P is (using the pressurized system). Should be about 5 psi according
to my tests.
Your results also show that there must be a SUBSTANTIAL pressure drop across
the engine block, that restricts flows in the actual system.
Note that at zero flow, your closed loop test and my open loop test are
equivalent if pressures at the inlet and outlet are measured.
Bill
I think pressure measurements on the real system will be disappointing
as far as determining the GPH. This flow meter is a God send.
I can loan it to anyone willing to test their system.
Paul Lamar
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