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Indicates, Measures and Controls the Level with the following technologies

The level of liquid and solid compounds (such as powders, mixtures, granulates, etc.) contained in containers, tanks, silos, diesel, oil, etc. is measured in height in metres.
Riels Instruments offers level sensors for tanks containing any type of material, these find application in cisterns, submersible pumps, wells, silos and many others.
In the case of liquids, the level or height measured is always the real effective average height of the liquid contained, while in the case of solids, the level or height measured is the real effective punctual height of the solid contained, height which is essentially a function of the measuring point.

The level sensors that you will find in the catalog are specifically designed for each specific purpose.


The main level meters and their operating principle are described below:

  • Capacitive level indicators or Capacitive level transmitters
  • Ultrasonic level indicators or Ultrasonic level transmitters
  • Microwave level indicators or Microwave level transmitters
  • Radar level transmitters
  • Communicating vessel level indicators (visual or magnetic)
  • Float level indicators
  • Probe level indicators (immersion and float)
  • Vibrating level indicators
  • Rotating level indicators
  • Magnetic level switch
  • Resistive level indicators
  • Optical level indicators
  • Conductivity level indicators
  • Levels by weight (load cells)

Level sensors for liquids and solids


Capacitive level indicators are suitable for measuring liquids even at high pressures and temperatures and for powdery or granulated solids, which have a high and constant relative permittivity with respect to the vacuum, and typically air.
These capacitive level transmitters allow continuous indication and level states. They are suitable for conductive and non-conductive liquids and offer good accuracy and good stability to mechanical and chemical aggression.
Ultrasonic level sensors are based on the variation of the transit time (or travel or flight) of a sound or an ultrasound, caused by the raising and/or lowering of the level in the tank to be measured.
The sound or ultrasound is emitted by a transmitter located at the top of the tank and is reflected by the level of the liquid or solid product in the tank, in a return echo detected by a receiver coupled to the transmitter.
Ultrasonic level transmitters are meters suitable for continuous indication and level status, suitable for liquids and powdery solids.
Ultrasonic level transmitters offer good precision and the measurement is independent of the physical characteristics of the product: (density mass, viscosity, etc.) and of the electrical characteristics of the product; (conductivity, permittivity, etc.)
Radar is defined as an electronic system capable of locating objects not visible to the naked eye and to determine their distance, speed, shape and size, exploiting the propagation properties of radio waves.
Radar level transmitters allow a measurement not in contact with liquids or solids, they are suitable for heavy pressure and temperature measurements, the measurement is independent of the product characteristics, they also offer high precision and repeatability.
The level meter with communicating vessels (visual) is a local level indicator made up of a column of liquid external to the container to be detected, suitable for high pressures and temperatures, it allows local indication of the level.
Similar level indicators with communicating vessels, but magnetic, have advantages which make them preferentially usable in the following applications of fluids: high pressure, high temperature, flammable or explosive, chemically aggressive, polluting for the environment, harmful or poisonous to the man.
Magnetic level gauges offer the advantage of local and remote indication. Compared to the previous visual level indicators, the measurement, instead of being read by the observer at the liquid/gas separation surface, is presented directly by the magnetic measuring device.

Level Sensors: Differences between Touch and Vibration


Probe level measurement is an automated measurement system, capable of periodically and/or continuously detecting the level of liquid, solid, mixtures, powders, etc., in tanks, silos and containers in general.
They are called probe level indicators as they automatically "feel" from the top of the container, the lowering of the contained material and therefore note the height of the container, determining the contained level.
Probing is carried out by a float suspended from a rope or a metal band, by a servo-driven motor which "feels" the floating of the float and transduces the lowering of the rope and/or the band, inversely proportional to the raising of the level , in a series of pulses directly displayed and/or transmitted at a distance.
Probe level indicators offer local and remote indication, are suitable for medium and high pressures, suitable for high heights (even over 20 meters), high precision (typically 1 mm).
The vibrating level indicators are suitable for level readings in liquids, powdery solids and solids in liquids.
They consist of a probe which, made to vibrate at its natural resonance frequency in the air, varies the vibration frequency in the presence of the liquid or solid to be detected.
Vibrating level indicators can be installed vertically or laterally to the tank to be detected and do not require calibration.

Rotating Level Sensors and Magnetic Float Level Switches



The range of level gauges includes rotary level indicators suitable for solid state measurement. They consist of a probe which is rotated by an electric motor. As the level increases, the measuring probe encounters greater resistance to rotation and therefore the increase in the rotation drive torque is detected by an electromechanical or electronic device which signals the level status.
Rotary level sensors do not require calibration and offer good repeatability.
Magnetic float level switches (or float level switches) are suitable for controlling the liquid level in tanks, vats, boilers and for controlling pumps, valves, alarm systems.
The assembly is vertical directly in the process or inserted laterally in a containment chamber external to the process.
Inside a blind vertical tube, in the lower part and integral with the fastening system, one or more contacts (up to six intervention points) with magnetic actuation (reed switch) are positioned.
One or more floats, free to slide along the guide tube, magnetically act on the contacts, switching their state according to the liquid level in the tank.
The switching points are defined during construction at the required heights and can be adjusted on site.
The magnetic float level switches can be equipped with a potentiometric transmitter for continuous level reading.
Float Level Switches for Tanks, Autoclaves and Steam Boilers
Float level switches

Suitable for any kind of liquid, even aggressive.

Floating ON/OFF Level switches for vertical or horizontal installations.

When the indicator float, in its travel, encounters the Reed switch built into the tube at predetermined distances, the contact, urged by the magnet housed in the float, opens or closes.
Easy to install, precise and intuitive, they do not require maintenance
Submersible Level probes

Suitable for neutral, alimentary, dirty, viscous, aggressive, corrosive, hydrocarbon, percolated fluids.

Hydrostatic Immersion Level Transmitters are based on the principle that a liquid contained in a vessel exerts a pressure proportional to the height of the liquid and determines its level height.

They can be combined with digital displays with or without alarms.
Trasmettitori di Livello ad Ultrasuoni | Idonei per liquidi e solidi
Ultrasonic Level probes

Suitable for liquids and solids.
NOT suitable for vapors or foams and for high solids.
Sensitive to noise and wind.

Ultrasonic Level Transmitters are suitable gauges for continuous indication and level states
Ultrasound Level Transmitters are based on the variation in the time of transit (or travel, or flight) of a sound, or an ultrasound, caused by raising and / or lowering the level in the tank to be measured.
Radar Level Transmitters | For dirty, viscous, aggressive or solid or dust fluids
Radar level probes

Suitable for neutral, nutritious, dirty, viscous, aggressive, solids or dust fluids.

Radar Level Transmitters are suitable gauges for continuous indication and level states.

Radar Level Transmitters are used for measurements of liquids or solids independent of product characteristics, in the presence of foams, vapors, acids, agitators and high pressures or temperatures.
Capacitive level indicators Suitable for liquids or solids
Capacitive Level Probes

Suitable for liquids or solids.

Capacitive level switches use an electric field to sense the presence of liquids or solid materials.

As material enters the field area, the capacity changes, activating the switch to signal the level reached.
Conductive Level Switches | Signal your Level alarm at the right height
Conductive Level probes

Suitable for conductive liquids with conductivity ranging from 0.3 μS to 10000 μS and used as level state detectors.

Conductive level switches detect the presence of conductive liquids by completing a circuit between two electrodes.

When the liquid closes the circuit, the switch is activated, signaling the level reached..
High pressures and temperatures are not a problem for level meters with communicating vessels
Level Switches with Communicating Vessels

Suitable for liquids, high pressures and temperatures.

Communicating (magnetic) vessel level meters allow local indication of the level via a transparent external column containing colored cylinders that rotate and change color based on the height of the level reached.

They can be supplied with electrical contacts or with a 4÷20 mA potentiometric transmitter for continuous level reading.
Vibrating Level switches | Versions with prongs or bar
Vibration level switches

Suitable for level state measurements in clean or dirty liquids, in solids and solids in liquids.

Vibration Level Indicators are made up of a probe that vibrates at its natural resonance frequency in the air, varies the vibration frequency in the presence of liquid or solid to be detected.
Rotary Level Switches are suitable for powdery or grainy solids
Rotary and Membrane Indicators

Suitable for powdery or granular solids.

The Rotary Level Switches are made up of a propeller probe that is rotated by an electric motor.

The measuring probe, increasing the level, encounters greater rotational resistance and hence the increase in rotation torque, is detected by an electromechanical device that reports its level state.
Anti-flooding sensors for leak detection and monitoring
Leak Detection and Monitoring

Suitable for the presence of a liquid on the floor, for example in oil storage rooms, collection tanks, control wells, channels, protective pipes, manholes, pipes, boiler rooms, cellars.

The anti-flooding detection systems are used in rooms where water, oil, gas oil, diesel leaks could occur which, if not checked in time, could cause dangerous situations or in any case serious material damage.
Electro Optical Level Switches | They do not require maintenance
Electro-Optical Level Switches

Suitable for liquids (non-transparent).

Optical Level Meters are similar to sonic ones. They use the reflection of light rather than that of sound.
Used in critical measurements, with physical pressure and temperature problems or chemical problems of corrosion and aggression.

They can operate through an optical window of transparent material placed above or sideways to the tank.