Chapter 25 Installation and Troubleshooting of Domestic Refrigerators and Freezers 657 Copyright Goodheart-Willcox Co., Inc. 8 Systems with Valve Adapters Valve adapters provide another method of connect- ing gauges and charging cylinders to a hermetic system. Figure 25-18 shows one part of the adapter fastened to the compressor dome. The other part of the adapter has a removable valve stem, Figure 25-19, that can be attached to the valve adapter, as shown in Figure 25-20. The valve stem operates a small needle valve mounted in the part of the adapter installed on the com- pressor. The part of the valve adapter containing the valve stem also has one or more ports for attaching gauges or service hoses. Synthetic or copper gaskets between the valve assembly and compressor fitting seal the joints. Using Valve 1. Clean the outside of the valve adapter with a clean cloth..hotlc 2. Remove the dust cap from the fitting on the compressor 3. Choose the correct valve stem drive.e. 4. Push the service valve stem forward in the body of the valve attachment. 5. Engage the valve stem in the valve adapter needle.. 6. Thread the valve stem portion of the valve adapter unit into the adapter body..y 7. Attach the flexible service line to the fitting but leave it loose..l 8. Before opening the valve adapter needle, tighten the packing unit around the valve stem. 9. Always test the assembly for leaks using a refrigerant pressure of 15 psig to 20 psig (100 kPa to 140 kPa)..a)kP U Us ing Valve AdAdaptersrsteap 1 1. C Cl ean th e outside ts id e of of t t h he valve adapter wit h a lean cl 2. Remove the d ust ca p fr om t he fitting mountedmounted o n t h e compressor ddome.me.o 3. Choose t he correct valve stem driv 4. Push th e service valv e stem fo rward in th e body of the valve attachment. 5. Engage the valve stem in the valve adapter needle 6. Thread the valve stem portion of the valve a dapter unit into the adapter bod 7. Attach the flexible service line to the fitting bu t leave it oose 8 . Before opening the valve adapter needle, tighten th e packing un it aroun d th e valve stem. 9 9. Always Al wa ys test the assembly for leaks usin g a a refrigerant pressure su re o f 15 psi g to 20 ps ig (10 (1 (1 00 00 k k Pa t o 14 14 0 0 kP a) Brazed or welded joint Valve Valve attachment threads Compressor housing Screwhead Handwheel Port Needle valve drive Valve stem Valve attachment threads Valve Valve adapter Compressor housing Gasket Valve stem Port Handwheel Needle valve drive Goodheart-Willcox Publisher Figure 25-19. A service valve attachment like the one shown is installed on a valve adapter. The handwheel is attached to the valve stem and needle valve drive, which operates the needle valve in the adapter. Goodheart-Willcox Publisher Figure 25-18. Service valve adapter installed in the dome of a hermetic compressor. A valve attachment must be fastened to the adapter before the valve can be opened. If it is not, refrigerant will escape to atmosphere. Goodheart-Willcox Publisher Figure 25-20. This cutaway shows a valve attachment connected to a valve adapter on the housing of a hermetic compressor.