Abstract:
Disclosed is an ultra-low temperature, dual-compressor (114,144), recirculating gas chilling system that includes a closed-loop mixed-refrigerant primary refrigeration system (110) in combination with a closed-loop gas secondary refrigeration loop (112). The ultra-low temperature, dual-compressor (114,144), recirculating gas chilling system disclosed is capable of providing continuous long term chilled gas and fast cooling of a high or ambient temperature object (158), such as a chuck used in processing semiconductor wafers or any such device. The gas chilling system is characterized by three modes of operation: a normal cooling mode, a bakeout mode, and a post-bake cooling mode.
Abstract:
Flow in a forward direction through a check valve (202) is detected by a signaling device in parallel with the check valve and sensing the pressure differential across the check valve. The signaling device outputs an electrical signal that indicates whether or not the pressure differential across the valve is sufficient to open the valve to flow. A flow restrictor such as a capillary tube (208) is in parallel with the check valve to by-pass a small portion of flow during normal operation and to equalize pressure across the check valve inlet and outlet when the check valve is otherwise closed to flow.
Abstract:
Refrigerants containing R-22 are replaced with new blends by using R-125, or R-125 with R-124, or R-218, or R-218 with R-124, in place of R-22. No hardware or oil composition changes are required to maintain temperatures, pressures and capacity substantially unchanged in a refrigeration system.