Which products can be measured with ultrasound?
The filling levels of almost all products can be measured with ultrasonic sensors. As long as liquids or bulk materials reflect the sound wave sufficiently, measurement is possible. However, the temperature, pressure and composition of the gas above the measured product have significant influence on the measurement!
Ultrasound sensors are also limited in their area of application due to the implemented (mostly synthetic) constructive materials .

What influence does temperature have on the measuring result?
The running time of the sonic impulse, which is used to determine the distance i.e. the filling level, is directly dependent on the temperature of the gas above the product to be measured. For this reason, every ultrasonic device has an integrated temperature sensor, which enables compensation of the temperature influence.

What influence do dust and steam have on the measuring result?
Dust and steam damp the sound wave to a great extent and therefore reduce the signal strength. This can lead to the complete loss of the measuring signal! Higher electroacoustic transducer transmitting power can reduce this influence a little. Nevertheless, dust and steam are important factors in ultrasound measurement and influence the reliability of the measurement greatly!

What correlation is there between the size of the electroacoustic transducer and the measurement range?
The size of the electroacoustic transducer depends on its operating frequency as well as its transmitting power.
The lower the operating frequency of an electroacoustic transducer, the greater the wavelength of the transmitting impulse – and the bigger the transducer. Since low frequencies are muffled less by the surrounding air than high frequencies, electroacoustic transducers with low operating frequencies are used for large measuring ranges.

What is the difference between contactless level measurement with ultrasound and contactless level measuring with radar?
Ultrasonic waves are mechanical waves and need a medium to travel in. This medium is the gas above the measured product. The propagation velocity of the ultrasonic wave varies considerably depending on the type of gas, its temperature and its pressure. The measuring result is thus directly dependent on these influencing factors! Radar waves are electromagnetic waves. They propagate without a physical medium, therefore also in vacuum! Their propagation velocity is virtually unaffected by gases at whatever temperature or pressure. The measuring result is thus independent of these process factors!