Model Number: DFQ40K

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 Fuel Quantity Test Set

Aero Express is an US Authorized Distributor for the Barfield DFQ40K Test Set.

To view click here:  Standard Warranty Policy  DFQ40K Data Sheet  DFQ40K Operation Manual 

AC Fuel Qty Comparison Chart  AC Fuel Qty Specifications Page 

Fuel Qty Adapter Cables  Fuel Qty Adapter Cables by Aircraft

Aero Express will buy, sell and  trade the DFQ40K depending on your needs.  The DFQ40K is designed for and is compatible with all aircraft, which have AC capacitance, based Fuel Quantity Indicating Systems including those equipped with transient suppressors.

The DFQ40K has the ability to measure the insulation breakdown of tank units, wiring and connectors associated with the system, capacitance of the tank units which measure the level of fuel in the tanks and simulation of capacitances required to test and calibrate the aircraft indicating system. In addition to performing the standard capacitance tests of the Tank(s) and or Compensator, the DFQ40K has an additional troubleshooting mode that will provide the user with a relative indication of a problem associated with the Phase of the return current like that provided by the Barfield 2548H tester. The DFQ40K measures Low Resistances, DC Voltage & Indicator Drive Current. The DFQ40K is also equipped to measure the Distance To Fault to localize problems with the HIZ coax, continuity of the Shield Monitor, if the aircraft is so equipped, and Bonding tests to 0.001 Ohm resolution.


  • Microprocessor based
  • Completely self- contained AC capacitance fuel quantity test system
  • Measures capacitance, insulation, DC voltage, resistance and distance to fault
  • Capacitance simulation and indicator testing
  • Custom multi-line backlit graphic display
  • Direct keypad entry and Tank and Comp simulation values
  • Uses all existing fuel quantity cables
  • Uses new generation of Smart Cables to perform Automated Test Routines
  • Calibration date available from display with user alerts to approaching calibration date
  • Numerous user prompts
  • Powered from common C-cell batteries with auto-off feature to conserve energy

1-Year Factory Barfield Warranty on all new products.


Express Calibration is an Authorized ISO-17025 Calibration and Repair shop for the Barfield DFQ40K.  Visit for full capabilities.

All units will be sold with a current calibration certificate. If factory new, a manufacturer’s Certificate of Conformance (C of C) will be provided.

Since its inception, Express Calibration Services has supported Aero Express’ endeavors in providing test equipment support services.

They perform calibrations for General Aviation, Corporate Aviation, OEMs, FAA Repair Stations, Military, as well as Regional and Air Transport Airlines. Express Calibration Services offers their services when you have a requirement for calibration or repair of your test equipment.