To facilitate control over a degree of vacuum of a freezing system and secure a long, stable operation of the freezing system by a pressure detector and a construction method using the detector whereby a pressure value can be grasped in a simple manner from an atmospheric pressure to a middle pressure of several Torrs to a low vacuum range and it is simply confirmed that an optional control value is attained in the control at the construction of the freezing system.
The apparatus is composed of a partition plate 3 which separates a space where a pressure value can be set optionally and a space where a pressure value is unknown and which can move while changing volumes of the two spaces, and an elastic means 2 fixed to between the partition plate and a wall face of at least one of the two spaces. The elastic means fixed between the partition plate and the wall face is expanded, shrunk by a pressure difference between the two spaces, whereby the unknown pressure value of the space is detected to be equal to the set pressure value by the pressure- detecting apparatus.
NAKAMA HIROTO
HIROTA MASANORI
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