Properties, identification and safe handling of refrigerants
This domain tests whether you can identify a refrigerant from labels and pressure-temperature data, state its safety class, and handle it without fractionating a blend, overpressurising a system or creating an ignition hazard.
Identification and properties
Refrigerants are identified by ASHRAE safety class (A1, A2L, A3, B1 and so on), GWP, glide and oil compatibility. R-410A and R-404A are zeotropic blends with glide: charge them as liquid from the cylinder to avoid composition change. R-32 is A2L (lower flammability), R-290 propane is A3, R-744 CO2 is A1 but very high pressure, and R-717 ammonia is toxic (B2L). Never rely on smell or cylinder colour alone-read the nameplate and P/T chart.
Safe handling
Keep cylinders upright and secured, fit valve caps, and stay below 50 °C. Use manifold gauges and hoses rated for the refrigerant; R-410A needs higher-pressure equipment. Avoid liquid slugging the compressor, and do not heat a cylinder with an open flame. POE oils are hygroscopic: keep them sealed.
Worked example: A nameplate reads R-32, 4.0 kg. From GWP 675, tCO2e = 4.0 × 675 ÷ 1000 = 2.7 tCO2e. The system is below the 5 tCO2e leak-check threshold, but R-32 is A2L, so the technician must eliminate ignition sources, use a detector rated for A2L, ventilate, and never vent the charge. The low tCO2e does not make venting legal.
Traps
Vapour-charging a zeotropic blend; assuming A1 means safe in a confined space; using R-22 pressure gauges on R-410A; mixing refrigerants in one cylinder; ignoring glide when interpreting suction pressure.