Products > Duckbill Valves

Duckbill Valves

Function

Duckbill check valves allow free flow with positive differential pressure. With negative differential pressure, backflow is checked.

Pressure drop across the valve is a feature unique to duckbill check valves. They can be designed to operate in a few millimeters (inches) of H2O to several hundred kPa (psi), depending on valve size, geometry and compound characteristics. Duckbill check valves are also designed to start functioning at specific opening and closing pressure ranges, depending on your specifications.

Size

We provide custom built duckbill valves. Call us today with your required specifications. Sizes generally range from 2.5 mm (0.1 in.) to 25.0 mm (1 in.) in diameter.

Compunding Capabilities

Not limited to the following polymeric families.

  • Nitrile, NBR
  • Fluorosilicone, FVMQ
  • Ethylene Propylene, EPDM
  • Silicone, VMQ, MQ, PVMQ
  • Hydrogenated Nitrile, HNBR
  • Butyl, IIR
  • Fuorocarbon, FKM
  • Epicholorhydrin, CO/ECO
  • Chloroprene, CR
  • Polyurethane, AU/EU
  • Styrene-butadiene, SBR
  • Polyacrylate Acrylic, ACM/AEM/ANM

Pre-load

Standard duckbill valves are not pre-loaded. Pre-load means the application of a force to a check valve to urge it shut. Pre-load has the following three effects which are always present together:

  • Pre-loaded valves are "normally closed". A normally open valve will have some small amount of leakage when pressure is applied in the reverse direction, until enough pressure is applied to urge the valve shut. A normally closed valve doe?s not require reverse pressure to seal.
  • Pre-loaded valves will require some significant pressure in the forward flow direction to obtain the onset of flow. This can be quite small if desired, or it can be larger if preventing the onset of flow is needed for system function.
  • Pre-loaded valves will have a pressure loss through the valve, higher than if it were not pre-loaded. In general, the more a valve is pre-loaded, the higher the pressure loss will be. Usually making the valve larger, is the only way to offset this effect.

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