Pump rattle

[MN Jake]

We have a sihi 36 cfm pump and I'm curious if anyone else experiences a rattle of sorts above 26". It is not the brass check valve prior to the regulator. That makes its own sound. The rattling is coming from the pump itself and it's gone many days like that. Any thoughts?

[GeneralStark]

Sounds like the pump is cavitating and likely needs a little air. You have a tight tubing system. When my liquid ring pump gets to about 27" it starts to cavitate and it sounds like it is barking, or rattling as you describe. I plumbed in a T and a small ball valve into the line between the pump and releaser and crack it slightly to give the pump a little air and the sound goes away. Some use a vacuum regulator for the same purpose.

[MN Jake]

We do have a vacuum regulator. I was hoping nothing was wrong and it makes sense what your saying. We have 2 totes for cooling water that are connected at the bottom, intake water comes from one tank and exhaust goes in the other. Pump is just above tank level. Is there any reason to control intake with a valve or just let the pump freely take water?

[GeneralStark]

I have not used a sihi LR pump but it is a likely a good idea to be able to control the flow of water to the pump. This may affect cavitation as well. Hopefully someone with more experience with this pump will chime in.

[BCPP]

No maple experience and have not used this pump but have some experience with fluid pumps. If it is cavitation it is important that you resolve it immediately. Itwhat you hear is the shock wave from microscopic vacuum bubbles that are collapsing at the impeller. The shock waves will eventually destroy the impeller. So either you fix the cavitation or it fixes itself!

[MN Jake]

No maple experience and have not used this pump but have some experience with fluid pumps. If it is cavitation it is important that you resolve it immediately. Itwhat you hear is the shock wave from microscopic vacuum bubbles that are collapsing at the impeller. The shock waves will eventually destroy the impeller. So either you fix the cavitation or it fixes itself!
Thanks, waiting for a call from the dealer now to talk about your points.

[Mark]

What is your water temp?

[Brian]

I have 2 pumps that do that and is music to my ears, because I know my vac is High!!! I would not add air. it don't hurt the pumps at all. Let the pumps hammer!!! good job on the leaks. Make a lot of it.

[GeneralStark]

I have 2 pumps that do that and is music to my ears, because I know my vac is High!!! I would not add air. it don't hurt the pumps at all. Let the pumps hammer!!! good job on the leaks. Make a lot of it.

I have also been told by several folks that cavitation in LR pumps will not damage the pump...In other types of pumps, then that is a different story.