3 Types of Non-Contact Level Sensors
There are three commonly used non-contact liquid level sensors, including capacitive liquid level sensors, ultrasonic liquid level sensors, and separate photoelectric liquid level sensors. The non-contact liquid level sensor can detect the liquid level without contacting the liquid. With this advantage, the application field of the non-contact liquid level sensor has been greatly expanded.
The common feature of these three types of non-contact liquid level sensors is that they are not affected by liquid color, corrosiveness, pressure, density, etc., and because the sensor does not directly contact the liquid, it is more hygienic, and it is convenient for users to clean the container, add liquid, etc.
Ultrasonic liquid level sensor
The ultrasonic liquid level sensor detects the liquid level according to the principle of sound wave reflection. Because the ultrasonic sensor can convert the water level into data and display it on the display board, the user can clearly know the real-time remaining water volume. The accuracy of the ultrasonic liquid level sensor can reach ±2mm, with high precision, and can detect the liquid level very accurately.
Because the ultrasonic transmitter has a large volume, it has requirements on the measuring range and the size of the liquid container to be measured. The container is too small to be detected, so it is mostly used in the industrial field. For example, the internal water tank of small household appliances such as coffee machines and water dispensers is not suitable for the use of ultrasonic liquid level sensors. In addition, the price of ultrasonic liquid level sensors is relatively high. When considering cost control, ultrasonic waves are not suitable for such small household appliances.
Capacitive liquid level sensor
The capacitive liquid level sensor is attached to the container to detect the liquid level, so the installation process is simple. Capacitive liquid level sensors are mostly used in the field of home appliances, because the positioning is because the sensor has the characteristics of small size and low price. If the capacitive liquid level sensor is installed on the body, the container can be moved freely. For example, the capacitive liquid level sensor is used to detect the low liquid level of the aromatherapy machine. When the sensor detects that the fragrance in the aromatherapy machine bottle is only 20 ml remaining, a signal reminder is given. After the device receives the signal, the buzzer alarm is turned on or the light is on. Then the user can take away the bottle to add liquid, or directly replace another bottle with a new one.
The disadvantage of capacitive liquid level sensors is that they can only be used on non-metallic containers and cannot detect liquids with low conductivity, such as diesel gasoline. It also cannot detect hot liquids, which can cause the sensor to fail.
Separate photoelectric liquid level sensor
The structure of the separate photoelectric liquid level sensor is to design the reflected light tracking part on the water tank, and the sensor does not directly contact the liquid, thus realizing non-contact detection.
It has all the characteristics of photoelectric sensor, high temperature resistance, high pressure resistance, corrosion resistance, high liquid level control accuracy, and the liquid level can be controlled within the range of ±1mm. It also uses resin encapsulation for all internal components, and there are no moving parts inside, so the reliability is high.
The separate photoelectric liquid level sensor adopts the principle of optical reflection to detect the liquid level, which has less influence on the measured liquid and is more hygienic. The key is that this sensor can be installed up, down, side, and oblique in multiple directions, and the installation process is simple.
