They generally fall in two 2 major groups.
Water level measuring devices.
Capacitance level sensors operate in the way that process fluids have dielectric constants significantly different to air.
The first product produced by solinst was the model 101 water level meter and forty years later hydrogeologists worldwide are still using it the model 101 water level meter first gained popularity among professionals in the united states for it s robust design stretch resistant tape and special markings in feet and tenths of feet.
Other reviews have noted that the device can pick up erroneous signals from case joints and pipe fittings.
They measure the change in capacitance between two plates produced by changes in level.
A 10 foot change in water level can be measured.
There are various types of level measurements tools.
They monitor material level at a preset point which could be either a low level in order for example to avoid the danger of a pump running dry or a high level in order to avoid a spillage or leakage.
High quality workmanship means devices are built to last.
The measurement system converts the potentiometer output to digital form and converts the results to the appropriate units of water level i e feet change.
Point level measurement devices.
Applications tank level monitoring in chemical food water treatment power and brewery industries.
However with a little experimentation you can set the minimum depth levels to ignore reflections from non water level objects above the water column.