Refrigerant Safety and Environmental Compliance
Domain focus
This domain tests refrigerant handling, safety, and environmental rules: EPA Section 608 recovery and evacuation, cylinder safety, ASHRAE 34 classifications, leak repair, and A2L awareness. The exam expects you to choose the compliant procedure, not just the fastest one.
Core rules
- Never vent refrigerant; recover it into a DOT-approved recovery cylinder using a recovery machine and scale.
- Do not fill a recovery cylinder above 80% of its water capacity; leave room for liquid expansion.
- Evacuate to 500 microns or lower for a tight system after repair, and use a micron gauge isolated from the pump.
- Know safety groups: A1 refrigerants are lower toxicity and nonflammable; A2L are lower flammability; A3 are flammable. Treat A2L with ignition-source controls and leak detection.
- Leak repair deadlines and evacuation requirements depend on appliance charge size and type; when unsure, follow the stricter manufacturer and EPA rule.
Worked example
A residential R-410A system holds 20 lb. After repairing a leak, recover refrigerant to 0 psig, replace the filter-drier, triple-evacuate with nitrogen, and pull to 500 microns. Hold the vacuum; a rise above 500 microns in 10 minutes indicates moisture or a leak. Only then recharge by weight using the nameplate charge plus line-set adjustment.
Traps
Overfilling a recovery cylinder, mixing refrigerants in one cylinder, using oxygen or shop air for pressure testing, and assuming A2L refrigerant behaves like A1 during brazing or leak repair.