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Author Topic: Question circulating glycol  (Read 1009 times)

Offline hmbrewing

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  • Posts: 78
Question circulating glycol
« on: November 09, 2018, 10:48:45 am »
Greetings!

I'm setting up a new chilling/heating system for my conicals. I have a cooling jacket for cooling and I would like to circulate a mixture of 30% Propylene glycol mixed with 70% distilled water. My setup includes a mini fridge that would have a container with this glycol/water mix and a cheap submersible pump. Fridge keeps everything nice and cold and the pond pump circulates water through the cooling jacket and back into the container. Gotta Brew (the peeps I purchased the cooling jacket from) specifically stated that glycol and submersible pumps may not go well together - but no reason why. Anyone have any experience circulating glycol through a submersible pump? Should I just go with straight water? Thanks!
I brew beer, I drink beer...it really is that simple

Offline TeeDubb

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  • San Jose, CA
Re: Question circulating glycol
« Reply #1 on: November 09, 2018, 01:58:03 pm »
Its simply a material compatibility issue. But you would have to know what the pump is made from (everything the liquid touches) to make an assessment.  If things do degrade, the pump would likely leak internally and fail or the housing and impeller may start to dissolve.  As an example, if the pump is made from PVC, it would not last long.

http://sevierlab.vet.cornell.edu/resources/Chemical-Resistance-Chart-Detail.pdf

So you don't waste gallons of glycol, you could submerge the pump in a sample of glycol for a few weeks and watch for changes, degradation. Or find a suitable pump.

Offline TeeDubb

  • Assistant Brewer
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  • Posts: 117
  • San Jose, CA
Re: Question circulating glycol
« Reply #2 on: November 09, 2018, 04:04:34 pm »
One other thing: there is also the matter of viscosity. A pump designed to lift or pump water may not perform the same for a more viscous fluid like PGW.  You have to consider the concentration and temperature.

Offline hmbrewing

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Re: Question circulating glycol
« Reply #3 on: November 09, 2018, 07:33:10 pm »
Got it. That all makes sense. I think I'll use straight H2O to be safe. Especially on the first few brews. I may get more daring later on. Thanks for the info!
I brew beer, I drink beer...it really is that simple