Dual Free Flow Valve (DFFV)

Dual’s Free Flow Valve operates on the discharge side of the pump as the flow through the pipeline starts or stops, the ball automatically rises or falls, opening and closing the valve. This occurs without noticeable shock or hammer, regardless of the line pressure or the speed of closure.


  • Rotating and floating ball – self adjusts to flow.
  • Self cleaning due to the freely rotating ball.
  • Long ball life due to ball rotation.
  • Full port opening. No obstruction to the flow.
  • Virtually no pressure drop. Eliminates pipe hammer. Long seat life. Seats are out of the flow and can be rotated in line to increase seat life fourfold.
  • Easy maintenance. Seat and ball can be inspected or replaced without removing the free flow from the pipeline.
  • Virtually maintenance free because of the simple design.


  • Valve housing is constructed of high quality carbon steel. Stainless steel is an option.
  • Valve housing can be natural rubber lined. A range of elastomer grades is available for corrosive duties (URETHANE or Ceramic).
  • Ball is made of hollow carbon steel and is urethane coated. Other elastomers are also available (Stainless Steel for high pressure).
  • The seat IS made in Abrasion Resistant AR steel (500 Brinnell hardness), URETHANE or Stainless Steel and is replaceable.
  • Flanges comply with AS, ANSI, DIN, SABS or BS.
  • Working Pressure Standards are 16, 25, 40, 80 and 100 Bar.
  • Operating temperature to 800 Higher conditions are possible if the valve is constructed from suitable material.
  • The Free Flow Valve can work in the horizontal and vertical position.
  • Flushing ports are fitted to the upper ball body.
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