Refrigerant Management & Service Procedures
Recovery, evacuation, charging procedures, nitrogen purging, brazing, filter-driers, and refrigerant oils.
- Describe proper refrigerant recovery procedures using certified equipment
- Explain evacuation targets and the vacuum decay test
- Identify correct charging methods for TXV and fixed orifice systems
- Explain the purpose of nitrogen purging during brazing
- Describe filter-drier function and refrigerant oil compatibility
Leçon 1
Recovery, Evacuation & Vacuum Procedures
Refrigerant Recovery
Before opening any refrigeration system for repair, the refrigerant must be recovered into an approved recovery cylinder using a certified recovery machine. It is illegal to vent refrigerant to the atmosphere.
Proper recovery requires:
- A certified recovery machine that meets EPA/AHRI standards
- An approved recovery cylinder (gray body with yellow top for mixed/unknown refrigerants)
- A scale to weigh the recovered refrigerant
- Never exceed 80% of the recovery cylinder's rated capacity
Never Vent Refrigerant
Intentionally venting refrigerant to the atmosphere is a federal violation subject to fines up to $44,539 per day per violation. Always use a certified recovery machine and comply with EPA regulations.
Evacuation
After repair and before charging, the system must be evacuated with a vacuum pump to remove air and moisture. The evacuation target for most systems is 500 microns or below, verified with a micron gauge and a decay test.
Why evacuation matters:
- Air (non-condensables) causes high head pressure and poor efficiency
- Moisture reacts with refrigerant and oil to form acids that destroy compressors
- A proper vacuum boils moisture at room temperature, removing it from the system
Vacuum Decay Test
After reaching 500 microns, close the valve between the vacuum pump and the system. Monitor the micron gauge:
- Holds below 500 microns - system is tight and dry, ready for charging
- Rises rapidly above 1,000 microns - indicates a leak, must be found and repaired
- Rises slowly to 800-1,200 microns then stabilizes - moisture still evaporating, continue pumping
Always recover refrigerant using a certified recovery machine and approved cylinder - never vent to atmosphere. Evacuation target is 500 microns or below, verified with a micron gauge and decay test. Non-condensables (air) in the system cause high head pressure and poor capacity.