Measuring levels is a key task in process control: a task that is carried out in a wide variety of areas.

This process requires operators to consider both the substance to be measured and the measurement environment.

And these are not the only factors to be considered: the installation situation and container size can also have an impact.

However, this is easy for anyone who can rely on a diverse technology portfolio and expert knowledge in integrating sensors into entire plant systems.

With its LFP Cubic and LFP Inox TDR level sensors, SICK offers suitable solutions for any application, in any environment.

Precise, reliable, and as efficient as possible: the same principles apply to level measurement processes as they do to other sub-processes in production.

A selection of suitable technology at as early a stage as possible helps to keep inefficient processes and wasted resources to a minimum.

The benefits of TDR technology: “guided microwaves”

When measuring liquids, the results can be affected by the various levels of the medium’s conductivity, density, and viscosity.

Furthermore, operators have to be aware of the build-up of deposits, chemical stability, and any moving parts in the tank (e.g., mixers or stirring units) that may affect the results.

The LFP Cubic and LFP Inox level sensors from SICK apply the “guided microwave” measurement principle (TDR: time domain reflectometry).

The sensor’s electronics system generates an electromagnetic impulse (reference pulse).

This pulse is guided along the probe, normally a metal rod or steel wire, from the entrance to the tank (signal) to the surface of the medium to be tested.

Part of the impulse is reflected off the surface and sent back along the probe into the sensor’s electronics system.

The difference in the time from the signal being transmitted and then received again is used to calculate the level, taking into the account the dielectric constant for the medium in question.

Depending on the operator’s requirements, the sensor can either emit the calculated level as an analog value (“continuous measurement”) or as several switch signals (“point level measurement”).

One of the other major benefits of this technology is that factors like pressure, temperature, vacuum, dust, and in particular foaming do not have a significant impact on the measurement result.

A flexible, low-cost solution

In the past, TDR technology was often seen as a rather complicated and costly process. However, it has recently established itself as a more cost-effective and attractive option for less complex measuring applications.

With the LFP Cubic, SICK offers customers a flexible and low-cost solution that is ideal for use in metal containers and tanks in the water industry, mechanical engineering, machine tool, plant construction, and building technology.

The LFP Cubic also offers customers a great deal of flexibility thanks to its modular probe concept that enables it to be used with either a rigid probe, coaxial tube, flexible probe, or as a compact variant without a probe.

A clean solution

Like the LFP Cubic, the LFP Inox delivers continuous measurement or point level measurement according to requirements in a single system; this too cuts costs significantly.

The LFP Inox is ideally equipped for use in hygiene- related processes as the sensor is certified under both EHEDG and 3-A, while the materials used comply with the requirements issued by the FDA.

Its temperature stability and pressure resistance also mean that there is nothing preventing the sensor from being used in CIP and SIP processes, in areas such as the food and beverages industries.

The housing and design have also been carefully thought out. With IP 67 and IP 69K enclosure ratings, the sensor can even withstand more intensive cleaning processes using high-pressure cleaners.

On request, LFP Cubic and LFP Inox sensors can also be PWIS-cleaned and then packed up safely for delivery. Special plasma ckeaning processed are used for this purpose.

Since the electronics are remote, the probe can also easily be sterilized in an autoclave – a typical requirement in the pharmaceuticals industry.

The benefits of a remote amplifier version

The remote amplifier version of both the LFP Inox and the LFP Cubic has a number of other benefits: it increases flexibility and saves space for installation, which is particularly useful when you are short on space.

This offers huge advantages for use in high tanks in particular. Since the electronics can be installed separately from the probe (at eye level, for example), both status and measurement result are always easy to read.

Changes can also be made to sensor settings and parameters with ease. This solution also protects the electronics unit from heat generated from use, enabling the probe to be used at high temperatures.


Sensors that are easy to commission, maintenance-free, and almost entirely independent of the properties of the medium to be measured (meaning that the sensors in the LFP range do not have to be recalibrated) pave the way for significant savings in terms of both time and money.

In doing so, they also make an important contribution to another objective: increasing process efficiency.

The reliability and strength of the measurement result play a vital role here, while also taking industry-specific requirements into account. The food industry, for instance, is often subject to constructive regulations when it comes to the cleaning and sterilization of the components in use.

These regulations are issued by bodies such as the European Hygienic Engineering Design Group (EHEDG) or the American 3-A Sanitary Standards.

Some applications also require devices to receive legal approval, which cannot be issued until the level sensors have been tested and certified.

Legal directives such as the German Federal Water Act (WHG) or corresponding EU directives govern the treatment of substances that could be harmful to water.

Companies that operate facilities to store, fill, or empty such substances are required to prove that their equipment is protected against overflowing.

This partner content is brought to you by SICK.

For more information, visit

Jessica Dickers is an experienced journalist, editor and content creator who is currently the Editor of Utility’s sister publication, Infrastructure. With a strong writing background, Jessica has experience in journalism, editing, print production, content marketing, event program creation, PR and editorial management. Her favourite part of her role as editor is collaborating with the sector to put together the best industry-leading content for the audience.

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