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Since87 · 11-13-2002, 12:36 PM

I did some pump power consumption testing last night and posted the results in a somwhat lengthy and heated thread over at oc-forums.

Anyway, I'll quickly sum up here.

The test I did, was to measure the power consumption of my Danner Mag5 pump with a Radian Research RD-21. I did this test with unrestricted flow and restricted flow. Unrestricted was a few feet of half inch ID tubing. Restricted was with the tubing pinched off as tight as I could with my fingers after taking multiple pictures with the tubing pinched in one hand and a crappy digital camera in the other. OMG I can hear the soapbox being dragged out...

I measured simultaneously:
The voltage applied to the pump.
The current through the pump.
And the power consumed by the pump.

I had previously measured the winding resistance of the pump at 14.1 Ohms.

I got the following results.

In the unrestricted case with 123 Volts connected to the pump:
The current was 0.801 Amps.
The power consumption was 35.3 Watts.

In the restricted case with 123 Volts connected to the pump:
The current was 0.757 Amps.
The power consumption was 24.6 Watts.

This surprised me, because I would have expected the pump to consume more power with its output restricted. (Although, I had seen hints at this with cruder testing earlier.)

The pump's efficiency definitely went down with restriction due to the power consumption in the winding resistance.

Unrestricted:
Presistive = I^2 * R = 0.801 * 0.801 *14.1 = 9.05 Watts.
R-Waste-Ratio = Presistive / Ptotal = 9.05 / 35.3 = 26%

Restricted:
Presistive = 8.08 Watts.
R-Waste-Ratio = 33%

I don't have a good explanation for the overall drop in power consumption with restriction though. Anyone know?

11-13-2002, 12:36 PM	#1
Since87 Pro/Guru - Uber Mod Join Date: Sep 2002 Location: Indiana Posts: 834	Pump power consumption with restiction. I did some pump power consumption testing last night and posted the results in a somwhat lengthy and heated thread over at oc-forums. Anyway, I'll quickly sum up here. The test I did, was to measure the power consumption of my Danner Mag5 pump with a Radian Research RD-21. I did this test with unrestricted flow and restricted flow. Unrestricted was a few feet of half inch ID tubing. Restricted was with the tubing pinched off as tight as I could with my fingers after taking multiple pictures with the tubing pinched in one hand and a crappy digital camera in the other. OMG I can hear the soapbox being dragged out... I measured simultaneously: The voltage applied to the pump. The current through the pump. And the power consumed by the pump. I had previously measured the winding resistance of the pump at 14.1 Ohms. I got the following results. In the unrestricted case with 123 Volts connected to the pump: The current was 0.801 Amps. The power consumption was 35.3 Watts. In the restricted case with 123 Volts connected to the pump: The current was 0.757 Amps. The power consumption was 24.6 Watts. This surprised me, because I would have expected the pump to consume more power with its output restricted. (Although, I had seen hints at this with cruder testing earlier.) The pump's efficiency definitely went down with restriction due to the power consumption in the winding resistance. Unrestricted: Presistive = I^2 * R = 0.801 * 0.801 *14.1 = 9.05 Watts. R-Waste-Ratio = Presistive / Ptotal = 9.05 / 35.3 = 26% Restricted: Presistive = 8.08 Watts. R-Waste-Ratio = 33% I don't have a good explanation for the overall drop in power consumption with restriction though. Anyone know?