Floats are suitable for simple detection of trip values in liquids. The float, complete with built-in switching element, is buoyant on the surface and is fixed at the level of the defined trip value. If this value is exceeded or not reached, the tilting motion triggers the switching process.

Vibration level measurement is a proven method for recording the limit level in liquids and bulk solids. A tuningfork sensor oscillates by means of a piezoelectric charge. When the sensor comes into contact with the product as it rises, the frequen cy of the oscillations changes. The evaluation electronics then convert this change into a switching signal.

This method is suitable for recording limit levels in all conductive fluids. To record the limit level, electrodes are arranged at a specified fill limit. If the contents of a vessel reach this limit, the contact between the electrodes closes, and the closed circuit triggers a switching signal.

Capacitive limit switches provide a simple method for limit level detection in light bulk solids. A rod or cable probe forms a capacitor together with the tank wall. As the quantity of product changes, so does the capacity of the capacitor. A full tank has a high capacity; a tank that is emptying has a lower capacity that corresponds with the rate at which it is emptying. This change in capacity is measured and used to calculate the fill level.

Magnetic immersion probes from Pepperl+Fuchs are designed for flexibility. Available in plastic or stainless steel, the robust probes adapt to the different requirements of liquid media. Providing both limit detection and continuous measurement, the probes allow both measurement methods to be used simultaneously.

Hydrostatic pressure measurement is a proven method of continuously determining the fill level of a product. This approach takes advantage of the fact that the pressure in a liquid increases steadily with increasing fill level. A stainless steel membrane transfers the pressure of the measuring sample to the measuring cells and converts it into a fill level signal proportional to the quantity.

Ultrasound is a contactless method of providing continuous level measurement. With this method, the time that elapses between an emitted ultrasonic pulse and the echo reflected from the product surface is measured. The runtime can then be used to calculate the exact distance between the emitter and the surface to determine the fill level.

This method is based on the principle of measuring the runtime of microwave pulses in liquids and bulk solids. For this purpose, a DC pulse is passed through a probe rod or cable and reflected at the product surface. The measured runtime of this pulse is used to calculate the level of the measured medium.