If one is looking for a level sensor, one can be quickly overwhelmed by the huge selection. A level sensor for limit level detection or continuous measurement could be ordered in a variety of technologies and design variants. But how do I find the appropriate level sensor for my application?
If one really wants to decide on a level sensor, the most important selection criterion may be the electrical output function. If one really wants to monitor a limit in a tank, e.g. dry running (empty) or overfilled (full), then your level sensor should actually be considered a level switch. However, if it’s vital that you 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 many 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 definitely 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 ? pressure gauge 10 bar , which permit the accurate measurement of level and its variation. The sensors could be based on a variety of measurement technologies such as for example magnetostriction, reed-chain technology, hydrostatic, ultrasound, radar and more ? the choice of 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 variety of measurement technologies such as for example reed contact technology, optoelectronics, conductivity, vibronic and more.
Each one of these technologies has advantages and disadvantages, along with 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 made after thorough assessment and frequently also a final test in the plant itself under real application parameters.
Note
WIKA offers you an extremely wide selection of level measuring instruments. More info on optoelectronic level switches, hydrostatic level sensors, float switches and additional instruments can be found on the WIKA website. You will discover videos on the functionality of the average person measuring principles on our YouTube channel. Your contact person will be pleased to advise you on selecting the most appropriate product solution.