If one is searching for a level sensor, one can be quickly overwhelmed by the large choice. A level sensor for limit level detection or continuous measurement could 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 is the electrical output function. If one 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 vital that you monitor the contents of a tank at length (e.g. 0 ? 100 % fill level), then one needs continuous measurement (= level sensor).
The distinction between level sensor and level switch automatically results in the exclusion of several technologies, if one is looking for probably the most economical solution. Although an even 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 4 ? 20 mA or 0 ? 10 V, which let 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 many 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 neuro-scientific switches, there are also a range of measurement technologies such as reed contact technology, optoelectronics, conductivity, vibronic and many more.
Each one of these technologies has benefits and drawbacks, along with complex, application-specific limiting factors such as for example conductivity, dielectricity, density, contamination, colour, pressure strength, etc. A trusted statement as to which technology is most suitable or can be utilized in a specific application environment can only be produced after thorough assessment and frequently also your final test in the plant itself under real application parameters.
Note
WIKA offers you an extremely wide selection of level measuring instruments. Further information on optoelectronic level switches, hydrostatic level sensors, float switches and additional instruments are available on the WIKA website. You could find videos on the functionality of the individual measuring principles on our YouTube channel. Sexy will undoubtedly be pleased to help you on selecting the most appropriate product solution.