| 摘要 |
PROBLEM TO BE SOLVED: To obtain a vacuum cooler performing stepwise cooling in which switching can be made at an appropriate timing between the first half vacuum process and the second half vacuum process. SOLUTION: The vacuum cooler comprises a processing tank 2 for containing foods, vacuum generators 1a, 1b of low and high vacuum systems, and an operation controller 7. In the vacuum cooling system, a first half vacuum process for operating the vacuum generator of low vacuum system is started at first and followed by a second half vacuum process for operating the vacuum generator of high vacuum system. A unit 11 for measuring the degree of vacuum in the processing tank is provided and when a preset degree of vacuum is exceeded, a signal notifying the switching timing from the first half vacuum process to the second half vacuum process is delivered. The operation controller 7 makes switching from the first half vacuum process to the second half vacuum process based on that signal.
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