Different Types of Level Sensors and their Applications

A level sensor is a device to observe, maintain and measure media levels. All industries use varied level sensor types to detect their products.

Let us understand in detail about the different kinds of level sensors used in various industries.

Level Sensor Classification

Level sensors are differentiated into two types:

Point level measurement - This shows when the media is present at a particular point.

Continuous level measurement - This shows the continuous level of the media as it falls and rises.

These types of level sensors are further differentiated into the following types:

Point level measurement

Baumer’s Cleverlevel switch works on the frequency sweep technology that radiates signal from its sensor tip to the media giving precise level measurement, unlike the vibrating fork.

The media acts as a virtual capacitor between the metal housing and the sensor tip. The virtual capacitance depends on the DK value of the media.

Let us learn about the different types of point level measurement sensors.

Capacitance

A capacitance sensor is a proximity sensor that produces an electrical charge and detects a level by the effect of this electrical current.

The capacitance level sensors are affordable than others, invasive to the products, small, precise, and does not have any moving parts.

This type of point level measurement cannot be calibrated and only detect some liquids.

Applications - tank level measurement in power, food, water treatment, chemical and brewery industries.

Optical

This type of sensor works by converting light rays into electric signals that measure the physical quantity of light and then translates it to measurement.

These optical level sensors do not have any moving parts and are not affected by high temperature or pressure. They are compact and can be used in liquid applications.

The optical sensors can be used as low-level indicators to avoid dry conditions while using coolant, hydraulics or even oil.

Applications - leak detection and tank level measurement

Vibrating

This type of point level sensor uses a fork-shaped sensing device having two lines that vibrate at a natural frequency. When the level changes, the frequency of the fork changes.

The vibrating level sensor is invasive to the product, compact, affordable, simple to install and mostly maintenance-free.

Applications - level control of media (liquid, powder and finely grained solids) within F&B, chemical processing and mining industries.

Conductivity

The conductivity sensor is also known as a resistance sensor. It uses a probe having a pair of electrodes to read conductivity.

When the media covers the probe, the electrodes create a part on the circuit which causes the current to flow, giving alerts on a high and low level.

This point level sensor does not include any moving parts, it is inexpensive and simple to use.

Applications - tank level measurement for extremely corrosive liquids, reagent monitoring and boiler water.

Float switch

This type of switch uses a float which is an instrument that will raise or lower when the product is removed or applied, which opens or closes the circuit as the level rises or lowers.

The float switch is a non-powered device and gives a direct indication. The drawbacks of the float switch are that they have moving parts and are large-sized, unlike other level sensors.

Applications - tank level applications where media like chemicals, water, oil, and hydraulic fluids are used.

Continuous level measurement

Here are the two different types of continuous level measurement sensors:

Ultrasonic

These sensors emit and receive ultrasonic waves. The time taken to reflect back the waves helps in measuring the distance.

This sensor does not include any moving parts, they are small-sized and reliable. They are also non-invasive and unchanged by the material’s properties.

Applications - non contact applications and used in systems requiring remote monitoring

Radar

This type of sensor transmits microwaves through an antenna on the sensor. The time taken to reflect back the microwaves from the product to the sensor is proportional to the level of the product.

This sensor is not affected by pressure, dust, or temperature. It can measure varied media like pastes, liquids, solids and powders. It is non-invasive and very precise.

Applications - used in systems with varying temperatures. Moist, dusty and vaporous environment.

Hydrostatic Level Transmitter

A pressure transmitter is installed at bottom of the tank. Change in media inside tank gives corresponding pressure output.