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 Psychological wants to select a level sensor, the most crucial 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 is important to monitor the contents of a tank at length (e.g. 0 ? 100 % fill level), the other needs continuous measurement (= level sensor).
The distinction between level sensor and level switch automatically leads to the exclusion of many technologies, if one is looking for 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 best option 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 own variation. The sensors can be based on a range of measurement technologies such as for example magnetostriction, reed-chain technology, hydrostatic, ultrasound, radar and more ? the choice which varies from manufacturer to manufacturer.
Point measurement with optoelectronic level switch
Level switches in a traditional 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 many different measurement technologies such as reed contact technology, optoelectronics, conductivity, vibronic and more.
Each of these technologies has benefits and drawbacks, and 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 particular application environment can only just be made after thorough assessment and often 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 will discover 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 likely product solution.