Ozone Depletion and Safety
The science in exam form
The ozone layer absorbs harmful UV-B. Chlorine and bromine atoms released from CFCs and HCFCs destroy ozone catalytically, so ODP is indexed to R-11 = 1.0. Typical values: R-22 ≈ 0.055; R-134a, R-32 and R-410A = 0. HFCs contain no chlorine, so they do not deplete ozone, but they are potent greenhouse gases. GWP (100-year): R-22 ≈ 1810, R-134a 1430, R-32 675, R-410A 2088.
The agreements
The Montreal Protocol (1987), strengthened at London 1990 and Copenhagen 1992, controls ozone-depleting substances. The 2016 Kigali Amendment adds an HFC phase-down. India follows a published HCFC phase-out schedule with restrictions on R-22 in new equipment, which is why the trade has moved to R-32 and R-410A.
Safety essentials
- Never vent refrigerant; recover it into a certified cylinder.
- Never use oxygen or compressed air for pressure testing - dry nitrogen with a regulator only. Oil plus oxygen means an explosion.
- Liquid refrigerant causes cold burns; wear gloves and goggles.
- Flammable A2L/A3 refrigerants need ventilation, no ignition source and leak detection.
- Ammonia is toxic: use escape sets, water spray, and never enter alone.
Worked example
A van carries four 10 kg R-410A cylinders. If all leaked, CO2 equivalent = 40 × 2088 = 83 520 kg, about 83.5 tonnes - comparable to a year of driving. That is why recovery is a legal duty, not a courtesy.
Traps
Saying HFCs damage the ozone layer (they do not; they are greenhouse gases), confusing ODP with GWP, and nitrogen-testing without a regulator.