Explosion calorimetry

Excitonic emission, F state, 35 380-381 Exogenous ligand binding, [M-3Fe0134S] clusters, 38 365-368 Explosion calorimetry, 24 10 Extended fullerenes, 44 2... 

Two more reactions may conveni tly be included in this section for, although strictly involving neither hot-zone nor explosion calorimetry, they have features in common with the processes studied using these methods. The reaction... 

Reactivity (instability) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test Explosion propagation with detonation Drop weight test Thermal decomposition test Influence test Self-acceleration temperature Card gap test (under confinement) JANAE Critical diameter Pyrophoricity... 

In 1969 a serious explosion took place in Basle when 287 kg (1.3 kmol) of 2-chloro-4,6-dinitroaniline was diazotized in 384 kg 40% nitrosylsulfuric acid. The temperature was increased from 30 °C to 50 °C and kept at that level. Shortly afterwards the explosion occurred three workers were killed and 31 injured, some seriously. The reaction had been carried out twice before in the same way without difficulty. Detailed investigations (Bersier et al., 1971) with the help of differential scanning calorimetry showed that, at the high concentration of that batch, a strongly exothermic reaction (1500 kJ/kg) starts at about 77 °C. In contrast, when the reactants were diluted with 96% sulfuric acid to twice the volume, the reaction was found to begin at 146 °C, generating only 200 kJ/kg. 

A more detailed investigation of the thermal behavior of the exploding [ ]rotanes by differential scanning calorimetry (DSC) measurements performed in aluminum crucibles with a perforated lid under an argon atmosphere revealed that slow decomposition of exp-[5]rotane 165 has already started at 90 °C and an explosive quantitative decomposition sets on at 150 °C with a release of energy to the extent of AH(jecomp = 208 kcal/mol. Exp-[6]rotane 166 decomposes from 100°C upwards with a maximum rate at 154°C and an energy release of AH(jg on,p=478 kcal/mol. The difference between the onset (115°C) and the maximum-rate decomposition temperature (125-136°C) in the case of exp-[8]rotane 168 is less pronounced, and AHjecomp 358 kcal/mol. The methy-... 

The worst hazard scenarios (excessive temperature and pressure rise accompanied by emission of toxic substances) must be worked out based upon calorimetric measurements (e.g. means to reduce hazards by using the inherent safety concept or Differential Scanning Calorimetry, DSC) and protection measures must be considered. If handling hazardous materials is considered too risky, procedures for generation of the hazardous reactants in situ in the reactor might be developed. Micro-reactor technology could also be an option. Completeness of the data on flammability, explosivity, (auto)ignition, static electricity, safe levels of exposure, environmental protection, transportation, etc. must be checked. Incompatibility of materials to be treated in a plant must be determined. 

A drum of 30% solution in water exploded an hour after filling at 50°C, despite having a vent. Calorimetry demonstrated an exothermic, autocatalytic hydrolysis to ammoniacal potassium bicarbonate. In theory, a pressure exceeding 30 bar is obtainable. Aqueous solutions are unstable even at room temperature. Similar hydrolysis may account for an explosive product with Gold(III) chloride. 

Differential scanning calorimetry (DSC) and dust explosion tests are usually conducted before a new chemical goes into the pilot-plant phase. 

J.C. Oxley, The Thermal Stabihty of Explosives Chapter 8 in Handbook of Thermal Analysis and Calorimetry Applications to Inorganic and Miscellaneous Materials Volume 2 , P.K. Gallagher and M.E. Brown, eds, Elsevier p. 349—369. Elsevier Amsterdam. 

One of the simplest calorimetric methods is combustion bomb calorimetry . In essence this involves the direct reaction of a sample material and a gas, such as O or F, within a sealed container and the measurement of the heat which is produced by the reaction. As the heat involved can be very large, and the rate of reaction very fast, the reaction may be explosive, hence the term combustion bomb . The calorimeter must be calibrated so that heat absorbed by the calorimeter is well characterised and the heat necessary to initiate reaction taken into account. The technique has no constraints concerning adiabatic or isothermal conditions hut is severely limited if the amount of reactants are small and/or the heat evolved is small. It is also not particularly suitable for intermetallic compounds where combustion is not part of the process during its formation. Its main use is in materials thermochemistry where it has been used in the determination of enthalpies of formation of carbides, borides, nitrides, etc. 

Calorimeter and Calorimetry. See below under "Calorimetric Measurements in Combustion, Deflagration, Explosion and Detonation ... 

The research papers which originated in the last couple of years in different countries in this field indicate that ED and Er are not generally reported and there is an emphasis on the study of comprehensive thermal behavior of explosives as a function of temperature or time by means of different thermal analytical techniques. Most commonly used methods of thermal analysis are differential thermal analysis (DTA), thermogravimetric analysis (TGA) or thermogravimetry and differential scanning calorimetry (DSC). 

The common methods of investigating the kinetics of explosive reactions are differential thermal analysis, thermogravimetric analysis and differential scanning calorimetry. 

Calorific Values of Explosives, Calorific value is defined by Weissberger (Ref 3) as the heat evolved when the substance is exploded in the absence of oxygen except for what it contains itself . This quantity is practically the same as the heat evolved when the substance is exploded under normal operating conditions (such as in bore holes or in shells). Experimental techniques differ somewhat from chose employed in ordinary combustion calorimetry. The bombs employed in calorific value techniques are smaller in capacity and possess very thick walls to withstand high pressures. For example the bomb described in Ref 2 is of 124cc capacity. It was developed at Woolwich Arsenal and modified by Taylor et al. 

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