Propylene glycol (RV antifreeze)

[Shockerengr]

I still think that propylene glycol will work if I mix it up stronger. I just don't know where to buy it locally.

If you can get pure propylene glycol, you can mix it such that it won't slush.

I use it in a chiller system at a local brewery to prevent ice on the evaporator.

 

[lowcountryjeff]

Chemical Engineer here. Here's some info on PG. First, when it's food grade, it is 100% non-toxic. You can drink it, bathe in it, mix it with your food, even atomize it and breathe it in and it won't hurt you. Second - In a pure state, it freezes (or melts for that matter) at -74 F. No more, no less. As you add water, that temperature goes up.

Here are some other data points, First is the Temperature (in degrees F), the second is the % PG (the rest is water):
-60F/60%; -50F/57%; -40F/54%; -30F/50%; -20F/46%; -10F/42%; 0F/36%.

Where it gets confusing, is that often PG mixtures (especially for RV Antifreeze) will list "Burst Protection". All this means is that it will freeze, but won't expand enough to burst a copper pipe. Per the Dowfrost Information Sheet (where I'm getting all this data), a -50 F "burst protection" requires 35% PG. As you look at the freeze protection (above), you see this mixture will freeze right around 0F - so it won't work as a circulating heat transfer fluid (at the temperatures you desire).

So what should you do? What I would do is buy pure PG and mix it 50/50 with water. So where do you get pure PG? Best bet (as mentioned by a previous writer) would be an animal supply store, such as Tractor Supply. They have the Ideal brand for $20 per gallon. I THINK it's pure (but could not read their label online). I would ask. Amazon is always an alternative, although a quick search gave me a price of $37 per gallon. Could you mix it with RV Antifreeze to "richen up" the RV Antifreeze? Sure, but one final warning about RV Antifreeze, sometime is includes Ethanol. Not harmful, but not as benign as PG. (Essentially, Ethanol is Grain Alcohol.)

I hope that helps!

 

[packet]

Call your nearest tractor/farm supply. It's not going to be "food grade" or "USP grade" (then, neither is RV antifreeze).

It is used to prevent ketosis in cattle/goats.

Any vet supply place online should have it. It's 100% pure propylene glycol and is food grade. I think mine was ~$20/gallon.

 

[BucknerBrauhaus]

Any vet supply place online should have it. It's 100% pure propylene glycol and is food grade. I think mine was ~$20/gallon.

I'll second this -- I use it for cutting nicotine for use in electronic cigarettes.
I haven't gotten dead from it yet (nor have I developed ketosis :cross

It is USP and about $20 per gallon from the local tractor supply store.

 

[fpweeks]

Subbed. I'm just wrapping up my DIY glycol chiller build and am trying to figure out what and at what mixture to use! This is useful info.

 

[WPStrassburg]

Attached is the Dowfrost data sheet with the freeze point chart for different solution percentages. If you are getting pure PG from the feed store then the numbers should be similar, but if someone can post up a brand I can double check. If you are using an ac or true chiller then shoot for 15* lower freeze point than what the refrigeration system suction is designed for to give a proper safety margin. So if you have your chiller set for a 25* suction use a 30% pg solution to give you a freeze point of 9.2*F. If you have a vat in your freezer that can get down to -10/-15* then go with something in the 45-50% range. If it's a vat in your freezer you can go a bit closer to the freezer temp compared to the 15* difference you need with a chiller. This stuff starts getting thick as the % solution goes up so keep that in mind when selecting a pump to circulate it.

View attachment Dowfrost.pdf

 

[bluelakebrewing]

Sub

 

[bschot]

Scribed

 

[jleiii]

I just checked Tractor Supply, and they have a no name brand of PG 'full strength" for under $4 per gallon, store only. I which I had time to go there before the pending blizzardmageddon or whatever you want to call it, and before they realize the price is wrong, or so it seems. I did not find this last time I looked.

I'm still up in the air over my final design, but PG is a critical part. I picked up mini radiators used on CPUs (and more) that will mount to my 4" box fans I already have in my 4 chamber heated fermentation cabinet. I bought a generic transmission cooler that will mount 2 more 4" fans that will go in the bottom of the cooler. I also got surplus diaphragm type water pumps to circulate the coolant.

Already have 4 ST1000 controllers set up for heating, and will tweak them to drive the waterpumps and, via relay, the cooler fans.

Great plan, now I just hope it all works as expected.

Getting Lager fermenting temps should be no issue with the cooler temp around 35F, but not gonna get lagering temps this way. The cooler is actually a mini chest freezer (Redi Whip display case) so I can bring it down to zero no problem, but then it's a dedicated freezer, and not sure I need that capacity otherwise. Although if I do dedicate this as a freezer then I can skip the cooler fan and 'trans cooler' and just have a 10 gal reservoir at around 0F and use that for wort cooling too. It pains me greatly to use excess water for wort cooling, and this would eliminate that entirely. 10 gallons of PG at this price is much more affordable than I had found recently.
Decisions, decisions......


John

 

[Stealthcruiser]

Don't let a little snow stop ya'.............Go get it......NOW!......

 

[jleiii]

Don't let a little snow stop ya'.............Go get it......NOW!......

I'll take my chances the price will last till the weekend. 5" so far, more to come then a high of 17 for tomorrow. Probably nothing more than a dusting for some folks!

Here are the key parts.

 

[jleiii]

I found that I had a gallon of -50 marine antifreeze left over from boat winterization at put it on the porch 2 nights ago. Went down to the single digits and it was solid slush in the morning. I doubt any small pump could move it.
I'm a lot less confidant that this is a good solution for DIY cooling except for "normal" temp control .
I wanted to use it for lagering down to 32 in my fermentation cabinet, and not sure its going to work now. Never realized that it slushes up above zero.
John