Firedamp whistle

A firedamp whistle is an instrument for prophylactic firedamp display .

history

In 1912, shortly after the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry opened in Berlin, Kaiser Wilhelm commissioned Fritz Haber to design a warning device for the occurrence of firedamp. Within a year he developed the firedamp whistle and presented it to the emperor in a lecture on October 28, 1913. Haber drove the marketing of the device and finally signed a contract with the Auergesellschaft . In practice, however, the device could not prevail, as the calibration of the pipes was not practical in the mining industry. In 1925, work on the firedamp whistle was finally stopped.

function

When using two equally tuned pipes at the same time , one of which is blown with atmospheric air and the second with a different gas, the two tones that are very close together result in a so-called beat . The function of the firedamp whistle is based on the fact that the sound when blowing a whistle depends on the speed of sound in the gas. The speed of sound of mine gas and air differ by around 31%. For a 1 percent methane-air mixture, the speed of sound is approximately 1.0031 times as great as air. If the pipes are tuned to 440 Hz in air, the air- methane- pipe has a frequency of 440 Hz · 1.0031 = 441.4 Hz. If you blow two equally tuned pipes once with air as a comparison and an air-methane pipe Mixture, the tones that are close together create a clearly audible beat. The wavelength λ is linked to the frequency and the speed of sound according to the formula , where the wavelength is given by the length of the whistle. If the gas mixture in the resonator changes, its resonance spectrum changes. By means of an absorber , disruptive air components such as air humidity and carbon dioxide were separated. The firedamp whistle reliably indicated methane levels in the mine air from around 1% by volume. ${\displaystyle f}$ ${\displaystyle c}$ ${\displaystyle \lambda ={\tfrac {c}{f}}}$

Web links

• Steven Garrett: Sonic gas analyzers for hydrogen and methane. Acoustical Society of America - Acoustics '08 Paris, accessed July 26, 2014 . 

Individual evidence

1. ↑ Dirk Van Laak : German as the Kaiser. In: Zeit.de. June 4, 1998, accessed July 21, 2014 . 
2. ^ Margit Szöllösi-Janze: Fritz Haber 1868-1934: A biography . Verlag CH Beck, 1998, ISBN 3-406-43548-3 , pp. 240-242.
3. ^ Dietrich Stoltzenberg: Fritz Haber: Chemist, Nobel Prize Winner, German, Jew. Wiley-VCH, Weinheim, 1998, ISBN 3-527-29573-9 , p. 219.
4. ^ Fritz Haber: About firedamp display. In: The natural sciences. 1, 1913, pp. 1049-1051, doi : 10.1007 / BF01492997 .