| 摘要 |
PROBLEM TO BE SOLVED: To provide a cryogenic freezer which can be installed easily. SOLUTION: In the main line 33 for connecting an outdoor compressor unit 1 which has a compressor 11 and a heat exchanger 12 with a cryogenic expander 5, the supply pope 31 and the return pipe 32 of the main line 33 are connected with each other by connection pipe 42 wherein an electrically operated valve 41 is interposed. A controller 46 controls the electrically operated valve 41 so that helium may flow at a specified flow rate to the cryogenic expander 5, based on the length and shape of the main line 33 and the helium gas pressure on the suction side of the compressor 11. By doing it so, there is no necessity to compute the charge pressure corresponding to the length and shape of the main line 33 and charge a freezer with helium gas so that it may come to the charge pressure when the user installs the cryogenic freezer, so the installation work of the cryogenic freezer can be facilitated.
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