Ultrasonic Level Sensing
Principle
An ultrasonic sensor emits high-frequency sound pulses toward a target, whether solid or liquid. The sound waves bounce back after hitting the surface, and the returning echo is analysed to accurately determine the distance to the surface. This distance can be translated into an analog output or used in digital (switch) devices.
Advantages
- Non-contact measurement
- Suitable for both solid and liquid applications
- Ideal for tanks with agitators or stirring mechanisms
- Covers a wider area for sampling than other methods
Disadvantages
- Prone to interference from foam, dust, vapour, or surface disruptions
- Not suitable for pressurized vessels or vacuums
- Has a small “dead zone” directly in front of the sensor
- Can be affected by rapid environmental changes
Considerations
Standard ultrasonic sensors can be misled by narrow channels, tank extrusions, or unusually shaped vessels, as they create additional echoes that can reflect and bounce around. Advanced models with “false echo suppression” help filter out these false echoes, focusing on the valid echo from the target surface.
