DIFFERENTIAL PRESSURE SENSOR VENTILATOR IN PRESSURE TYPE SEWER SYSTEM

PROBLEM TO BE SOLVED: To attain accurate pressure difference detection by a differential pressure sensor over a long period of time, regarding a ventilator for a pump unit in a pressure type sewer system. SOLUTION: The differential pressure sensor 28 controls the operation of a driving motor 30 of a grinder pump 20 in a sewage pit. Air pressure corresponding to the liquid level height in the sewage pit is introduced into a first diaphragm chamber 40 on the lower side of a diaphragm 38 in the differential pressure sensor 28, and a switch 44 is turned on/off in response to the differential pressure between the air pressure and the reference pressure of a second diaphragm chamber 42 on the upper side of the diaphragm 38 to control the operation of the driving motor 30. The second diaphragm chamber 42 is opened into a control panel on the ground through a vent tube 34, and atmospheric pressure serving as the reference pressure is introduced into the second diaphragm chamber 42. COPYRIGHT: (C)2009,JPO&INPIT