Level measurement is a crucial task in industry, and ultrasonic level sensors and radar level sensors are two common technology choices. How to choose is also an important choice.
What is an ultrasonic level sensor?
An ultrasonic level sensor is a sensor that utilizes the ultrasonic principle to measure the height of a liquid or solid surface. It realizes liquid level measurement by transmitting ultrasonic pulses and measuring the time of pulse return to determine the distance between the liquid surface and the sensor.
Principle Of Operation Of Ultrasonic Level Sensors:
- Transmitting ultrasound: The sensor transmits short pulses of ultrasound signals through a built-in ultrasound transmitter.
- Pulse propagation: The ultrasonic pulse propagates at the speed of sound to the surface of the liquid and is reflected by the liquid surface.
- Receive reflected signal: The sensor’s receiver receives the ultrasonic signal reflected from the liquid surface.
- Calculate the distance: According to the time difference between transmission and reception, the sensor calculates the ultrasonic propagation time and multiplies the speed of sound by the time difference to get the distance between the liquid surface and the sensor.
- Output level information: By converting the distance to liquid level, the sensor outputs liquid level information for monitoring or control system use.
Types Of Ultrasonic Level Sensors
- Side-mounted ultrasonic level meter: Mounted on the side wall of the container, it measures the level height of the liquid or material by sending and receiving ultrasonic waves. AK7000E ultrasonic level sensor can be mounted on the side wall of the vessel for measurement.
- Immersion type ultrasonic level gauge: Nstalled in the liquid, partially or completely immersed in the liquid, used to measure the distance from the surface of the liquid to the sensor.
- Open Channel Ultrasonic Level Gauge: Used to measure the liquid level in open channels, channels or rivers, by measuring the distance from the liquid surface to the sensor to obtain liquid level information.
- Closed Pipe Ultrasonic Level Gauge: Suitable for closed pipe or container, through the pipe wall reflecting ultrasonic waves to measure the liquid or material level height.
- Pulsed Ultrasonic Level Gauge: Uses short pulses of ultrasonic waves to determine the liquid level height by measuring the echo time of the pulses.
Ultrasonic Level Sensor Applications
- Liquid storage tank monitoring: Used to measure the horizontal height of liquid in liquid storage tanks to monitor level changes.
- Environmental monitoring: Used to monitor the level of natural water bodies, rivers, or reservoirs for environmental monitoring and water resource management.
- Wastewater treatment: Used to monitor the level of different stages in a wastewater treatment system to optimize the treatment process.
What is a radar level sensor?
A radar level sensor is an instrument that uses radar waves to measure the distance to the surface of a liquid or solid. It determines the distance between the surface of the liquid and the radar level meter by transmitting radar waves and measuring the return time of the waves, thus realizing accurate measurement of the liquid level.
Working Principle Of Radar Level sensor
- Transmitting radar waves: Radar level sensors transmit short pulses of radar waves through a built-in radar antenna.
- Wave propagation: Radar waves travel at the speed of light through the air and are partially reflected when they encounter a liquid or solid surface.
- Receiving the reflected signal: The receiver of the radar level gauge receives the radar wave signal reflected from the liquid or solid surface.
- Calculate the distance: According to the time difference between transmission and reception, the radar level meter calculates the time of radar wave propagation and multiplies the time difference by the speed of light to get the distance between the liquid surface and the radar level meter.
- Output liquid level information: By converting the distance to liquid level height, the radar level meter outputs liquid level information for monitoring or control system use.
Radar level meters usually have the advantages of high accuracy, high reliability, and applicability to complex environments, so they are widely used in industry, industrial use of water, water treatment, environmental protection, and other fields.
Types of Radar Level sensors
There are two main types of radar level sensors, guided wave radar (TDR) and non-contact radar. Guided wave radar causes waves to propagate through conducting wires or guided waves, while non-contact radar propagates waves directly through the air.
Radar Level Sensor Applications
- Chemical/Petrochemical
- Granular solids
- Pharmaceuticals
- Wastewater
Differences Between Ultrasonic And Radar Level Sensors
| Characteristics | Ultrasonic Level Sensor | Radar Level Sensor |
| Principle | Measurement of liquid level height using ultrasonic pulses. | Measurement of liquid surface height using radar beams. |
| Applicable media | Suitable for most liquid media, including corrosive liquids. | Suitable for a wide range of liquid and solid media, independent of liquid properties. |
| Measuring accuracy | High accuracy, typically in the millimeter range. | High accuracy, typically in the millimeter to centimeter range. |
| Installation position | Easily mounted on top or on the side of the vessel. | Flexible mounting position, on the top, side or bottom of the vessel. |
| Environmental influences | Highly affected by temperature, humidity and gases. | Stable to environmental factors such as temperature and humidity. |
| Application-oriented | Suitable for general level measurement applications. | Suitable for complex environments, high temperatures, high pressures, etc. |
Limitations of Ultrasonic and Radar Level Sensors
Limitations of Ultrasonic Level Sensors
- Media effects: Ultrasound is sensitive to the properties of the medium, such as dielectric constant, temperature, density, etc., which may affect its accuracy.
- Surface coating: The ultrasonic level sensor in the measurement process may be affected by the container surface coating, especially adhesion or multi-layer coating may lead to signal attenuation.
- Bubbles and particles: the presence of bubbles or particles in the liquid, ultrasound may be scattered or absorbed, thus reducing the accuracy of the measurement.
- Temperature effects: Temperature changes may result in changes in the velocity of ultrasonic propagation, which in turn may affect the measurement results.
- Vibration and fluctuation: Vibration or fluctuation in the container may cause interference with the reflection of ultrasound, affecting the accurate measurement of liquid level.
Limitations of radar level sensors
- Weather effects: Strong weather conditions (e.g., rain, snow, high winds) may affect the propagation of the radar signal and thus the accuracy of the level measurement.
- Installation location: The installation location of the radar level gauge needs to be considered, as different locations may be obstructed or blocked, affecting signal propagation and reception.
- Price: Radar level meters are generally more expensive than other level measurement technologies, which may limit their options in some applications.
Summary
Ultrasonic level sensors and radar level sensors have their own advantages and disadvantages and are suitable for different application scenarios. When selecting one, factors such as cost, accuracy, and environmental conditions need to be considered and an informed decision made based on specific needs. Both technologies play an important role in industrial automation, providing reliable solutions for liquid level measurement.
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