Calorimetry of high explosives

Abstract

The object of this investigation was to determine concurrently the quantities of heat and volume of gases produced when high explosives are denoted under standard conditions of confinement and compression, in order to obtain a measure of the energy developed, and to investigate the nature of the gases evolved and the chemical reactions which occur in the period after explosion. In previous work on the heat of detonation of explosives, the experimental data quoted are very incomplete, especially in respect to the volume of the gases and water, thus making it impossible to deduce the heat evolved when the water and other volatile products are in the gaseous state. Frequently the explosives is denoted in an unconfined condition in a space which may be 100 times its own volume. This is an abnormal condition, since when fired for practical effect explosives are always confined in some manner, and the state of confinement affects not only the rate of cooling in the after explosion period, but also the pressure under which the gaseous reactions take place. These changes are reflected in the composition of the gases and in the heat of detonation. In the case of propellants, for which calorimetric bombs have been designed to resist comparatively slowly rising pressures up to about 50 tons per square inch, the technique of calorimetric work has been fairly well established, but the difficulties are greatly increased if the explosive, instead of being simply ignited, has to be brought up to true detonation, when a mean maximum pressure of the order of 300 tons per square inch during 1/200000th second may be developed.