FAQ-L.6: For which gases is the loss estimate calculated and displayed in l / min in the LeakExpert® app?
In the expansion of compressed gases, the estimation of the loss through a leak is based (among athers) on the flow velocity / speed of sound. This is, for example:
| Medium | Speed of sound longitudinal in m/s (at 20 °C unless otherwise stated) |
Dry air ≙ compressed air (Nitrogen approx. 78%, oxygen approx. 20%) | 344 m/s |
| Nitrogen | 348 m/s |
| Oxygen (bei 0 °C) | 314 m/s |
| Hydrogen | 1300 m/s |
Source: www.schweizer-fn.de/stoff/akustik/schallgeschwindigkeit.php
The algorithm for estimating losses in the LeakExpert® app is only suitable for gases similar to the speed of sound in air (e.g. nitrogen), since the algorithm was largely determined empirically. The relationship between the pressure (pressure system - atmosphere difference) and the sound level (determined by the SONAPHONE®) is fundamental to the algorithm. For other gases, the speed of sound deviates significantly from the medium air, so the relationship between pressure and sound level is not known and the LeakExpert® app does not determine any loss (note in the app). However, a qualitative assessment of the sound level is also possible for other gases (e.g. leakage yes / no or loss high / low). For this reason, other gases can also be selected for documentation in the LeakExpert® app.
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