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Bob,
Good to have some data. I have attached a crude sketch of how pumps (centrifugal) act when in Series or Parallel configuration. When is series, the pressures at any given flowrate add, when is parallel, the flows at any given pressure add.
The added factor to be considered is the load curve that you are working against. Where the load curve crosses the pump curve(s) is where the flow will stabilize.
It looks like your pumps are on the low side of pressure generation given the restrictions that you are asking them to pump through.
Bill Schertz
KIS Cruiser # 4045
Here is the raw data without any corrections for anything. Data is
Voltage, current, flow, and temperature. Temperature was measured with
a thermocouple on the output fitting on the engine just before the flow
meter.
Pump A Only:
13.8 V 8.2 A 5.75 GPM 56 F
12.0 V 6.8 A 4.5 GPM 56 F
13.0 V 7.7 A 5.25 GPM 56 F
14.0 V 8.4 A 6 GPM 56 F
14.5 V 8.8 A 6 GPM 56 F
Pump B Only:
14.5 V 9.6 A 5.75 GPM 56 F
14.0 V 9.1 A 6 GPM 56 F
14.5 V 9.5 A 6.25 GPM 56 F (The guage was sticking a bit)
13.0 V 8.3 A 5.5 GPM 56 F
12.0 V 7.5 A 5.25 GPM 56 F
Pumps A and B:
12.0 V 13.6 A 10.5 GPM 56 F
13.0 V 14.8 A 11 GPM 56 F
13.8 V 16.0 A 11.75 GPM 56 F
14.5 V 16.6 A 12.4 GPM 56 F
12.0 V 13.4 A 10.5 GPM 56 F
I tried to heat the water with a heat gun, and a 16,000 BTU space
heater. aimed at one of the radiators. After 15 minutes, there was
very little temperature change. It didn't look like I would get any
data at a significantly different temperature. There is just too much
mass to change temperature very much. (Without the engine running of
course.)
There is also a good possibility that the pumps in series will flow at
a higher rate. I will have to see about reconfiguring for that. Right
now, I'm not real pleased with these big AN fittings. Nothing fit
right. I ended up with a major mess of spaghetti where it was
difficult to get to all of the fittings. Next time, I will use the
reusable fittings and make them in place.
Rusty,
I will be very interested in your Craig-Davies experiment. It seems to
me that this flow rate is very marginal. I had considered using a
single Mezirie WP336, but thought having two pumps for redundency would
be preferable. Earlier I tested the unrestricted flow rate for one of
these pumps at 16 GPM using cold water. The only way it could meet
specifications would be to see an increase in flow at higher
temperatures.
Bob W.
-- http://www.bob-white.com
N93BD - Rotary Powered BD-4 (real soon)
Homepage: http://www.flyrotary.com/
Archive: http://lancaironline.net/lists/flyrotary/List.html
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