GB1374833A - Backflow preventors - Google Patents

Abstract

1374833 Valves PEGLER-HATTERSLEY Ltd 11 April 1972 [20 April 1971] 16717/72 Heading F2V A three valve assembly consisting of two check and one relief valve, comprises a central body portion 10 the ends of which are in screwthreaded engagement with spigot carrying end caps 12 and 14. Cap 12 anchors a first diaphragm 32 which has a central aperture 34 and which co-operates with a seat member 36 extending from a filter assembly 38. Similarly, cap 14 anchors a second diaphragm 40 which has a central aperture 42 and which co-operates with a seat member 44 extending from a hollow chamber 22 apertured at 27, a further filter assembly 46 being disposed proximate the spigot 16 of cap 14. Flow in the direction indicated by arrows, tends to move both diaphragms away from their respective chambers so creating a flow path 16, 38, 34, 23, 27, 42, 46 and 16. Should the pressure differential across the assembly fall below a certain value, then diaphragm 40 is seated against member 44 and the pressure acting on this diaphragm tends to move a piston assembly 52, 48, 46 leftwardly, as seen in the drawing. This serves to displace diaphragm 32 from an annular flange 24 and so open chamber 23 to the piston assembly containing chamber 20, the latter being vented to drain by an opening 18. Similar venting is obtained in the event of diaphragm rupture or leakage between a seating member and its associated diaphragm. Modifications of the above embodiment are depicted in Figs. 3 to 6, not shown.