What Is Duckbill Check Valve Design Guide And Types?

Duckbill check valve is also named rubber check valve, rubber duckbill valve, a flexible back pressure valve, which has special structure like duckbill. It is an air, gas, liquid, water backflow preventer which has the function of forwarding flow in positive direction while non-return in opposite direction. Rubber duckbill check valve is applicable widely to drainage system, sewer, breast pump and manual respirator.

How Does A Duckbill Check Valve Work?

A duckbill valve is a slow closing rubber check valve. Food grade silicone or rubber is usually chosen as duck bill valve material. 

The valve opens when the air or fluid flows through the valve. As the flow rate or pressure increases, the degree of opening of the duck bill valve will also increases. When the flow of water stops, the backwater pressure or atmospheric pressure will firmly push the duckbill valve to prevent backflow of liquid or gas.  

The pressure required to open the duckbill valve is very low. The pressure of the small duck bill valve produced is about 1 to 5 kPa. With the duckbill valve opening and closing conveniently and sealing well, duckbill valve backflow can be effectively prevented to meet the application requirements in many fields like medical devices, machines and devices for everyday use, electronics, irrigation of devices, animal husbandry, etc.

Duckbill Check Valve Operation:

Duckbill check valve are operated by a pressure differential. Rubber duckbill valve will open to allow flowing under a certain upstream pressure. And the back pressure will close the valve to prevent backflow. 

Duckbill Check Valve Types & Installation

Flanged Duckbill Check Valve

Flanged type duckbill check valve is mounted onto the pipe with flanges.

Slip on / Sleeved Duckbill Valve

A slip on style check valve typically is installed at the end of a discharge pipe.

Rubber Sleeved Duckbill Valve with Inner Undercut

Inner undercut will fix the duckbill check valve with the device tightly.

Flanged Non Return Valve with Outer Undercut

Rubber duckbill valve with outer undercut also usually assemble with the device for fixation.

Duckbill Check Valve Design Guide 

Duckbill Valve Material Selection: It depends on the working environment and application. Duckbill check valves are available in various elastomer material, including medical and food-grade silicone, liquid silicone rubber (LSR) for medical or baby products like duckbill valve for breast pump and hydrocarbon-resistant fluorosilicone rubber (FVMQ) to fit a broad range of media and temperatures. 

Also EPDM, Buna N & Nitrile Rubber, Neoprene / CR, Fluorocarbon rubber (FKM, FPM, Viton) can be chosen to make flow control valve for some application, like duckbill drain valve. 

Rubber Duckbill Valve Structure

• Angle & Width of rubber duckbill valve end: A certain width needed for rubber duckbill check valve positioning and die cutting proceeding. Meanwhile, if it is a sharp angle at the end, it is easy to cut inaccurately.

• Size of slit & lip: The longer the length of slit, the easier it will be opened under certain pressure. But it will not easy to close. 

• Structure design based on installation way: Flanged or slip on duckbill valve will be designed for different location place. Sometimes undercut is needed for better fixation.

Duckbill Check Valve Cracking Pressure / Opening Pressure

Material hardness and rebound resilience will affect the cracking pressure needed for the duckbill check valve. Generally, material with high hardness will have better rebound resilience. High elastic silicone rubber like Wacker or liquid silicone rubber (LSR) will also make the duckbill valve open & close easily.

Rubber Check Valve Die-Cutting Tool Design

The die-cutting tool will have angel 45-55 degrees in the end to proceed the cutting process. The tool won't remove the material, just leave a “cut”. If the tool is not blunt enough, it is easily to remove the material or leave burrs and flashing in the slit so that the duckbill cehck valve sealing effect will be affected.

Our Duckbill Check Valve Quality Control

As duckbill check valve manufacturer & supplier, we have:

• Free Design support & Material suggestion for your application 

• Free Sample & Prototype samples for your different cracking pressure needed

• Production: Professional compression molding, liquid silicone rubber(LSR) injection molding, slit die cutting technology

• Assembly & Packaging one-stop service