[bobo5195]

Originally Posted by stev

Simple the DDC pump.

Know as the Danger Den DDC-12V or the Swiftech MCP350 12 VDC Pump.

See detailed and calibrated testing here ...
http://www.systemcooling.com/swiftech_mcp350-01.html

"... The rotor/impeller is the only moving part in the pump and since there is no rotating motor shaft there is no shaft seal to potentially leak. ... An electronically commutated 6-pole stator drives the pump rotor/impeller magnetically. ... In addition to producing a sinusoidal signal (instead of a square wave) to drive the stator coils, the controlling circuits also include a tachometer signal output and a variable speed input signal. "




• Nominal voltage: 12 VDC
• Operating voltage range: 6 to 13.2 VDC
• Nominal power (@ 12V): 8.3 W
• Nominal current (@ 12V): .69 A
• Nominal head (@ 12V): 13.05’ (5.7 PSI)
• Nominal flow (@ 12V): ~92 GPH (350 LPH)
• Connection size: 3/8” OD barb (10mm)
• Maximum working pressure: 22 PSI (1.5 Bar)
• Operating temperature range: Up to 140F (60C)
• Electrical connector: 4-pin Molex
• Weight: 7.3 oz (207 g)
• Noise (quiet room): 24~26 dBA @ 2’
• Motor type: Electronically commutated, brushless DC, spherical
• Pump MTBF*: 50,000 Hours

* Note: The 50,000 hr MTBF rating is based on Laing’s performance claims for their brushless DC motor with a lifetime in excess of 50,000 hours when operated at 12V. In addition, Laing has an extensive automated test program that measures total bearing wear on MCP350 pumps to further support their claims.

So, with the ceramic bearing, wear is not even noticable.

Magnetic bearings have the problem that they dont damp small vibrations very well so tolerences have to be larger making things less efficent.

One way to improve noise would be to increase efficentcy of the pump. Im figuring noise is caused by areas of cavitation in the pump so a pump of higher efficantcy would be better. Companies dont bother making these as its not really worth it for water pumps.

I researched this for a related project some time ago, about the only thing that reduces noise without costing loads of money is two flow exits. Apparently this has a large effect on perceived noise. It loses you about 5% efficentcy (mostly head as opposed to flow rate) but it works.