Mechanism for analysing gas in container - exploits change of pressure with gas density in oscillating flow

摘要

An oscillating flow of the gas is generated in a probe (2) connected between the gas container (1) and a second variable volume box (3). The pressure difference between a tapping on the probe (4) and the gas container (5) is measured (6) and the amplitude of this alternating signal is a function of the gas density. A wide variety of probe shapes and tapping positions may be used. The alternating flow may be produced loudspeaker and the pressure may be measured by microphone. The mechanism if suitable for determing the concentration of helium in air. The probe geometrics include a design with a concentric tube with a side entry tip leading to a pressure tapping.