Hydraulics and Pressure Drop Testing

The most scientific way to determine a blocks hydraulic resistance is to test pressure drop. Pressure drop is a measurement of pressure loss across a block that varies with flow rate.  This is basically a measurement of energy loss, and directly influences how much flow rate you will have.

Equipment:

• Dwyer Digital Manometer 475 Mark III - Accuracy .5% of Full Scale.  Range 0-200" W.C., Resolution .1" W.C.
• King Instruments 7520 Series 0-5GPM, 250mm scale - Accuracy 2% of Full Scale.  Range 0-5GPM, Resolution .1GPM (can be interpolated to .02GPM)
• Water Source - Household water pressure - 50PSI at >5GPM - Because flow rate readings are instantaneous, household tap water and water pressure are a good and powerful source for pressure drop testing.

And if you're not familiar with what this means, I'm providing a relative chart below with several CPU waterblocks.  For increased flow rates, the lower pressure drop results will net the best flow rate results.  This is important for users with multiple block loops, as you need to keep an eye on flow rate and make sure you don't install too many high restriction blocks in the same loop. Too much restriction could lower flow rate to the point where your other blocks or radiators in the same loop begin to loose some thermal efficiency.

The Aqua Computers Double Impact CPU water block is amongst the "High Restriction" grouping of water blocks.  In a CPU only loop, this higher restriction has little influence on the net temperature result, but it may create too much restriction for multiple block loops.  In general I would suggest a stronger pump to take full advantage of this higher restriction block.  Recent information is indicating that some of the high restriction/nozzle type blocks seem to benefit from additional pumping power and flow rate than we originally thought.  I would also suggest that you are very careful about multiple block loops and ensure you still have adequate flow rates.