Duck billed valve (check valve)

Duck billed valve (check valve), also known as rubber check valve, flexible check valve, etc., is a type of rubber check valve without movable components except for connecting flanges and clamps. It is mainly used for the outlet of urban rainwater discharged into rivers, lakes, and seas to prevent backflow of water when the water level in rivers, lakes, and seas is higher than the drainage pipeline. The duckbill valve is made of elastic chloroprene rubber and artificial fibers through special processing, with a shape similar to a duckbill and two types: rolled edge and flat mouth. The working principle of the duckbill valve is based on the principle of fluid dynamics. When the liquid passes through the valve, pressure is generated, and the duckbill valve will automatically open. When the flow pressure increases, the opening amplitude of the outlet of the duckbill valve will increase accordingly. When the water flow stops or the water level of rivers, lakes, and seas is higher than the outlet to form backflow pressure, the specific structural form of the duckbill valve will cause the duckbill valve to return to its original closed state, preventing liquid or odor from flowing back. The opening pressure of the duckbill valve produced by Shanghai Meiyan Yi Pump Valve is relatively small. Usually, when the forward and reverse water level difference exceeds 10mm, the valve outlet can be opened or closed with minimal head loss.