WATER LEVEL MONITORING DEVICE

PROBLEM TO BE SOLVED: To provide a water level monitoring device having wide flexibility and high executability. SOLUTION: A hydraulic backpressure valve 1 is equipped with sensors 12a, 12b guided by sensor guides 11a, 11b, and the level w of water for water seal in the hydraulic backpressure valve 1 is monitored in two steps by a control device 2. The c parts of the sensor guides 11a, 11b has respectively a bellows structure which can be adjusted to have an optional length. The sensor guides 11a, 11b can cope with the hydraulic backpressure valves 1 having various sizes by expanding or contracting the bellows structure. In addition, the executability can be heightened by contracting the bellows structure at the execution time of the sensor guides 11a, 11b and expanding it up to the optimum length after execution. COPYRIGHT: (C)2003,JPO