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 radiator 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 477 Mark V - Accuracy .5% of Full Scale.  Range 0-20.00 PSI range, Resolution .01 PSI
• King Instruments 7520 Series 0-5GPM, 250mm scale - Accuracy 2% of Full Scale.  Range 0-5GPM, Resolution .1 GPM (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 my results are as follows, the pressure drop results are very very good!

And if you're not familiar with what this means, I'm providing a relative chart below comparing a few other published and tested curves to the acquired results.  Keep in mind these comparison curves were based on other testing facilities, so there could be some error in different test beds but pressure drop is generally a fairly repeatable test if good equipment is used.  The XSPC RS240 is right near the bottom of the group, it is the best flowing of the single row tube style radiators, very nice.  Upon careful inspection of the interior from what I can see, these radiators flare the tube ends more than others and this reduces entrances losses which helps lower pressure drop, very nice! This will allow you to maximize your system flow rates for excellent thermal efficiency in your water blocks.  This is yet another great product from XSPC with bottom line performance.

Cost Comparison

So another important consideration with most people is cost.  For a fair cost comparison, I chose the good folks at watercoolingshop.com since they carry both the XSPC and Thermochill PA series radiators.  

At watercoolingshop.com the prices were including VAT as of 4-10-2008

XSPC RS240 = UV Blue £25.99 (Black = £23.99)
Thermochill A120.2 = £49.99
HWlabs BI GTS240 = £30.98

So in terms of cost using the black RS240, you can save 23% over a GTS 240 radiator and 52% less than a Thermochill PA120.2, that's a great price!

Thermal Testing Link

Since I'm not quite set up yet for thermal testing radiators, I'm going to provide a link Tw1st3d provided me, thanks!  It's a comparison of the XSPC RS320 to that of a HWlabs BIP360 and the XSPC performed better than the HWlabs radiator by 2-3 degrees, that's great!!

Xtremecomputing's XSPC 360 vs Hwlabs BIP 360 thermal test comparison.