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bwana · 09-06-2004, 09:52 PM

There is MUCH qualitative talk about flow rate, but I have not yet found 1 post where that number is actually measured in a closed loop.

Given that magnetic pumps will vary the flow depending on back pressure, it's impossible to calculate the flow rate without first measuring the resistance of a loop (to do that, the loop has to be open anyways)

One way to measure flow rate would be to calculate it from the temperature difference of the water before and after it passes over the cpu. sincethe heat output of the cpu is known and the heat transferred to the water is measurable, the flow rate could be calculated. One could use one of those laser thingees that measure temp. Shoot the tygon before and after the cpu and presto. Trouble is, i dont have one of those thingees.

A more elegant method might be by light scatterring. Without going into the physics of it, the analogy would be the same way an optical mouse measures velocity.

Come to think of it, has anyone used an optical mouse to measure water velocity in their loop? Since the cross sectional area of the tube is known, flow can be calculated.

I really would like to know what is the actual number - how many gpm will a d4 pump through a tdx and a bonne with 6 feet of 1/2 inch tygon?

09-06-2004, 09:52 PM	#1
bwana Cooling Neophyte Join Date: Sep 2004 Location: us Posts: 9	a measurement of flow rate? There is MUCH qualitative talk about flow rate, but I have not yet found 1 post where that number is actually measured in a closed loop. Given that magnetic pumps will vary the flow depending on back pressure, it's impossible to calculate the flow rate without first measuring the resistance of a loop (to do that, the loop has to be open anyways) One way to measure flow rate would be to calculate it from the temperature difference of the water before and after it passes over the cpu. sincethe heat output of the cpu is known and the heat transferred to the water is measurable, the flow rate could be calculated. One could use one of those laser thingees that measure temp. Shoot the tygon before and after the cpu and presto. Trouble is, i dont have one of those thingees. A more elegant method might be by light scatterring. Without going into the physics of it, the analogy would be the same way an optical mouse measures velocity. Come to think of it, has anyone used an optical mouse to measure water velocity in their loop? Since the cross sectional area of the tube is known, flow can be calculated. I really would like to know what is the actual number - how many gpm will a d4 pump through a tdx and a bonne with 6 feet of 1/2 inch tygon?