A rubber duckbill check valve is an elastomeric, two-section valve that operates as a pressure differential across the device – the pressure from a liquid pushes the two halves apart allowing the fluid to pass through. Inspired by nature, they resemble the beak of a duck with a flat front end and are used in a wide range of applications from pumping stations to wet well aeration and mixing.
Choosing the right type of duckbill check valve for your application depends on several factors. The primary considerations are material selection, back pressure and flow rate.
Material Selectivity: There are many different elastomer materials that can be used to make duckbill check valves, including medical and food-grade silicone, liquid silicone rubber (LSR) for medical or baby products like duckbill valve for breast pump and hydrocarbon-resistant fluorosilicone rubber (FVMQ) to fit a broad range of media and temperatures. Other elastomers such as EPDM, Buna N & Nitrile Rubber, Neoprene / CR, Fluorocarbon rubber (FKM, FPM, Viton) can also be chosen to make one way valve for various applications.
Durability and Reliability: A rubber duckbill check valve will withstand harsh environments with little maintenance. This makes them a popular choice for use in wastewater treatment plants, outfalls and other municipal water systems where sewage discharge is required to be protected from contaminant runoff.
A rubber duckbill check valve is a simple, reliable and cost effective alternative to conventional flap and swing check valves manufactured from metal that can malfunction, rust or seize due to the presence of corrosive materials or abrasive suspended solids. Unlike their counterparts, rubber duckbill check valves are constructed from reinforced rubber, eliminating the mechanical wear that can occur with swing and flap check valves.
The duckbill shape is a highly functional design that allows the valve to open and close at different pressures for pressure relief and sealing & backflow functions. The lips of the duckbill valve should open at low air pressure for pressure relief and close at higher air or hydraulic pressure for sealing & backflow functions.
Duckbill Check Valves are typically made from NBR, EPDM, medical / food grade silicone or other elastomers and can be cut to size by using a die cutter or shear. They are available in slip on or flanged types depending on the connection requirements and pipe flange pattern.
Installation: The duckbill valve is installed on the end of a connecting pipe flange or headwall. The valve flange must be lined up with the appropriate drilling pattern and fasteners must be inserted to secure it in place. Lifting equipment is required for large sizes.
A duckbill check valve is a passive flow device that will only open when the system’s upstream pressure exceeds its downstream pressure by a specific amount, or by a predetermined percentage. Typical applications include Combined Sewer Overflows (CSOs), Sanitary Sewer Overflows and storm water outfalls, where the upstream pressure of the system must be controlled by a specific percentage of back pressure.