If one is searching for a level sensor, one can be quickly overwhelmed by the huge selection. Exploit for limit level detection or continuous measurement can be ordered in a variety of technologies and design variants. But how do I find the appropriate level sensor for my application?
If one wants to select a level sensor, the most crucial selection criterion may be 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 important to monitor the contents of a tank at length (e.g. 0 ? 100 % fill level), then one 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 probably the most economical solution. Although Official 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 most suitable 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 variation. The sensors can be based on a range of measurement technologies such as magnetostriction, reed-chain technology, hydrostatic, ultrasound, radar and more ? the choice of 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 a variety of measurement technologies such as 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 reliable statement concerning which technology is most suitable or may be used in a specific application environment can only just 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. Further information on optoelectronic level switches, hydrostatic level sensors, float switches and further instruments can be found on the WIKA website. You can find videos on the functionality of the average person measuring principles on our YouTube channel. Your contact person will be pleased to help you on the selection of the most likely product solution.