CHECKING APPARATUS OF LEAK FOR DOUBLE CUTOFF GAS VALVE

PURPOSE:To make an apparatus small in size by providing first and second diaphragms and a controller which compares a detected pressure value by an electric signal with a set pressure value and discriminates the presence or absence of leak abnormality of first and second cutoff valves. CONSTITUTION:A first cutoff valve 1 being closed while a second cutoff valve 2 being opened, a control signal is supplied from a controller 10 to an electromagnetic proportional coil 26 and a first diaphragm 22 is displaced through a plunger 27 so that the internal pressure of a chamber, an object of detection, between the valves 1 and 2 be atmospheric pressure. While reading the internal pressure of a compression- decomposition chamber 24 on the basis of a pressure detection signal from a pressure sensor 30, on the occasion, the controller 10 electrifies the coil 26 to reduce the internal pressure of the chamber, the object of detection, to the atmospheric pressure. Then, the coil 26 is put in non-excitation and leak abnormality of the valve 1 is determined. Both the valves 1 and 2 being closed, subsequently, the respective internal pressure of the chamber 24 and the chamber, the object of detection, is increased through the controller 10 and the coil 26. When the pressure reaches a prescribed set pressure, the coil 26 is put in non-excitation state and abnormality of the valve 2 is determined.