Arrrrrggg....Waterpump is LOUD!!!!

[Michael_Myers]

I just installed (almost) my watercooling system. Pump is busy pumping away right now. Water is flowing. Testing for leaks.....and this thing is LOUD. I was worried about the sound from the 120mm panflow fan. (had never heard one before)...

I even got a rheostat to control the power to the 120mm fan so I could turn it down. Now that I have heard it for the first time, I am NOT worried about it. I can barely hear it.
(that was before I turned the pump on)

The pump LITERALY drowns out the sound of the fan. This is not good. It is either one of two things. One: The air hasn't worked it's way out yet. It DID get more quiet, the more air I got out of the system,,,,,,,,but I seem to have hit a dead end there as no more air seems to be escaping. (I have tilted the resevoir and everything trying to get the air to bleed out.....that worked, but again, seems I've hit the wall there)

TWO: I picked up a cheap 140gph mag drive pump at the local pet store. I believe on the instruction sheet somewhere it said it was made by Danner........but on the box it said Pondmaster I believe.

Suggestions? Or links to QUIET water pumps. And is there A big temp difference in using inline pumps as opposed to submersible pumps........cause at this point the resevoir thing......although cool.....is giving me headaches because I can't tell if there is air trapped in there or not. Thanks. Sorry for the ramble. It's late.

(BUT AT LEAST IT IS NOT LEAKING:D :D )

[Badger]

That pump should be silent. You have cavitation which can be caused by air in the system or too much flow restiction.
Every centrifugal pump has a 'minimum-flow' value, if due to flow restriction the pump cannot deliver at least it's 'minimum flow' it will cavitate and produce the noise you're hearing.
This can be demonstraten by clamping the inlet or outlet tube, when the restriction becomes too great cavitation will occur.

[cjtune]

Yeah, pumps do make a lot of noise when there's air going through the impeller chamber or ir it's trapped in the gap between stator and rotor but frankly, the first time I ran my submersible, it was super silent. Maybe you got a defective unit whose shaft or bearing was mounted wrongly (eccentricity).

Pumps have a minimum inlet pressure requirement, not a miniumum flow requirement. You can constrict the outlet and the flow will drop but not cavitate. The static pressure at the inlet should must be higher than the vaporization pressure of water at const. temp after deducting the suction pressure the pump supplies. Normally for fish pumps this is not an issue as they are very weak compared to the industrial pumps that often suffer this. But of course, water will flow faster and static pressure will drop (Bernoulli principle) in constricted sections of tubing so try to rectify any of this.

[Badger]

Your right about the suction pressure, the correct term is NPSH (Net Pump Suction Head). However almost all centrifugal pumps also have a minimum flow requiremen below which cavitation will accur.
Just nip the outlet tube of your pump and wou will see for yourself.

Industrial pumps and piping systems are my living.

[Flash]

It's probably air in the pump. I had the same problem with a Danner pump and never could get the thing to quiet down. You might want to check an article at Procooling about sealing Danner pumps, as they tend to leak air and/or water without proper sealing.

[Bender]

Here (http://www.procooling.com/articles/html/magdrive_tips.shtml) is the link to the procooling article flash was talking about. I am thinking about doing the same thing with my Maxi-Jet 1200 since it is a very similar pump.

[Colin]

Don't forget to put clamps on all of the barbs. Air can sneak in without them.

You may be able to seal your pump with just a little silicone grease on the O ring. That's the way they are supposed to work although most of use seal them with silicone calking.

[cjtune]

Originally posted by Badger
Your right about the suction pressure, the correct term is NPSH (Net Pump Suction Head). However almost all centrifugal pumps also have a minimum flow requiremen below which cavitation will accur.
Just nip the outlet tube of your pump and wou will see for yourself.

Industrial pumps and piping systems are my living.

(Gives Badger the Mechanical Engineers handshake)

.....but it's not really a minimum flow rate thing. Neither is it the pump's fault. By mass conservation, the flowrate before, in, and after the constriction (the section you nipped) should be the same. But as these pose head losses to the pump, and actual flow rate will be smaller (depending on pump characteristic) than simple theory. As fluids flow faster, static pressure drops. If it drops enough or drops in an already low pressure region, cavitation will happen. Cavitation will make this worse as it reduces the net cross-sectional area and thus the fluid speeds up again. Valves can restrict flow rate of pumps but cavitation doesn't necessarily happen.