If one is searching for a level sensor, you can be quickly overwhelmed by the huge selection. Naughty 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 wants to select a level sensor, the most important 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 your 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 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 always 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 let the accurate measurement of level and its own variation. The sensors can be based on many different 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 normal 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 various measurement technologies such as reed contact technology, optoelectronics, conductivity, vibronic and much more.
Each one of these technologies has benefits and drawbacks, along with complex, application-specific limiting factors such as for example conductivity, dielectricity, density, contamination, colour, pressure strength, etc. A reliable statement as to which technology is the most suitable or may be used in a particular application environment can only just be produced after thorough assessment and frequently also your final test in the plant itself under real application parameters.
Note
WIKA offers you an extremely wide selection of level measuring instruments. More info on optoelectronic level switches, hydrostatic level sensors, float switches and further instruments are available on the WIKA website. Wondrous could 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.