Firedamp whistle
A firedamp whistle (Schlagwetterpfeife) is a warning device for firedamp, the flammable gas often found in coal mines. In 1912, German Emperor Wilhelm II asked Fritz Haber to build such a system. Haber developed the methane whistle and showed it to the emperor in 1913. He tried to sell it and even signed a contract with Auergesellschaft, but it never became practical because calibrating pipes for real mine conditions was difficult.
The device used two identical pipes. One pipe was blown with air, the other with a gas mix. The sound depends on the speed of sound in the gas, and methane makes the tone slightly higher than air, so the two tones form an audible beat. For a 1% methane–air mix, the speed of sound is about 1.0031 times that of air. If a pipe is tuned to 440 Hz in air, the air–methane pipe would be about 441.4 Hz. As the gas mix changes, the beat changes, signaling different methane levels. An absorber could remove humidity and carbon dioxide from the sample.
The methane whistle indicated methane in mine air at 1% by volume or more.
This page was last edited on 2 February 2026, at 04:09 (CET).