A tank connected for remote level monitoring via the LoRaWAN network

How to keep track of the level in fuel oil tanks at any time so as to predict when they need to be refilled?


The Lev’O+ Liquid Level solution is a remote reading solution based on the autonomous battery-powered Toran’O sensor associated with a relative pressure probe. Measurement data is transmitted periodically over the public or private LoRaWAN network to the remote application.

The LEV’O+ Liquid Level solution helps rationalise the supply stream and optimise delivery rounds.

The system can be easily installed on all types of tanks in AtEx Zone 1 environments.

Lev’O+ Liquid Level allows the remote reading of other information such as volume metering or status report.

By remotely monitoring the level present in tanks, distributors and maintainers are able to plan and optimise deliveries more efficiently.


Benefits of the system:

  • Better management of procurement and supply.
  • Reduction of logistics costs through the optimum triggering of deliveries.
  • Reduction of the carbon footprint through reduced transportation.

Lev’O+ Liquid Level solution features

The Lev’O+ Liquid Level solution allows the level in a tank to be measured using a relative pressure probe that delivers a 4-20 mA signal.

The probe is calibrated for a height of 3 metres and remotely connected using a 5-metre long waterproof cable:

  • the 4 mA value corresponds to a fuel oil level of zero,
  • the 20 mA value corresponds to a fuel oil level of 3 metres,
  • the accuracy is given in the data sheet, (0.8% of the full scale, i.e. 2.4 cm),
  • 14-bit converter, i.e. 4096 measurement points.

Installation and commissioning are both quick and easy:

  • The level probe is to be positioned and maintained above the bottom of the tank to avoid potential residues.
  • The probe is connected to the Toran’O transmitter sensor via a junction box which allows the relative pressure probe to be set to the atmospheric pressure and the sensor to be place in an AtEx zone and/or under the best radio frequency network coverage.

Example of remote reading of the height of fuel oil in a cylindrical tank.

Measurement probe and calculation formula:

Height (m) = DeltaP / (g × fluid density)


Calculation for fuel oil (density of 855):
With a value of 11.8 mA transmitted by the sensor, there should be 1.74 m of fluid above the probe.
DeltaP = 0.01875 x 11.8 – 0.075 = 0.14625 bar = 14625 Pascal
Height (m) = 14625 / (9.81 × 855) = 1.74 m

Example of installation of the Lev’O+ Liquid Level solution

Key points of the Lev’O+ Liquid Level solution:

  • Remote tank level reading
  • Transmission over public or private LoRaWAN network
  • Based on the Toran’O AtEx Zone1 multifunction sensor
  • Autonomy > 10 years (1 transmission/day)
  • SAFT LS17500 3.6V/3600mAh replaceable lithium battery.
  • IP55 housing, or IP68 waterproof version
  • AtEx Zone 1 certified
  • Easy installation
  • 4-20 mA relative pressure sensing probe


WATTECO, your IoT partner

Over 30 years of experience

in the design, development, industrialisation and manufacturing of electronic products

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our production workshop is based in Hennebont (56), France, and we are an ISO 9001 certified company