The compressor in my chilled water setup sprung a leak in one of the lines. It was R12. I took it into the refrigeration repair shop (they are the ones that found the leak,) and since R12 is not readily availabe anymore (and expensive), they put in R414B. The tech said that it works better than R12 anyway. Here is a quick link to R414B, it is a blend of R-22, R-124, R142b, and R-600a.
http://www.refrigerants.com/hcfc-r414b.htm