Rubber-Flex Duckbill Check Valves - RF-DBI In-Line | Cla-Val

Cla-Val RF-DBI In-Line Duckbill Check Valve

The RF-DBI is an elastomeric in-line check valve designed for pressurized pipelines. It is installed between two pipe flanges and incorporates an integral elastomeric flange gasket, eliminating the need for a separate metallic valve body. Valve selection is based on pipe ID, flange drilling pattern, flow rate, line pressure, and backpressure requirements.

Operation

Forward flow opens the duckbill lips, allowing media passage. Under reverse pressure, the elastomer compresses, restricting backflow. The design is passive—no electrical, pneumatic, or hydraulic actuators are required. There are no shafts, hinges, or metallic seats in the flow path, minimizing maintenance and leakage risks.

Installation and Connection

• Mounts between flanged pipe connections.
• Standard ANSI 125/150# flange drilling; other patterns available on request.
• Suitable for horizontal or vertical installation.
• For horizontal lines, the duckbill opening should be oriented vertically within the pipe.
• Flange bolts should be initially tightened “snug tight” and then torqued to specification.

Elastomer Materials

Available in EPDM (for wastewater, dilute acids), Buna-N (kerosene, oils, hydrocarbons), Neoprene (moderate chemicals, ozone, marine fouling), Natural Rubber (abrasion, elasticity), and specialty options such as Viton, Butyl, or Hypalon for specific chemical resistance.

Typical Applications

• Pumping stations and wastewater networks
• Stormwater and drainage lines
• Biological treatment plants
• Industrial water with suspended solids
• Pipelines requiring passive check function without metallic moving parts

RF-DBI vs. RF-DBF

The RF-DBF is bolted to the pipe flange end or outlet. The RF-DBI is inserted in-line and clamped between two flanges, suitable for closed, pressurized pipeline systems where in-line check function is required.

FAQ

What data is required for selection?
Pipe ID, flange drilling, elastomer type, min/max flow, line pressure, and backpressure.

Is there headloss?
Yes. Headloss is determined from flow/headloss curves for each size and operating condition.