Duckbill Check Valve

Duckbill Check Valve Manufacturer for Wastewater, Drainage & Backflow Prevention

Duckbill check valves provide automatic backflow prevention for municipal stormwater, wastewater effluent, and tidal outfall lines. The flexible rubber sleeve opens with low forward pressure and seals tight against reverse flow without mechanical hinges, gates, or springs.

We manufacture slip-on and flanged duckbill check valves from DN50 to DN2400 (2 inches to 96 inches). Every valve is constructed using a custom rubber matrix reinforced with multi-ply synthetic fabric.

Product Range

Slip-On Duckbill Check Valves (Series DB-S)

Mounting Method: Slides directly over the plain end of steel, HDPE, PVC, or concrete pipes. Secured using stainless steel heavy-duty T-bolt clamps.
Size Range: DN50 to DN1200 (2 inches to 48 inches)
Best For: Direct pipe end retrofits, outfall pipes, drainage culverts, and space-restricted sumps.

Flanged Duckbill Check Valves (Series DB-F)

Mounting Method: Built with a fully molded rubber flange. Bolted between mating pipe flanges using metal backing rings.
Size Range: DN100 to DN2400 (4 inches to 96 inches)
Best For: In-line flange connections, pump discharge lines, and municipal wastewater outfalls.

In-Line / Jacketed Duckbill Valves (Series DB-I)

Mounting Method: Enclosed inside a metal spool pipe casing with flanged ends on both sides.
Size Range: DN50 to DN1000 (2 inches to 40 inches)
Best For: Indoor piping runs, buried pipelines, and high-velocity pumping applications.

Materials

Rubber Grade	Material Name	Resistance Features	Target Application
EPDM	Ethylene Propylene	Resists ozone, UV rays, aging, and mild acids	Municipal drainage, raw sewage, outfalls
NBR	Nitrile Rubber	Resists mineral oils, grease, and fuels	Industrial wastewater, oil separators
Neoprene	Chloroprene	Resists seawater, weathering, and wear	Coastal outfall systems, marine discharge
CSM	Hypalon	High resistance to strong oxidizers and chemicals	Chemical processing discharge lines

Structural and Hardware Specifications

Internal Fabric Layers: High-tenacity polyester or nylon tire cord fabric woven into the rubber wall.

Clamps (Slip-On Series): AISI 304 or AISI 316 stainless steel T-bolt clamps.

Backing Rings (Flanged Series): Galvanized carbon steel, AISI 304, or AISI 316 stainless steel split rings.

Operating Parameters

Parameter	Specification
Pipe Size Range	DN50 to DN2400 (2 inches to 96 inches)
Cracking Pressure	0.01 bar to 0.03 bar (0.15 PSI to 0.45 PSI)
Max Working Backpressure	Up to 10 bar (145 PSI), custom reinforced per pressure head
Operating Temperature	EPDM: -30 to +120 degrees C; NBR: -20 to +90 degrees C
Flange Standard	ASME B16.5 Class 150, EN 1092-1 PN10 / PN16, AS 2129 Table E

Industry Applications

Municipal Stormwater & Flood Control

Installed on riverbanks and seawalls to stop floodwater from entering storm sewers.

Wastewater Treatment Plants

Used on effluent discharge pipes and scum lines to maintain single-direction flow without clogging.

Coastal Outfalls

Prevents seawater from entering freshwater drainage lines during high tide.

Pump Station Outlets

Mounted on pump discharges to stop backflow and eliminate water hammer shock when pumps stop.

Custom Manufacturing Capabilities

Pressure Modeling: We calculate rubber wall thickness and fabric layers based on your maximum static backpressure and flow rate.

Fabric Layup & Vulcanization: High-tensile fabric layers are wrapped around precision metal mandrels, followed by high-pressure steam vulcanization in autoclaves.

Flange and Lip Machining: Sealing lips and flange bolt holes are trimmed precisely to ensure leak-free field installation.

Quality Control & Testing Standards

Hydrostatic Backpressure Test

Valves are mounted on test rigs and pressurized to 1.5 times rated backpressure to confirm zero reverse leakage and zero structural inversion.

Forward Flow Test

Confirms the flexible lips open fully at the specified low opening pressure.

Elastomer Physical Test

Tensile strength, elongation, and ozone resistance tests are conducted per ISO 37 and ISO 1431 standards.

Material Traceability

Raw material batch logs and vulcanization records are kept for every production order.

Certifications

ISO 9001:2015 Quality Management System
Material Test Reports (MTR) provided with full compound property data

Packaging & Shipping Protection

Internal Shape Support

Foam inserts or wooden supports are placed inside large valves to maintain original lip shape and prevent permanent deformation.

UV & Moisture Protection

Sealed in opaque black plastic wrap to block UV rays and moisture during sea freight.

Export Wooden Crates

Packed in ISPM-15 heat-treated wooden boxes, secured internally to prevent moving or crushing.

Included Documents

Inspection Certificates, Material Data Sheets, and Installation Manuals are included in every shipment.

Our Factory

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FAQ

Q: How does a duckbill check valve handle debris without leaking?

A: The rubber lips are flexible. When solid particles like sand, twigs, or sludge pass through during reverse pressure, the rubber folds around the debris and maintains a tight seal. Rigid metal flap gates often get stuck open under the same conditions.

Q: What causes duckbill valve inversion, and how do you prevent it?

A: Inversion happens when reverse backpressure is stronger than the rubber wall, pushing the duckbill inside out. We prevent inversion by calculating your maximum reverse water head and adding extra fabric layers or internal stiffness ribs during molding.

Q: Can a slip-on duckbill valve fit an uneven or oversized concrete pipe?

A: Yes. Measure the exact outside diameter (OD) and shape of your pipe end before ordering. We adjust the sleeve mold to match your pipe OD, ensuring the stainless steel clamps seal evenly without slipping.

Q: What routine maintenance is required for rubber duckbill valves?

A: Duckbill valves require zero routine maintenance because they have no mechanical hinges, pins, or springs to rust or grease. Occasional visual checks for external debris around the discharge end are usually enough.

We're well-known as one of the most experienced duckbill check valve suppliers in China. With abundant experience, we warmly welcome you to buy high quality duckbill check valve in stock here and get quotation from our factory. For price consultation, contact us.

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