Prevention of used water return flow to supply duct - involves two detachable stop valve units and load relief valve, in housing

摘要

A housing unit (10) with a coaxial water inlet (12) and release openings and a water outlet opening (14) is incorporated in a provision for checking return flow of water from a place of use into a water supply duct. Other components include a detachable stop valve assembly (34) between inlet (28) and central (30) chambers, held by a removable retainer (41) inside the chamber. There is a second similarly held (45) stop valve assembly (36) between the central and outlet chambers (32). There is a load relief valve (90) between central and release chambers prestressed in the open position, membrane (124) on housing and load relief valve, for closing this, and a detachable housing cover. Construction is simplified, and higher through-flow is practicable with a given valve size.