An inhibited propylene glycol such as “DowFrost” is best.
DowFrost contains special corrosion inhibitors for low system maintenance and better heat transfer compared to other glycols.
It also has a longer fluid life, up to 20 years in some cases.
Use of Uninhibited Glycol
Even through uninhibited glycols do lower the freeze point, they are often more corrosive than water.
The corrosion rate of ethylene glycol on iron, for example, is more than 2.5 times faster than plain water. On steel, it is 4.5 times faster.
Automotive Based Antifreeze
Automotive based antifreeze Should never be used!
Automotive antifreeze contains silicate based inhibitors, which are compatible with automotive components.
In an industrial application, the silicates will coat the heat transfer surfaces and reduce the cooling efficiency of the system.
Silicates can also significantly reduce the life of pump seals.
Sources of Inhibited Propylene Glycol
For a complete literature package, material, safety data sheets and purchasing information, contact the following: Dow Chemical 1-800-447-4369 (Canada 1-800-363-6250) Dowfrost inhibited propylene glycol.
A refractometer should be used on a regular basis to determine the mixture strength according to freeze point.