If one is searching for a level sensor, one can be quickly overwhelmed by the huge selection. A level sensor for limit level detection or continuous measurement could be ordered in a number of technologies and design variants. But how do I find the appropriate 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 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), the other needs continuous measurement (= level sensor).
The distinction between level sensor and level switch automatically leads to the exclusion of several technologies, if one wants 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 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 could be based on various measurement technologies such as magnetostriction, reed-chain technology, hydrostatic, ultrasound, radar and much more ? the choice of 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 neuro-scientific switches, additionally, there are a variety of measurement technologies such as for example reed contact technology, optoelectronics, conductivity, vibronic and more.
Each one of these technologies has advantages and disadvantages, and also complex, application-specific limiting factors such as conductivity, dielectricity, density, contamination, colour, pressure strength, etc. Unknowingly as to which technology is the most suitable or can be utilized in a specific 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 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 likely product solution.