| 摘要 |
<p>A backflow preventer valve has a body with a vent chamber, the inner end of which forms a relief valve seat; the base of a cup member, supported on the inner edge of an annular flexible diaphragm with the outer edge secured to the valve body, engages with the relief valve seat to close off the vent chamber. The cup member has an internal check valve seat and contains a check valve biased against the check valve seat.</p> |
