DFI – Dual-Flap Isolation Valve

DFI – Dual-Flap Isolation Valve

A Flap Valve You Can Trust

Unlike many other flap valves, with Fike DFI™ you’ll find no design shortcuts. No inferior parts or materials. No inaccurate testing and certifications. Just an ultra-reliable, compact passive explosion isolation valve that’s tested and proven to perform accurately under pressures which it may experience during a deflagration.

Currently available in sizes up to DN800 (32 inches), Fike DFI™ reliably isolates pressure and flames from interconnected equipment with the following important advantages: 

Proven Safe

Experiments have proven that testing standard EN16447 does not accurately represent real-world conditions. Therefore, this standard is currently under review, and many flap valves certified under this standard may fail to safely isolate deflagrations from interconnected pipes and vessels. Testing methods for Fike DFI not only meet EN16447’s requirements but exceed it by:

  1. Including a protected zone pipeline with additional dust injectors
  2. Holding flaps in an open position until the precise time of ignition or flow reversal
  3. Using explosion vent panels instead of open venting ports
  4. Using fans with real process flow and turbulence levels

This means you can trust that Fike DFI has been tested under all real-world applications’ conditions and variables, including those found in your unique process. 

Flexible Installation

Fike DFI avoids the need for any pipeline rework because it can be installed in nearly all geometries and orientations, and is:

  • Engineered to perform in both horizontal and vertical pipes and close to bends
  • Able to be installed closer to a vessel than other flap valves due to its fast-closing, lightweight flaps
  • Compact in its design with a reduced footprint using two smaller flaps instead of one large flap
  • Available in sizes up to DN800 (32 inches)

Wide Application Range

Suitable for nearly every application, Fike DFI is the ideal standard flap valve that protects against nearly all industries and applications under real-world conditions:

  • high explosion pressures up to 1.5 barg
  • ST1 dusts (sugar, powdered milk, charcoal, sulfur, zinc, etc.)
  • ST2 dusts (wood, flour, etc.)
  • light metal dusts (aluminum)
  • low MIE (minimum ignition energy) dusts

If you have questions about DFI, explosion isolation, your current explosion flap valve or testing standard EN16447, or if you are ready to protect your process with DFI, contact a Fike explosion protection expert today!


Dust Layer Accumulation (DLA) Sensor

Detects the natural build-up of dust that may accumulate at the bottom of the Fike DFI. When the sensor activates, an electrical signal is sent to the Fike Interface Module or your process or equipment control system indicating the trouble status and requesting immediate, automated and orderly process shutdown.

The use of a dust layer accumulation sensor and connection to process shutdown is required by NFPA 69. If not used, NFPA 69 requires in lieu a documented risk assessment and an appropriate inspection protocol and frequency, accepted by the authority having jurisdiction.

Air Pulse Cleaning Valve


Allows the use of timed bursts of pressurized air to prevent dust build-up from the flap seals and from the bottom interior of the valve that could affect flap valve performance. The Air Pulse Cleaning timing circuit is regulated by either the Fike Interface Module or a programmable logic controller (PLC).

Air pulse cleaning ensures the most reliable operation of the DFI valve.

Fike Interface Module 

By using the Fike Interface Module, you will experience the following additional advantages to maintain safety and protect business continuity:

  • Real-Time Status Updates – Gain immediate visual indication whether DFI’s locking mechanism is in a ready, locked or trouble state if enough dust has accumulated to affect the flap valve’s performance.
  • Automatic System Shutdown – Reliably connects DFI’s sensors to process or equipment control, providing emergency shutdown during an explosion and controlled shutdown during a trouble status. Simple connection removes the need for intrinsic safety barriers.
  • Monitor and Mitigate Dust Buildup – Dust accumulation sensor uses infrared to indicate when dust buildup reaches levels which may compromise the flap valve. Air Pulse Controls will automatically and periodically clear the valve free of dust.