A blend of R-22, R-124 and R-142b with hydrocarbon
R-600a (isobutane) added to improve mineral oil miscibility. This
blend can be used to retrofit R-12 automotive air conditioning
systems as well as stationary refrigeration systems. The pressure
and system capacity match R-12 in 45F to 50F evaporators, and the
discharge pressure in hot condensers is only 5 to 10 psi higher
than R-12 (a benefit in automotove AC and warmer refrigeration
environments). The temperature glide runs about 13F in the evaporator.
The addition of isobutane to this blend significantly improves
mineral oil compatibility, particularly for high viscosity oils
used in auto AC.