% of Glycol to Water

[Dfitz]

I'll temporarily be using my fermentation freezer to chill a drum of water/ propylene grycol mixture and run it through my new conical's coil to hold temps and crash cool when ready. I plan to fill the drum with approx. 8 gal. total. From what I've read this will take a glycol ratiio of 32%. I'm understanding this to be 2.5 gal. of glycol to 5 gal of water. This seems a bit heavy to me. Am I incorrect in this interpretation?

 

[getack]

What does the instructions on the bottle say?

 

[getack]

I just had a thought about this.

Literally the only reason why propylene/ethylene glycol is added to water is to lower the freezing point and possibly increase the boiling point. This is why it's added to water in a car's cooling circuit.

Water has by far the best thermal heat capacity of most substances that we can easily get our hands on. This means water is extremely good at transporting heat. Adding anything to water (such as glycol) will actually reduce it's ability to hold, and thus transport heat.

I think you are not in danger of anything freezing in your system. You have an 8 gal drum in the freezer with presumably a pump circulating water though a stainless coil in your conical fermentor. So you are constantly moving the water and introducing heat into the system. I'm not sure how commercial glycol chillers are supposed to work but I assume you are not supposed to pump freezing liquid through your beer to bring down the temperature.

Also, If you use ethylene glycol and you spring a leak in your beer and you don't realize it, you and all your loved ones drinking your beer is dead. If you spring a leak and spill some on the floor and you don't realize it, all your pets will be dead.

If you are still concerned about your system freezing for whatever reason, just add some salt or dump a thing of vodka into the drum. Same results. Probably cheaper and less unknown chemicals brought into close proximity to your beer.

 

[getack]

I just re-read your post and noted you actually mentioned using propylene glycol.
You can ignore my stuff about killing people because PG is pretty benign.

Not so sure about whatever else they add to it like dyes, corrosion inhibitors and so on...

 

[IslandLizard]

I'd say a Google search should yield a useful table of dilutions and associated lowered freezing points.

If you keep your fermentation chamber's controller set for say 30F, you would only need to drop the freezing temps of the water/propylene glycol mixture to 10F. That gives you 20°F leeway before the drum content starts to get slushy or solid. It should never reach that point unless your controller fails. Best is to have the controller's sensor measure the temp of your glycol mixture in the drum.

 

[Dfitz]

The main issue I find in not using glycol to maintain say 67F is the tendency for lines to freeze during the circulation down time. Say I'm cooling my hex fluid to 45F to maintain a decent medium, if I put the probe in my hex this will cause lines to freeze. Adding glycol will prevent this freezing. I realize I really don't need a 30% mixture to prevent freezing in this regard but when it comes time to crash to 35F it likely will be necessary. I understand the loss I'll suffer adding too much glycol however, lines freezing during cycling would be a worse condition than a loss in thermal temp. The instructions say 32% is optimum but also have several amounst and temps above and below this percentage. I guess a little trial and error will be necessary.