Differential fuel flow meter

DFM D differential fuel flow meter is designed for diesel fuel consumption measurement in fuel lines of vehicles and stationary engines, and is used as part of GPS vehicle tracking system. In addition, DFM D registers working time of engine in various modes of operation. DFM D is used for consumption monitoring of:

  • diesel fuel;
  • heating oil;
  • other types of liquid fuel with a kinematic viscosity of 1.5 to 6 mm2/ s.

DFM D fuel flow meters, which re equipped with display, are used as a stand-alone (autonomous) solution for accounting fuel consumption, not requiring any connection to a web-server. DFM D are more suitable for modern engines (Common rail or pump injector fuel systems) of vehicles and stationary units.

Fuel consumption meter


Preventing fuel theft
Engine testing for fuel consumption
Machine running time trackingMachine running time tracking

Advantages of DFM D

Differential measurement of fuel consumption

DFM D has two measuring chambers for supply and return fuel lines. The flowmeter measures fuel consumption in each line and computes the difference between supply and return. The result is stored in an appropriate Counter. Values of Counters are sent to telematics (monitoring) unit as digital messages (for DFM with RS232, RS485 or CAN output).

Built-in battery

In case of absence of an external power source, for example, from the on-board network, DFM keeps on to register data to the internal memory. When external power is restored, all accumulated data will be transferred to the on-board monitoring terminal.

Replaceable mud filter

Installed in the inlet of DFM D. Protects flow meter supply chamber from particles of dirt and sand, which went through fine filter. The mud filter significantly increases reliability and durability of the flowmeter. The filter is replaced “on site”, without a need of disassembly-assembly operations and additional verification of flowmeter accuracy and body integrity.

Fuel consumption and operating time Counters

Fuel consumption

  • Instant fuel consumption, L/H
  • Hourly fuel consumption in “Forward” line
  • Hourly fuel consumption in “Return” line
  • Total fuel consumption, L
  • Total fuel consumption in “Idling” mode of engine operation
  • Total fuel consumption in “Optimal” mode of engine operation
  • Total fuel consumption in “Overload” mode of engine operation
  • Total fuel consumption in “Negative” mode of flow meter operation (return exceeds supply)

Engine operating time

  • Total operating time, h
  • Total operating time in “Idling” engine operation mode
  • Total operating time in “Optimal” engine operation mode
  • Total operating time in “Overload” engine operation mode
  • Total operating time in “Negative” flow meter operation mode
  • Total operating time of Supply chamber
  • Total operating time of Return chamber
  • Operating time of Supply and Return chambers in each mode of engine operation


  • Engine operating time in “Tampering” mode, h
  • Engine operating time in “Interference” mode, h
  • Current engine operation mode as per fuel consumption rate
  • Fuel temperature
  • Temperature correction status
  • Correction coefficient value
  • Battery charge

DFM D types

Differential fuel counter with LCD display

DFM CD differential (two-chamber) fuel counter

Two-chamber fuel flowmeter

DFM D differential fuel flow meter with output signal cable

DFM D installation

DFM D are installed in both line of fuel system – supply (feed) and return. Each chamber of DFM D is connected to an appropriate line, chambers are marked “F” for feed line and “R” for return line. Exact place of flow meter installation depends on fuel system specifications of particular vehicle. For general guidance, please, refer to DFM Operation Manual.

It is possible to install several DFM D and connect them to telematics unit via a single cable – it is especially useful for machinery equipped with more than one fuel consuming units (e.g. river boat has two propelling motors, boiler, diesel generators and other auxiliary systems). For more information, please, refer to CAN/S6 telematics interface page.


Connecting thread M14x1.5
Nominal pressure, bar 2
MAX pressure, bar 25
Supply voltage, V 10-45
Overvoltage protection, V ≤100
Current consumption, mA (24 V/12 V), mA 25 / 50
Operating temperature, (without/with display), °C -40..+85/
Ingress Protection Rating IP54
Relative accuracy error per chamber, %, not more than 1
Model Chamber volume, ml MIN flow rate in each chamber, l/h MAX flow rate in each chamber, l/h
DFM 100D 5 10 100
DFM 250D 12,5 50 250
DFM 500D 20 100 500

DFM modifications

Following DFM types are available:

  • fuel flow meters with display, one-chamber or differential);
  • fuel flow meters without display, one-chamber or differential).

DFM order identification codes* A symbol is not specified for differential fuel flow meters.

** For autonomous fuel flow meters Z version is not used.

*** This version is delivered upon special order. Designation U is available only for one-chamber flowmeters.

Output signals (specified in purchase order): pulse, digital RS232, digital RS485, digital CAN/S6

Other products for fuel monitoring and fuel oil measurement

Single-chamber flow meter

flow rate 1-500 l/h

Single-chamber flow meter

Wireless flow meters

flow rate 1-600 l/h

Wireless flow meters

Industrial flow meter

flow rate 0,72-25 m3/h

Industrial flow meter

Flow meter for heavy machinery

flow rate 20-4,000 l/h

Flow meter for heavy machinery

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E-mail: [email protected]

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