| 摘要 |
An automatic shut-off valve for installation on a sing pool or spa main drain. The automatic shut-off valve has a soft gasket, ball, and ball spring between a grate and a housing. The grate is free to reciprocate up and down relative to the housing. Downward reciprocation of the grate urges the ball into sealable engagement with a valve seat in the housing. During operation, a swimmer covers sufficient grate apertures so that the grate is moved downwards as urged by the main drain suction, towards a swimming pool or spa main drain over which the automatic shut-off valve is mounted. The downward motion of the grate urges the ball into sealable engagement with a valve seat in the housing, where it is securely held by the main drain suction. In this fashion, the ball is entrapped instead of the swimmer, thus avoiding possible disembowelment and/or drowning on the part of the swimmer.
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