Comparative evaluation of risk of a split air conditioner and refrigerator using hydrocarbon refrigerants

•Comparison of flammability risk of R290 air-conditioner with R600a refrigerator.•Consequences analysed for range of leak hole sizes and ignition frequencies.•Explains why large charge air conditioner has smaller risk than refrigerator.•Risk of broad use of R290 split air conditioners regarded as negligible.

The use of flammable refrigerants, such as R290 (propane), as an alternative to HCFC R22 in room split air conditioners (SACs) is being pursued. Concerns exist that current experience for safe application of R290 SACs is minimal. Conversely, there is extensive application of domestic and small commercial hydrocarbon refrigeration systems; this experience can help determine safety implications to wider use of R290 SACs. This study uses established quantitative risk assessment methods to estimate frequency and severity of ignition of R600a domestic refrigerators, which corresponds to current experience. The methodologies are also applied to R290 SACs based on their particular characteristics to estimate the associated risk. Results show the frequency and severity of ignition of SACs are significantly lower than domestic refrigerators due to the SAC installation characteristics being more conducive for dispersion of leaked refrigerant and less potential for confinement of a flammable mixture in the event of ignition.