Althon HDPE Flap Valves can be used in Surface, Sewer and Water Process applications. They are a Simple and Highly Effective way to Prevent Water Backflow into a system. Our Flap Valves are manufactured in HDPE and Stainless Steel 316. Althon HDPE Flap Valves are Lightweight and High Strength. Our Flap Valves are therefore Easy to Install, Responsive and very Reliable. Althon Standard HDPE Flap Valves start at 100mm in diameter. We would be pleased to assist with Bespoke Flap Valves. Please visit the Bespoke HDPE Flap Valve section of our website.