How Does an Ultrasonic Liquid Level Meter Work?
An ultrasonic liquid level meter uses the time-of-flight principle to determine the distance between a sensor and a liquid surface.
The sensor emits an ultrasonic pulse toward the liquid. When the sound wave reaches the surface, part of the signal is reflected back to the sensor.
The transmitter measures the time required for the signal to travel to the liquid surface and return.
The relationship between measuring distance and travel time is:
Distance = Speed of Sound × Travel Time ÷ 2
After determining the distance to the liquid surface, the transmitter calculates the liquid level using the configured tank reference height.
For example, if the reference measurement height is 5 meters and the detected liquid surface is 1 meter below the sensor reference point, the calculated liquid level is 4 meters.
This calculation assumes that the mounting reference and level zero point have been configured correctly.
The instrument can then convert the measured level into a corresponding output signal for monitoring and process control.
How to Select the Right Ultrasonic Liquid Level Meter
Determine the Maximum Measuring Distance
Measure the distance between the intended sensor location and the lowest liquid surface to be monitored.
The selected GLP-7 configuration must cover the full required measurement distance while allowing for the instrument's blind zone.
Check the Blind Zone
The GLP-7 specifications list a blind zone of 0.25–0.5 meters, depending on the configuration.
The maximum liquid level must remain outside the applicable blind zone for reliable measurement.
Do not select a transmitter based only on the tank height without considering the mounting position.
Evaluate Liquid Surface Conditions
Ultrasonic level transmitters work best when the reflected acoustic signal can return reliably to the sensor.
Heavy foam, excessive turbulence, filling streams, vapor concentration changes, and internal obstructions may reduce measurement reliability.
For more demanding conditions, a radar level transmitter may be a more appropriate solution.
Select the Output and Power Configuration
Check whether your monitoring system requires a 4–20 mA signal, an RS485 interface, or a compatible HART configuration.
The supply voltage, cable arrangement, and communication protocol should be specified together.
Confirm Installation Requirements
Before installation, check the process opening, mounting thread, available clearance, electrical connections, and environmental conditions.
Correct mounting is important for measurement stability and long-term operation.
Installation Recommendations for Ultrasonic Level Measurement
The following practices help improve measurement reliability:
Install the sensor above the liquid surface. Position it so that the measurement path is directed toward the intended liquid surface.
Avoid internal obstructions. Keep the ultrasonic beam away from ladders, pipes, agitators, and other objects that may produce unwanted echoes.
Consider filling streams. Avoid positioning the sensor where incoming liquid interferes with the acoustic signal.
Maintain adequate blind-zone clearance. Ensure that the maximum liquid level does not enter the instrument's blind zone.
Configure the measurement reference. Set the correct zero point, tank height, and output scaling according to the installation.
Check operating conditions. Confirm that temperature, pressure, humidity, and mounting conditions remain within the selected model's ratings.
Commissioning should include verification of the measured level against a known physical reference.
Ultrasonic vs. Radar Liquid Level Measurement
Both ultrasonic and radar level transmitters can provide non-contact liquid level measurement, but their operating principles differ.
| Comparison | Ultrasonic Level Meter | Radar Level Transmitter |
|---|
| Technology | Sound waves | Electromagnetic waves |
| Contact with Liquid | No | No |
| Typical Application | Water tanks and suitable industrial liquids | Water, chemicals and more demanding process conditions |
| Effect of Vapor Conditions | Can influence sound propagation | Generally less sensitive to changes in vapor temperature |
| Foam | Can reduce echo reliability | Depends on foam properties and radar configuration |
| Installation | Requires suitable acoustic path and blind-zone clearance | Requires suitable antenna, clearance and echo conditions |
| Selection Priority | Suitable ambient-pressure applications with favorable echo conditions | Applications needing greater tolerance of certain process conditions |
For water tanks and conventional wastewater level monitoring, an ultrasonic liquid level meter may provide a practical solution.
For complex process tanks involving significant vapor effects or challenging measurement conditions, GALLOP can help evaluate its radar level measurement products.
Why Choose GALLOP GLP-7?
GALLOP has supplied industrial measurement instruments since 2005 and provides technical selection and OEM/ODM services to international customers.
For GLP-7 ultrasonic level measurement projects, we offer:
Application-based instrument selection
Compact and split-type configuration options
Industrial output and power supply options
Local level indication
Support for suitable OEM requirements
Factory inspection and quality control
Technical assistance with installation and operation
Our team can help customers select a suitable configuration according to tank dimensions, measurement range, operating conditions, and monitoring system requirements.
Frequently Asked Questions
What is an ultrasonic liquid level meter?
An ultrasonic liquid level meter is a non-contact instrument that uses reflected sound waves to determine the distance to a liquid surface and calculate liquid level.
What is the maximum measuring range of the GALLOP GLP-7?
GALLOP lists measuring range options up to 20 meters for the GLP-7. The suitable configuration depends on the installation and required measurement distance.
Can the GLP-7 measure wastewater levels?
Yes, it can be used for suitable wastewater level measurement applications. Heavy foam, turbulent surfaces, vapor conditions, and tank obstructions should be evaluated before installation.
Can an ultrasonic liquid level meter be used in a pressurized tank?
Ultrasonic level measurement is generally more appropriate for ambient-pressure or suitable low-pressure applications. The process pressure, vapor conditions, and device rating must be checked. For demanding pressurized tanks, radar technology may be preferable.
What is the difference between an ultrasonic level meter and an ultrasonic flow meter?
An ultrasonic level meter measures the distance to a surface to determine liquid level. An ultrasonic flow meter measures or calculates fluid flow using an appropriate flow measurement principle. These instruments are designed for different measurement tasks.
Request a GLP-7 Ultrasonic Liquid Level Meter Quote
Need a non-contact liquid level measurement solution for your project?
Contact GALLOP with your tank height, liquid type, measurement range, operating conditions, power supply, and required output signal.
Our team can help select a suitable GLP-7 configuration, answer technical questions, and provide a quotation for your application.
