What Is a Liquid Level Sensor?
A liquid level sensor is a sensor that can determine the type of liquid flowing in a container or piping. It can detect when liquid flow in a pipe is interrupted or when another liquid is mixed in.
It can discriminate between two types of liquids that have been measured in advance. The sensor can determine which liquid is flowing in the piping, whether it is mixed in or not, or whether neither is flowing in the piping.
Liquids, such as tap water, distilled water, alcohol, chemicals, cleaning solutions, and oil, can be detected. Some models are under development, and future developments are expected.
Applications of Liquid Level Sensors
Liquid level sensors are small and easy to install, so they are installed on pipes and other equipment in factories. In food factories and other places where safety is important, it is critical to determine whether a liquid leaking from a pipe is water or a chemical, so some factories are installing liquid type determination sensors to help with maintenance.
Although there are only some liquid level sensors on the market today, they are needed in many areas, and we can expect to see more examples of their use in the future as further development progresses.
Principle of Liquid Level Sensors
Liquid level sensors are new sensors, and a type that uses the difference in dielectric constant of liquids is currently on the market. Another type, currently under development, uses optical fibers.
In the type that detects differences in the dielectric constant of a liquid, the sensor part is immersed in the liquid and the dielectric constant is measured. It is possible to determine the type of liquid, determine the state of emptiness, and detect leaks. In addition to tap water, alcohol, various chemical solutions, and oil, this type can also be used for highly viscous liquids such as paints and adhesives.
The optical fiber type can be used for measurement in explosion-proof areas by using a bend-resistant optical fiber for the detection section. This type can also be used to measure liquids such as oil and gasoline, which can ignite.
Another type of liquid identification device that is still in the research and development stage but is being considered is one that determines the type of liquid based on the rate at which the temperature of the liquid rises. This device consists of a liquid type sensing section with a heating element and a temperature sensing element, and a liquid temperature sensing section. A single pulse voltage is applied to the liquid type sensing section to generate heat, and the liquid temperature is measured at the liquid temperature sensing section. The type of liquid can be determined from the change in liquid temperature before the pulse voltage is applied and after a certain period has elapsed after the voltage is applied.