Assembly for prevention of backflow in valves

摘要: A valve assembly (15, 15A, 15B) which is suitable for backflow prevention in a stop cock (10) having an inlet (11), seat (12) and outlet (13). The may be attachable to the includes body (20) at least one opening (24) also including chamber (26) (23). There provided balance tube (30) communicates with has end engaged sealing against of flow fluid from (11) (13), piston (40) located within engageable (24), biasing means (45) operable unseat (23) enable (13) communicate (24). In further embodiment (figure 5) (15B) third (62) handle (17) member (61) biased open by spring (64) pressure allow atmospheric air break vacuum (11). fundamental advantage that it can prevent when opened or closed utilised downstream exceeds upstream predetermined amount.