| 摘要 |
PROBLEM TO BE SOLVED: To prevent the protrusion of a valve box into a conduit by forming connection flanges on the upper circumference of the valve box and the upper opening circumference of a riser opposite to each other, respectively, and installing a connection short pipe for preventing the valve box lower end from protruding into the conduit between both the connection flanges. SOLUTION: An air valve 1 is formed of a valve box 3 having a float chamber 2 in the inner part, a valve element part 4 provided in the upper part of the valve box 3, a cap 5 covering the valve element part 4, a float 6 housed within the float chamber 2 in such a manner as to be vertically movable, and a free valve element 7. The valve box 3 has a connection flange 8 on the body circumference, and this flange 8 is connected to the connection flange 13 of a riser 12 integrated to a conduit 11 to mount the air valve 1 on the conduit 11. At this time, when the height H of the riser 12 is smaller than the length L of the valve box 3, a connection short pipe 21 is interposed between both the connection flanges 8, 13 to perform the mounting of the air valve 1, so that the valve box 3 never protrudes into the conduit 11.
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