Vapor pressure of expls

The impetus for the study of the vapor pressure of expls has been provided in the past by considerations of health and safety. For example, TNT vapors are toxic, while those of Nitroglycerin (NG) and Ethyleneglycoldinitrate (EGDN) produce severe headache. Consequently, to protect workers in manufacturing plants and... 

A variety of methods has been used in measuring the vapor pressure of expls. In general these may be classified (in chronological order) as ... 

We now present empirical equations for the vapor pressure of expls grouped according to type (all pressures in Torr and temps in °K) ... 

As already mentioned there is wide divergence of measured values of the vapor pressure of TNT. For DNT the two published values of the relation between p and T agree well. There appear to be no replicate vapor pressure measurements for the other expls listed above... 

An extensive and detailed coverage of the MS of expls in general has been documented (Ref 163). Volatile constituents of Comp A-3, Comp B, pressed TNT and cast TNT were surveyed with a residual gas analyzer MS (Ref 40). The mass spectra of all possible TNT (except for 3,4,5-TNT) and DNT isomers in the vapor phase were obtained as a function of ionizing voltage (Refs 65 84). The use of membrane inlet systems for the separation of TNT vapor in trace vapor detection is described and an analysis of the membrane inlet system for quadrupole mass spectroscopy is presented (Refs 95 113). Estimations of the vapor pressure of TNT were made mass spectrometrically in the range of 50—... 

R.B. Cundall et al, "Vapor Pressure Measurements on Some Organic High Explosives , J-ChemSoc, Faraday Trans I, 74 (6), 1339—45 (1978) CA 89, 181933 (1978) [Equilibrium vap press were detd for various expls by the Knudson cell technique. The data for HMX follows the Clausius-Clapeyron eqtn. The values detd for the const A and B in the eqtn, log10p = A—(B/T), plus the std enthalpy, entropy and Gibbs energy of sublimation from the authors calcns are presented in Table 7 ... 

When analyzing the energetics of a reaction one must remember that chemical equilibria depend on the total pressure of the system and that, therefore, the heat of reaction of an expln or of a propint changes as the products expand and the total pressure decreases. This problem is particularly acute in detonations for which the compn of the shocked state is unknown and for which the calorimetrically measured heat is in fact for the frozen or the expanded compn. Moreover, often the tabulated heats of detonation are corrected for the heat of vaporization of the water which is one of the principle reaction products. Whereas tabulated data constitute the base from which the theoretical properties of expls can be calcd, there is no connection between the heat of expln, the heat of formation and the sensitivity of an expl. For instance, aliphatic... 

Many hypotheses for initiation of liquid expls have been proposed, of which Bowden et al (Refs 13, 14a 27) suggested adiabatic compression of gas bubbles Johansson et al (Ref 28) - vapor or droplet burning Andreev (Ref 29) - droplet formation or suspension behind a burning front is capable of causing a transition to detonation Bolkhovitinov (Ref 33a) - crystallization of the material under pressure Cook et al (Ref 34b) - initiation occurs with the development of a pressure-generated metallic state accompanied by a plasma that provides the postulated requirement of high heat conductivity... 

This reaction is highly exothermic. If the heat of the reaction is not conducted thru the walls of a closed container at a rate capable of maintaining an equilibrium temperature, an increase in pressure results with an increase in reaction rate, leading to explosive conditions. Acid salts, such as stannic chloride and zinc chloride, and bases, such as alkali metal hydroxides, either solid or in aqueous solution, and tertiary amines are all effective catalysts. It is, therefore, imperative that the concentration of such contaminants be kept at a minimum when transporting or storing sizeable quantities of ethylene oxide Accdg to Hess Tilton (Ref 16), a 90% decompn takes place if 100% vapor of EtnO in a closed container is. initiated with MF. There is no upper limit of EtnO in air (the previously reported value of 80% was in error), but the lower expl limit is 3% (Ref 17, p 87)... 

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