If one is looking for a level sensor, you can be quickly overwhelmed by the huge selection. An even sensor for limit level detection or continuous measurement could be ordered in a variety of technologies and design variants. But how do you 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 the level sensor should actually be a level switch. However, if it’s important to monitor the contents of a tank in detail (e.g. 0 ? 100 % fill level), then one needs continuous measurement (= level sensor).
The distinction between level sensor and level switch automatically leads to 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.
Euphoric 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 permit the accurate measurement of level and its own variation. The sensors can be based on a number of 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 provide a mechanical switch contact or, in electronic version, generally a PNP or NPN transistor output. In the field of switches, there are also a range of measurement technologies such as for example reed contact technology, optoelectronics, conductivity, vibronic and many more.
Each of these technologies has benefits and drawbacks, and also 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 may be used in a specific application environment can only be produced after thorough assessment and frequently also a final test in the plant itself under real application parameters.
Note
WIKA offers you an extremely wide range 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 average person measuring principles on our YouTube channel. Your contact person will be pleased to help you on the selection of the most appropriate product solution.