Back flow blocking device for combustion device exhaust flue has valve element raised from valve seat provided by flow restriction by pressure of flue gases with integral guide element at rear of valve element

摘要

The back flow blocking device has a tubular body (1) inserted in a vertical section of the exhaust flue, provided on its inside with a flow restriction having a valve seat and a cooperating valve element (8), e.g. of plastics, which is raised from the valve seat by the pressure of the flue gases. The guide element is provided by a plate, its rear surface rear surface having a perpendicular guide element (10) cooperating with a guide (11) provided by the flow restriction.