Flap Valve 4 Inch DN100 Class 150 ASME B16.5

The Supreme Valves 4-inch DN100 Flap Valve is a non-return (check) valve designed to prevent backflow in water distribution, wastewater, and drainage systems. The hinged flap design allows forward flow while automatically closing to block reverse flow, protecting pumps and pipeline systems from damage due to backflow.

Available in both cast iron (ASTM A126B) and ductile iron (ASTM A395) body materials, with stainless steel hinge components for corrosion resistance. The wafer-style body design allows for compact installation between pipeline flanges, reducing weight and cost compared to traditional full-flanged check valves.

Class 150 pressure rating per ASME B16.5/16.34 provides a maximum working pressure of 270 PSI (19 bar), suitable for municipal water systems, sewage pumping stations, and drainage applications throughout Qatar and the Middle East.

Applications

• Sewage Lift Stations
• Water Distribution
• Storm Water Drainage
• Pump Discharge
• Effluent Treatment

What is a flap valve and how does it work?

A flap valve (also called swing flap or non-return flap valve) is a simple check valve design where a hinged flap or disc swings open to allow forward flow and automatically closes when flow stops or reverses. The flap is attached to a hinge at the top of the valve body, and gravity or a counterweight helps ensure closure when backflow occurs.

What is the difference between a flap valve and a swing check valve?

Flap valves and swing check valves share the same operating principle (a hinged disc that swings open with forward flow) but differ in body construction. Swing check valves typically have a full-body flanged construction similar to gate valves, while flap valves often have a wafer-style body that sandwiches between pipeline flanges. The wafer design is lighter and more compact.

Can flap valves be installed in horizontal and vertical orientations?

Flap valves can be installed in both horizontal and vertical orientations, though performance varies. For horizontal installation, the valve should be mounted with the hinge axis horizontal and the flap hanging downward at rest (gravity-assisted closure). For vertical installation with upward flow, the flap hangs closed when there is no flow.

What materials are used in flap valves for wastewater service?

Flap valve bodies are typically constructed from Cast Iron ASTM A126 Class B or Ductile Iron ASTM A395. The flap itself may be cast iron with a rubber seal bonded to the seating face for bubble-tight closure. Hinge components use stainless steel (SS304 or SS316) for corrosion resistance in sewage service.

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