Pump Issues...

OK folks, I need some advice – especially you engineer type…

For background – I have a single tier, reticulating HERMS setup with 2-SS chugger pumps (the newer ones with the larger impeller)…

The problem – The pumps work fine. However, on occasion (sometimes frequently) the pumps start to make a whining noise and sometimes it’s a downright load screeching noise. These is alleviated by turning the pump off and then back on again…its fine for 5 or 10 minutes, but then it does it again…This is fairly bothersome in that I can’t leave the brew rig un-attended to do other things.

A few notes:
• I do prime them after I switch the hosing around
• I notice this at all stage of pumping (recirculation mash, sparge, whirl pooling the boil, etc.).
• It is especially bad after I have added whirfloc during the last 10 minutes (and whirl pooling at the same time)

Pictures:
Photo #1 is standing in front of the rig, looking directly at the pump
Photo #2 is standing over the rig, looking down at the pump

An engineer friend of mine said that if you have a 90 degree turn just prior to the pump you will get cavitation. What do you think is going on???

This is not a disaster….just a little irritated….

I've seen (and heard) this first hand at the brewpub I briefly worked at.

It's a "boil cavitation". There's steam in there that gets trapped and it creates cavitation. The solution is to:

1) open the valve on the in side of the pump fully
2) close the valve on the out side of the pump slightly, creating back pressure. (in other words, throttle back on the output side of the pump)

This back pressure will increase the boiling point of the wort (PV=nRT...) and will prevent steam from being created in the pump.

MC

Thanks MC - I will give that a try during my next brew day. I am pretty sure I did that the last time, but still had the issue...I'll pay more attention next time.

I have had really good luck with having my pump head inlet at the 6 o'clock position and the outlet at the 12 o'clock position. I have a burp valve as well right after my outlet. Makes priming really easy.