Anti-Freeze...again

[pete hagan]

I have searched and read all the posts about anti-freeze but I did not read WHY the propylene glycol vers standard ethylene auto anti-freeze. Since I just survived 5 days with no power here in KY (not as bad as 2003) I am interested in understanding the difference as it applies to a glass laser tube. No chemists explanations just laymen terms please. My cooler has a plastic tank but I don’t know the polymer it’s made off and I replaced the rubber coolant lines supplied by the mfg with the reinforced plastic tubing found at any hardware store.

I use distilled water and really don’t have any issues with the setup except for humidity which during most days my central HVAC system takes care of.

So what’s the reason for propylene vs. ethylene glycol?

[Dan Hintz]

Propylene glycol is typically used when there is a chance for contact with potable water or food stuffs... not soemthing we have to worry about.

Ethylene glycol is more appropriate for us due to it's lower viscosity, which typically translates to higher cooling efficiency due to lower head pressures. In our low-pressure case, it's probably a non-issue either way.

All of that said, I could probably come up with some reasons to use propylene over ethylene...

[Art Krenzel]

I have looked into the chemistry of using a glycol product as antifreeze protection for my laser engraver and discussed it with my laser manufacturer. The consenus recommendation is to use PROPYLENE GLYCOL over ETHYLENE GLYCOL but only as much as you need to offset the freezing potential. Both compounds contain additives which protect aluminum from corrosion and are compatible with polypropylene pumps, vinyl hoses and, of course, glass. It does not polymerize under IR lighting conditions so as to create a potential "strings" problem in the coolant. FTIR is used in their labs to analyze the product and does not create any difficulty.

The best reason to use PROPYLENE GYLCOL over ETHYLENE GLYCOL is that ETHYLENE GLYCOL is poisonous and PROPYLENE GLYCOL is not. We eventually have to replace the laser and drain the tube and "possibly" get soaked with it. In that case it would be better that the liquid be PROPLYLENE GLYCOL.

You can read all about the hazards of handling the glycols at the manufacturer's website: http://www.peakantifreeze.com/tech/tech_a.html

[Bill Cunningham]

Remember also, that if you have pets, they LOVE the taste of Ethylene Glycol because it's sweet. It's also deadly in small amounts to virtually all animals..

[Art Krenzel]

I have looked into the chemistry of using a glycol product as antifreeze protection for my laser engraver and discussed it with my laser manufacturer. The consenus recommendation is to use PROPYLENE GLYCOL over ETHYLENE GLYCOL but only as much as you need to offset the freezing potential. Both compounds contain additives which protect aluminum from corrosion and are compatible with polypropylene pumps, vinyl hoses and, of course, glass. It does not polymerize under IR lighting conditions so as to create a potential "strings" problem in the coolant. FTIR is used in their labs to analyze the product and does not create any difficulty.

The best reason to use PROPYLENE GYLCOL over ETHYLENE GLYCOL is that ETHYLENE GLYCOL is poisonous and PROPYLENE GLYCOL is not. We eventually have to replace the laser and drain the tube and "possibly" get soaked with it. In that case it would be better that the liquid be PROPLYLENE GLYCOL.

You can read all about the hazards of handling the glycols at the manufacturer's website: http://www.peakantifreeze.com/tech/tech_a.html

I would like to expand on this a bit. The Chemist at Old World Chemicals who manufacture antifreezes suggested that there are two versions of the propylene glycol - one with additives to make it capable of being used in your automobile and there is one which only has a pH stablizer and dye for use as an RV antifreezing agent.
SIERRA is the brand name used in automobiles and PEAK is used as an RV antifreeze agent. To protect the metal elements in the laser cooling system (radiator, etc) you should use the SIERRA brand of PROPYLENE GLYCOL.

[Bill Cunningham]

If you have a WestMarine in your area, they sell it by the gallon for marine engine winterizing .. The cheap stuff at the hardware store is usually for winterizing plumbing systems.. KY gets a bit of winter, you should be able to find both types without a problem..

[Zsolt Paul]

My chiller is recommended to run on water only. Are you guys talking about using anti-freeze for units recommended for water only, or are yours spec.-ed for anti-freeze?

[Rich Fleming]

I've been using RV antifreeze in my "homemade" water chiller for my laser for almost a year now and haven't had any problems - I do thin it with distilled water a little though