Use sensors to measure a tank level based upon what type of sensor is being employed. It is also important what readout or display is being used for displaying information for the sensor.
Readouts can be digital or computer interfaced. Alternately, they can be mechanical gauges or simply a clear area of a tank for visual inspection. Sensors come in a multitude of types, including visual, float, magnetostrictive, pressure transducer and conductivity.
Visual sensors are the oldest and simplest, consisting of a clear area up the length of the tank where the level can be inspected. A float sensor resides in a narrow external cylinder along the tank allowing for visual inspection of the tank level. Magnetostrictive sensors operate by measuring the speed of an electromagnetic torsional wave transmitted to a magnetic float along a wire within the tank. This provides a very high accuracy reading of the level.
A pressure transducer is a common sensor for tanks storing gas instead of liquid. By using a diaphragm and a pressure cavity, the sensor detects warping of the diaphragm to calculate pressure in the tank to determine how full it is.
Conductivity sensors are used for boolean operations such as shutting off a system when a certain fluid level is reached. It operates by emitting an electrical charge. If a conductive liquid reaches the level of the emitting probe, it passes through the liquid to the receiving probe.