| 摘要 |
<p>An air valve is disclosed suitable for relieving a vacuum in a pipe and preventing the escape of fluid therefrom. The valve includes a body having an inner chamber, an air inlet with inner and outer concentrically spaced valve seats, an opening for cummunicating the chamber witha pipe, and a stationary guide element. A valve element is displaceably mounted in the chamber and is normally urged to a closed position while being shiftable to an open position in response to a vacuum in the pipe. The valve element includes an annular disc of elastomeric material, and a hub mounted for axial movement along the guide element. The hub includes holes communicating the opening with the chamber and with an inner side of the disc when the valve element is in its open and closed positions. Thus, a vacuum at the opening is transmitted through the holes to the inner side of the disc to urge the disc open, and the absence of a vacuum or positive pressure, at the opening causes the disc to close. The hub includes a flange upon which an inner edge of an outer disc side sits usuch that the disc is cantilevered outwardly from the hub. This flange terminates short of the inner valve seat such that inthe valve-closed position, the outer disc side sealingly engages the inner and outer valve seats to prevent escape of fluid from the opening.</p> |
