RAC1.Trade Safety

1. General Workshop Safety

• Housekeeping: Keep the floor free from oil, grease, and water to prevent slips.

• Lifting: Use leg muscles, not back muscles, when lifting heavy condensers or compressors. Use a trolley for gas cylinders.

• Emergency: Know the location of the Main Switch, Fire Extinguishers, and First Aid Kit.

• Reporting: All accidents, however minor, must be reported to the supervisor.

2. Refrigerant Handling Safety

Refrigerants are the primary hazard in RAC.

• Cylinder Color Coding: * R-12: White | R-22: Light Green | R-134a: Light Blue | R-410A: Rose/Pink.

• Filling Limit: Never fill a cylinder more than 80% of its volume to allow for liquid expansion (Hydrostatic pressure).

• Ventilation: Refrigerants are heavier than air; they displace oxygen in pits or basements, leading to asphyxiation (suffocation).

• Frostbite: Direct liquid refrigerant contact with skin/eyes causes “cold burns” or frostbite. Always wear goggles and gloves.

• Phosgene Gas: Never use a torch near a refrigerant leak. R-12/R-22 produce toxic Phosgene gas when exposed to open flames.

• Leak Detection: * Use Soap Bubble Test (safest).

  • Electronic Leak Detector (most sensitive).

  • Halide Torch (only for CFC/HCFC; flame turns green/blue).

3. Electrical Safety

• Lockout/Tagout (LOTO): Always isolate the power source and lock the switch before servicing a unit.

• Earthing: Ensure the metal body of the refrigerator/AC is properly earthed to prevent electric shock.

• Capacitor Discharge: Disconnect power and short the terminals of a capacitor using a 20k-ohm resistor before touching (to avoid stored charge shock).

• Fuses: Always replace a blown fuse with the same rating. Never bypass a fuse with a copper wire.

• Safe Current: * 30 mA: Can cause respiratory paralysis.

  • 75 mA+: Can cause heart failure (Ventricular Fibrillation).

4. High-Pressure Safety (Nitrogen & Brazing)

• Nitrogen Testing: Always use a Pressure Regulating Valve when using Dry Nitrogen for leak testing. Never connect a Nitrogen cylinder directly to the system.

• Brazing:

  • Wear Tinted Goggles (No. 4 or 5) to protect against infrared radiation.

  • Ensure the system is completely empty and open to the atmosphere before heating (to prevent explosions).

• Oxygen Danger: Never use Oxygen for leak testing or cleaning. Oxygen + Oil/Grease = Explosion.

5. Personal Protective Equipment (PPE)

6. Fire Safety (The Fire Triangle)

• Fire Triangle: Fuel + Heat + Oxygen. Removing any one stops the fire.

• Extinguisher Types for RAC:

  • Class C (Electrical): Use CO2 or Dry Chemical Powder (DCP).

  • Class B (Oil/Refrigerant): Use Foam or DCP.

  • Note: Never use water on electrical or oil fires.

Quick Revision Check (Fact Box)

• Deep Vacuum: Measured in Microns (standard: 500 microns).

• Pressure Gauge: Red is high side, Blue is low side (Manifold Gauge).

• Recovery: Always use a recovery machine; venting refrigerants is illegal (damages the Ozone Layer).