Backflow preventer and system separator especially for the fire service area

摘要

The invention relates to a backflow preventer, in particular for fire service use, with a housing which encloses a main flow channel; with a valve seat within the housing on the main flow channel; with a valve body which is movable relative to the valve seat in order to shut off the main flow channel together with the valve seat in a closed position and to open the main flow channel in an open position; wherein the valve body can be moved alternately between its closed position and its open position by a pressure difference in the main flow channel and / or by the force of a spring element. The backflow preventer according to the invention is characterized in that the main flow channel in the region of the valve body is divided into at least one outer flow channel and one inner flow channel is and the valve body encloses the inner flow channel and forms at least one valve body valve seat on the inner flow channel and comprises at least one primary and one secondary valve plate, the valve plates being arranged such that in the closed position the primary valve plate lies sealingly on the valve seat on the main flow channel and the secondary valve plate sealingly rests on the valve body valve seat on the inner flow channel, and in the open position the primary valve disk from the valve seat on the main tströmkanal is lifted and releases the outer flow channel, and the secondary valve plate is lifted from the valve body valve seat on the inner flow channel and releases the inner flow channel.