Theoretical and experimental investigation on the flame-retarding characteristic of R245fa

Some binary mixtures comprised of R245fa and flammable refrigerant were expected to be a drop-in replacement for R11 or R22. The flame-inhibiting characteristic of R245fa had great significance on evaluating the security of that binary mixture. This paper analyzed the retardant mechanism of R245fa on flammable refrigerants, and the influence factors on flammable limits of refrigerants. With two different ignition styles, an electric igniter and a common lighter, the flame-retarding characteristics of R245fa on some hydrocarbons (HCs) and hydrofluorocarbons (HFCs) refrigerants were studied experimentally. A new index (flame-retarding coefficient) that could be used to evaluate the flame-retarding effect of fire retardants was put forward. The test results showed that the flammable limits of refrigerants were greatly affected by ignition power and ignition mode, and the flame-retarding effect of R245fa on HCs was worse, and was a little better on HFCs, but both worse than that of R134a, R125 and R227ea.

► Analyze the flame-retarding mechanism of R245fa.
► The theoretical ranking of flame-inhibiting effects is R227ea > R125 > R134a > R245fa.
► Ignition power and mode influence the flammable limits and ranges.
► Flame-inhibiting effect of R245fa on the HFCs is better than that of HCs.
► Put forward a parameter, flame-retarding coefficient (FRC).