If one is looking for a level sensor, you can be quickly overwhelmed by the large choice. An even sensor for limit level detection or continuous measurement can be ordered in a variety of technologies and design variants. But how do you find the appropriate level sensor for my application?
If one really wants to decide on a level sensor, the most crucial selection criterion is the electrical output function. If one really 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 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 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 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 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 range of measurement technologies such as 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, additionally, there are a number of measurement technologies such as for example reed contact technology, optoelectronics, conductivity, vibronic and more.
Each of these technologies has benefits and drawbacks, as well as complex, application-specific limiting factors such as conductivity, dielectricity, density, contamination, colour, pressure strength, etc. A trusted statement as to which technology is the most suitable or may be used 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 an extremely wide selection of level measuring instruments. Step-by-step on optoelectronic level switches, hydrostatic level sensors, float switches and additional instruments can be found on the WIKA website. You could find videos on the functionality of the average person measuring principles on our YouTube channel. Your contact person will be pleased to advise you on the selection of the most likely product solution.