Description Graf anti-backflow damper or non-return valve for 110mm (DN100) pipe. Graf anti-backflow damper is an ideal way of preventing ground or surface water from getting back into the rainwater tank and contaminating your clean rainwater. Use if the location is subject to flooding or backflow from drain or soakaway. Cube-shaped heavy-duty plastic with cover secured by four finger nuts. The non-return valve can also be connected to the outlet of the u-tube siphon exit on the Graf Carat range of tanks, but ensure it is protected from earth movement.
