Intrinsically Safe Amplifier

Featured Product from Dover Flexo Electronics, Inc.

Intrinsically Safe Amplifier-Image

Intrinsically Safe Amplifier
An intrinsically safe interface between transducers and a Dover controller, drive system or computer. FireGuard is UL Listed for use when tension transducers and analog tension meter (optional) are located in hazardous Class I Division 1 or 2 area.

The FireGuard2™ is an intrinsically safe (energy-limiting) electronic interface between tension transducers and a Dover tension controller, drive system or computer. This UL-listed device is designed for use when your tension transducers and an analog tension meter (optional) are located in a hazardous Class I Division 1 or 2 area.

While similar to the TrueTension Indicators in function, the FireGuard2 additionally reduces risk of fire or explosion. This hazard-preventing tension amplifier is a critical component in assuring plant process safety.

The FireGuard2 is typically used as part of a tension control and display system when tension transducers or tension readouts are installed in the areas made hazardous by flammable vapor. This could include vapor from acetylene mixtures, butadiene, ethylene oxide, propylene oxide, hydrogen mixtures, acetone, alcohol, ammonia, benzine, benzol, butane, gasoline, lacquer, varnish, solvent vapors, natural gas, propane, or similar compounds.The FireGuard2 greatly reduces the risk of fire or explosion in manufacturing area defined as Class I Division 1 or 2 by Article 500 of the National Electrical Code (NEC).

Each FireGuard2 contains a power supply for the tension transducers and is easily adjusted with its Quik-Cal push-button zero and calibration circuitry.

The amplifier outputs to a non-hazardous area include a 0-10VDC undamped, isolated output, a 4-20mA undamped, isolated output, and a 0-1 mA damped output for use with a tension meter. Outputs to the hazardous area are energy-limited connections for approved DFE transducers, and a 0-1mA damped, energy-limiting output for an optional DFE-supplied UL-rated analog tension meter (#723-1420).

The FireGuard2's dual calibration feature allows calibration of a single pair of tension transducers for operation over two different ranges. Input voltage is 24 VDC @500mA.

A removable steel cover protects and provides easy access to the terminal blocks for all electrical connections. The FireGuard2™ can be mounted to a machine structure or wall through flange mounting holes in the top and bottom edge of the enclosure.

The FireGuard2™ is a UL listed device, and can be used as a superior replacement for the discontinued original FireGuard™.


  • Use as an amplifier or control interface in potentially hazardous areas
  • Reduces risk of fire and explosion
  • Can be used with drive systems, computers or DFE controllers
  • UL Listed



  • 24 VDC power input.
  • 0-10V isolated, undamped output to the non-hazardous area
  • 4-20mA isolated, undamped output to non-hazardous area
  • 0-1mA damped output for tension meter, non-hazardous area
  • +5 VDC current-limited power supply for optional digital meter, non-hazardous area
  • 0-1mA damped output for tension meter, energy limited to hazardous area
  • +5V/+10V power supply for tension transducers, energy limited to hazardous area
  • Quik-Cal™ push-button Zero and Calibration
  • Dual Calibration feature allows for 2nd calibration setting, if desired. May require optional dual meter scale for meter.
  • NEMA1 protective steel enclosure with cover.
  • Status LED. Steady light indicates unit is on. Light blinks during calibration, flashes in case of error.


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About DFE
DFE is the natural choice of process and maintenance engineers for upgrading existing machinery with modern, efficient tension control. OEMs and machinery builders choose DFE to incorporate the most reliable, cost-effective tension controls into their machine designs. Consistent quality, product reliability and superior technical support translate into low cost of ownership for all our customers.

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Our products are used in unwind, rewind, and intermediate applications for any moving continuous material which undergoes an operation such as printing, coating, laminating, treating, metallizing, rewinding, unwinding, slitting, coating or other processes. Tension measurement and control systems for flexible packaging and paper, film and foil converting are our specialty.

We have over 84,000 tension transducers installed in manufacturing facilities everywhere. DFE transducers (sometimes referred to as 'load cells') are the industry standard for direct tension sensing and  measurement. We are a recognized leader in tension technology.

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