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450 Series – Flap Gates

Best Flap Gates for Backflow Prevention

Made in the USA since 1977

General Information

The 450 Series Flap Gates from Whipps, Inc. are a dependable, low-maintenance solution for preventing backflow in gravity flow, pump discharge, tidal drainage, and flood control systems. Designed for efficiency and reliability, these flap gates operate automatically without manual or power assistance. This is done by the flap gate opening under internal pressure to allow discharge and closing tightly against a resilient seal to stop reverse flow.

Built with rugged construction and corrosion-resistant materials, the 450 Series delivers long-lasting durability in even the most demanding environments. Each gate is custom-fabricated to handle specific flow conditions, sizes, and mounting arrangements, ensuring precise performance across a wide range of applications.

Whipps flap gates are engineered for strength and effective backflow prevention. All models incorporate resilient seals that provide a secure closure and minimize leakage. The quiet, cushioned design eliminates the loud slamming action often seen in traditional flap gates, while the field-replaceable seals simplify maintenance and extend service life.

450 Series Models

Model 451

Features a thick, reinforced rubber flap that rests on a resilient seal.

Flexes opens under internal water pressure, then seals tightly when external pressure builds.

Well-suited for a variety of standard flow conditions and smaller installations.

Model 452

Uses a stainless steel or aluminum flap mounted with heavy-duty hinges.

Engineered for larger gate sizes and applications with higher head pressures.

Provides the strength and durability required in demanding flow control environments.

The 450 Series is available in stainless steel, aluminum, or reinforced rubber for corrosion resistance and dependable performance. For specialized installations, Whipps also offers options for openings of any shape or size. Gates can be custom-mounted to wall thimbles, along channels, or directly in structures, providing flexibility to meet exact site requirements.

The 450 Series Flap Gates are trusted across a wide range of industries and installations, including municipal wastewater treatment systems, stormwater and tidal drainage, flood control structures, pump discharge lines, and hydroelectric or industrial facilities. Backed by decades of engineering expertise and precision fabrication, these gates provide reliable, cost-effective backflow prevention. With robust construction, superior sealing, and flexible design options, the 450 Series delivers the performance and durability operators need to protect critical water management systems with confidence.

Product Advantages

Performance

The use of compressible seals provides superior leakage performance compared to a traditional cast iron flap gate with bronze seating faces.

Design Flexibility

All flap gates are custom built for each application, enabling various mounting arrangements and a nearly unlimited range of sizes.

Functionality

Our flap gates open under very low unseating heads, particularly with rubber flap gates.

Ease of Maintenance

If debris becomes wedged in the flap or accumulates behind it, personnel can easily lift and clear the debris, especially with rubber flap gates.

Quiet Operation

Due to the use of resilient seals, there is no slamming action between the flap and the frame, even in pump discharge applications.

Corrosion Resistance

Painting or recoating stainless steel is not required to resist corrosion in water and wastewater.

Field Replaceable Seals

If the seals were to ever become damaged, they are easily removable and replaceable. In contrast, the bronze seating faces on traditional cast iron flap gates cannot be replaced in the field.

3D Model of 451 Flap Gate Mounted to Pipe

451 – Pipe Flap Gate with Rubber Flap

Model 451 flap gates use a rubber flap to release fluid while preventing backflow. Reinforced with rugged members usually made form stainless steel. Mounting to a wall thimble or pipe flange available.

451 – Rectangle Flap Gate with Rubber Flap

Model 451 flap gates use a rubber flap to release fluid while preventing backflow. Reinforced with rugged members usually made form stainless steel. Mounting to a wall thimble or pipe flange available.

451 – Square Flap Gate with Rubber Flap

Model 451 flap gates use a rubber flap to release fluid while preventing backflow. Reinforced with rugged members usually made form stainless steel. Mounting to a wall thimble or pipe flange available.

452 – Pipe Flange Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

452 – Pontoon Flap Gate

The Model 452 Pontoon Flap Gate use a rugged, metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage even in high head conditions.

452 – Rectangle Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

3D Model of 452 Flap Gate Pipe Mounted 2

452 – Semicircle Pipe Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

452 – Square Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

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450 Series – Flap Gates

Best Flap Gates for Backflow Prevention

Made in the USA since 1977

General Information

450 Series Models

Product Advantages

Performance

Design Flexibility

Functionality

Ease of Maintenance

Quiet Operation

Corrosion Resistance

Field Replaceable Seals

451 – Pipe Flap Gate with Rubber Flap

Model 451 flap gates use a rubber flap to release fluid while preventing backflow. Reinforced with rugged members usually made form stainless steel. Mounting to a wall thimble or pipe flange available.

451 – Rectangle Flap Gate with Rubber Flap

Model 451 flap gates use a rubber flap to release fluid while preventing backflow. Reinforced with rugged members usually made form stainless steel. Mounting to a wall thimble or pipe flange available.

451 – Square Flap Gate with Rubber Flap

Model 451 flap gates use a rubber flap to release fluid while preventing backflow. Reinforced with rugged members usually made form stainless steel. Mounting to a wall thimble or pipe flange available.

452 – Pipe Flange Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

452 – Pontoon Flap Gate

The Model 452 Pontoon Flap Gate use a rugged, metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage even in high head conditions.

452 – Rectangle Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

452 – Semicircle Pipe Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

452 – Square Flap Gate with Metal Flap

Model 452 flap gates use a metal flap to release fluid while preventing backflow. The rugged gate flap rest on a resilient, compressible seal providing low leakage when closed. Mounting to a wall thimble or pipe flange available.

450 Series Videos

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Not Looking for FLAP GATES?

Check Out Our Other Product Series