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 I find the right level sensor for my application?
If one really wants to decide on a level sensor, the most important 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 leads to the exclusion of several technologies, if one wants probably 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 permit the accurate measurement of level and its own 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 which varies from manufacturer to manufacturer.
Point measurement with optoelectronic level switch
Level switches in a traditional float switch design offer a mechanical switch contact or, in electronic version, generally a PNP or NPN transistor output. In neuro-scientific switches, additionally, there are a number of measurement technologies such as for example reed contact technology, optoelectronics, conductivity, vibronic and many more.
Each of these technologies has advantages and disadvantages, and also complex, application-specific limiting factors such as for example conductivity, dielectricity, density, contamination, colour, pressure strength, etc. Alive concerning which technology is most suitable or can be used in a particular application environment can only be made after thorough assessment and frequently also your final test in the plant itself under real application parameters.
Note
WIKA offers you an extremely wide range of level measuring instruments. More info on optoelectronic level switches, hydrostatic level sensors, float switches and further instruments can be found on the WIKA website. You will find videos on the functionality of the individual measuring principles on our YouTube channel. Your contact person will be pleased to advise you on the selection of the most appropriate product solution.