The Cool-Flame and Two-Stage Ignition Systems in Ether – Air Mixtures at Room Temperature

Abstract

THE normal and cool-flame systems in diethyl ether – air, etc., mixtures have been defined by means of diagrams showing the influence of pressure on their respective ranges of inflammability¹. Whereas the normal flame range centres upon approximately the theoretical mixture or that capable of developing the highest flame temperature and consequent flame speed, the cool-flame range appears to centre upon the mixture giving rise to the fastest reaction in slow combustion. High-tension sparks are employed for igniting the normal flames, but a suitably heated element must be used for the cool flames. If the experimental pressures in the cool-flame range be increased, pressure-composition limits may also be defined for the initiation of a second-stage 'blue' flame in the cool-flame products; this arises from the autogenous decomposition of peroxidic material formed in these products. This two-stage phenomenon is identical with that occurring in media spontaneously ignited at suitable temperatures and pressures², the essential difference being that with artificial ignition in cold media, the limiting pressures are much higher.