| 摘要 |
PROBLEM TO BE SOLVED: To provide an air operation valve for chemicals capable of confirming valve opening and valve closing operations through a position of a tip of an indicating member even from a distance, while securing compatibility with explosive and corrosive atmosphere. SOLUTION: Opening and closing of a valve are carried out by reciprocating motion of a piston rod 10 within a cylinder 9. An end portion of an indicator 19 moves outside a cover 13 along the motion of the piston rod 10. Therefore, a position of an end portion of an indicator 14 and operations of opening and closing of the valve have a predetermined relationship. Thus, the operations of opening and closing of the valve are confirmed by an electric signal outputted from a photosensor 16 detecting the position of the end portion of the indicator 14. At that time, the photosensor 16 and the end portion of the indicator 14 are covered with a case 17, and the inside of the case 17 is filled with an inert gas supplied through a purge port 18.
|
