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DF / DF-AM (Integral Air / Remote Manual Stop)

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The Chalwyn DF and DF-AM automatic valves with integral air filters are self-contained with flow actuated overspeed shutdown. They require no external electrical or mechanical input devices. The closing force is provided by the intake air flow passing through the valve. The valve closes automatically when the engine speed exceeds a pre-set point. The valve automatically resets open soon after the engine has stopped, so the engine is ready for re-starting.

The DF automatic valve includes an integral air filter mounted directly on the intake of the valve to reduce the size and complexity of installing the valve into engine packages where space is limited. This eliminates the requirement to find a location to support and mount a separate air filter and the associated air intake line upstream of the valve.

The Model DF is an automatic valve with automatic reset. The DF-AM adds a manually actuated pull “T” handle cable stop. The cable is available in lengths 0f 1.0, 1.5, 2.0, and 3.0 meters.

The valves are available in two size ranges and are selected by combination of the Air Intake Line bore size and the engine power at its rated speed.

DF Valve Range

Engine Power

Air Intake Hose Size





Mini (Mini-Bendix type)

1.5 - 27

2 - 36

35 - 44

1⅜ - 1¾

Standard (Bendix type)

7.5 - 93

10 - 125

40 - 96

19/16  - 

Features and Benefits

  • Easy to install
  • Integral air filter for compact engine packages
  • No external power source or speed signal required
  • Air flow actuated
  • Automatic reset after engine stops
  • Option for remote pull "T" handle close
  • Trip setpoint calibrated on engine