| 摘要 |
<p>A liner (10) for a pool (12) is provided with a plurality of one way valves (14) to selectively allow water to flow from an upper side (18) of the liner to below a lower side (20). The valves (14) open automatically upon initial lifting of the liner (14) by use of an air lift system (36). As the liner (10) is lifted from the surface (17) of the pool (12) a pressure head is created which forces the valves (14) open while they are disposed in the water (16). The valves (14) include a resiliently biased flap (24) which is forced open by the pressure head. However when the valves (14) are lifted above the level of the water they automatically shut by combination of the biasing of the flaps (24) and the absence of the pressure differential.</p> |
