3 Refrigerant Recovery Procedures
Learn how to safely set up refrigerant recovery equipment, choose and adapt recovery methods, and verify applicable evacuation requirements.
Purpose and safety
removes refrigerant from an appliance and stores it in an external container. It does not necessarily clean or purify the refrigerant. In the United States, Section 608 prohibits intentional venting during stationary air-conditioning and refrigeration service.
Use equipment approved for the refrigerant, follow the equipment manufacturer's instructions, and comply with applicable regulations. Verify the required endpoint before opening the appliance.
Equipment and setup
A typical setup includes a compatible recovery machine, an approved , a scale, pressure-rated hoses, and gauges or a manifold. A filter-drier may be required or recommended.
Use a separate, properly identified cylinder for each refrigerant; do not mix refrigerants. Check the cylinder's condition, compatibility with the refrigerant, and allowable fill weight. Weigh it throughout recovery and never exceed its marked fill limit, because liquid refrigerant expands as it warms. Follow the recovery-machine manual for the correct hose and cylinder-port arrangement; setups vary by equipment and method.
Before connecting equipment, identify the refrigerant and system condition, isolate the appliance as needed, and confirm that the machine and cylinder are suitable. Securely connect hoses to the system service ports and machine, then connect the machine outlet to the cylinder as its manual directs. Open valves in the specified order, check for leaks, and monitor system pressure, cylinder weight, and machine operation.
Avoid trapping liquid between closed valves. If liquid entering the machine causes knocking, throttle the inlet as the manual directs. Do not allow liquid slugging to damage the compressor.
Recovery methods
removes refrigerant as a gas. It is generally slower than removing liquid first, but is used to clear refrigerant remaining in the system. Connect the system's vapor-side service connection to the recovery-machine inlet and operate the machine according to its manual.
removes liquid through an appropriate liquid-side connection using a machine and setup rated for that procedure. It can greatly shorten recovery time. Control the flow so liquid does not enter the recovery machine too rapidly; after the liquid is removed, continue with .
uses pressure and a siphon effect to transfer accessible bulk liquid from the appliance to the . It requires an appropriate system layout and enough accessible liquid, so it is not suitable for every system. It does not remove the remaining vapor. Monitor the cylinder on a scale and stop before its fill limit. A siphon can continue after the machine is switched off, so close the valves as directed by the equipment manual. Finish by recovering the remaining refrigerant with the vapor method.
Adapting to system conditions
Adjust the method to the system condition, while following equipment instructions and applicable regulations.
Normally charged system: Recover accessible liquid first when the equipment and connections allow it, then recover vapor. Follow the machine's instructions and verify the required endpoint.
Low charge or low pressure: Recovery may be slow. Check for restrictions or leaks, and use only manufacturer-approved methods to improve heat transfer or recovery rate. Never use an open flame or vent refrigerant to speed the work.
Inoperative compressor: Do not rely on the appliance's compressor to move refrigerant. Use an appropriate recovery machine and connect to the available sides of the system as required by the appliance and equipment instructions.
Leaking system: Isolate leaking sections from non-leaking sections where possible. EPA allows an exception if a leak prevents the normal or would substantially contaminate recovered refrigerant: evacuate sound sections to the required level and leaking sections to the lowest attainable pressure, not above .
Low-pressure appliance: Use equipment and procedures intended for low-pressure systems. For certain non-major repairs not followed by evacuation to the atmosphere, EPA requires the appliance to be pressurized to before opening. This is not a general substitute for recovery; follow the applicable rule and equipment instructions.
Burned-out compressor or contaminated refrigerant: Use procedures and equipment that prevent contamination from spreading. Collect the refrigerant in a clearly identified, dedicated cylinder and do not combine it with clean refrigerant.
Required evacuation levels
For appliances containing more than pounds of refrigerant, EPA evacuation levels depend on the appliance's pressure class, its full charge, and whether the recovery equipment was manufactured before or on or after November , . The very-high-pressure and high-pressure values below are in inches of mercury vacuum relative to standard atmospheric pressure. The low-pressure values are in millimeters of mercury absolute. Small appliances and motor-vehicle air conditioners have separate requirements.
Very-high-pressure appliances: with equipment made before November , , and with equipment made on or after that date.
High-pressure appliances with a charge under pounds: for equipment from either date category.
High-pressure appliances with a charge of pounds or more: for equipment made before November , , and for equipment made on or after that date.
Medium-pressure appliances with a charge under pounds: for equipment made before November , , and for equipment made on or after that date.
Medium-pressure appliances with a charge of pounds or more: for equipment made before November , , and for equipment made on or after that date.
Low-pressure appliances: with equipment from either date category.
Stabilizing and verifying pressure
When the machine reaches the required , close system valves as directed and allow the pressure to stabilize. A pressure rise may indicate refrigerant remains in liquid or oil. Continue recovery if necessary and verify the endpoint before opening the appliance.