Ultrasonic level transmitters serve as a core sensing tool in industrial automation. They measure without touching the medium, handle tough environments well, and stay reliable over long stretches of time.
That’s why plants across petrochemicals, water treatment, food and pharmaceuticals lean on them so heavily—there’s really no straightforward substitute for what they do in these process industries.
About Ultrasonic Level Measurement
Ultrasonic measurement is a proven and cost-effective level measurement solution for liquids and bulk solids. It uses sound waves to determine the distance between the sensor and a target surface, such as a liquid or solid in a container.
Ultrasonic level measurement enables continuous, non-contact, and maintenance-free level measurement. It can measure a wide range of materials. Including liquids, pastes, sludges, and granular materials. It is a reliable, cost-effective, and versatile method of level measurement.
What is An Ultrasonic Level Transmitter?
Ultrasonic level transmitter is a device that uses sound waves to measure the level of liquid or solid materials. It is a continuous level measurement device. It can provide real-time, non-contact measurement. It is widely used in industry, agriculture, commerce and other fields.
Advantages of Ultrasonic Level Transmitters:
Non-contact measurement: This allows use in harsh environments or with corrosive liquids without direct contact.
Versatility: They can be used to measure liquid levels in a variety of applications. Including tanks, reservoirs, and open channels.
Accuracy: Ultrasonic technology provides accurate and reliable level measurement. Especially when temperature compensated.
In summary, ultrasonic level transmitters provide a versatile and reliable solution for level measurement in a variety of industrial and environmental applications， due to their non-contact measurement capabilities and ability to handle a variety of liquids and environments.
Working Principle of Ultrasonic Level Sensor
Ultrasonic level sensors work by transmitting a high-frequency sound pulse and measuring the time it takes for the pulse to return after bouncing off a surface. This time difference is then converted into a level reading. The core calculation involves the speed of sound and the time of flight of the ultrasonic pulse.
Here is a more detailed explanation of how it works:
1. Ultrasonic pulse: The transmitter sends a high-frequency sound wave to the surface of the material being measured.
2. Reflection: The pulse passes through an air gap and reflects off a liquid or solid surface.
3. Time of flight: The sensor measures the time it takes for the reflected pulse to return.
4. Distance calculation: The time of flight is converted to a distance measurement. This distance is then used to calculate the level.
5. Level measurement: This distance, along with the tank dimensions, is used to determine the level.
The calculation formula for determining liquid level using an ultrasonic level transmitter is: L = E – D
• L: the measured liquid level.
• E: the empty tank distance (the distance from the sensor to the tank bottom).
• D: the distance measured from the sensor to the liquid surface (calculated using the above formula).
Distance is calculated using the following formula: D = (c * t) / 2 , where:
• Distance (D) :the distance between the sensor and the liquid surface.
• Speed of sound (c) :the speed of an ultrasonic pulse in a medium (such as air).
• Time (t) : the time it takes for the pulse to reach the liquid surface and return.
Examples:
•Speed of sound: Assume that the speed of sound in air is 343 m/s.
•Time of flight: The time required for the pulse to travel to the liquid surface and back is 0.005 seconds.
•Distance: Distance = (343 m/s*0.005 sec)/2 = 0.86 m.
•Level: If the empty tank distance (E) is 2 m, the liquid level (Level) is 2-0.86 = 1.14 m.
Applications of Ultrasonic Level Transmitter
Ultrasonic level transmitters are widely used in a variety of applications across multiple industries. They are used to monitor and control liquid levels in tanks, silos and other storage vessels. They can measure a variety of materials. Including liquids, pastes, sludge and granular materials.
Difference Between Transmitter and Sensor
Sensors and transmitters are two different components. Although transmitters and sensors are often used together, they have different functions and roles:
Main Difference | Sensor | Transmitter |
Function | Detect and measure physical parameters and convert them into raw signals. | Receive and process raw signals from sensors. |
Signal Output | Converts these parameters into a raw signal, which can be voltage, current or resistance. | Converts the raw signal into a standardized electrical output. Typically, 4-20 mA or a digital signal. |
Communication | Not suitable for direct long-distance communication. | Designed for long-distance communication. |
Location | Usually directly at the point of measurement. | It may be located some distance from the sensor. |
Complexity | Sensors are usually simpler and smaller and more compact. They only need to detect and respond to inputs, not transmit signals. | Transmitters are usually larger and more complex. This is because they need to generate a signal and transmit it over long distances. |
Applications | Real-time monitoring and measurement of liquid or solid levels. | Integration into automation systems for level monitoring and control. |
How to Use Ultrasonic Level Transmitter?
- Installation: Install the transmitter on the container. Avoid obstacles, vibrations, and other factors that affect the measurement. Make sure it is unobstructed and can contact the liquid smoothly.
- Power supply: Connect the transmitter to a suitable DC power supply and ensure that the correct voltage is provided.
- Signal connection: Connect the transmitter to the control system through a standard signal such as 4-20mA.
- Setting of operating parameters: Set the operating parameters of the transmitter according to the specific application and accuracy.
- Calibration: Calibrate the transmitter before use. Including setting the empty distance and span.
- Temperature compensation: The speed of sound changes with temperature. It may affect the measurement accuracy.
- Testing: Test the performance and accuracy of the transmitter by simulating or actual liquid level changes.
- Maintenance: Clean the sensor surface regularly and check the connection. And monitor the performance of the ultrasonic level transmitter.
- Interference: Pay attention to potential interference caused by factors such as wind, vibration, and temperature changes.
Advantages of Ultrasonic Level Sensor
Non-contact measurement: Since the sensor never touches the medium directly, it sidesteps corrosion, surface wear and contamination issues entirely. It handles corrosive, viscous and particle-laden liquids without much trouble, and the equipment itself tends to last considerably longer.
High Measurement Accuracy: The device fires high-frequency ultrasonic pulses and runs the returns through digital signal processing, so the readings stay sharp and consistent. Typical accuracy falls between ±0.25% and ±0.5% of full scale, with resolution down to the millimeter—plenty tight for most industrial process control jobs.
Wide Range of Applications: It can measure anything from a few centimeters up to several tens of meters, which covers open tanks, sealed vessels, open channels and natural rivers alike.Besides, its measurement performance is barely influenced by changes in medium physical properties, such as density, viscosity and dielectric constant.
Easy Installation and Maintenance: The installation process is simple and convenient. Only a reserved opening on the top or side wall of the container is needed, and all construction work can be completed without shutting down the production line. Free of any movable mechanical components, the device requires almost no daily maintenance, which effectively cuts down the total life-cycle operating cost of the equipment.
High Safety: Featuring intrinsic safety and non-contact detection, the device is an ideal choice for level detection of hazardous media, including flammable, explosive, toxic, as well as high-temperature and high-pressure substances. It greatly improves the overall safety level of on-site industrial operation.
Good Environmental Adaptability: Most modern ultrasonic level transmitters are built with temperature compensation, false echo suppression and automatic gain control functions. These optimized designs ensure consistent and reliable measurement stability even in harsh and complex working conditions with steam, dust or foam interference.
Limitations of Ultrasonic Level Sensor
Susceptibility to Surface Conditions: Ultrasonic measurement performance is easily disrupted by poor liquid surface conditions. Foam, steam, floating dust and violent liquid turbulence can disperse and absorb ultrasonic pulses, which weakens signal intensity substantially. In extreme scenarios, the returning echo signal may become undetectable or vanish completely, triggering inaccurate level data and occasional signal dropout.
Existence of measurement blind zones: Each time the probe emits an ultrasonic pulse, it requires a brief reset and recovery time. This forms a dead measurement area directly under the sensor probe, which usually covers a range of 0.3 to 0.6 meters. Any liquid level variation within this blind area cannot be detected precisely, restricting the minimum measuring range of the device.
Temperature affects stability: Ambient air temperature is a key factor influencing ultrasonic propagation velocity. Every 1°C change in temperature will cause around 0.17% measurement deviation. Without effective temperature correction functions built into the system, fixed systematic errors will occur during ongoing level monitoring.
Installation locati0n requirements: Sensor installation needs to avoid on-site interference sources such as material inlets, mixers and various internal tank fittings. A clear vertical pathway between the probe and liquid surface is essential for valid detection. Equipment applicability drops significantly in confined installation spaces or tanks with intricate internal structures.
Limitations under special operating conditions: Ultrasonic signals simply don’t travel properly under ultra-high pressure or in a vacuum. The signal either gets warped or lost along the way, so the readings become unreliable and the device struggles to stay stable. For these kinds of extreme environments, ultrasonic level transmitters aren’t the right tool.
Relatively high cost: Ultrasonic level measuring devices incur higher purchasing and field installation expenses than conventional options, such as float level sensors and hydrostatic pressure transmitters. For basic industrial monitoring scenarios with simple working conditions, this type of equipment cannot achieve favorable cost-effectiveness.
Ultrasonic level sensors play an important role in industrial automation due to their reliability, accuracy and versatility. Their non-contact design and ability to measure in a variety of environments make them a popular choice for various level measurement applications. They provide a reliable means of level monitoring and control for all industries.
Sino-Inst is a professional supplier in the water treatment industry. We provide a variety of water level measurement equipment. Including ultrasonic flow meters, radar level gauges, pressure transmitters, etc. If you have any questions or needs, please contact our team. We will tailor a solution for you.
