| 摘要 |
A device which prevents the reverse flow of water from a point of use into a water supply system has a casing 10 with a central chamber 30 coaxially aligned with inlet and outlet chambers 28, 30 and isolated therefrom by respective, aligned inlet and outlet check valves 34, 36. Between the inlet and outlet check valves is a diaphragm actuated relief valve (not shown) which opens to drain the passage between the check valves if they should malfunction or if there is a drop in the supply line pressure sufficient to cause actual or potential reverse flow back toward the supply line. The inlet and outlet check valves are each removably secured in place by retaining rings 45 which are sprung into grooves 11 in the central chamber 30. <IMAGE> |
