Level sensor – what are its characteristics?

In view of the variety of devices available on the market, it is worth starting with the characteristics of the device. Thus, a level sensor is defined as a device that continuously measures the content of the tank in which the sensor operates. In addition to the level sensor, there is also a level switch, which measures the limit values - tank empty or overfilled. At the same time, it is worth noting at this point that the level sensor is a device that can also act as a level switch by providing information about limit values.

Types of level sensors

There are many types of level sensors, and their choice depends on the type of liquid or substance to be measured, the process conditions in which they are to be used, as well as the customer's budget and requirements. Among
most popular include hydrostatic probes, float switches and capacitive level sensors.

Hydrostatic probes

The first proposition among level sensors is hydrostatic probes. This is a device that is used to measure the level in tanks, wells and shafts where it is necessary to test the level of liquids. When measuring, the probe is directly immersed in the liquid to be monitored, placed as close as possible to the bottom of the tank.

Hydrostatic probes from the JUMO MAERA series

Based on the hydrostatic measuring principle, level probes from the JUMO MAERA series operate.

The advantages of the JUMO MAERA level probes are:

• Reliable hydrostatic measurement and low maintenance costs.
• Resistance to factors such as foam, dust, steam or conductivity of the medium
• Level measurement independent of tank shape and installation.
• Easy installation from above at the measuring point
• High chemical resistance, thanks to the availability of various materials.
• Flexibility of application in containers, tanks, pools and water wells, among others
• Level measurement up to 300 m possible

Float switch

This is a simple level measurement method for convenient filling or emptying of tanks. The float switch, due to the use of a low-density hollow float mechanism, rises and falls with the change in liquid level. If it is connected to the closing or opening elements of the tanks, it allows the tanks to be conveniently emptied or filled.

JUMO NESOS series float switches

JUMO offers the JUMO NESOS series of float switches and level transmitters. Their advantages are:

• Due to the availability of numerous float materials and forms, customisation is possible.
• The level measurement is independent of the tank geometry and allows accurate point measurement
• The level transmitter is resistant to the effects of many factors such as foam, conductivity, pressure, vacuum, steam or condensation.
• Use in industrial, process and process engineering applications.
• Servicing is easy due to the fast error checking.
• High chemical resistance
• Point level measurement can be used to control PLC inputs, valves, signals, motors or pumps.
• The switch allows level measurement for low filling heights from 0.1 to 4 m.

Capacitive level sensor

The capacitive level sensor is another available option. It is characterised by its ability to measure both liquids and solids. It is used similarly to hydrostatic probes, as it is also immersed in the material under test. The capacitive sensor can be used in pressurised tanks.

New to the JUMO range is the JUMO ZELOS capacitive level sensor. This device is particularly suitable for industrial applications where protection against overfilling or dry running is required, or for the detection of media such as sludge in separation processes.

Selection Criteria for Level Sensors

When planning to select a level sensor, it is important to consider the conditions in which the device will operate. Below are some guidelines on the criteria that should be taken into account when choosing this type of sensor.

Characteristics of the Measuring Medium and Application

When selecting a level sensor, it is essential to consider the conditions in which it will operate. The material in the tank has specific characteristics; some sensors work with liquids, others with solids. Therefore, this criterion should be considered when choosing a level sensor.

Medium Temperature

In addition to the characteristics of the medium, its temperature must also be considered. It is crucial to pay attention to the temperature range within which the level sensor will guarantee accurate measurement.

Measurement Range

The measurement range is another criterion, defining at what liquid pressure the sensor will perform measurements in the case of hydrostatic probes.

Sensor Type and Installation Method

The types of sensors were mentioned earlier and are undoubtedly an important selection criterion that will influence the purchasing decision. It involves matching the sensor to the material it will work with while considering how it will be installed in the tank.

Length of the Probe

When monitoring large tanks, finding a probe of the appropriate length that can handle such conditions might be important. Therefore, this criterion should also be taken into account.

Material of the Sensor

Level sensors are made from various materials, and this criterion is crucial when measuring materials that may have aggressive properties, potentially damaging ordinary sensors. The proper material must also be considered by buyers who need sensors suitable for explosive hazard areas.

By paying attention to the above criteria, the likelihood that the chosen sensor will meet the user's expectations is significantly increased.

What is the Lifespan of a Level Sensor?

The lifespan of a level sensor depends on several factors. Some of them include:

Type of Sensor

There are different types of level sensors, such as ultrasonic, radar, capacitive, and hydrostatic. Each type has different operational parameters and may be better suited to specific working conditions.

Environmental Conditions

Temperature, pressure, the presence of corrosion, chemicals, or the intensity of mechanical impacts (e.g., vibrations) significantly affect the sensor's durability.

Quality of Construction

Sensors made from higher-quality materials, such as stainless steel or special plastics, are generally more resistant to damage and corrosion.

Measurement Frequency

Sensors that are used frequently may wear out more quickly.

Maintenance and Usage

Regular maintenance and following the manufacturer's recommendations can significantly extend the device's lifespan.

The typical lifespan of a level sensor can range from a few years to even 20 years, but this is a very general estimate. For more precise information, it is advisable to refer to the technical specifications of a specific sensor model and the manufacturer's recommendations.

How often do you replace level probes?

There is no definitive answer to this question - the frequency of replacing level probes depends on many factors, including the type of probe and the operating conditions. Here are some general guidelines:

• Operating conditions: Probes operating in harsh conditions, such as high pressures, extreme temperatures, the presence of aggressive chemicals or constant vibration, may require more frequent replacement.

• Failure rate: If a probe starts to fail frequently or requires frequent repairs, this may be a sign that it is nearing time for replacement.
• Inspection and test results: Regular inspections and functional tests can help determine the health of the probe. If test results indicate a reduction in the accuracy or reliability of the device, this may be a signal for replacement.