[july57]

I've been working on a water cooled build. As my room mate and I were bleeding the system, the pump started to rattle. We though it had caught some air. Way we ended up doing was loosening an extra plug on the discharge. A few drops of liquid came out, no air. I removed the pump from the loop and just made it pump water from the sink, no rattle and a lot of flow, good pressure. It looks cavitation to me. Any other thoughts? And how do we deal with it?

 

[Namkab]

You will get tiny air bubbles in the loop that will pass through pump and make noise for up to a day or two, its normal.

 

[july57]

I didn't sound like trapped air. It sounded like the impeller was rattling against the case. I added a potentiometer to the power cables leading to the pump. I did this to drop the speed of the pump. I dropped the voltage by about 1.5V and that took care of it. there is still plenty of flow and no damaging cavitation. The little bubbles cause a squeal in my pump (it's a Koolance 450s) not a rattle sound.
I wish i would have taken a video of the pump and the change in sound.

 

[Namkab]

Okay I gotcha now, I can see why you were concerned. I experienced the same thing with my D5s, they liked certain points in their RPM range over others.

 

[Cavi Mike]

I'm not sure you know what cavitation is because it sure isn't damaging unless you're in a sub trying to evade enemy detection.

Cavitation is simple really - the low-pressure area in front of the blades of the impeller cause the liquid water to become a gas. It doesn't damage anything and it will condense right back to a liquid shortly thereafter. It's not air and can't displace the water because it is water.

 

[Namkab]

Quote:

Originally Posted by Cavi Mike

I'm not sure you know what cavitation is because it sure isn't damaging unless you're in a sub trying to evade enemy detection.

Cavitation is simple really - the low-pressure area in front of the blades of the impeller cause the liquid water to become a gas. It doesn't damage anything and it will condense right back to a liquid shortly thereafter. It's not air and can't displace the water because it is water.

Spoiler: Warning: Spoiler!

Cavitation is not happening in these tiny little pumps....

 

[july57]

What can be causing the rattling? It was really sudden. There was no steady worsening just one minute everything was fine the next rattling. I haven't had the time to take it apart and check the impeller. But it still rattles if I remove the potentiometer