Fuel Flow Meter Tutorial

What is a Fuel Flow Meter

Fuel flow meter is a device used to measure volumetric fuel consumption, that is, fuel volume passing through the fuel line per unit of time. The results of its measurements are provided in the form of meter readings (the same as with water or an electricity meter). Based on this information, a GPS tracking and telematics platform calculates the following data:

  • Fuel consumption per time period
  • Average fuel consumption, for ex., liters per 100 km/miles per gallon (mpg)

In addition to fuels, the device is able to measure the flow rate of many other types of liquids and bulk materials. For instance, a water meter in an apartment can be as well treated as a flow meter. Therefore, hereinafter a fuel flow meter will be referred to as a flow meter.

Operating principle

A flow meter refers to devices for direct volumetric measurement of fuel consumption with a ring-type measuring chamber.

Unit structure

The principle of flow meter operation is based on measuring fuel volume that passes through a measurement chamber. The chamber is the main element that affects the accuracy and durability of a flow meter. Here is how it all works together:

Измерительная камера расходомера

Measurement chamber

  1. Under pressure of the fluid flowing through the flow meter inlet nozzle to the inlet of the measuring chamber, the ring slides along the inner surface of the chamber at the same time as it slides along the web.
Кольцо измерительной камеры расходомера

Ring-type measurement chamber

Перегородка измерительной камеры расходомера

The web

  1. The ring pushes the fluid inside and outside the chamber out through the outlet into the outlet nozzle.

Measuring chamber operating scheme

  1. One turn of the ring pushes out the volume of fluid equal to the volume of the chamber. At the same time, the electronic board of the flow meter makes one output impulse. Thus, when fuel passes through a flow meter, an electrical impulse is formed.

Flow meter electronic board

In manufacturer’s guidelines, it is usually specified how many impulses are required for 1 L / 0.26 US GAL of fuel to flow through the device. One impulse corresponds to fuel consumption (which is equal to the volume of the measurement chamber), so you just need to calculate the difference between the chamber volume and one liter of fuel.

For example, for a Technoton DFM 100D flow meter, 1 L corresponds to 200 pulses. This way, the measurement chamber volume for this flow meter will be 5 ml. (1/200 L). This data is then entered to a telematics platform as a coefficient for the measuring sensor (“Sensors and Buttons” section). Based on this coefficient, the impulses are converted into liters. The telematics platform is to process the received data, “decompose” consumed fuel data and provide users with information in a table format.

Application

Flow meters are designed to measure fuel consumption in the fuel line of various vehicles and stationary installations. The application area includes:

  • Vehicles. This can be a railroad, air or water transport.
  • Additional vehicle equipment. For ex., a compressor unit or other equipment mounted to a vehicle chassis.
  • Stationary installations. Flow meters can be installed inside the tanks used in small corporate gas stations.

Flow meter readings are not affected by fuel fluctuations in the tank. Therefore, you can unlock the device full potential when operating under the following conditions:

  • Constant fuel fluctuations in the tank when driving on a rough terrain. For example, a flow meter can be used on agricultural machinery (tractors, harvesters, etc.), off-road vehicles or water transport.
  • Fuel tank long-lasting (several hours to several days) inclinations. This usually happens when parking a vehicle on a steep ascent or descent. Such inclinations are typical for a rotary hoe, asphalt milling machines or other types of street maintenance equipment.
  • Fuel fluctuations + long-lasting inclinations. For instance, when working in a quarry with mining trucks.

The specific design of a fuel tank often does not allow to install several Fuel Level Sensors, and using a one single sensor will lead to a higher error rate. In this case, we recommend to opt for flow meters in order to perform a more accurate measurement of the fuel consumed.

Watch this video, showing flow meter operation on a rough terrain – 2 minutes.

Working fluids

A flow meter is able to measure any liquid with a kinematic viscosity of 1.5 to 6 mm2/s.

To ensure high measurement precision and a flow meter stable operation, all the units of its measurement chamber must be lubricated (for diesel fuel consumption measurement only). Why diesel? This is due to the lubricating properties of diesel that help reduce friction between surfaces. When it comes to gasoline, the mechanism in most cases works “dry” (except for two-stroke engines having gasoline mixed with engine oil). This “dry” operating accelerates wear, reduces the measurement accuracy and leads to an additional error for the flow meter. Therefore, actually, a flow meter can be applied to measure diesel fuel consumption only.

Types of Flow Meters

As of the end of 2018, flow meters manufactured by the Technoton company had been ranked as the most widely used ones. In our guide, we will classify flow meters as per Technoton. Other manufacturers produce similar models of flow meters as well but may use their proper terms. For example, the Mechatronics manufacturer company refers to flow meters as “fuel consumption sensors”.

To get a better understanding of the existing types of flow meters, we advise first taking a closer look at the engine fuel system.

The most common scheme of the fuel system of a diesel engine

  1. Fuel tank
  2. Rough filter
  3. Low-pressure fuel pump
  4. Fine filter
  5. High-pressure fuel pump
  6. Injectors
  7. Bypass valve

On the scheme you can differentiate:

  • Supply fuel line (marked by orange and red arrows) that delivers fuel from the tank to the “engine” (to be more precise, to the high-pressure fuel pump and injectors).
  • Return fuel line (marked by blue arrows) that removes excess fuel from the “engine” (from the high-pressure fuel pump and injections) and transfers it to the tank.

The low-pressure fuel pump delivers much more fuel to the input of the high-pressure fuel pump than the engine needs in any operation mode. Excess fuel from the high-pressure fuel pump and injectors flows back to the fuel tank through the return line.

For example, for a John Deere tractor, the readings at idle period will be: in the supply fuel line: 200 liters per hour, on the return line: 197 liters per hour. Engine fuel consumption will be 3 liters per hour.

Single-chamber flow meter

Single-chamber flow meter measures the amount of fuel flowing through the fuel supply line, that is, from the fuel tank to the “engine”.

Single-chamber flow meter

Single chamber flow meters are divided into the following types:

  • Autonomous flow meter – its measurement results are displayed on the upper part of the flow meter. Such devices are powered by a built-in battery and are best used to control unauthorized fuel draining on stationary tanks, etc.
  • With interface cable – such meters are used to transfer data to a monitoring platform. To do this, it is enough to connect to the GPS tracker using one of the following interfaces:
    • Impulse interface
    • RS-232
    • RS-485
    • CAN

    Flow meters with interface cable are supplied with electrical power from an onboard vehicle power source. In case of an external power outage, the device continues operating from the built-in battery and saves fuel consumption data in the back-up memory. Once the power is restored, all the accumulated data is transferred from the internal memory to the monitoring platform.

    The operating status of the meter is determined by looking at the LED indicator placed on its upper part: if the device functions correctly, the indicator flashes.

    Optionally, a flow meter with an interface cable can be equipped with a display for showing measurement results.

Dual-chamber flow meter

A flow meter with two measurement chambers is called dual-chamber or differential. Dual-chamber fuel flow meters measure fuel consumption as the difference in volume of fuel flowing through the supply and return fuel lines, i.e. the amount of fuel delivered from the tank to the engine minus the fuel volume from the engine to the tank.

Differential flow meter

Differential flowmeters are:

  • Autonomous flow meter – its measurement results are displayed on the upper part of the flow meter. Such devices are powered by a built-in battery and used for fuel monitoring in vehicles (data transmission to a monitoring platform is not allowed).
  • With interface cable – it can transfer data to a monitoring platform. To do this, connect to a GPS tracker with one of the following interfaces:
    • Impulse interface
    • RS-232
    • RS-485
    • CAN

    Differential flow meters with an interface cable are supplied with electrical power from an onboard vehicle power source. In case of an external power outage, the device continues operating from the built-in battery and saves the fuel consumption data in the back-up memory. Once the power is restored, all the accumulated data is transferred from the internal memory to the monitoring platform.

    The operating status of a differential flow meter is determined by looking at the LED indicator placed on its upper part: if the device functions correctly, the indicator flashes.

    Optionally, a differential flow meter with an interface cable can be equipped with a display for showing measurement results.

CAN-bus flow meter

Automakers may provide an opportunity to transmit data on fuel consumption via a CAN-bus network of vehicles or special equipment. A CAN-bus flow meter is not a physical device but an algorithm that calculates fuel consumption based on the operating time of injectors. The operating time is multiplied by the amount of fuel that passes through the injector per unit of time. The results are then adjusted taking into account other CAN parameters. In the end, one gets quite accurate data on the fuel consumed for diesel and gasoline vehicles.

In a monitoring and telematics platform, the data is present in the form of a digital meter that indicates the fuel consumed in liters/gallons during the entire period of vehicle operation. To know how much fuel is consumed per day, it is enough to subtract the meter readings from the beginning of the day with those from the end of the day. Based on this principle, the Flow Meter report will be built (see how it looks in the Reports section).

You can find out whether fuel consumption data can be transmitted via a CAN-bus of your vehicle by switching to this table of CAN parameters. Choose your car model and check if the “Total fuel consumption” parameter is marked as +.

As for the devices produced by third-party manufacturers, for example, Nozzle Crocodile, they can as well count fuel consumption based on the injectors operation time but have lower accuracy in comparison with the standard CAN flow meter. As a rule, such devices are used to control fuel consumption in case other methods are not available. For example, one can use them for measuring gas consumption on LPG (Autogas) vehicles.

Contactless NozzleCrocodile reader, manufactured by Technoton.

Flow meter selection

What should be considered includes:

  • Engine power – this parameter influences the minimum and the maximum engine fuel consumption (liters per hour). Manufacturers of flow meters specify two separate parameters corresponding to fuel consumption:
    • Maximum flow rate – shows the maximum amount of fuel that can pass through the measured chamber of the flow meter (liters per hour). The max. flow rate must be greater than the max. engine fuel consumption value.
    • Minimum flow rate – indicates the minimum amount of fuel required for a measured chamber to start operating. The min. flow rate must be less than the min. fuel consumption value of the engine.

    In case a fuel consumption value is greater than the max flow rate, the engine will not receive the required amount of fuel and will not reach its full power so that it becomes unstable or stall.

    Please bear in mind that in some situations (for example, when a vehicle stands idle or runs at a low speed), a fuel consumption value may be less than the min flow rate. This data will not be taken into account by the flow meter and will lead to lower accuracy.

    Flow meter selection depending on the engine power:

    Engine power, kWEngine power, hpMaximum flow rate, l/hMinimum flow rate, l/hExamples of vehicles and machineryRecommended flow meters by Technoton
    0-800-109501Small tractor for housing and communal servicesDFM 50
    80-150109-2041002Rotary hoeDFM 100, DFM 100D
    150-300204-4082505Combined harvester, wheeled all-terrain vehicleDFM 250, DFM 250D
    300-600408-81650010Dump truckDFM 500, DFM 500D

    In the absence of data on engine power, we recommend to search for fuel consumption value for each transport category separately.

  • Whether you have a car or special equipment under warranty, it is better to use differential flow meters. They work well and the installation process does not require making changes to the fuel system.
  • Connection interfaces — the following types of interfaces are used to connect flow meters to GPS trackers:
    • Impulse inputs
    • Serial interfaces:
      • RS-232
      • RS-485
      • CAN-like

    The interface for connecting a flow meter to a GPS tracker is selected when ordering the meter from a manufacturer. Please note that a flow meter can have only one interface and it should correspond with that of the tracker. Hence, before ordering it is worth checking what interfaces are available on your GPS tracking unit.

Flow meter installation process

A flow meter is installed in the fuel system of a vehicle or special equipment. Once again let us turn back to the typical scheme of the fuel system:

Typical diagram of the diesel engine fuel system

  1. Fuel tank
  2. Rough filter
  3. Low-pressure fuel pump
  4. Fine filter
  5. High-pressure fuel pump
  6. Injectors
  7. Bypass valve

A flow meter can be installed:

  • Between the rough filter and the low-pressure fuel pump (within the supply fuel line). This scheme is called “On suction side”.
  • Between the fine filter and the high-pressure fuel pump (within the supply fuel line). This scheme is called “On pressure side”.

Depending on the type of flow meter selected (single-chamber or differential), it may be necessary to make certain changes to the fuel system.

To install a flow meter you will need:

  • An installer man. On complex fuel lines, for example, on ships, the help of several installers may be needed
  • A mounting kit
  • A bracket
  • Automobile hand tool kit (cap key, drive socket, and screwdriver sets)
  • A welding machine (preferably of an inverter type)
  • Pyrometer
  • Pressure gauge

A bracket

A mounting kit

Flow meter installation routine

Regardless of the selected flow meter and the connection scheme, the following actions are to be performed during the installation process:

  1. Checks on the engine stable operation. Start the engine and check its operation for 5-10 minutes at idle and 5-10 minutes in movement under load. The engine must run evenly, not stall under load, loss of power must not be felt. Please note that once a flow meter is installed, less fuel will reach the engine and the existing problems may worsen.
  2. Inspect all fuel pipes of the vehicle for damage and fuel leakage. As a result of a flow meter installation, less fuel will reach the engine, so that it may lack the incoming fuel.
  3. Check the pressure in the fuel line with a pressure gauge. A pressure gauge measures the pressure in the fuel line at various engine operating conditions (at idle, at the maximum speed, etc.)
  4. Avoid high-temperature areas with vibrations. Choose an installation scheme taking into account a flow meter possible location, it can be either “On suction” or “On Pressure”.
  5. Screw a mounting bracket to the vehicle frame area. A bracket is a special metal plate to which a flow meter is bolted.
    When fitting the mounting plate of the flow meter vehicle frame drilling is prohibited! If fitting of the mounting plate is impossible with bolts, spot welding is allowed.
  6. Break the fuel line at the connection point with the flow meter. The existing fuel pipes are removed and the new ones are installed in their place (usually that are reinforced hoses). Later, several kit items are installed at the ends of the new pipes in order to:
    • connect to the flow meter inlet
    • connect to the flow meter outlet
    • receive fuel from the return fuel line (depending on the installation scheme)

    The new fuel pipes need to have some spare length in order to compensate length changes due to the temperature.

  7. Install a fuel deaeration system in order to avoid foam in the return pipe. To remove air bubbles and prevent them from getting into the fuel line, use a deaerator.
    This will improve the measurement accuracy and allow the fuel to flow through the measuring chamber without any foam.

Technoton DFM DA 250 deaerator

  1. For proper operation of the modified fuel system, install a bypass valve at the high-pressure fuel pump output, which will support the necessary pressure and help to prevent:
    • Fuel flowing in the opposite direction
    • Fuel system’s hydraulic shocks
  2. Mount a fuel return line depending on the selected flow meter and the installation scheme. The mounting process is described above.
  3. With the help of a low-pressure fuel pump, remove the air from the fuel supply line. To do this:
    • Loosen the bracket at the fuel injector inlet
    • Manually pump the fuel with the help of a low-pressure fuel pump
    • Make sure that there is no air coming from the the injector inlet
    • Fasten the bracket
  4. Use a manometer to check the fuel line pressure at different operating modes of the engine, for ex., at idle, maximum speed, etc. Compare this data with the previous results (before installation). Deviation should be no more than 5%.
  5. Connect the flow meter to the onboard power supply and a laptop through an adapter (the same as with FLS). Then, configure the sensor with the help of a special application on your laptop.

Universal Adapter

  1. Disconnect the flow meter from the computer, then tie an interface cable with a cable route. Connect the opposite side of the cable route to the GPS tracking device.

Depending on a fuel system, the installation of the flow meter may take from 4 hours to 3 days.

The longest flow meters are installed on ships that require non-standard connectors for fuel pipes. Please consider this before starting a mounting process as it may be impossible to purchase such connectors near the installation site.

Video on flow meter installation on a tractor – 20 minutes

Single-chamber flow meter installation — On suction side

Installation of a single-chamber flow meter according to the “On suction side” scheme is the following:

Installation of a single-chamber flow meter as per “On suction side” scheme:

  1. Fuel tank
  2. Rough filter
  3. Low-pressure fuel pump
  4. Fine filter
  5. High-pressure fuel pump
  6. Injectors
  7. Additional fine filter
  8. Non-return valve (* recommended)
  9. Bypass valve
  10. Single-chamber flow meter

The following changes will be made to the standard fuel system:

  • The return fuel line scheme is modified. The line coming from a bypass valve of the high-pressure pump has to be redirected to the low-pressure fuel pump input. This eliminates the need to recount fuel from the return line. The return line coming from the injectors remains the same. When injectors operate correctly their return flow is less than 0,1 % of fuel consumption, and therefore this can be negligible.
  • An additional fine filter is installed between the rough filter and the flow meter. It prevents measuring chamber from clogging and can function as a deaerator in case there is not much air in the fuel.

Advantages:

  • minimal interference into the fuel system;
  • easy installation;
  • applicable for most engines.

Disadvantages:

  • requires installation of an additional fine filter and causes extra costs;
  • additional load on the low pressure fuel pump;
  • fuel in the tank is not heated by a return flow line (fuel heater is sometimes required).

Single-chamber flow meter installation — On pressure side

Installation of a single-chamber flow meter according to this scheme is the following:

Installation of a single-chamber flow meter as per “On pressure side” scheme:

  1. Fuel tank
  2. Rough filter
  3. Low-pressure fuel pump
  4. Fine filter
  5. High-pressure fuel pump
  6. Injectors
  7. Non-return valve
  8. Bypass valve (* recommended)
  9. Single-chamber flow meter
  10. Plug

The following changes will be made to the standard fuel system:

  • The return fuel line has to be modified. Fine filter output is equipped with a bypass valve and then is connected with the return line via a pipe. The excess fuel pumped by low-pressure fuel pump will be dropped back to the fuel tank from fine filter’s side. Hence, only the amount of fuel consumed by the engine will flow through the flow meter.
  • A bypass valve is removed from a high-pressure fuel pump output, the appeared space has to be plugged.

Advantages:

  • A flow meter is installed after a regular fine filter;
  • fuel flows under pressure and does not overload the low-pressure fuel pump;
  • return fuel can heat fuel in the tank.

Disadvantages:

  • High-pressure fuel pump is slightly deteriorated;
  • return flow fuel is lower than with a regular fuel system.

Differential flow meter installation “On suction side”

Installation of a differential/two-chamber flow meter according to this scheme is the following:

Installation of a differential flow meter as per “On suction side” scheme:

  1. Fuel tank
  2. Rough filter
  3. Fine filter
  4. Low-pressure fuel pump
  5. High-pressure fuel pump
  6. Injectors
  7. Differential flow meter
  8. Non-return valve (recommended)

The following changes will be made to the standard fuel system

  • An additional fine filter is installed between the rough filter and the straight-flow measured chamber. It prevents the chamber from clogging and can function as a deaerator in case there is not much air in the fuel.
  • The return fuel line is connected with the return-flow chamber inlet via a pipe.
  • The chamber outlet is connected to the tank by a pipe.

Advantages:

  • no changes in the fuel system;
  • installation possible for the engine during the warranty period.

Disadvantages:

  • higher costs;
  • higher fuel consumption measurement error (up to 3%);
  • additional fine filter and meter increase load on the low-pressure fuel pump.

Differential flow meter installation “On pressure side”

Installation of a differential/two-chamber flow meter according to this scheme is the following:

Installation of a differential flow meter as per “On pressure side” scheme:

  1. Fuel tank
  2. Rough filter
  3. Low-pressure fuel pump
  4. Fine filter
  5. Differential flow meter
  6. Injectors
  7. High-pressure fuel pump

The following changes will be made to the standard fuel system:

  • The return fuel line is connected with the return-flow chamber inlet via a pipe. The chamber outlet is connected to the tank by a pipe.
  • The return-flow measurement chamber output is connected to the fuel tank via a pipe.

Advantages:

  • no changes in the fuel system;
  • installation possible for the engine during warranty period.

Disadvantages:

  • higher costs (when compared with a single-chamber installation);
  • higher fuel consumption measurement error;

CAN-bus flow meter installation

The installation of a CAN-bus flow meter (algorithm) is performed by connecting a GPS tracking device to a CAN bus and reading the “Total fuel consumption” parameter.

To connect to a CAN-bus, first, you should find it in your vehicle. CAN bus is a twisted pair (two wires twisted around each other). To find the CAN bus in your vehicle, refer to the wiring diagrams, otherwise it will be impossible to find it in the mish-mash of car wires.

Once it is located, you can connect to it via a CAN Crocodile contactless reader (recommended as it won’t damage the wires) or connect to it directly (less recommended).

General procedure for connecting to the CAN bus:

  1. First, you need to know the brand, model and year of manufacture of the car to which you want to connect a CAN-bus.
  2. Later, by looking at this table, check whether the full fuel consumption parameter is transmitted to the CAN-bus of your car. If not transmitted, there is no sense in continuing.
  1. Go to your tracker manufacturer’s website to select a CAN module brand that fits.
  2. For example, when connecting Teltonika trackers to passenger cars, the CAN-module LV-CAN 200 is used, and for trucks, it will be ALLCAN 300.
  3. Ask the CAN module vendor to supply a connection diagram for your vehicle brand, model and year of manufacture. Usually it takes not more than 30 min to find the right diagram.
  4. Connect the CAN module to the CAN bus according to the diagram.
  5. Use a a mini-USB to USB cable to connect the CAN module to the dashboard and the laptop with pre-downloaded setup software.
  6. Launch the software for configuring the CAN module and insert the number given in the diagram to set up the CAN module.
  7. Disconnected the CAN module from the computer and then connect it to the tracker.

The operating time is approximately 30 minutes (considering the diagram is available).

Installation of several flow meters on one vehicle

Sometimes more than one flow meter is installed on a single vehicle. This is often the case when a vehicle has two parallel fuel lines.

For example, one line delivers fuel to the engine that runs the car while the other transfers fuel to the engine of the compressor unit mounted on the same vehicle. To control fuel in each of the lines, it is necessary to install several flow meters. You can connect flow meters to a tracker in several ways, for ex., via a RS-485 interface.

How to connect a flow meter to a GPS tracker

As of 2018, the following interfaces were used to connect a flow meter to a GPS tracker:

  • For hardware flow meters:
    • Impulse interface;
    • Serial interfaces:
      • RS-232
      • RS-485
      • CAN-like
  • For CAN-bus flow meters:
    • By connecting to a CAN bus network

Impulse interface

Equipment: Flow meter with an impulse output, a GPS tracker with an impulse input (for example, Wonde Proud VT350).

Specifications: From the GPS tracker to the monitoring platform, the impulse value (raw data) is transmitted in the form of equal impulses.

In order to convert impulses to liters, it is necessary to enter a special coefficient into a monitoring platform (to do it, head to the Measurement Sensor settings). The coefficient is calculated based on the number of impulses corresponding to one liter. You can find this data in your manufacturer’s guidelines. For example, for a Technoton DFM 100D flow meter, one liter corresponds to 200 impulses.

Advantages: It can be used with relatively old models of GPS trackers

Disadvantages: The impulse interface is supported on a smaller number of GPS trackers as compared to digital interfaces.

Application: Flow meters with an impulse interface are usually ordered for connecting to trackers that had been installed a few years ago.

Digital interfaces

Equipment: Flow meter with RS-232 (or RS-485) interface, tracker with RS-232 (or RS-485) interface.

Specifications: From the GPS tracker to the monitoring platform, the impulse value (raw data) is transmitted as digital signals (conventional numbers without units of measurement) over the copper wires (wiki about RS-232 and wiki about RS-485), all in digital form.

To convert conventional numbers to liters, it is necessary to enter a special coefficient into the monitoring platform (to do it, head to the Measurement Sensor settings). The coefficient is calculated based on the conventional numbers corresponding to one liter. You can find this data in your manufacturer’s guidelines. For example, for a Technoton DFM 100D flow meter, one liter corresponds to 200 conventional numbers.

Advantages: Wires help to achieve an ultimate noise immunity during signal transmission. Besides you will be able to connect more than one sensor on one tracker (through RS-485 interface, RS-232 allows to connect only one sensor). Check the GPS tracker manufacturer’s website to see the number of fuel sensors to be connected via RS-485.

Disadvantages: Trackers with digital interfaces are usually more pricey than similar trackers without digital inputs.

Application: It is easier to find a GPS tracker with a digital interface. In practice, only one interface is required to be connected to a flow meter. Just make sure you consider whether the GPS tracker has RS-232 or RS-485 input.

CAN-like bus/ S6 Interface

Equipment: A flow meter with a CAN-like interface, a CAN module for reading data from a CAN bus, a tracker compatible with a CAN module.

Specifications: Technoton, a world-famous Belarus-based manufacturer, promotes the idea of an universal interface for factory-installed and additional sensors (including flow meters). Technoton offers CAN 2.0 for this purpose. Its operating principle is the following: the row data is first sent to the CAN bus network, then it is read by a CAN module and transferred to the monitoring platform.

In order to convert the received row data to liters, it is necessary to enter a special coefficient into the monitoring platform. The coefficient is calculated based on the number of CAN units in one liter. You can find this data in your manufacturer’s guidelines. For example, for a Technoton DFM 100D flow meter, one liter corresponds to 200 CAN units.

Advantages: This approach yields a few benefits. Mainly it removes any limitations on the number of devices to be connected to one tracker.

Disadvantages: Fuel sensors operating on CAN interface will cost more compared to similar solutions with other outputs. That’s why this technology hasn’t become widespread.

Application: It is rarely used due to the higher cost of the flow meter. Connecting more than one flow meter in practice is seldom required.

CAN flow meter

Equipment: CAN module for CAN data reading, CAN module-compatible GPS tracker or OBD2 GPS tracker supporting OBD data reading.

Specifications: Information on the total vehicle fuel consumption is transmitted in the form of a virtual counter. The values ​​of the counter are indicated in liters, therefore, you don’t need to enter a separate coefficient into the monitoring platform.

Advantages: High data accuracy, fast non invasive installation or DIY installation in case of OBD2 tracker. No extra money spent on sensor setup.

Disadvantages: Not all cars transmit information on the total fuel consumption via a CAN-bus.

Application: The simplicity of obtaining data is positively perceived by end users and can help to organize a better accounting of fuel consumption.

Flow meter vs Fuel level sensor

To solve tasks related to fuel control, your end customers or partners can choose between a flow meter (FM) and a fuel level sensor (FLS). To help them choose, we recommend first looking at the key features:

IndicatorFLSFM
The amount of fuel in the tankYesNo
Fuel fillings and drainingYesNo
Fuel consumption per time periodYesYes
Average fuel consumption for ex., l/100kmYesYes
Fuel control when driving on rough terrainYes. It’s recommended to install two or more FLS in each tank.Yes
Fuel control during a long-lasting inclinations (for ex., asphalt milling machines.Yes. It’s recommended to install two or more FLS in each tank.Yes
Interfaces for connection with a GPS trackerAnalog, Frequency, RS-232, RS-485, CANImpulse, RS-232, RS-485, CAN
Changes to the fuel lineNot requiredRequired. Changes to fuel system are required in some cases
CalibrationRequiredNot required
Installation time4 hrs approx.from 4 hrs to several days
Equipment pricefrom 46 to 155 US$from 232 to 697 US$

To sum up:

FLS is cheaper and easier to install

FLS allows to control more parameters

FM only allows to keep records on the fuel that has been consumed. In case you need to detect fuel thefts, it is required to know the amount of fuel in the tank at the beginning and at the end of the period (for this purpose, installing a flow meter is not enough).

Therefore, we recommend to use a flow meter only in cases when a fuel level sensor cannot be implemented.

Flow Meter: Data Visualization on Navixy

How to create a sensor

To view flow meter data on the monitoring platform, first you will need to create a measurement sensor (Devices and settings=> Sensors and buttons => Add measurement sensor).

In the pop-up window that appears, you need to:

  • Insert a name for the sensor, for ex., Fuel consumption.
  • Choose the input to which the sensor will be connected, for example, select the FLS #1 option if the meter is connected to RS-485.
  • Select a type of the sensor. Select the “Flow meter” from the drop-down list.

After that, head to Advanced Settings and specify the Multiplier (coefficient) calculated by the following formula:

К= 1/N,

Where N is the number of impulses/conditional units/CAN-units corresponding to one liter of fuel. This number can be found in user guidelines. For example, for a Technoton DFM 100D flow meter, one liter corresponds to 200 impulses. This way, in the Advanced Settings you should insert a coefficient of 0.005 (1/200). After that, all the data coming from the flow meter will be multiplied by 0.005 (or divided by 200, which is the same). As a result, the user will get a virtual counter showing a number of liters spent by the car since a flow meter installation.

As for a CAN flow meter, it transmits all the data in the form of liters, so there is no need to enter any coefficient at all. In this case, the sensor creation window will look like this:

Please note that a measuring sensor is created automatically in case the data coming from a CAN flow meter is read by an OBD tracker.

To transfer the meter readings from liters to gallons, it is enough to change the system of measures to English or English (US) in the Account Settings.

Widget

The flow meter current value is displayed on the OBD2 & CAN or Sensor Readings widget.

Report

In order to view information on the fuel consumption according to a flow meter, head to the “Fuel consumption” report. The report can be generated for those objects to which a
“Flow meter” type measuring sensor has been added. The report shows the following data in the form of a table:

  • Meter readings on fuel consumption — shows the start and end value as per date
  • Fuel consumption — shows the amount of fuel consumed per day
  • Fuel consumption per 100 km — shows an average fuel consumption

Each line contains information for one day. There is also a summary page at the bottom of the report.

Leading flow meters manufacturers

Technoton (Belarus)

PhotoModelDescription
DFMSingle-chamber flow meter

ТТХ: EN / RU / ES

DFM DDual-chamber/Differential flow meter

ТТХ: EN / RU / ES

Mechatronika (Belorussia)

  • Marketed in: Russia and CIS, Europe, Latin America
  • Exhibited in: trade shows in Belorussia
  • Available languages: English, Spanish, Russian, French, Portugese, Polish http://mechatronics.by/
  • FB
PhotoModelDescription
Eurosens DirectSingle-chamber flow meter

ТТХ: EN / RU / ES

Eurosens DeltaDual-chamber/Differential flow meter

ТТХ: EN / RU / ES

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