Editing Scroll compressor (section)

===Valves===
Scroll compressors never have a suction valve, but depending on the application may or may not have a discharge valve. The use of a dynamic discharge valve is more prominent in high pressure ratio applications, typical of refrigeration. Typically, an air-conditioning scroll does not have a dynamic discharge valve. The use of a dynamic discharge valve improves scroll compressor efficiency over a wide range of operating conditions, when the operating pressure ratio is well above the built-in pressure ratio of the compressors. If the compressor is designed to operate near a single operating point, then the scroll compressor can actually gain efficiency around this point if there is no dynamic discharge valve present (since there are additional discharge flow losses associated with the presence of the discharge valve as well as discharge ports tend to be smaller when the discharge is present).<ref>{{cite journal |author=Jim Wheeler |date=November 1988 |title=Scroll Compressors: The Inside Story |journal=Contracting Business |pages=36 |publisher=Penton Media }}</ref><ref>{{cite journal |first1=James W. |last1=Bush |first2=John P. |last2=Elson |title=Scroll Compressor Design Criteria for Residential Air Conditioning and Heat Pump Applications |journal=Proceedings of the 1988 International Compressor Engineering Conference |volume=1 |pages=83–92 |date=July 1988 }}</ref>