AC Diagnostics & Repair

R32 vs R410A vs R22 Refrigerant Gas Charging: Pressures & Safety Rules

Published on 2026-06-07 · 7 min read · By ACServiceOS Team

Charging refrigerant is one of the highest-margin services for AC workshops, but it carries serious safety risks. With flammable R32 now dominating new Indian inverter ACs, technicians must follow precise pressure, vacuuming, and charging protocols.

Technician weighing R32 refrigerant cylinder on digital scale while charging outdoor unit

Refrigerant Operating Pressures Comparison Table

1. R32 (Mildly Flammable A2L): Suction Pressure: 120-135 PSI; Standing Pressure: 240-260 PSI. 2. R410A (Near-Azeotropic Blend): Suction Pressure: 120-130 PSI; Standing Pressure: 230-250 PSI. 3. R22 (Legacy HCFC): Suction Pressure: 60-70 PSI; Standing Pressure: 150-160 PSI.

Always Charge R410A in Liquid State

R410A is a 50/50 blend of R32 and R125. Charging it as a gas causes fractionation (one gas leaks faster than the other), altering chemical balance. Always invert the R410A cylinder and charge slowly in liquid state into the suction line.

Gram-Accurate Weighing Scale vs Guessing by Pressure

Inverter ACs with electronic expansion valves (EEV) constantly adjust suction pressure based on ambient heat. Charging purely by gauge pressure causes overcharging or undercharging. Always weigh the exact charge specified on the unit nameplate (e.g., 650 grams) using an electronic charging scale.

Crucial Flammability Safety for R32 Refrigerant

Never use an open flame torch to braze an R32 system without first recovering gas and purging the lines with dry nitrogen. Ensure the work area is well-ventilated to avoid flammable vapor pockets.

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Official Indian Industry & Regulatory References