4. How Does Ultrasound Behave in Overpressure Conditions?
The speed of sound decreases by less than 1 % between sea level and 3000 m altitude. Atmospheric fluctuations at a specific location are also negligibly low and the effects on the speed of sound are scarcely measurable. If an application involves overpressure of more than 1 bar compared to standard pressure, the speed of sound increases while air damping decreases. This means that ultrasonic sensors have an increased detection range in the case of overpressure compared to standard pressure conditions. From overpressure of around 3 bar above standard pressure, parameter settings in the sensors must be changed so that the increased detection range and lower air damping do not cause interference and measurement errors.
In installation situations with overpressure, it is important to note that most standard ultrasonic sensors are not designed to be installed with just their front in the pressure range when the rest of the sensor is outside the pressure range. Special models are available for these installation situations. However, installing standard models completely in the overpressure area is not a problem. Only the information above regarding possible parameter adjustments at higher pressures must be considered.