| 摘要 |
PURPOSE:To hold a shut-off state even if a differential pressure becomes below a set value and to facilitate returning of a state to the beginning, by providing a holding means which holds a piston in its moving position during shut-off and a releasing means which is capable of releasing a holding means. CONSTITUTION:When a line connected to an outcoming port 21a is broken, a differential pressure is produced by an orifice 22a, and a tapered valve part 24b of a piston 24 is seated on a seat part 21b of a body 21. Thereafter, a spool 25 is returned to its original position through a spring 28, and steel balls 26 are forcibly pushed in an annular recess 20f in a retainer 20. As a result, the piston 24 continues to be held in a shut-off state. With a crank 29 rotated through rotation of a handle 30, the spool 25 is pushed rightward against the spring 28, and the steel balls 26 come out from the annular recess 20f in the retainer 20. |
