Méthode perfectionnée pour la détermination de la composition de gaz

166,266. Williams, L. D., and Williams, A. Oct. 1, 1919. Gas analysis.-Apparatus for the estimation of gas mixtures by measuring the alteration of the pressure or volume resulting from combustion or absorption of one of the constituents is adapted to work with samples under a pressure of several atmospheres by the provision of a pump and a pressure gauge. The applications include the estimation of methane in air; of hydrogen and petrol in the atmospheres of airship sheds, submarines and oil tanlsers ; and of carbon dioxide in flue gases. In one form of apparatus, Fig. 1, the gas to be analyzed, under a pressure of several atmospheres as indicated by the gauge J, is forced by a pump A simultaneously into a pressure chamber B, a combustion chamber C and a compensating chamber D. The chambers C, D are provided with diaphragms F, E and an interconnecting rod G which operates a pointer H to indicate the alteration in pressure; the combustion chamber C contains a platinum wire M, and chamber D, a gold-plated platinum wire N. On closing an electric circuit, combustion takes place in the chamber C but not in chamber D, which merely serves to compensate for the. increase in pressure due to local heating of the gas and may be dispensed with. Another form of apparatus, Fig. 4, comprises a metal chamber a containing a catalytic heater b, a diaphragm d and a superimposed chamber e, into which fits a fine-bore glass tube g containing coloured water, from which the fall in pressure can be directly read off. The, two chambers are made of differentially expanding material in order to compensate for change in temperature. In a further form of apparatus, Fig. 5, the gas under pressure is forced into two chambers l, p, one of which l contains the catalytic heater m. The difference in volume caused by combustion is measured by the movement of the diaphragm q which separates the chambers as indicated by the number of turns of the calibrated screw t required to maintain an electric circuit. In each case the apparatus may be adapted for absorption instead of combustion of the constituent to be estimated, and the metal parts are massive or water-cooled to permit of rapid relstoration of normal temperature.