Backflow preventer for liquid pressure lines

摘要

A backflow preventer for liquid pressure lines has a housing with an upstream connection stub (1) and a downstream connection stub (4), to which there is assigned in each case one spring-loaded inflow and outflow valve (7 and 16, respectively). Located between these valves (7, 16) is a central chamber (22) having an outwardly directed discharge opening (4'') with a discharge valve seat (23) which encloses the latter, is fixed to the housing and interacts with a valve rod (25) which, counter to a restoring spring (34) acting on it, is to be subjected to the supply-flow pressure occurring in a pressure chamber (28), which can be connected to the upstream connection stub (1), and is consequently to be displaced axially into its closure position which closes the discharge valve (23). In order to provide an even greater degree of security against backflow, the valve rod is configured as a piston separating pipe (25) which extends coaxially between the supply and discharge valve (7 and 16), has a loading flange (25'') located in the pressure chamber (28), and, in its closure position which closes the discharge valve (23), the supply valve (7) being open, is penetrated by a flow of the liquid and, in its separating position which releases the discharge opening, bears with its supply end (25') in a sealing manner on a valve sealing seat (e.g. 8<IV>), located behind the supply valve (7), and consequently additionally ... the central chamber (22), extending into the piston separating pipe (25), with respect to the ... Original abstract incomplete.