| 摘要 |
A one way air admittance valve (2) for admitting air into a pipe (3), which valve (2) comprises a body portion (4) for fitting to the pipe (3), at least one air inlet port (6) in the body portion (4), and rigid sealing means (16) which is longitudinally movable between a first position in which it seals the air inlet port (6) and a second position in which the air inlet port (6) is open for the admittance of air into the pipe (3), the valve (2) being such that there is only one sealing means (16) for all of the air inlet ports (6), the sealing means (16) being such that it seals at two separate areas (18, 20), and the two separate areas (18, 20) being such that in the first position of the sealing means air in the air inlet port (6) is prevented by the sealing means from passing to the centre of the sealing means and around the periphery of the sealing means. |
