Platinum-Cured LSR
Medical and food-contact designs commonly use platinum-cured LSR. Transparent or translucent grades can also make it easier to observe the fluid path.
Custom Silicone Duckbill Valves
Compact elastomer check valves for low cracking pressure, reliable backflow prevention, and quiet one-way fluid control.
- Custom slit length, lip thickness, hardness, and cracking pressure
- Silicone, LSR, FVMQ, EPDM, NBR, and CR material options
- Medical, dispensing, automotive, drainage, and fluid-system support
What Is a Duckbill Valve?
A duckbill valve is a one-piece elastomer check valve with two flexible lips that meet at a central slit. The flattened outlet resembles a duck's bill, which gives the valve its name.
The valve has no spring, hinge, or metal moving parts. Forward pressure separates the lips and opens the flow path. When pressure falls or reverses, the elastomer recovers and the slit closes to prevent backflow.
Duckbill Valve Materials
The elastomer must be soft enough to open at the target pressure and resilient enough to bring the slit back into full contact after repeated cycles.
Specialty Elastomers
FVMQ, EPDM, NBR, and CR can be selected when the valve needs greater resistance to oil, fuel, chemicals, weather, or other operating conditions.
Types of Duckbill Valves
Duckbill valves can be configured around flow, leakage control, manufacturing method, installation style, and available space.
Single
Single Duckbill Valve
The standard one-piece design for low- to medium-flow liquid or gas control in compact assemblies.
Double
Double Duckbill Valve
Two valve sections are arranged in series to add a second sealing barrier where lower reverse leakage is required.
Process
Molded or Precision-Slit
The slit can be formed as part of the molding approach or introduced after molding with precision cutting, depending on the design and consistency requirements.
Mini
Miniature Duckbill Valve
Very small valves can be developed for precision medical and microfluidic systems that need compact size and very low opening pressure.
How Does a Duckbill Valve Work?
Pressure difference opens the slit in one direction while the elastic lips create a passive seal against reverse flow.
Lips Stay Closed at Rest
Without forward pressure, the two elastomer lips remain in contact and keep the central slit closed.
Forward Pressure Opens the Slit
When upstream pressure exceeds the cracking pressure, the lips separate and create a passage for fluid or gas.
Reverse Pressure Reinforces Closure
As pressure falls or reverses, the lips recover and press together again, helping prevent backflow.
Duckbill Valve Manufacturing
Duckbill valves are commonly made by LSR injection molding or silicone compression molding. LSR processing uses accurately metered material and a temperature-controlled precision mold to produce the valve body and thin flexible lips with tight dimensional control.
Compression-molded designs may be formed first and then slit with precision cutting equipment. The cutting tool must stay sharp and well aligned because burrs, asymmetry, or damage along the slit can prevent complete closure and cause leakage.
Duckbill Valve Performance
Cracking pressure and reverse sealing are controlled by the slit, lip geometry, hardness, elastic modulus, and installation condition.
| Property | Typical Guidance | Design Meaning |
|---|---|---|
| Cracking Pressure | Common small valves: about 0 to 5 kPa; specialized medical designs can be lower | Longer slits, thinner lips, and softer material generally reduce opening pressure. |
| Reverse Pressure | Application-dependent; source design guidance notes about 100 to 500 kPa for some valves | Reverse sealing depends strongly on lip thickness, slit structure, material, and support around the valve. |
| Hardness | Typically 30 to 70 Shore A | Hardness must balance easy opening with enough elastic recovery for reliable slit closure. |
| Temperature Range | Silicone and FVMQ designs may target about -60°C to 230°C | The final allowable range depends on material grade, fluid, pressure, and service environment. |
| Sterilization | Suitable medical LSR grades may support autoclave, EO, and gamma processes | Sterilization compatibility should be validated on the final valve design and material grade. |
How to Ensure Reliable One-Way Flow
Duckbill valve performance depends on a controlled balance between opening force, slit closure, material recovery, and installation support.
Slit Length and Lip Thickness
A longer slit or thinner wall lowers cracking pressure, but excessive flexibility can reduce closing force and sealing reliability.
Tip Geometry and Slit Quality
The outlet should provide a stable cutting or molding area. Burrs, rough edges, or off-center slits can create leakage paths.
Hardness and Elastic Recovery
Very soft material may deform or shift, while overly hard material can raise opening pressure. High resilience and low compression set are important.
Installation Preload and Orientation
Flanges, clamps, and interference fits should hold the valve securely without restricting lip movement or allowing the valve body to invert under pressure.
Duckbill Valve Applications
Duckbill valves are used across small medical fluid systems and large drainage systems because they provide simple one-way control without metal moving parts.
Medical Devices
Used in breast pumps, resuscitation and ventilation systems, anesthesia equipment, infusion sets, catheter backflow control, and drainage devices.
Home and Consumer Products
Used in liquid dispensing systems, cleaning-equipment tanks, drainage valves, and soap or detergent pumps.
Automotive
Used in fuel systems, oil separation, washer systems, emissions control, transmissions, and brake-related backflow functions.
Drainage and Irrigation
Larger duckbill valves can control stormwater, wastewater, tidal backflow, drip irrigation, and fertilizer injection systems.
Need a Custom Silicone Duckbill Valve?
Share your cracking pressure, reverse pressure, flow, fluid, installation method, and valve size. Fecision can review the lip and slit geometry for your application.