Level gauge (level sensor)

Level sensors are used as controllers for filling containers, tanks, reservoirs, trenches, pipelines with liquids or bulk materials. They are used not only for level measurements but also as limit switches (to prevent overflow or dry running). Depending on the type of controlled technological process, traditional level meters measuring the amount of substance in the container over the entire area or narrow-limit ones, which trigger more precisely only at a certain section, can be used.

Features of Level Meters

Functionally, devices are divided into two types: indicators that allow tracking a certain filling point (max or min) and level meters designed for continuous monitoring. The scope of application of the devices is determined by their operating principle (which can be based on acoustics, optics, hydrostatics, electrical conductivity). They can also be contact or non-contact.

When choosing modern level meters, the goals for which measurements will be conducted are taken into account. The type of measured liquid – its density, hazard category, and other characteristics – is also considered. The operating principle of the level meter is selected based on the container material. Devices can operate with an analog signal, as relays, or as radar.

When selecting, sanitary standards, resistance to mechanical impacts, vibrations, chemicals, and the possibility of operation in explosive environments (depending on the specifics of the technological processes) are necessarily considered.

Application Area of Level Meters

Monitoring the level of liquid or dry substance in a reservoir or container is a necessity for many automated technological processes, as well as in water supply systems, liquid delivery, and so on.

This equipment is designed for measuring levels of solid, liquid, and bulk substances located in open and closed reservoirs under pressure or without it. It ensures measurement accuracy regardless of contamination level and medium composition.

Main Types of Level Meters

Level meters are classified by operating modes into devices for continuous measurement or for discrete control. They are also divided by the type of measured product into equipment intended for liquids (petroleum products, water, solutions, suspensions) and for dry bulk elements (granules, powders).

Devices intended for liquid level control are also classified by operating principle:

• Electrode: discrete control of the working medium using its electrical conductivity. The working medium (electrical conductor) reaches the electrode, closing the electrical circuit and generating a signal. When the amount of the working medium decreases, the circuit opens. The set may include several electrodes with adjustable lengths. These are simple devices but can only operate in electrically conductive media (e.g., water);
• Capacitive: based on the principle of determining the capacitance of a capacitor, where the capacitor consists of an insulated electrode and the walls of the reservoir in which it is located. When the liquid level changes, the area (and thus the capacitance) of the capacitor changes. Such level meters can provide continuous monitoring of the working medium at depths up to 50 m and temperatures up to +250°C. They are characterized by high sensitivity;
• Float: the liquid level is determined by mechanical movement of a sealed hollow float on the surface. When the level height changes, a micro switch is triggered, signaling the level change. These devices can be used in fuel tanks and water cisterns – in other words, in containers with different types of media regardless of their temperature and density;
• Magnetic: consist of a measuring tube with a float and built-in magnet. The same liquid level is created in the reservoir and the tube, and the magnet acts on a magnetic indicator installed outside. These devices can be used for various types of liquids except petroleum products;
• Visual: equipped with a sight glass and often used in steam boiler rooms or chemical production;
• Hydrostatic: can be flush-mounted or submersible, allowing level measurement even under high pressure of the working medium regardless of the liquid type. Suitable for homogeneous media in water bodies, storage tanks, wells, industrial reservoirs.

Advantages of Hydrostatic Level Meters

The operating principle of the hydrostatic level meter is based on converting the pressure values of the liquid column into the height of this column according to the known density of the medium. A manometer (excess pressure sensor connected at the lower limit level) can be used to measure hydrostatic pressure. Differential pressure sensors are most commonly used, allowing measurement of liquid level in units operating under pressure.

These models can be used for liquids with different flow properties, including viscous ones, as well as for pastes. They are also suitable for level control in open reservoirs and for determining the liquid interface level.

The key advantages of such devices include:

• High accuracy;
• Continuous measurement capability;
• Simple compact design;
• Suitable for viscous and foamy media;
• High resistance to interference;
• Can be integrated into autonomous systems due to low power consumption;
• Do not require complex maintenance.

These devices are contact types, meaning they are not dependent on the condition of the liquid surface in the tank.

The company «Izmerkon» offers hydrostatic and capacitive level sensors (including autonomous types) for various types of tanks used in general or specialized industrial enterprises. We offer small-sized sensors for monitoring standard, viscous, or aggressive liquids, available in standard, chemical-resistant, or explosion-proof designs.