Flammability classification
Refrigerants are divided into three groups according to flammability:
Class 1: indicates refrigerants that do not show flame propagation when tested in air at 21 XC and 101 kPa; Class 2: indicates refrigerants having a lower flammability limit of more than 0.10 kg/m3 at 21 XC and
101 kPa and a heat of
combustion of less than 19 kJ/kg;
Class 3: indicates refrigerants that are highly flammable as defined by a lower flammability limit of less than or equal to 0.10 kg/ m3 at 21 XC and 101 kPa or a heat of combustion greater than or equal to 19 kJ/kg.