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 right 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 Forgotten 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 in detail (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 many 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 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 permit the accurate measurement of level and its own variation. The sensors could be based on many different measurement technologies such as 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 offer a mechanical switch contact or, in electronic version, generally a PNP or NPN transistor output. In neuro-scientific switches, there are also various 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 reliable 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 often also your final test in the plant itself under real application parameters.
Note
WIKA offers you a very wide range of level measuring instruments. More info on optoelectronic level switches, hydrostatic level sensors, float switches and further instruments are available on the WIKA website. You can get videos on the functionality of the individual measuring principles on our YouTube channel. Your contact person will undoubtedly be pleased to help you on selecting the most appropriate product solution.