Views: 137 Author: Sophie Xu Publish Time: 2021-08-04 Origin: Site
Duckbill umbrella valve & duckill flapper valve are combination valve which function as two way flow control valve, bidirectional valve. Duck bill umbrella valve refer to the valve with a duckbill valve in one side and a mushroom valve in another side while duckbill flapper valve is combined by a duckill walve and a flapper check valve. They are made of FDA / LFGB approved silicone material, widely used for sealing, flow controlling, liquid dispensing & air releasing.
Duckbill umbrella combination valve can be applied in two different ways. Like in fuel tank, when fuel consumed, the duckbill valve lets air in the tank at low-pressure differential in order to replace the fuel and prevent from creating a vacuum in the tank. When the tank is held upside down, the duckbill closed and prevents fuel dripping out. When the tank gets hot, the umbrella valve opens and vents the gases to atmosphere. Another is duckbill valve and the umbrella valve directing the flow to separated conduits. In this way duckbill umbrella valve provides two valve functions. Umbrella opens up in the inlet stroke and at the outlet stroke, the umbrella closed and the fluid is directed through the duckbill valve. This is a convenient way to make a diaphragm pump.
Duckbill umbrella / flapper combination valve is available in various elastomer material, including medical and food-grade silicone, liquid silicone rubber (LSR) for bottle cap, dispensing closure and hydrocarbon-resistant fluorosilicone rubber (FVMQ) to fit a broad range of media and temperatures for fuel tank.
Also EPDM, Buna N & Nitrile Rubber, Neoprene / CR, Fluorocarbon rubber (FKM, FPM, Viton) can be chosen to make two way contrl valve.
Angle & Width of rubber duckbill valve end: A certain width needed for rubber duckbill check valve positioning and die cutting proceeding. Meanwhile, if it is a sharp angle at the end, it is easy to cut inaccurately.
Size of slit & lip: The longer the length of slit, the easier it will be opened under certain pressure. But it will not easy to close.
Duckbill Flapper Combination Valve: Flapper check valve can be level with one of the two sides to reduce the complexity of machining process and save mold and die cutting position tool price.
Burrs & Material Loss in Valve Slit
The problem generally caused by not enough sharp die-cutting tools. With blunt tool, the duckbill check valve slit is easy to have flashing in the slit and even make the slit into a gap, fully opened. Operation staff operating techniques can also affect whether the slit can be cut well. Generally, the slit should be cut perfectly the first time. It will leave burrs if proceed second cutting.
Slit “Close” Problems for Combination Valve
The burrs will lead to unclosed slit
The material restoring force will also affect the slit close
Using sharp die cutting tools & Proper positioning of rubber duckbill check valve in die cutting process.
Choosing high-elastic silicone rubber material so that the slits of one way check valve can open & close easily.