Which refrigerants are safe to mix together?

In the context of refrigerants, mixing different types is generally unsafe and not advisable. Each refrigerant has its own unique properties, including pressure, temperature characteristics, and chemical composition. When mixed, these differences can lead to system inefficiencies, damage to components, or even dangerous chemical reactions.

R11 and R12 are both chlorofluorocarbon (CFC) refrigerants, but they have different molecular weights and pressure characteristics, making them unsuitable for mixing. Similarly, R12 (a CFC) and R134a (a hydrofluorocarbon or HFC) have significant differences in their chemical makeup and operating pressures, and mixing them can result in overly high pressures that can damage the system or cause safety risks. Likewise, R12 and R22 (a hydrochlorofluorocarbon or HCFC) are incompatible for the same reasons; mixing them can also lead to harmful reactions and pressure issues.

Choosing not to mix any of these refrigerants ensures the safety and efficiency of refrigeration systems. Thus, stating that none of the listed combinations are safe to mix is indeed accurate.