recovery cylinder. A mixture may be impossible to reclaim. If a reclaim facility receives a cylinder of mixed refrigerant, it may not be able to reclaim the mixture. The facility may agree to destroy the refrig- erant, but it will typically charge a fee for the service. The length and diameter of the hose connecting the recovery machine to the system affects the efficiency and time required for the recovery process. Long hoses and small diameters cause exces- sive pressure drop and increased recovery time. All pump before use. Evacuation prevents contamina- tion in the cylinder by two refrigerants. 15.10 Recovery Procedures It is important to recover only one type of refrig- erant into a recovery cylinder. Each recovery cylinder should be designated and properly marked for a specific refrigerant type. Do not mix refrigerants in a Oil drain plug Compressor Open Open Cracked open Compressor Check valve High- pressure switch Gas Recovery cylinder Scale Heated oil separator Liquid Check valve Cracked open Low- pressure switch Filter-drier Oil separator Recovery unit Fan Evaporator Condenser Oil sight glass Goodheart-Willcox Publisher Figure 15‑12. Recovery units now come with oil-less compressors, eliminating the need to change the oil in a recovery unit. 270 Heating and Cooling Essentials Copyright Goodheart-Willcox Co., Inc.