| 摘要 |
<p>Backflow preventers especially suitable for fitting in drinking water pipes have a through-flow housing (1) containing an inlet and an outlet pipe (2 and 3) with a spring-loaded inlet valve (4) inside it and a spring-loaded outlet valve (8) and a central chamber (13) arranged between the two valves (4, 8). When the differential pressure between said central chamber and the inlet pipe (2) dropes below a set minimum, said chamber can be caused to communicate with the outside atmosphere via a discharge valve which then opens, the body (28) of which is connected for this purpose to control components (18, 18') actuatable on one side by the inlet pipe pressure and on the other by the pressure in the central chamber, and can be raised from its outlet valve seat (30), freeing both a water outlet aperture and a ventilating aperture leading to the central chamber (13). In order to obtain an even simpler design for this outlet valve and improved water drainage and ventilation facilities for the central chamber (13), the water outlet aperture of the outlet valve and the ventilation aperture are combined into a single connecting aperture (14, 32) with a relatively large cross-section between the central chamber (13) and the outer atmosphere which can be steplessly opened more widely by the valve body (28) depending on the extent to which it is open.</p> |
