Acoustic gas analyser - measures speed of sound from microphone membrane oscillations, having EM parts behind protective wall

摘要

An acoustic gas analyser continuously measures the composition of gaseous mixtures of known components using the speed of sound in the gas as the measurement parameter. The speed of sound is determined from the frequency of an oscillator stimulated by the gas flow and acquired via a microphone (9 to 11) membrane (9) subjected to the gas press. on both sides. The measurement head is vacuum tight to prevent air ingress and has no electrical components in contact with the medium in case of formation of explosive mixtures. The vibrating membrane of the microphone is sealed off from electromagnetic parts (10,11) by a protective wall (12). The microphone electromagnetic parts consist of a magnetic yoke (10) with detector coils (11) and extension arms (21) passing through seals in the protective wall (12).