15.1 1 Recycle Equipment Recycle units remove contaminants from refrigerant prior to returning the refrigerant to the system from which it came or to other equip- ment belonging to the same owner. Recycle units contain a liquid pump that withdraws liquid refrigerant from the bottom of the recovery cylinder, circulates it through a large filter-drier, and returns the liquid to the top of the recovery cylinder. Most recycle units use one or more replaceable-core filter-driers for cleaning the refrigerant. It may take four to six hours of recir- culation (including filter element changes) to remove sufficient moisture, acid, and particulate matter before the refrigerant is suitable for reuse. See Figure 15‑17 for a diagram of recycle unit operation. The cleanliness of recycled refrigerant does not meet the specifications for new refrigerant, and chemical tests are not required. Some recycle units have built-in methods to determine the acid and moisture content of the recycled liquid refrig- erant. Individual testing kits are available for performing acidity and moisture tests, if desired. Recycling is done at the job site or the local service shop. Recovery and recycle units are often housed in one system, called an R&R system, that performs both operations. 15.12 Capture Methods In some repair situations, the refrigerant can be stored temporarily in another part of the system not in need of repair. For example, a 3. Crack open the service valves. 4. Connect the gauge manifold center hose to the recovery unit intake valve. 5. Connect a separate hose from the recovery unit output valve to the recovery cylinder vapor valve. 6. Carefully purge all hoses. 7. Place the recovery cylinder on a refrigerant scale and perform any settings necessary for monitoring the recovery process. 8. Open the recovery cylinder vapor valve, the recovery unit valves, and the gauge manifold hand valves. 9. Start the recovery unit and monitor the pressure gauges and refrigerant scale. 10. When an appropriate vacuum level has been reached, the recovery is complete. Check the system being recovered and the recovery equipment for appropriate vacuum level values. In all methods of recovery, it is best to try to remove as much liquid refrigerant as possible before recovering the rest of the refrigerant as a vapor. If the refrigerant is only recovered as a vapor, the process will take a long time because the liquid refrigerant will have to first boil off into a vapor before it can be removed. Recovery connections and start-up procedures may vary among manufacturers. Follow the manufacturer’s instructions provided with each unit. Connections and procedures will vary if refrigerant is removed in the liquid state. Always use a recovery cylinder designated for use with the type of refrigerant being recovered. Recycle unit Recovery cylinder Goodheart-Willcox Publisher Figure 15‑17. A pump draws liquid refrigerant from the bottom of the cylinder and circulates it through a replaceable- core filter-drier to remove moisture and contaminants from the refrigerant. Chapter 15 Refrigerant Recovery and Recycling 273 Copyright Goodheart-Willcox Co., Inc.