| 摘要 |
PROBLEM TO BE SOLVED: To enable an LPG supplier to keep track of residual liquid amounts of each end users and to receive an alarm at an appropriate residual liquid amount per each end user by using an inexpensive device. SOLUTION: A level gauge 1 detecting an LPG residual liquid amount inside a bulk storage tank features having three or more contacts and a measuring device 4, each contact respectively becomes electrically closed at a certain residual liquid amount, and the measuring device 4, stores an alarm set value 12 determining a residual liquid amount for generating an alarm, outputs an alarm 17 when the residual liquid amount determined by the alarm set value 12 and the residual liquid amount corresponding to contacts which are closed at the moment matches, outputs a residual liquid amount 11 corresponding to contacts which are closed at the moment or had become closed immediately before, and modifies the residual liquid amount of the alarm set value 12 based upon a command 18 from outside.
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