Introduction to types of industrial liquid level gauges
Liquid level gauge, as the name suggests, is a tool used to measure and display the height of liquid in a container. The purpose of the liquid level gauge is very important. It is widely used in railway transportation, industrial water conservancy and hydropower, electronic technology industry, steel manufacturing industry... various industries, and it is most commonly used in various industrial automatic control environments.
There are many ways to measure liquid level, so there are many types of liquid level gauges: glass tube level gauge, magnetic flap level gauge, hydrostatic level gauge, differential pressure level gauge, float level gauge, Radar level gauge, capacitive level gauge...etc.
From the measurement principle of liquid level meter, it can be divided into contact measurement and non-contact measurement.
Contact level gauge
● Magnetic Level Gauge
A liquid level gauge that mainly operates based on the principle of buoyancy and magnetic coupling. When the magnetic flap in the liquid level gauge moves up and down as the liquid level changes, when the liquid level rises or drops to a certain level, the magnetic flap will be attracted to the sensor. The position change of this flap is detected by the sensor and converted into a corresponding electrical signal to determine the height of the liquid level.
The magnetic flap liquid level gauge has the direct-reading characteristic of local display. It usually does not need to be combined with multiple groups of liquid level gauges. The remote control can directly output the resistance value signal, and can also be used in conjunction with the transmission module. It can achieve high sealing and leakage prevention, and its superiority is even more evident in high temperature, high pressure, and corrosion-resistant situations.
The disadvantage is that the magnetic float is in direct contact with the medium, so the float sealing requirements must be strict, and viscous media cannot be measured. In addition, it should be noted that if the magnetic material of the magnetic flap liquid level gauge is demagnetized, it may easily cause the liquid level gauge to be unable to operate normally or receive instructions.
● Float level gauge
The float level gauge is a type of input level gauge. Its working principle is based on the principle of buoyancy. When the liquid level rises, the float rises accordingly. By reading the position of the float, the height of the liquid level can be determined. This type of liquid level gauge is commonly used in various containers, tanks or storage tanks to monitor the level of liquids or to control processes.
Simple design, easy installation and use, and strong compatibility with liquid media... are all the advantages of the float level gauge; however, there may be a certain amount of inertia during the movement, causing the liquid level to fluctuate. The measurement is not accurate enough and can only return a range of values. It is not suitable for measuring high temperature, high pressure or corrosive liquids.
● Glass tube level gauge
A contact type liquid level meter that connects the flange to the container to form a connector, and can directly read the liquid level in the container through the glass plate. Glass tube liquid level gauges are widely used in liquid level measurement and monitoring in simple liquid level measurement situations and small and medium-sized automation projects.
Glass tube liquid level gauge has the advantages of economical and practical, simple structure, convenient installation, reliable operation and long service life. But the shortcomings are also very clear. The surface of the glass tube is easily stained, making reading difficult. It is only for on-site visual inspection and cannot transmit data remotely.
● Differential pressure level gauge
Differential pressure level gauges usually consist of a device called a differential pressure transmitter, connecting pipes and static pressure pipes, and calculate the liquid level based on the pressure difference exerted between the surface of the liquid and the bottom of the liquid.
High precision, strong reliability, suitable for various liquids, and not affected by the properties of the liquid are the advantages of the differential pressure level gauge. The disadvantage is that the differential pressure level gauge is highly dependent on the density and temperature of the liquid and requires installation. The calibration steps are more complicated.
● Hydrostatic Level Gauge
The working principle of the hydrostatic level gauge is based on the relationship between the height of the liquid and the static pressure generated by the liquid. The static pressure of a liquid is proportional to the height of the liquid, so the liquid level can be calculated by measuring the pressure sensed by the static pressure sensor. However, it is important to note that the measured pressure will also vary depending on the density of the liquid being measured. are different, so the liquid level needs to be corrected.
The advantage of the hydrostatic level gauge is that it is widely popular and easy to calibrate. However, the disadvantage is that it has high requirements for the location and installation of the static pressure sensor, is easily affected by temperature and pressure, and is prone to inaccurate accuracy.
Non-contact liquid level gauge
● Capacitive Level Gauge
The working principle of capacitive level gauge is based on the capacitance change between the liquid and the electrode. When the liquid level rises or falls, the capacitance value between the liquid and the electrode changes accordingly, and the capacitance converter measures and interprets these capacitance values to calculate the liquid level position.
Capacitive liquid level gauge is suitable for a variety of different liquids, is not affected by liquid characteristics, and has high measurement accuracy. But at the same time, there are also some limitations, such as being affected by factors such as dielectric constant and temperature, and requiring higher electrode positions...and so on.
● Radar Level Gauge
A device that uses radar technology to measure the height of a liquid or the position of a liquid in a container. It usually includes a radar transmitter and a radar receiver to determine the location of the liquid by transmitting and receiving radar signals.
The advantage of radar level gauge is that it does not require a transmission medium, is not affected by pressure changes, vacuum, temperature changes, inert gases, smoke, steam, etc., has no blind spots, is highly accurate, and can be used in various environments. The disadvantages of radar level gauges are that they are expensive and require many parameters to be set. Special attention must be paid to whether the antenna is stained with any substances (which will affect accuracy).
● Ultrasonic level gauge
The working principle of ultrasonic liquid level gauge is based on the propagation time of ultrasonic signal between air and liquid. When an ultrasonic signal is emitted to the surface of a liquid, part of the signal will be reflected back. The receiver receives these reflected signals and calculates the height or position of the liquid by measuring the time delay of the signal.
Advantages of ultrasonic liquid level meter: no mechanical transmission part, high reliability, not affected by liquid viscosity, density, etc. The disadvantage is that it has measurement blind spots and cannot measure volatile media.
The above is an introduction to the more common liquid level meters on the market. Each liquid level meter has its own advantages, disadvantages and scope of application. The most suitable one is mainly selected based on the characteristics of the medium being measured in the project, as well as the industrial environment and cost considerations. Level gauge.
Any PLC programming and customized automatic control engineering needs
Longzhong offers Technical Advisory Services | Telephone:06-243-7822
