How an Ultrasonic Sensor Works: Usage and Function
What is an Ultrasonic Sensor and What Are Its Applications
An ultrasonic level sensor is an electronic device used to measure the distance between the sensor itself and the surface of a material, whether liquid or solid, through the emission of high-frequency sound waves, inaudible to the human ear. The operating principle is based on the echo: the sensor emits an ultrasonic pulse that propagates in the air, bounces off the surface of the material and returns to the device. By measuring the time taken by the sound wave to complete this journey, the sensor is able to calculate the distance precisely.
Definition and Operating Principle
Ultrasonic sensors are precise and reliable devices, designed to measure the distance or level of materials using high-frequency sound waves.
Here is how they are structured and how they are used:
Main Components:
Main Components:
- Ultrasonic transducer: generates and receives high-frequency sound pulses.
- Control circuit: processes the return signal and calculates the distance or level based on the response time.
- Power system: provides the energy necessary for the sensor to function.
- Connection interfaces: allow the sensor to be integrated with automation systems, PLCs or monitoring software.
- Positioning of the sensor based on the specific application (tank, silo, pipeline, etc.)
- Configuration of parameters via software or local interface (measurement range, alarm thresholds, type of output).
- The sensor emits an ultrasonic pulse that, hitting the surface of the material, is reflected towards the transducer.
- The internal circuit calculates the time elapsed between emission and reception to determine the distance or level.
- Via digital interfaces (e.g. display, 4÷20 mA output, Modbus), it is possible to display and analyze the measurements in real time or integrate them into control systems.
- The measured data are converted into analog or digital signals.
Applications in Industrial Sectors
Ultrasonic level sensors are used in various industrial and civil sectors:
- Water management: monitoring the level in tanks, basins and water treatment plants.
- Agriculture: managing the water level in automated irrigation systems.
- Storage and silos: checking the levels of liquid or solid material.
Advantages and Limitations of Ultrasound Technology
- High precision in detecting distances even on complex surfaces.
- No physical contact during measurement.
Technical Limits
- Sensitivity to temperature and pressure variations.
- Restrictions in environments with highly absorbent materials.
- Not suitable in the presence of vapors or foams.
Why is it important to choose the right instrument?
Choosing the right ultrasonic level transmitter is essential to ensure precision, reliability and operational continuity in industrial processes.This is why it is so important to make the right choice:
Precision in measurement:
An unsuitable transmitter can provide incorrect or unstable readings, leading to dosing errors, false or missed alarms.
With an adequate instrument, however, you have reliable data in real time, essential to maintain product quality and plant efficiency.
Compatibility with the application environment:
Each application has its own challenges: tanks with vapors, powders, foam, agitators or inclined surfaces. The right sensor takes into account distance, materials, environmental conditions and container structure. A correct analysis avoids malfunctions and improves the instrument's lifespan.
Cost optimization:
Choosing the cheapest instrument may seem advantageous, but if it is not suitable, the risk is to have to replace it in a short time. On the contrary, a suitable instrument optimizes costs over time thanks to stable performance and reliability.
Riels Instruments recommends the following products for your pressure measurements:
Ultrasonic Level Probes
Ultrasonic Level Transmitter Range up to 20 meters
Ultrasonic Level Transmitters Range up to 30 meters
Ultrasonic Level Transmitters with Integrated Display
Fundamental criteria when choosing an ultrasonic level transmitter
Measurement distance (Range): you need to know the maximum height of the tank or silo. Ultrasonic transmitters have a distance limit: choosing one with a range that is too short will lead to incorrect or incomplete measurements. Choose a transmitter with a range that is 20-30% greater than the actual height of the container.
Environmental conditions: ultrasonic level transmitters can be affected by steam, dust, high temperature, turbulence. These conditions can attenuate or reflect the acoustic signal. In these cases, transmitters with automatic compensations or alternative solutions are needed (for example, a radar level transmitter).
Type of material to measure: evaluate whether the material is a still liquid, agitated or foamy surface, granular or powdery solid.
Environmental conditions: ultrasonic level transmitters can be affected by steam, dust, high temperature, turbulence. These conditions can attenuate or reflect the acoustic signal. In these cases, transmitters with automatic compensations or alternative solutions are needed (for example, a radar level transmitter).
Type of material to measure: evaluate whether the material is a still liquid, agitated or foamy surface, granular or powdery solid.
The more unstable or irregular the surface, the more an advanced signal processing algorithm and a narrow acoustic cone are needed.
Tank geometry: Tall, narrow tanks, with agitators, internal piping or metal structures can generate false echoes.
Tank geometry: Tall, narrow tanks, with agitators, internal piping or metal structures can generate false echoes.
You need a transmitter with intelligent filters or the ability to map and ignore obstacles.
Degree of protection (IP/ATEX):
Wet or dusty environment? You will need at least IP66 or higher.
Potentially explosive atmospheres? Check for ATEX or IECEx certification.
Degree of protection (IP/ATEX):
Wet or dusty environment? You will need at least IP66 or higher.
Potentially explosive atmospheres? Check for ATEX or IECEx certification.
Frequently asked questions about ultrasonic level transmitters
How does an ultrasonic level transmitter work?
The sensor emits a sound wave that bounces off the surface of the material.
By calculating the return time of the echo, the device determines the distance and therefore the level.
By calculating the return time of the echo, the device determines the distance and therefore the level.
In which applications is it more suitable than other types of sensors?
It is ideal for non-aggressive liquids, water, powdered or granulated solids, where there is no contact with the material and there are no extreme conditions (e.g. high pressure, high temperatures, foam, vapor).