One of the more accurate, higher resolution level sensors on the market is the magnetostrictive stem float, or probe level sensor. This continuous liquid level solution is able to determine level within only a few millimeters.
It works by using a ferromagnetic metal, which aligns itself with magnetic fields at the molecular level. By creating two competing magnetic fields, the magnetostrictive level sensor is able to generate a signal denoting the liquid level.
A magnetostrictive probe is built by suspending a ferromagnetic metal wire inside a long stem. Electronics at the top of the stem generate an electrical pulse that travels down the wire, at regular intervals. This creates the first magnetic field. The second is created inside a float that moves up and down the stem with the liquid level. It contains a magnet. When the electrical pulse reaches the float, and the two magnetic fields collide, the metal wire inside the stem twists, and a vibration is sent back up the wire.
This vibration is the key to determining an accurate level. It travels at a known speed, and therefore can be timed to accurately measure the distance from the electronics in the sensor housing, at the top of the stem, to the float at the surface of the liquid, and back again. Unlike other technologies that rely on frequencies traveling through the air, the magnetostrictive probe is not as sensitive to such variables as temperature, humidity, and the like. It is therefore extremely accurate, with a resolution of only a few millimeters.
A good example of a magnetostrictive level probe sensor is the Flex-stem MPX-F. This technology is very durable and highly accurate. It is also perfectly suited for dual levels, where an interface between to liquids must be measured. For questions about this technology, and its various applications, contact us at sales@apgsensors.com, or at (888) 525-7300.
