What Is a Liquid Level Indicator?
A Liquid Level Indicator is an instrument that measures the height of the liquid level inside a container or tank.
In some cases, it can also measure the amount of powder remaining. It is also sometimes called a Level Meter.
Various measurement methods have been developed, including float, tube, and ultrasonic types, depending on the object to be measured and the conditions of use. Accuracy and reliability are important for Liquid Level Indicators.
Since incorrect liquid level measurements can affect the production process, Liquid Level Indicators must be maintained and calibrated on a regular basis. With proper care, accurate liquid level measurements can be obtained over the long term.
Applications of Liquid Level Indicators
Liquid Level Indicators are used in a wide variety of industries and applications:
1. The Petroleum Industry
The petroleum industry uses Liquid Level Indicators to manage fuel inventories and schedule deliveries. They are also used as sensors to detect fuel leaks.
2. Food Industry
In the food industry, Liquid Level Indicators are used in the production of milk, cheese, and other products. They are used to control product quality and determine the fullness of containers, thereby contributing to the improvement of the efficiency of the entire production line.
3. Chemical Industry
Liquid Level Indicators can be used to measure the liquid level of containers for liquid chemicals. It is used for process control and quality control.
Principle of Liquid Level Indicator
Liquid Level Indicators measure liquid levels by utilizing buoyancy, pressure, and electrical phase differences. More accurate Liquid Level Indicators have been developed by combining these principles and adding innovations.
1. Buoyancy Type
Buoyancy-type liquid level gauges measure the liquid level by using a floating body.
2. Phase Difference Type
In the phase difference type, a high-frequency electrical signal is sent into the liquid, and the phase difference between the signal reflected at the boundary between the liquid and gas is measured to determine the liquid level.
3. Pressure Type
The pressure type measures the liquid level by measuring the pressure generated by the weight of the liquid.
Types of Liquid Level Indicators
There are various types of Liquid Level Indicators, depending on the measurement method. The following are examples of Liquid Level Indicator types:
1. Float Type Liquid Level Indicator
Liquid Level Indicator measures the liquid level using a float called a float. The float, which contains a magnet, floats on the liquid surface and outputs a signal. The measuring principle is similar to that of a ball tap used for flushing toilets, etc., and often has an electrical contact output for use in control.
Float Level Indicators can be broadly classified into two types: wind-up and non-wind-up. Retractable types include spring-balanced and counterweighted types, while nonretractable types include arm float and ball float types.
2. Tube Liquid Level Indicator
Liquid Level Indicator is a tube attached to the outside of the container that is linked to the height of the liquid surface. If the tube is made of glass, the liquid level can be visually confirmed from the outside. The installation of Liquid Level Indicators should be considered when designing tanks and containers.
Liquid Level Indicators are used in a wide range of applications, such as for measuring the liquid level in boilers and water tanks.
3. Ultrasonic Liquid Level Indicator
This is a method of measuring the liquid level by transmitting ultrasonic waves toward the liquid surface and measuring the time taken for the waves to reflect back. This method is characterized by the fact that the Liquid Level Indicator does not come into contact with the liquid to be measured and by the fact that it can be easily installed.
Since the ultrasonic type requires the signal to be converted to liquid level, it is common for such a system to be equipped with a control board for calculation. Continuous measurement is possible and often has an analog output signal.
4. Differential Pressure Type Liquid Level Indicator
Liquid Level Indicator converts the pressure difference between the bottom and top of the tank to be measured into the liquid level. It cannot be easily retrofitted because the liquid density must be known and a measurement outlet is required at the bottom of the tank.
However, since it can be used for sealed tanks, it is widely used for pressure tanks such as boilers.
5. Capacitance Type Liquid Level Indicator
An electrode is inserted into the tank, and changes in the electrostatic capacitance on the electrode are detected and converted to liquid level. It is characterized by its ability to be used in harsh environments such as high temperatures and high pressures.
How to Select a Liquid Level Indicator
It is important to select a Liquid Level Indicator that is appropriate for the type and characteristics of the liquid. If the liquid is corrosive or at high temperatures and pressures, a pressure Liquid Level Indicator with high durability and high accuracy is suitable. On the other hand, if the liquid is volatile, a Buoyancy Liquid Level Indicator or a Phase Difference Liquid Level Indicator is suitable.
Measurement accuracy is another important factor. The required measurement accuracy varies depending on the nature and temperature of the liquid to be measured. When selecting a Liquid Level Indicator, it is important to select the appropriate measurement accuracy.
The type of Liquid Level Indicator should also be selected according to the installation location. A small Liquid Level Indicator is suitable for installation in a small space. There are also Liquid Level Indicators with special shapes to fit the complex shapes of tanks.
The functional aspects of Liquid Level Indicators should also be considered. Selecting a Liquid Level Indicator with remote control and data logging capabilities will allow for efficient operation and monitoring.