To prevent the leakage from a seal part around a valve opening part when the valve opening part is closed, by preventing the attachment of a treated material and the like passed through the valve opening part, to the seal part around the valve opening part, when the valve opening part is opened.
Annular hollow seal members 13a, 13b are mounted around the valve opening part 10c on each inner surface at a clearance part 10d side of an upper main body 10a and a lower main body 10b, and the seal members 13a, 13b are expanded by introducing the compressed air in valve opening and closing motion, to seal between the circumference of the valve opening part 10c at each inner face of the clearance part 10d side of the upper main body 10a and the lower main body 10b, and both surfaces of a valve element 11, whereby the attachment of the treated material and the like passing through the valve opening part 10c to the seal part around the valve opening part 10c can be prevented, and the leakage from the seal part around the valve opening part 10c can be prevented when the valve opening part 10c is closed.
HIRANO HIROYUKI
KOIZUMI TOSHIYUKI
YAMAGUCHI OSAMU
Masashi Yoshioka