It depends on what one means by "safe" or "how safe?" and the precautions taken. Propane (R-290) is thermodynamically suitable as a refrigerant, but it is flammable. Because it is heavier than air, this dictates ventilation at floor level, prohibiting smoking nearby, and possibly adding an odorant to help in detecting any leaks.
Searches on "propane refrigerant" and "propane refrigerant safety" turned up many interesting articles. The lack of ODP (ozone depletion potential) and GWP (global warming potential) has led to renewed interest in propane as a refrigerant.
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In vino veritas; in cervisia carmen; in aqua E. coli.
Agree - used very often in petroChem process plants where the entire area is zoned correctly. Cost a bit more initially because the API does not allow cast iron compressors for flammable gases.
Refrigeration System
Re: RELATED TO REFRIGERATION SYSTEM
