Definition of flap valve in US English:

flap valve

(also flapper valve)


  • A valve opened and closed by a plate hinged at one side.

    • ‘The valve assembly includes one or more flapper valves that are able to pass a ball through at a minimum flow rate of fluid, enabling the ball to be used to operate the disconnect device.’
    • ‘The divers were expected to start work tonight on installing a section of pipe and a flap valve to an existing culvert.’
    • ‘Its only moving parts are a spring-loaded ‘clack’ valve and a non-return flap valve.’
    • ‘We have done some work in Malton by installing flap valves into the drainage system and these have had an effect in keeping water levels down slightly.’
    • ‘There the nozzle moves a flapper valve that seals the system out of the way.’