The Ductile Iron 90° Duckbill Check Valve (also known as a Tide Flex Valve or rubber check valve) is a one-way flow control device specifically designed for stormwater and wastewater outfalls into tidal waters. The valve consists of a ductile iron flanged body (for bolting to the end of a pipe) and a flexible rubber duckbill sleeve that extends from the body at a 90° angle, pointing downward. The rubber sleeve is molded from high quality EPDM or natural rubber with reinforcing fabric. Under forward flow (discharge), the rubber lips open, allowing water to exit. When flow stops or reverse flow occurs (tide coming in), the rubber lips collapse and seal tightly against each other — completely preventing backflow. The 90° downward orientation directs discharge toward the bottom, reducing surface splash and erosion. Because there are no metal parts in the flow path, the valve never corrodes or jams.
Why Choose Us / Advantage
Absolute Backflow Prevention: Zero reverse flow — protects upstream environment from tidal saltwater intrusion.
No Fouling: Rubber lips do not accumulate marine growth — self-cleaning during discharge.
Low Cracking Pressure: Opens with as little as 0.1 psi forward pressure.
Long Life: 20+ year service life in tidal applications.
Easy Installation: Bolt directly to existing outfall pipe flange.
Technical Data
★ Body Material Ductile Iron QT450 (epoxy coated)
★ Duckbill Material EPDM rubber (w/ fabric reinforcement)
★ Orientation 90° downward discharge
★ Cracking Pressure 0.1 – 0.3 psi (very low)
★ Pressure Rating PN10 / Class 125
★ Size Range DN50 – DN1200 (2″ – 48″)
★ Connection Flanged (ANSI / EN / BS)
★ Maintenance None required
Applications
● Stormwater outfalls into rivers, lakes, or oceans
● Wastewater treatment plant discharge into tidal waters
● Irrigation drainage outlets
● Flood control pump station discharges
● Submarine outfall pipelines
