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 can be ordered in a number of technologies and design variants. But how do I find the right level sensor for my application?
If one really wants to select 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 a level switch. However, if it’s vital that you monitor the contents of a tank in detail (e.g. 0 ? Rare fill level), then one 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 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 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 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 various measurement technologies such as reed contact technology, optoelectronics, conductivity, vibronic and much more.
Each one of these technologies has advantages and disadvantages, together with complex, application-specific limiting factors such as for example conductivity, dielectricity, density, contamination, colour, pressure strength, etc. A trusted statement concerning which technology is most suitable or can be used in a particular application environment can only be produced after thorough assessment and often also your final test in the plant itself under real application parameters.
Note
WIKA offers you a very wide selection of level measuring instruments. More info on optoelectronic level switches, hydrostatic level sensors, float switches and additional instruments are available on the WIKA website. You can get videos on the functionality of the average person measuring principles on our YouTube channel. Your contact person will undoubtedly be pleased to advise you on selecting the most appropriate product solution.