Anyone Use CMA as Bilge Antifreeze ?

[allanpeda]

I spent a lot of money in November flushing out the system with Proylene Glycol. At six dollars a gallon, I realize that putting this in the bilge to protect the pump is a bit pricey. So I do some research. Calcium Magnesium Acetate (CMA) is an anti freeze that is also a corrosion *inhibitor*. I'm thinking of putting it in the bilge next winter (even on dry dock rain can get in and make problems). Anyone else try this stuff?

Chemical & Engineering News: WHAT'S THAT STUFF? - AIRCRAFT DEICERS

Calcium magnesium acetate - Wikipedia, the free encyclopedia

Cryotech CMA® Product Performance

http://snipurl.com/cma-antifreeze

Milazzo Industries 40050 "Quad Melt" With Calcium Magnesium Acetate 50Lb. (Quad Melt)

[GordMay]

As far as I know, CMA is a substitute for granular road salt (de-icer), not for liquid propylene glycol anti-freeze.

[allanpeda]

Originally Posted by GordMay

As far as I know, CMA is a substitute for granular road salt (de-icer), not for liquid propylene glycol anti-freeze.

My first reference, Chemical and Engineering News (provided above) discusses CMA as a used for aircraft deicing. It is also mentioned in the fourth link.

[Kettlewell]

You're spending too much for the pink antifreeze. I usually get mine at WalMart for something like $3 and change per gallon. You can often get it in the spring on sale and it won't go bad by the fall. Other times I've gone into one of the local marine stores (not West Marine) and bought it in case lots for pretty close to WalMart prices. You might also check around at the RV shops which sell the exact same stuff.

[thinwater]

Originally Posted by Kettlewell

You're spending too much for the pink antifreeze. I usually get mine at WalMart for something like $3 and change per gallon. You can often get it in the spring on sale and it won't go bad by the fall. Other times I've gone into one of the local marine stores (not West Marine) and bought it in case lots for pretty close to WalMart prices. You might also check around at the RV shops which sell the exact same stuff.

You can't compare pricing without knowing the PG concentration; dilution rates vary greatly and the cheaper stuff is mostly water.

[allanpeda]

Originally Posted by thinwater

You can't compare pricing without knowing the PG concentration; dilution rates vary greatly and the cheaper stuff is mostly water.

The freezing point curve flattens out at over 60% propylene glycol, so 50% is a good number.

I'm of the opinion that it would be good to toss some CMA in the bilge, or also keep it handy for de-icing the gunwales.

It (CMA) certainly wouldn't be more corrosive than seawater, though it's only effective to -9°C (15°F). I do keep a heater in the cabin.

The chemistry of all this is fairly straightforward. The more dissimilar molecules are kept in solution, the more they break up the ability of ice to form a regular crystal structure.

[Kettlewell]

The WalMart pink stuff says it is good to 50 below zero. Doesn't usually get that cold around here. Are you saying that is not accurate?

[allanpeda]

Originally Posted by Kettlewell

The WalMart pink stuff says it is good to 50 below zero. Doesn't usually get that cold around here. Are you saying that is not accurate?

The freezing point curves are developed for a fully feezing solution, and what really happens is the water starts to separate out and you get ice along the edges, which of course could involve the bilge pump. I don't really worry about it, as there is latent heat in the water, as well as the insulating effects of the cabin and of course the heater.

There could also be other chemicals in it that further lower the MP. By the way, all the alarm about ethylene glycol being toxic to sea life is apparently misplaced. Certainly you can't drink it, but it is not especially toxic to marine life.

[thinwater]

Originally Posted by Kettlewell

The WalMart pink stuff says it is good to 50 below zero. Doesn't usually get that cold around here. Are you saying that is not accurate?

That would be the "burst point" not the freeze point. The freeze point (when the first crystals appear and bilge pumps fail) is probably closer to +10F, but they don't print that because it is not am impressive number. On the hard, this isn't going to matter much. You'll get slush, not hard ice, until the last bit of PG freezes, down around -50F. However, that is probably the burst point for copper pipe; PVC will burst more easily.

Freeze proofing products with PG should ALWAYS be purchased on the basis of PG content, though most manufacturers resist placing that information on the label. Do not buy those, as you have no real idea what you are buying. There are too many ways to lie about burst point (to start with, there is no generally accepted test method).

Perhaps this post will add something to the discussion:
http://sail-delmarva.blogspot.com/20...reeze-and.html

The basis of freezing point depression may be straight forward, but the reality is very far from simple.

[ggray]

Don't know about CMA, but best price I've found for pink stuff was at Ace Hardware early in season.

[GordMay]

From Allan's first reference, Chemical and Engineering News, discussing CMA as a used for aircraft deicing:

“... chloride salts are prohibited for use on aircraft because they can be corrosive. So like automobile antifreeze, aircraft deicing fluids are aqueous solutions of a glycol, or mixture of glycols, along with proprietary additives. Depending on the formulation required, the additives might include a surfactant, polymer thickening agent, pH buffer, corrosion inhibitor, flame retardant, or dye...
... Either alone or in combination, the glycols, calcium magnesium acetate, sodium acetate, sodium formate, and urea are used on runways and airport roadways ...”

[allanpeda]

Originally Posted by GordMay

From Allan's first reference, Chemical and Engineering News, discussing CMA as a used for aircraft deicing:

“... chloride salts are prohibited for use on aircraft because they can be corrosive. So like automobile antifreeze, aircraft deicing fluids are aqueous solutions of a glycol, or mixture of glycols, along with proprietary additives. Depending on the formulation required, the additives might include a surfactant, polymer thickening agent, pH buffer, corrosion inhibitor, flame retardant, or dye...
... Either alone or in combination, the glycols, calcium magnesium acetate, sodium acetate, sodium formate, and urea are used on runways and airport roadways ...”

This is because of the viscosity of glycol allows it to adhere to the wings better. In both cases we are talking anti freeze. What is your point? De-icing is essentially the same application as anti freeze in the context of a bilge. Chemistry 101 freezing point depression.

If you point is don't do it because it ain't been done before, then okay. But I see no factual basis for any claims that it would not work.

[cfarrar]

Just make sure anything you put in the bilge will not harm the seal, impeller, and other parts in your bilge pump. Otherwise...

[thinwater]

Originally Posted by allanpeda

This is because of the viscosity of glycol allows it to adhere to the wings better. In both cases we are talking anti freeze. What is your point? De-icing is essentially the same application as anti freeze in the context of a bilge. Chemistry 101 freezing point depression.

If you point is don't do it because it ain't been done before, then okay. But I see no factual basis for any claims that it would not work.

Well, as long as we are adding fun details that are off the thread a bit....

Aircraft deicing fluid is simply glycol and water, heated to melt the ice off control surfaces. Anti-icing fluid is a freeze preventative that contains thickeners to make it cling and resisit wash-off by rain. This is required when the plane has any chance of signifigant hold-over on the ground. It is designed to shear off when the plane aproaches takeoff speed. The viscosity increase is provided by polymers and is not from the glycol, which is quite thin when diluted with even modest amounts of water.

[allanpeda]

Update: Going on six years and CMA works terrific to prevent bilge ice up when in the yard, and no corrosion so far. I have fifty pound of it and I use about a pint a year in the bilge (after sponging dry) and have been tossing some in the head as well.