Apparatus for measuring the concentration of gases

Abstract From the Canadian patent

A tubular measuring chamber is described for temporarily holding alveolar breath for determining the quantity of alcohol in the breath by infra red radiation absorption. The radiation path length between an I.R. source and a condenser lens and detector is made a multiple of the actual length of the tube by bending the tube meanderingly with definite bends. The internal surface of the tube is made highly reflective to I.R. and plane reflectors are located at definite bends in the tube or between different sections of tube to deflect radiation from one tube section to the next. A saliva trap and mouthpiece to receive the breath is connected mid-way along the tube between the radiation source …