FMU30 Ultrasonic Level Meter Overview
The FMU30 is an integrated ultrasonic transmitter designed for non-contact measurement of liquids, slurries, and solids. It performs level detection via ultrasonic pulses, making commissioning fast and easy, and is suitable for engineering technicians and procurement personnel.
The instrument has a built-in temperature sensor that automatically compensates for changes in the speed of sound caused by temperature variations, ensuring measurement stability. It also supports on-site envelope curve display for instrument diagnostics and maintenance.
Measurement Principle and Key Technologies
Ultrasonic Ranging Principle
The sensor emits ultrasonic pulses. After the pulses hit the material surface, they are reflected, and the sensor receives the echo and calculates the time difference between transmission and reception to determine the distance. The formula is: D = c · t/2, L = E - D.
Among them, BD is the blanking distance, D is the distance from the sensor diaphragm to the material surface, E is the empty tank height (zero point), F is the full tank height (full scale), and L is the level. The full-scale level height F must not enter the blanking distance BD, otherwise the echo signal cannot be identified.
Compared with radar level meters, ultrasonic level meters have slightly lower accuracy and stability, but they are cheaper and suitable for cost-sensitive applications.
Current Output and Alarm
The instrument outputs a 4-20 mA current signal, with 4 mA corresponding to 0% and 20 mA corresponding to 100%. The level height can be converted by detecting the current. When the current exceeds the range by 5%-10%, the instrument will issue an alarm.
Technical Parameters
The FMU30 offers two measuring ranges. The specific parameters are shown in the table below:
| Parameter | Version 1 | Version 2 |
|---|---|---|
| Liquid measuring range | 5 m | 8 m |
| Solid measuring range | 2 m | 3.5 m |
| Blanking distance | 0.25 m | 0.35 m |
| Ambient temperature | -20°C ~ +60°C | |
| Storage temperature | -40°C ~ +80°C | |
| Process pressure | 0.7 ~ 3 bar abs. (10.15 ~ 43.5 psi) | |
Wiring and Installation Guide
Wiring Method
Connect the 24 V power supply to the terminals below the display unit according to the positive and negative poles. The wiring is simple and convenient.
Installation Precautions
- Do not install the instrument in the center of the tank. The distance between the sensor and the tank wall should be about 1/6 of the tank diameter.
- When measuring solid levels with an angle of repose, the sensor diaphragm should be installed perpendicular to the material surface.
- Within the signal beam range (emission angle α), limit switches, temperature sensors, and other components must not be installed.
- In narrow channels or other occasions with strong interfering echoes, an ultrasonic guide tube can be used. The minimum pipe diameter is 100 mm, and the inside of the pipe must be kept clean.
Device Structure
The figure below shows the structure of the FMU30 for reference during installation and maintenance.
Summary and Consultation
The FMU30 ultrasonic level meter has a simple structure and is easy to commission, making it suitable for a variety of level measurement scenarios. For more commissioning methods or product information, you can add the WeChat below for consultation, or call 153 2371 3323, or visit the official account or official website http://ainstru.com/.