tapflap

Tapflap is a term used in mechanical design to describe a small, hinged flap that acts as a flow-control element within a channel or housing.

A tapflap typically consists of a thin plate attached to a hinge at one edge, forming part of a passage that it can seal or partially obstruct.

Operation relies on pressure differentials, gravity, or a dedicated actuator to move the flap. When the upstream pressure exceeds the downstream pressure, the flap tends to lift or rotate open; when pressure equalizes or flips, the flap returns to its closed position, limiting backflow.

Applications are varied. In microfluidic devices, tapflaps serve as check valves and flow regulators. In consumer packaging, simple flap designs can reduce spills by restricting pouring until a threshold is reached.

Variants range from passive, gravity-biased designs to magnetically, electromagnetically, or acoustically actuated forms. Materials include silicone elastomer, polyimide, and metal, chosen for flexibility, chemical resistance, and sealing performance.

The term is used in niche engineering literature and product literature but is not a standardized component across industries, leading to a wide range of geometries and actuation schemes.

Related concepts include flap valves and check valves.