| 摘要 |
PURPOSE:To enable to reset only in case of no gas leakage at secondary side by a method wherein a control circuit, which opens a test valve for the fixed time, is provided. CONSTITUTION:When the shut-off signal is supplied, the supply of the driving signal to a coil 23 is interrupted and the pressure within a chamber 25 becomes low and a valve body 14 and a responding body 28 returns to their original positions to close the opening of a port 13. When the reset signal is supplied, the control circuit 4 supplies the driving signal to the test valve 6 only for the fixed time in order to open the test valve 6. Consequently, the gas within an inlet passage 11 flows through a by path 5 to an outlet passage 12. If there is no gas leakage at the side of the passage 12, the gas flow stops after a short time, resulting in stopping an impeller 31. The circuit 4 checks pulse from a Hall element 33 after the fixed time and, when no pulse signal is sent, sends the driving signal to the coil 23. |
