Corrosion inhibitors for ethylene glycol heat transfer fluid

[Dave Mount]

Kind of a wild shot, but thought someone here might know something. . .

In my spare time I am the icemaker (uncompensated) for the local curling club, which also means that I have responsibility for the ice plant, something I have zero qualifications for. All my learning has been on the job and from reading. The plant uses R22 freon as the refrigerant, but the fluid that circulates under the ice is 40% ethylene glycol. We have about 10 gallons a year of fluid loss from the system that I have to replace.

A local paint manufacturer uses pure ethylene glycol and buys in bulk, and is willing to sell us some at cost. However, this is ethylene glycol only, it does not contain the corrosion inhibitors/stabilizers that commercial heat transfer fluid has added.

I've not found any information on separate "add-in" corrosion inhibitors that would allow me to make the pure ethylene glycol into heat transfer fluid. I'm envisioning some little vial of the secret additives that I could add when I mix in the water (40 glycol/60 water in our case) and add it to the system. We use de-ionized water for the ice, so I have that to use for diluting the ethylene glycol.

Anyone able to provide some steerage?

Thanks.

Dave

[Kev Williams]

Here's one: https://onlinelibrary.wiley.com/doi/...ctb.5010091103

Here's another: https://www.hindawi.com/journals/ijc/2019/9020489/

--bear in mind I too am clueless about such science, so I hope these help!

[Bill Dufour]

What is there to corrode? I assume plastic pipes and tubing with a metal pump? They used to sell stuff to add to car cooling systems to rejuvenate the additives. Where is the water going. If it is evaporation the additives are still there. Be careful young children and animals who drink coolant die quickly and painfully. They only have to swallow a few ounces.
Maybe tie in a zinc to the metal.
Bill D.

https://www.amazon.com/Genuine-Ford-.../dp/B00BNVK208

[Lee Schierer]

First off I would be concerned where the "10 gallons per year" are going. If it is leaking into the ground it could become a serious health issue.

Is there any thing in the system that needs corrosion protection? Cast iron engines need it to prevent rust. What is the piping and other components in your system.

[Jamie Buxton]

Could you just use automotive antifreeze? Whatever it is nowadays, it does inside an engine exactly what you want: move heat from one place to another. And it has the anti-corrosion properties you want -- most engines still have a lot of iron and steel in them. Furthermore, you can buy it at any auto parts store.

[Bill Dufour]

Warning Will Robinson! if you are dumping 10 gallons a year into the ground water you will be caught and face massive fines. Abandoned gas station down the road from my brother bought the vacant lot across the street and downhill just so no one would dig there and find there oil plume.
Bil lD

[Frank Pratt]

Warning Will Robinson! if you are dumping 10 gallons a year into the ground water you will be caught and face massive fines. Abandoned gas station down the road from my brother bought the vacant lot across the street and downhill just so no one would dig there and find there oil plume.
Bil lD

A negative environmental assessment can render a valuable piece of real estate worthless because of the cleanup costs.

[Flamone LaChaud]

It's more likely a factor of evaporation out of the system if he's only losing 10 gallons per year from what is probably 100+gallon system. You have to realize that 40% ethylene glycol means that the other 60% is water . . . so just like your car's radiator needs to be refilled occasionally - so does this system. PC Watercooling enthusiasts make a similar mixture, and they have to top off monthly or else air gets into the system and causes issues.

[Lee Schierer]

It's more likely a factor of evaporation out of the system if he's only losing 10 gallons per year from what is probably 100+gallon system. You have to realize that 40% ethylene glycol means that the other 60% is water . . . so just like your car's radiator needs to be refilled occasionally - so does this system. PC Watercooling enthusiasts make a similar mixture, and they have to top off monthly or else air gets into the system and causes issues.

How does a closed loop system evaporate? Also 40% of 10 gallons is still 4 gallons of antifreeze which is not a good thing to pour on the ground.

[Frank Pratt]

It's more likely a factor of evaporation out of the system if he's only losing 10 gallons per year from what is probably 100+gallon system. You have to realize that 40% ethylene glycol means that the other 60% is water . . . so just like your car's radiator needs to be refilled occasionally - so does this system. PC Watercooling enthusiasts make a similar mixture, and they have to top off monthly or else air gets into the system and causes issues.

I don't buy that at all. I've never added coolant to a vehicle that didn't have a leak. And I've never seen an ice plant that didn't have a sealed system.

[Flamone LaChaud]

I'm basing this off of my experience with PC watercooling, and usually even the best sealed closed loop system still will have some minimal loss at the pump/reservoir, even if there are zero leaks in the piping and fixtures. (and when you've spent nearly three grand on hardware and a cooling system, the last thing you want is leaks around electronic equipment) Granted, I have zero experience in ice rinks or industrial sized cooling systems, and the experience I do have is in removing large amounts of heat from small components . . .nor did I stay at a Holiday Inn Express at any time in the past . . .so what I have seen might be an outlier. Just trying to put out a less hazardous hypothesis than the closed system being slightly less closed than one might like.

[Tom Stenzel]

I'm with Frank on the loss. If I had to add antifreeze to a car there was a leak somewhere. In the case of the cars I owned that cost $150 or less, multiple leaks.

Also in this system the fluid temperature isn't higher than ambient, it's lower. How much evaporation are you going to have? At some point someone will have to go leak hunting.

Some corrosion inhibitors will likely be needed. Even if there's metals exposed that shouldn't corrode on their own there might be a galvanic issue with differing metals that reduces parts to junk.

-Tom

[Dave Mount]

Wow, this went a long way from corrosion inhibitors.

The total system is several hundred gallons of heat transfer fluid. . .there are literally miles of plastic tube in the concrete slab. The system is theoretically sealed, but even threaded fittings are not necessarily perfectly sealed. Just like the discussion above, some people tell me there are "expected losses" from these systems, though I've never gotten a detailed explanation of how that happens. Two years ago when we added fluid, the existing fluid tested higher than the 40% glycol that is spec'd, and we only had to add water. That suggests that water is lost preferentially to glycol, which would argue for an evaporative loss (because water has a higher vapor pressure than ethylene glycol does, and if it were just leaking fluid, the losses would be equal).

There are no fittings in the slab, and no cracks in the slab, so I've no reason to believe there are undetected losses there. The manifolds that distribute and collect the fluid have over 100 fittings and are in a concrete trench about 2 feet deep and 4 feet wide, which the builders of the facility did not leave me access to. However, I have used a fiber optic camera to take a peek in there -- I can't see anything that suggests an accumulation of glycol, but four gallons spread over 300 square feet would be 0.02" deep if evenly distributed, and that's not counting breakdown or evaporation. Per Wikipedia, ethylene glycol breaks down in about 10 days in air.

Neither humans nor animals can access the header trench, it's under the floor with no access short of removing the floor. I will be fixing that issue in the next year or so to provide hatches for access, but right now, even if there is an active leak in the manifold (and there's no evidence of that), there is no access, so poisoning of children or pets is not an issue.

A key part of the system that is not plastic is the heat exchanger (expansion chamber) where freon is vaporized to absorb heat, and the heat is moved from glycol to freon. I don't know the composition of the piping in there, but I was told by another curling ice tech there was an ice plant in Canada (albeit ammonia-based rather than freon-based) that killed 3 people when corrosion in the ice plant caused an ammonia leak. Ergo, I am not inclined to ignore the corrosion issue.

So -- folks can rest easy that we're not creating a hazardous waste site or a public health hazard. Sounds like no one knows of an easy add-in corrosion inhibitor. I'll just order the official heat transfer fluid at greater expense.

Thanks.

Dave

[Frank Pratt]

Dave, I believe there is a dye that you can put in the system that will show up where even the tiniest leaks are. Might be worthwhile to look into that.

[Dave Mount]

Many of the commercial heat transfer liquids are dyed, I believe in part for that reason.