Refrigerants, lubricants, their properties, handling and environmental regulations
What this domain tests
Refrigerant properties and selection, safety groups, ODP and GWP, Indian and international regulation, recovery practice, and the lubricants with their matching rules.
Core rules
- Key properties: boiling point at atmospheric pressure (R134a −26 °C, R22 −41 °C, R410A −51 °C, R717 −33 °C, R600a −12 °C), critical temperature (R134a 101 °C, R410A about 71 °C, R744 31 °C), latent heat, oil miscibility, dielectric strength, toxicity and flammability.
- ASHRAE safety groups: A1 for R134a and R410A, A2L for R32, A3 for R290 and R600a, B2L for ammonia R717.
- ODP: R11 and R12 = 1.0, R22 = 0.055, all HFCs = 0. GWP: R22 about 1810, R134a 1430, R410A 2088, R32 675, R290 about 3, R744 = 1.
- The Montreal Protocol phases out ozone-depleting substances; India's ODS (Regulation and Control) Rules, 2000 control their production and trade. The HCFC phase-out schedule runs freeze 2013, 35 % cut by 2020, 67.5 % by 2025, 97.5 % by 2030. The Kigali Amendment covers HFCs, with India's baseline 2024–2026 and freeze in 2028.
- Never vent refrigerant: recover, recycle, reclaim. Zeotropic blends such as R410A and R404A must be charged as liquid, otherwise composition shifts (glide, fractionation).
- Lubricants: mineral oil and alkylbenzene for CFC/HCFC; POE and PAG for HFCs (highly hygroscopic, keep sealed); PVE for R32 and R290. Watch viscosity grade, pour point, floc point and dielectric strength; moisture in POE forms acid and sludge.
Worked example
A plant holds 1.5 kg of R410A. CO2 equivalent = charge x GWP / 1000 = 1.5 x 2088 / 1000 = 3.13 tonne CO2e. The same mass of R290 gives 1.5 x 3 / 1000 = 0.0045 tonne CO2e, but R290 is A3 flammable and its charge per circuit is limited by the appliance standard.
Traps
Quoting GWP where ODP is asked; vapour-charging a zeotropic blend; leaving POE oil exposed to air; identifying refrigerant by cylinder colour; assuming R32 and R410A are interchangeable without checking pressures.