| 摘要 |
An automatic shut-off valve for installation on a swimming pool or spa main drain. The automatic shut-off valve has a ball and ball spring between a diaphragm and a housing. The diaphragm is made of resilient material. Downward force on the diaphragm urges the ball into sealable engagement with a valve seat in the housing. During operation, a swimmer covers sufficient diaphragm base apertures so that the diaphragm center 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 diaphragm 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. Back-up shut-off function is provided by a cap spring-loaded into a closed position whence it migrates should the ball become dislodged. An alternate embodiment automatic shut-off valve is disclosed wherein an integral are diaphragm and base replaces the diaphragm/diaphragm base combination of the preferred embodiment.
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