HC-12a

HC-12a, also called ES-12a, OZ-12a, etc. are "drop-in" replacement refrigerants for Freon-12 and to a lesser extent, R-134a. HC-12a is a mixture of hydrocarbons (specifically R-290 and R-600a--propane and isobutane respectively) and is therefore considered nearly non-ozone-depleting when compared to R-12 (Freon) or R-134a. The mixture can be used in refrigeration systems designed for R-12. HC-12a provides better cooling than an R-12 system retrofitted to R-134a, with much greater energy efficiency as well. Unlike R-134a, HC-12a is completely compatible with the hoses and oils used in R-12 systems, making the conversion much easier to accomplish. HC-12a is also patent-free due to its non-synthetic nature.

As of July 15, 1995, it is illegal to replace R-12 with HC-12a. It is not illegal to purchase HC-12a, or to use it in refrigeration systems that were not originally charged with R-12, except for in certain states that prohibit the use of flammable refrigerants in automobiles. [US EPA, "Legal Status of HC-12a" http://www.epa.gov/Ozone/snap/refrigerants/hc-12a.html]

Some advantages to using the HC-12a mixture over retrofitting to R-134a are cost and labor. Since HC-12a is a "drop-in" replacement, no seals need to be replaced and minimal effort has to be put in to changing the refrigeration system around. Disadvantages to using the HC-12a mixture in R-12 systems is that it is potentially dangerous and is illegal in the United States. The refrigerant used is propane and other hydrocarbons which are flammable. However, it should also be noted that R-134a (and other refrigerants) are just as flammable when mixed with refrigerant oil, yet the quantity of refrigerant and oil in a typical system is so low that the danger in any case is minimal. Additionally, when R-134a is exposed to flame, it releases phosgene gas (which is highly toxic), whereas HC-12a is completely non-toxic.

Material Safety Data Sheet for HC-12a: http://www.hc12ausa.com/hc12/msds.html

References