Ultrasonic Level Transmitters: A Comprehensive Guide to Technology, Applications, and Best Practices

Accurate level measurement is essential across many industries, and vital to efficient operations. 

Ultrasonic level transmitters provide a dependable, non-contact, and economical solution for gauging levels within tanks plus containers. These instruments are utilized for multiple tasks, from water treatment sites to chemical processing facilities. 

This post aims to supply a thorough guide, allowing you to grasp the tech, uses, and best practices for ultrasonic-level transmitters.

Understanding the Basics of Ultrasonic Level Measurement

What are Ultrasonic Waves?

• Ultrasonic waves are sound waves that exist above our hearing ability; this is beyond 20 kHz. The usual range is between 40 and 200 kHz.

The Time-of-Flight Principle:

• These transmitters operate by emitting sound pulses. They then measure the time it requires for any echo to come back, which allows them to determine distance.
• The formula is: Distance = (Sound Speed in Air x Travel Time) / 2.
• A temperature sensor is often present in these devices to compensate for sound speed changes as temperature varies.

Key Components of an Ultrasonic Level Transmitter:

• Transducer: A piezoelectric crystal switches electric energy into ultrasound waves, also turning returning waves into an electrical signal.
• Pulse Transmission Circuit: This circuit generates a pulse; which is then converted to a sound wave.
• Receiver/Sensor: A receiver captures the reflected wave, converting it into an electrical signal.
• Control Circuit (Microcontroller): This part manages operations, calculating distance and level and converting it for an output signal.
• Temperature sensor: This sensor provides the device with temperature readings, which compensates for the way temperature affects sound speed.

Types of Ultrasonic Level Transmitters and Sensors

By Measurement Method:

• Single Transmitter, Single Receiver: They're simple with reduced cost; however, their accuracy may be lower.
• Multi-Transmitter, Multi-Receiver: Such systems have higher accuracy, and liquid motion does not affect them as much, yet their cost is greater.

By Application:

• Sanitary Ultrasonic Level Sensors: Created with hygienic applications in mind.
• High-Temperature Ultrasonic Level Sensors: These work properly within high-temperature settings.
• Solids Ultrasonic Level Sensors: They're optimized to gauge solids' levels.
• Remote Ultrasonic Level Sensors: They allow the sensor to be separate from electronics.
• 2-Wire Loop Powered Ultrasonic Level Sensors: These reduce expenses regarding wiring.
• Wireless Remote Ultrasonic Level Sensors: Uses radio for information transfer.

By Mounting Method:

• Tank Ultrasonic Level Transmitters: Placed on tank walls for liquid level tracking.
• Immersion Ultrasonic Level Transmitters: The sensor goes inside the liquid to measure distance.

Other Types:

• Pulsed Ultrasonic Level Transmitters: They utilize pulsed waves to obtain exact measurements.
• Digital Ultrasonic Level Transmitters: They output digital signals, preventing signal interference.

Contact vs. Non-Contact Ultrasonic Sensors:

• Non-contact sensors don't touch the material. They are good for use when dealing with corrosive, contaminated, or particle-filled liquids.

Key Features and Benefits

• Non-Contact Measurement: Because no direct contact occurs, they are appropriate for use with harsh, boiling, and unsafe materials.
• Versatility: They measure many materials, from liquids to solids to slurries and solvents.
• Ease of Installation and Use: These instruments have an easy setup and are not hard to configure.
• Maintenance-Free: With no moving parts, maintenance is minimal and there’s no need for regular calibration.
• Unaffected by Media Properties: Changes to density, dielectric constant, or conductivity don’t alter the measurement result.
• Temperature Compensation: These systems feature a temperature sensor that adjusts for changes in sound speed.
• Cost-Effective: They can be more economical when compared to alternative technology, like radar.

Applications of Ultrasonic Level Transmitters

• Water and Wastewater Treatment:
  • Use them for level measurement at water treatment plants, basins, dams, canals, and wastewater facilities.
  • Measure level differences across bar screens to automate cleaning processes.
  • Measure flow within open channel systems.
• Chemical Industry:
  • Monitor levels in storage tanks and reactors.
  • Measure harsh chemicals.
• Food and Beverage Production:
  • Monitor levels within tanks.
  • Control liquid levels in the course of the production.
• Oil and Gas Industry:
  • Measure level in oil storage tanks plus processing sites.
• Pharmaceutical Industry:
  • Achieve precise liquid measurements within production processes.
• Agriculture:
  • Monitor levels in irrigation and feeding systems.
• Other Applications:
  • They provide level data inside silos and hoppers.
  • They can be used to indicate levels on conveyors.
  • They have marine applications.
  • These sensors can monitor sludge levels.
  • They can measure levels within the mining business.

Limitations of Ultrasonic Level Transmitters

• Environmental Factors:
  • Temperature and Pressure: Extreme temperature and pressure impact the sound’s velocity.
  • Dust, Foam, and Vapor: These may absorb or scatter sound waves causing inaccurate readings.
  • They cannot function under vacuum conditions.
• Surface Conditions: Turbulent liquids and rough surfaces may complicate readings.
• Material Limitations: The construction material limits temperature to about 158 °F (70 °C) and pressure to 43 psi (3 bar).
• Range Limitations: They may not have the range of other forms of level sensing.
• Interference: Obstacles, for example, pipes, beams, and agitators create false echoes.
• Accuracy: Radar's accuracy is generally higher.

Installation and Best Practices of Ultrasonic Level Transmitters

Mounting:

• Position the device at a normal distance above the highest level.
• The transmitter needs to be 50 cm above the highest fluid levels.
• Use plastic isolation kits rather than stainless steel.
• Mount the transducer, making it perpendicular to the surface.
• Keep the device out of direct sunlight, away from vibration and electric wiring.

Calibration:

• Calibration has considerable importance.
• Confirm the proper empty distance and measurement range.
• Proper calibration promotes precise measurements.

Signal Processing:

• Use equipment with signal processing to manage obstructions.
• Employ software that ignores false echoes.

Environmental Considerations:

• Avoid interference caused by wind, strong vibration, and temp variations.

Temperature Compensation:

• Confirm there is compensation for sound speed changes because of changing temp.

Damping:

• Use damping to control the rate of level and output signal fluctuation.

Sensor Selection:

• Choose a sensor with signal filtering, temperature compensation, and self-cleaning abilities.
• Select sensors with the proper measuring range and accuracy.

Troubleshooting Common Issues

• Signal Loss:
  • Check obstructions or build-up on the transducer.
  • Handle excessive foam, dust, or vapor.
• Erratic Readings:
  • Control fluctuations by using damping.
  • Check for liquid or surface issues.
• Calibration Drift:
  • Conduct calibration checks regularly.
• False Echoes:
  • Use devices with software to mask false echoes.
• Temperature Issues:
  • Make certain temperature compensation is working correctly.

Emerging Trends and Innovations

• IIoT and Cloud Integration: Level transmitters are connecting to cloud platforms for data analytics.
• AI for Signal Processing: New uses for AI to perform signal processing may be possible.
• Advanced Sensor Materials: Innovations are ongoing in energy use, along with new materials for transducers.

Cost-Benefit Analysis

• Initial Investment vs. Total Cost of Ownership: Look at the cost of ultrasonic-level transmitters.
• Savings in Maintenance and Downtime: Lower maintenance brings cost savings; compared to pricier methods like radar level instruments.

Safety and Compliance

• Hazardous Environment Certifications: Understand industry standards for potentially hazardous locations.
• Safety Protocols: Adhere to safety guidelines for differing application settings.

Conclusion

Ultrasonic level transmitters offer reliable, accurate, and varied means for level sensing. Their wide application range, with many types and benefits, makes them suitable for many industries. For level measurement needs, you might like to consider these instruments. Request a quote today for advanced ultrasonic level measurement solutions and cost-effective instrumentation.