The Check-Flex® G3 is built from layers of fabric reinforced rubber, which are hot vulcanised into a single piece valve.

The symmetrical valve delivers full port flow and fast drainage, with minimal length and is ideal for locations that are higher than bed level or permanently submerged, where clearance below pipe invert level is available.

The G3 is an ideal economic replacement for failing flap valves on CSO/ESO, including pumped flows. The tough one piece reinforced Neoprene construction is offers long life in all drainage locations, including coastal and saltwater areas without periodic mainte- nance.

In partially filled pipes, the low upstream head acts on the large area of the G3 walls (compared to the flap valve chord), delivers the force to open the valve and clear shingle and rocks. The G3 valves will reliably drain a pipe of standing water and are self-clearing of flow debris. In tidal zones, the valves will continue to work as the valve is submerged.

The flange of the valve forms a deep gasket to the wall, (35mm). The flange contains a fully encapsulated backing ring, so that the standard valve is suitable for marine use.

Duckbill valves work on the same principle as Leonardo Da Vinci’s mitre lock gate design. The back pressure of the tide or river water presses the valve walls together to make a seal that can hold a vacuum. The G3 responds instantly to pressure changes on the walls allowing pipes to be drained down to lowest wave trough level, maximising the upstream attenuation.

There are SDP (Slide Direct to Pipe) versions available where a connection to an exposed pipe can be made, such as an outfall pipe in rock armour, or is soft ground that cannot support the structure of a headwall. The valves can be installed directly into river flows without sidewall protection. These valves are often used for land drainage and to maintain saltwater marshes or SAC’s using lightweight plastic pipe and SDP valves to control backflow.