Ultrasonic Level Transmitter: Working Principle, Advantages, and Applications

An ultrasonic level transmitter is a widely used industrial automation measurement device that can quickly and accurately measure the level and volume of liquids in containers. It operates based on high-frequency ultrasonic vibrations and the propagation characteristics of ultrasonic waves through a medium.

What Is an Ultrasonic Level Transmitter?

An ultrasonic level transmitter is an instrument used to measure the liquid level or material height inside tanks, water reservoirs, and vessels. It works by emitting ultrasonic pulses and receiving the reflected signals to determine the liquid level. Because it uses non-contact, non-invasive technology, it is widely applied to level measurement in containers of various shapes and sizes.

Working Principle of an Ultrasonic Level Transmitter

An ultrasonic level transmitter measures liquid level by transmitting and receiving ultrasonic signals. When the ultrasonic pulse is reflected by the liquid surface inside a tank or vessel, the sensor receives the echo and calculates the distance between the sensor and the liquid surface, thereby determining the liquid level.

What Are the Advantages and Disadvantages of Ultrasonic Level Transmitter?

Advantages of Ultrasonic Level Transmitters

1. Non-contact measurement

The sensor does not come into direct contact with the measured medium, so it does not contaminate the liquid. It is also not affected by corrosion or wear from the process fluid, making it suitable for corrosive and chemical environments.

2. Strong adaptability

Ultrasonic level transmitters are suitable for various types of liquids and containers, such as storage tanks, pipelines, and chemical reactors. They can operate reliably in harsh conditions including high temperature, high pressure, and corrosive environments, and are largely unaffected by medium viscosity, density, or humidity.

3. Multiple measuring ranges and material options

Ultrasonic liquid level sensor are available in different measuring ranges, such as 5 m, 10 m, and 15 m, to meet diverse industrial requirements. Probe materials such as corrosion-resistant PVDF ensure reliable measurement in aggressive liquids and environments.

4. High resistance to interference

Ultrasonic liquid level sensor offer strong immunity to interference and can operate stably in environments with strong electromagnetic fields, such as substations and transmission towers.

5. Easy installation and maintenance

With a simple structure, compact size, and light weight, ultrasonic level transmitters are easy to install and maintain. Because they do not contact the process fluid, installation does not require special consideration of corrosion or contamination.

6. Real-time monitoring and automation

Ultrasonic liquid level sensor provide real-time level measurement and can communicate with host systems or PLCs to enable remote monitoring and automated control.

Limitations of Ultrasonic Level Transmitters

1. Presence of a blind zone

The blind zone refers to the area that cannot be measured by the instrument. During ultrasonic pulse transmission, a small region near the transducer cannot receive reflected signals. The size of the blind zone depends on the measuring range: shorter ranges result in smaller blind zones, while longer ranges increase the blind zone.

2. Sensitivity to mist, dust, foam, and volatile media

Ultrasonic liquid level sensor are not suitable for applications with heavy mist, dust, media that generate large amounts of foam, or highly volatile substances. These conditions can absorb or disrupt ultrasonic signals, leading to signal loss and reduced accuracy.

3. Sensitivity to obstacles

Because ultrasonic level measurement relies on sound wave reflection, obstacles within the measuring path can interfere with signal transmission, causing signal loss or measurement errors.

4. Measurement affected by temperature

Medium temperature is a key factor influencing ultrasonic level transmitter performance. When the temperature inside a closed vessel differs from the ambient environment, condensation may form on the probe, reducing measurement accuracy. During installation, a compressed air purge can be used to keep the probe dry and prevent accuracy degradation caused by condensation.

Where Are Ultrasonic Level Transmitters Used?

1. Industrial applications

In industrial production, Ultrasonic liquid level sensor are commonly used for level monitoring in storage tanks, process vessels, and small containers to ensure smooth and stable operations. They are especially well suited for wastewater and corrosive liquids, where their strong signal penetration and fast response make them an ideal choice.

2. Environmental monitoring

In environmental monitoring, ultrasonic level transmitters are used to measure water levels in rivers, lakes, reservoirs, and roadway areas, providing real-time and reliable data for flood warnings and water resource management.

3. Healthcare

Ultrasonic liquid level sensor also play an important role in the healthcare field. They are used to monitor liquid medication reservoirs in medical equipment, infusion systems, and in-body fluid monitoring devices, ensuring accurate drug delivery and safe fluid management for patients.

4. Construction and water conservancy projects

In construction projects, ultrasonic level transmitters are widely applied to monitor liquid levels in buildings, basements, and water storage tanks. In water conservancy applications, they are used for level monitoring and control in pools and water tanks, helping to prevent flooding, leakage, and other incidents.

5. Agriculture and food industry

In agriculture, ultrasonic level transmitters are used to monitor water levels in irrigation systems, ensuring crops receive adequate irrigation. In food storage and processing, they are used to detect the level of raw materials or finished products, preventing overfilling or underfilling and ensuring product quality and safety.

6. Aerospace

In the aerospace field, Ultrasonic liquid level sensor are commonly used in fuel tanks of aircraft and spacecraft to monitor fuel levels and changes in real time, ensuring operational safety and stable performance.

7. Water quality monitoring

Ultrasonic liquid level sensor can also be used in water quality monitoring. By measuring the propagation speed of ultrasonic waves in water and the strength of echo signals, the concentration of suspended solids can be estimated, enabling real-time water quality monitoring.