The Series 35-1 flanged duckbill check valve is optimal for situations not suited for slip-on check valves – usually because the piping or outfall system already has a flange. The uniform body design of the Series 35-1 duckbill check valve is comprised of a rubber duckbill check sleeve, and is low maintenance. It is ideal for tough sewer system control, storm sewer overflow and corrosive slurry applications.


  • Reliable backflow prevention
  • Minimal bottom clearance required
  • 100% elastomer construction eliminates maintenance
  • Will not corrode, warp or freeze open or shut
  • 1”-2” Cracking Pressure, Low Headloss
  • Curved Bill enhances sealing around debris
  • Custom built for each application based on pressure and flow conditions
  • Available in diameters from 4" (100mm) to 72” (1800mm)

Materials of Construction

    • Elastomer
    • ANSI Class 125/150#, DIN PN6, PN10, PN16, or custom drilling patterns
    • Retaining Rings
    • Galvanised Steel (Std.)
      • 304 Stainless Steel
      • 316 Stainless Steel
      • Special Alloys Available


In some applications, a slip-on Tideflex duckbill check valve (TF-1) is not feasible because of an existing mating flange or wall thimble, or a flanged connection is preferred, or it is desired to mount the valve directly to a concrete wall. In these cases, the 35-1 Duckbill Check Valve is the solution.

Series 35-1 Duckbill Check Valves are manufactured similarly to the Tideflex TF-1 Duckbill Check Valve, with the addition of an integral elastomeric flange. The flange size drilling conforms to ANSI Class 125/150# and is also available with DIN drillings and other standard or customised drilling patterns.

All Series 35-1 Duckbill Check Valves are furnished complete with retaining rings for installation.

The Tideflex Duckbill Check Valve is a revolutionary design for backflow prevention. Tideflex Valves are a one-piece rubber matrix of numerous natural and synthetic elastomers and ply reinforcement, similar in construction to a truck tire.

Tideflex are cost-effective because they do not need periodic maintenance or repair to keep them operational and they have a 30 year operational life span. Tideflex operate using line pressure and back pressure to open and close so no outside energy source is required.

The valve has an extremely low cracking pressure so the valve self-draining which eliminates standing water and maximises storage volume in the upstream pipe. Tideflex Valves have low headloss, they do not rust or corrode and are not affected by UV so performance and reliability is constant thru the life of the valve.

The flexibility of the Tideflex allows the valve to compress around trapped solids providing a much better seal than flap gates, as confirmed by the USEPA. With the development of the patented curved bill, sealing capabilities are even further improved because the curve bill is more flexible than the rest of the valve and therefore compress more around solids.

For higher back pressure ratings or to lower headloss while maintaining back pressure ratings, the Saddle Support Technology (SST) can be used in conjunction with the Series 35-1.

If you require any assistance or more information please contact us by phone on 01603 488700 or by email sales@althon.co.uk

Tideflex Check Valve Series 35-1

    Brochures, Datasheets and Installation Instructions for Tideflex Check Valve Series 35-1