R600a

R-600a, or isobutane, is a hydrocarbon refrigerant widely used in household refrigeration. It is the branched isomer of butane (chemical formula C4H10; CAS 75-28-5).

Properties: R-600a has a very low global warming potential (GWP around 3) and zero ozone depletion potential (ODP 0). It is flammable and is classified by ASHRAE as safety class A3 (high flammability). Its boiling point is −11.7 °C at standard pressure, which enables efficient heat transfer with small refrigerant charges in appliances.

Applications: It is primarily used in domestic refrigerators and freezers, typically with small refrigerator charges. It is also found in some portable air conditioners and small heat pumps. Compared with older HFCs like R-134a, R-600a offers lower environmental impact, though its flammability requires appliance designs to accommodate hydrocarbons.

Safety and handling: Because of its flammability, systems using R-600a must be designed for hydrocarbon refrigerants, and service should be performed by qualified technicians with proper ventilation and leak detection. Many regions regulate maximum charge sizes and implement safety standards for household appliances to minimize ignition risk.

Regulatory and environmental context: Since the late 20th century, R-600a has become a common substitute for high-GWP refrigerants in domestic appliances, contributing to lower greenhouse gas emissions from refrigeration. Its use is balanced by safety considerations, proper labeling, and adherence to appliance standards.