Author Topic: Propylene glycol (RV antifreeze) (Read 13843 times)

zahc · « **Reply #25 on:** September 20, 2011, 07:06:49 PM »

Ok, in the freezer there is a block of ice with a coil of copper pipe embedded in it. From the coil, the hose runs out of the freezer, through the heat exchanger which cools my fermentation chamber. The heat exchanger consists of the waterblock I used to use for my computer's water-cooling, which has a CPU heatsink/fan bolted to it. After it goes through the heat exchanger it just discharges into a small tank made out of a juice bottle. In the juice bottle tank, I have a submersible fountain pump, that pumps the liquid back out to the coil in the freezer. It's closed loop. The coolant does not run out. It does not come in anywhere, and it doesn't run out anywhere. That's what I call closed loop. But it's not sealed, it's vented.

Anyway, according to DOW's tables and my hydrometer, my RV antifreeze is 50% propylene glycol, assuming that and water are the only ingredients. Which still surprises me that it slushed, but it did. My freezer must be turned down pretty low. Right now I have 50% ethanol, 50% Vodka, and 25% vodka and glycol solutions in the freezer to experiment.

280plus · « **Reply #26 on:** September 20, 2011, 07:32:25 PM »

They need an olive...

Doggy Daddy · « **Reply #27 on:** September 21, 2011, 08:43:25 AM »

Quote from: 280plus on September 20, 2011, 07:32:25 PM

They need an olive...

DD

zahc · « **Reply #28 on:** September 21, 2011, 11:45:33 AM »

Ok I'm confused.

The 50% ethanol/RV antifreeze did not slush, but the 50% vodka and RV antifreeze slushed. Everclear is like $15 for a small bottle. I'm about to give up on the food-grade bit and use isopropyl. I have no idea how cold my freezer is but I'm thinking it might be a bit low. Isn't 0F the usual target?

280plus · « **Reply #29 on:** September 21, 2011, 12:52:16 PM »

you should be able to adjust the freezer temp? Sounds like a good thermometer is in order to see what you've got in there and then as long as the thermostat for the fridge/freezer is working correctly you should be able to raise the box temp. My first guess would be your fridge is running constantly. My next guess would be the vodka has water in it which diluted the RV stuff. I'd avoid alcohol altogether if it was me. Flammability issues for one thing. What about a salt brine?

Balog · « **Reply #30 on:** September 21, 2011, 12:54:05 PM »

Or just go air cooled. Run it through a few heat sinks with fans instead of the freezer.

RaspberrySurprise · « **Reply #31 on:** September 21, 2011, 01:18:45 PM »

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Is there anything else I could use? I didn't want to use car antifreeze because of the whole kidney failure thing

I'm confused about this, isn't the idea that the coolant shouldn't be mixing with your beer anyways? Or anything else for that matter?

zahc · « **Reply #32 on:** September 21, 2011, 02:06:23 PM »

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you should be able to adjust the freezer temp? Sounds like a good thermometer is in order to see what you've got in there

I have plenty of adjustment on the freezer, so that's a good idea. For all I know it's -20F and I can just turn it up to 0F and the problem will go away.

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Or just go air cooled. Run it through a few heat sinks with fans instead of the freezer.

The house is 80F. There's no way to cool down to 60F, no matter how many heatsinks you use. Although if you figured that one out, you'd be pretty famous.

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isn't the idea that the coolant shouldn't be mixing with your beer anyways? Or anything else for that matter?

It shouldn't be mixing with anything, but if I sprung a leak, I would rather not have to throw out all the food in my freezer, which I would probably do if I dumped a bunch of car antifreeze in there. I also don't think the pump will last very long pumping alcohol. I think I need to find some pure propylene glycol and mix it up stronger than 50%.

zxcvbob · « **Reply #33 on:** September 21, 2011, 02:29:16 PM »

How many times do I have to mention non-toxic car antifreeze? (if you don't want to use it, that's fine. Just consider it) Maybe that's too easy...

Jim147 · « **Reply #34 on:** September 21, 2011, 02:37:43 PM »

Your freezer evaporator temp is going to be close to -20Â°. If you can adjust it up and not get it short cycling that might work.

Salt brine will get you about -6Â° at a perfect mix of 23.3%.

If you can't get straight propylene glycol get 60%. That's what you would need to mix the straight stuff to if you get it.

jim

280plus · « **Reply #35 on:** September 21, 2011, 02:58:13 PM »

To the best of my knowledge you can only get 100% glycol in the can in places like Alaska etc. Anything sold in the lower 48 is already mixed down but the question is always "by how much?" which you need to determine before you go adding water. I learned this the hard way.

What i would do is with the freezer/fridge running SLOWLY turn back the t'stat till it just clicks off. Wait a day or so, and see where you're at after that. From that point you should only make like 1/2 number adjustments to tweak it in to where you want it. Always waiting at least a day between adjustments. Good fridge tweaking takes time.

Scout26 · « **Reply #36 on:** September 21, 2011, 03:10:16 PM »

I'm going to go for two in row here and say "Buy a thermometer and put it in your freezer"

WINNING !!!!

zahc · « **Reply #37 on:** September 21, 2011, 03:42:16 PM »

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How many times do I have to mention non-toxic car antifreeze? (if you don't want to use it, that's fine. Just consider it) Maybe that's too easy...

Isn't non-toxic car antifreeze just propylene glycol? I would assume the car antifreeze is pre-mixed with water the same as RV antifreeze, but maybe not.

280plus · « **Reply #38 on:** September 21, 2011, 04:05:44 PM »

I repeat, they are ALL premixed with some water. Unless you live in Alaska. the question is, how much water. Each brand will differ.

birdman · « **Reply #39 on:** September 21, 2011, 05:37:33 PM »

Propylene glycol isn't really non-toxic, it's "less toxic". Also, it degrades much faster with exposure to air (as in your open loop system), and can be biologically fouled...so I would either use alcohol (methanol or ethanol) or normal toxic ethylene glycol.

Vodka-antifreeze will likely perform worse than water-antifreeze (as you found out).

I would suggest just buy the prediluted pristine 50/50, which should get you down to -30F

Or, if you want get the non diluted "prestone extended life" coolant (95% ethylene glycol, balance diethylene glycol) and mix 7-3 with water to get the 70% solution which will give the lowest freezing point.
(msds for the non-diluted):
http://www.mightyautoparts.com/pdf/msds/vs7/af-888.pdf

From auto zone:
http://www.autozone.com/autozone/accessories/Prestone-Antifreeze-and-coolant?itemIdentifier=525501

Not prediluted with water.

Jim147 · « **Reply #40 on:** September 21, 2011, 05:48:52 PM »

Do you plan to run this pump all the time when you get it working?

If so, what about just picking up a little more heat before returning to the freezer. Maybe a few loops of copper picking up the 80Â° ambient of the house might keep it from slushing up.

Try a pool supply store for propylene glycol and see what they can get.

jim

zahc · « **Reply #41 on:** September 21, 2011, 05:53:32 PM »

I'm cycling the pump on and off to regulate the temperature of my fermentation chamber.

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Try a pool supply store for propylene glycol and see what they can get.

Good suggestion. I'm not sure it's really the season here in TX, though.

zxcvbob · « **Reply #42 on:** September 21, 2011, 05:59:57 PM »

Could you use kerosene instead of a water-based coolant?

Jim147 · « **Reply #43 on:** September 21, 2011, 07:08:56 PM »

I had to go run a service call and my mind went to work while driving.

Propylene Glycol/water solutions are not really recommended for what you are doing due to the fact that they do slush below freezing. The huge heat load of an internal combustion engine will clear out the slush pretty quick but you don't have near enough load.

What about glycerine?

jim

birdman · « **Reply #44 on:** September 21, 2011, 07:46:11 PM »

Quote from: Jim147 on September 21, 2011, 07:08:56 PM

I had to go run a service call and my mind went to work while driving.

Propylene Glycol/water solutions are not really recommended for what you are doing due to the fact that they do slush below freezing. The huge heat load of an internal combustion engine will clear out the slush pretty quick but you don't have near enough load.

What about glycerine?

jim

Good luck pumping glycerine at 0degF.

I'll say it again. Methanol or pure ethanol. And you can just go buy methanol. And if you can freeze that with your freezer....well, stop playing in the cryogenics lab.
If worried about leaks, put some dye in it.

Or...gasoline.

Jim147 · « **Reply #45 on:** September 22, 2011, 12:43:41 AM »

Does it jell up near 0Â°? I haven't used it at that temp but it is very slippery at room temp.

The ethyl and propylene glycol mix should work. Are you worried about needing to add more alcohol all the time due to evaporation?

Just putting this out there like the glycerine, maybe you could add some really light mineral oil to the mix and have it make a barrier over your sump to keep the alcohol in.

jim

birdman · « **Reply #46 on:** September 23, 2011, 09:52:30 AM »

Quote from: Jim147 on September 22, 2011, 12:43:41 AM

Does it jell up near 0Â°? I haven't used it at that temp but it is very slippery at room temp.

The ethyl and propylene glycol mix should work. Are you worried about needing to add more alcohol all the time due to evaporation?

Just putting this out there like the glycerine, maybe you could add some really light mineral oil to the mix and have it make a barrier over your sump to keep the alcohol in.

jim

Ethanol/glycol will slush more, at a higher temperature than an optimum mixture of water/glycol as the two alcohols don't have the same incompatible crystalline structure (the glycol will freeze out)

Mineral oil will dissolve in ethanol, so it won't make a layer (and it will freeze out). Even if it didn't dissolve, it wouldn't make a layer, as mineral oil (0.8g/cc) is denser than ethanol (0.789g/cc).

I STILL see no reason why pure (azeotrope) ethanol, or methanol isn't an obvious choice...both are readily available at low cost, can be easily dyed so you can detect leaks, and will not freeze at any temperatures your system can obtain, even right on the evaporator.

zahc · « **Reply #47 on:** September 23, 2011, 01:35:46 PM »

As I've pointed out, alcohol is flammable, and I assume that it will dissolve my $11 Harbor Freight fountain pump. I guess I'm not out that much if it does. But it could be easily diluted with water to take the flammability out...I know that in Ohio, they regularly use 25% methanol in water to load tractor tires. I assume that diluted that much, it's not too flammable.

birdman · « **Reply #48 on:** September 23, 2011, 06:11:24 PM »

Quote from: zahc on September 23, 2011, 01:35:46 PM

As I've pointed out, alcohol is flammable, and I assume that it will dissolve my $11 Harbor Freight fountain pump. I guess I'm not out that much if it does. But it could be easily diluted with water to take the flammability out...I know that in Ohio, they regularly use 25% methanol in water to load tractor tires. I assume that diluted that much, it's not too flammable.

Ah. The vapor will be flammable regardless of dilution. Hmm...low temperature non flammable coolants...that's a tough one actually.

zxcvbob · « **Reply #49 on:** September 23, 2011, 08:30:29 PM »

Quote from: birdman on September 23, 2011, 06:11:24 PM

Ah. The vapor will be flammable regardless of dilution. Hmm...low temperature non flammable coolants...that's a tough one actually.

Calcium chloride in water is good down to about -50Â°.

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Author Topic: Propylene glycol (RV antifreeze) (Read 13843 times)