Flap Gate

Flap Gate

Flap gates are mostly installed at the outlets of drainage pipelines, which open and close automatically relying on the water level difference between the inside and outside.

The gate body is available in two materials: cast iron and steel, equipped with rubber sealing gaskets for water stop. When the internal water level is higher than the external one, the gate will be pushed open automatically for drainage; it closes by itself to block backwater in case of water backflow.


No hoisting equipment or manual operation is required. Featuring resistance to sediment corrosion and water flow impact, flap gates are widely applied in municipal sewage discharge, pump station tailwater outlets and river culverts. They are easy to install and require little maintenance in later service.

Specifications


1.Hydraulic Automatic Opening & Closing

Opens and closes automatically by the water level difference inside and outside the pipeline. No motor or manual operation required, achieving zero-energy operation.

2. One-Way Water Sealing

Only allows water inside the pipe to flow outward. It forms an automatic tight seal under high external water levels to prevent backflow of river water and rainwater.

3. Power-Free Operation

Free of any electrical and driving components. It can reliably prevent backflow even during power outages or pump station malfunctions, delivering outstanding flood control stability.


4. Simple Structure

Consists of only four core parts: gate leaf, gate frame, hinges and rubber sealing strips. Fewer components mean low failure rate.

5. Multi-Scenario Installation

Compatible with multiple mounting methods including pipeline flange connection, concrete water outlets and external mounting on channel side walls.

6. Low-Noise Opening & Closing

Driven by hydraulic pressure and self-weight. No gears or motors during operation, resulting in zero vibration and noise.


7. Multi-Media Compatibility

Suitable for conveying rainwater, domestic sewage, clear river water and mild neutral industrial wastewater.

8. Multiple Anti-Corrosion Materials Available

Optional materials: cast iron, anti-corrosion carbon steel, 304 / 316 stainless steel and FRP, suitable for corrosive water environments.

9. Low Maintenance Cost

Without transmission or electrical accessories. Routine inspection only covers hinge rust and sealing strip aging.


10. Low-Temperature Weather Resistance

No electronic parts to malfunction under low temperatures. Simple thermal insulation enables stable performance under winter icing conditions.

11. Low Opening Resistance

A slight internal water pressure can push the gate open, avoiding pipeline water accumulation even under small drainage flow rates.

12. Wide Engineering Versatility

Widely applied in municipal pipe networks, flood drainage pump stations, residential sewage systems, sponge city projects and water conservancy channel works.


Item

Technical Index

Product Type

Round / Square Flap Gate

Nominal Diameter & Opening Size

DN300–DN3000; Square opening: 300×300mm–3000×3000mm, non-standard customization available

Main Body Material

Cast Iron / Carbon Steel / Stainless Steel

Sealing Parts

Anti-aging rubber waterstop strip, extrusion sealing structure

Seepage Rate under Closed State

≤0.04L/(s·m)

Operating Water Head Range

0–30m

Opening Starting Pressure

Minimum opening water level differential: 0.08–0.12m

Connection & Installation Method

Flange connection, pre-embedded concrete casting

Hinge Structure

External movable hinge

Anti-corrosion Treatment

Overall sand blasting for rust removal + anti-corrosion paint coating

Impact Resistance

Resists impact of floating debris in flood season; no plastic deformation on gate leaf

Applicable Media

River water, rainwater, domestic sewage, mild industrial wastewater

Ambient Temperature

-30℃ ~ 65℃ for outdoor operation

Designed Service Life

Gate service life ≥ 25 years

Opening Angle

Max automatic opening angle: 30°–90°



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