Rubber-Flex Duckbill Check Valves - RF-DBF-SB Sloped Bottom | Cla-Val

Cla-Val RF-DBF-SB Sloped Bottom Duckbill Check Valve

The RF-DBF-SB is a flanged elastomeric check valve with a sloped bottom, designed for installation on existing pipelines in chambers, outfalls, and vaults where the pipe invert is close to the floor. The eccentric geometry enables drainage at the lowest point and minimizes solids retention.

Operation

Upstream flow opens the valve lips. In backpressure or reverse flow, the lips seal tightly to prevent backflow. The design contains no shafts, hinges, seats, or external actuators, reducing mechanical wear points.

Technical Specifications

• Size range: 3"–72"; technical data available for 12"–72".
• Flange drilling: ANSI 125/150# standard; ANSI 250/300, DIN, JIS, BS, AS, or custom drilling available.
• Retaining hardware: 304 or 316 stainless steel rings/clamps.
• Cracking pressure: 1"–2" water column.
• Body materials: Neoprene, EPDM, and other elastomers; NSF/ANSI 61 certified versions available on request.

Suitable Media and Applications

• Wastewater, sludge, stormwater with debris
• Effluent from biological treatment plants
• Sewage pump stations
• Chambers with limited installation height
• Tidal or flood backflow protection
• Seawater to catch basins or freshwater systems

RF-DBF-SB vs RF-DBF

The RF-DBF features a symmetric flanged geometry. The RF-DBF-SB is specified when the pipe invert is low and a sloped bottom is required for drainage and improved hydraulic passage near the floor. A slip-on version, RF-DBO-SB, is available for mounting on existing pipe ends.

Installation Notes

For horizontal installation, the sloped bottom is oriented at the 6 o’clock position. Rotation up to 35° is permissible only to maintain floor clearance. Tighten retaining rings in a cross pattern and ensure flange faces are clean.

FAQ

Is an actuator required?
No. This is a passive check valve with no actuator.

When is the SB version selected?
When the outfall or chamber does not provide sufficient clearance below the pipe invert.

What should be checked during maintenance?
Inspect for lip wear, elastomer cuts, trapped solids, and condition of flange clamping.