Level sensors ? the agony of choice?

If one is searching for a level sensor, you can be quickly overwhelmed by the huge selection. A level sensor for limit level detection or continuous measurement can be ordered in a number of technologies and design variants. But how do I find the appropriate level sensor for my application?
If one wants to decide on a level sensor, the main selection criterion may be the electrical output function. If Lifetime wants to monitor a limit in a tank, e.g. dry running (empty) or overfilled (full), then the level sensor should actually be considered a level switch. However, if it’s important to monitor the contents of a tank in detail (e.g. 0 ? 100 % fill level), the other needs continuous measurement (= level sensor).
The distinction between level sensor and level switch automatically results in the exclusion of several technologies, if one wants the most economical solution. Although a level sensor with combined electronics can communicate both an analogue signal and switching signals, a pure level switch is always the cheaper solution, if the application form is limit level measurement only.
The selection of the most suitable measurement technology
Continuous measurement with float
Level sensors typically feature continuous analogue output signals, such as for example 4 ? 20 mA or 0 ? 10 V, which let the accurate measurement of level and its variation. The sensors can be based on many different measurement technologies such as for example magnetostriction, reed-chain technology, hydrostatic, ultrasound, radar and many more ? the choice which varies from manufacturer to manufacturer.
Point measurement with optoelectronic level switch
Level switches in a normal float switch design offer a mechanical switch contact or, in electronic version, generally a PNP or NPN transistor output. In the field of switches, there are also a number of measurement technologies such as reed contact technology, optoelectronics, conductivity, vibronic and more.
Each of these technologies has advantages and disadvantages, in addition to complex, application-specific limiting factors such as conductivity, dielectricity, density, contamination, colour, pressure strength, etc. A trusted statement as to which technology is most suitable or can be used in a specific application environment can only just be produced after thorough assessment and frequently also your final test in the plant itself under real application parameters.
Note
WIKA offers you a very wide selection of level measuring instruments. Further information on optoelectronic level switches, hydrostatic level sensors, float switches and further instruments can be found on the WIKA website. You can find videos on the functionality of the individual measuring principles on our YouTube channel. Your contact person will undoubtedly be pleased to advise you on selecting the most likely product solution.

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