Accelerating rate calorimeter studies of water-induced thermal hazards of fireworks tip mixture
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Accelerating rate calorimeter studies of water-induced thermal hazards of fireworks tip mixture Vethathiri Pakkirisamy Sridhar • Mahadevan Surianarayanan Suthangathan Paramashivan Sivapirakasam • Asit Baran Mandal
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Received: 16 July 2012 / Accepted: 17 September 2012 / Published online: 9 October 2012 Akade´miai Kiado´, Budapest, Hungary 2012
Abstract The objective of this article is to generate thermal decomposition data on fireworks tip mixture, a mixture used to coat the tip of fireworks, for easy ignition. This mixture has reportedly involved in triggering many accidents in fireworks industry. Different quantities of water were added to the mixture and its thermal characteristics were studied. Differential scanning calorimeter was used for screening tests and accelerating rate calorimeter was used for detailed studies in adiabatic and isothermal modes. The self-heat rate data obtained showed onset temperature for different quantity of water, at a range of 80–170 C. The mixture with 40 % water wt/wt had onset at 80 C in adiabatic mode. The same mixture on isoaging at 40 C exhibited exothermic characteristics with a substantial rise in system pressure (57 bar). The heats of exothermic decomposition and Arrhenius kinetics were also computed. Keywords Fireworks tip mixture Differential scanning calorimeter Accelerating rate calorimeter Self-heat rate Thermal decomposition Heats of reaction Abbreviations KNO3 Potassium nitrate BaNO3 Barium nitrate Al Aluminum C Concentration V. P. Sridhar M. Surianarayanan (&) A. B. Mandal Thermochemical Laboratory, Department of Chemical Engineering, Central Leather Research Institute (CLRI), Adyar, Chennai 600020, Tamilnadu, India e-mail: [email protected] S. P. Sivapirakasam Department of Mechanical Engineering, National Institute of Technology, Tiruchirapalli 620015, India
T T0 TF DHr / DT DTad mS mB k mT k* Ea R A Cp Cps CpB
Temperature/C Initial temperature/C Final temperature/C Heat of reaction/J g-1 Thermal inertia Temperature difference/C Corrected temperature difference/C Mass of sample/g Mass of bomb/g Rate coefficient Rate of temperature increase/C min-1 Pseudo rate constant Activation energy/kC mol-1 Universal gas constant Pre-exponential factor/s-1 Average heat capacity/J g-1 K-1 Average heat capacity of sample/J g-1 K-1 Average heat capacity of bomb/J g-1 K-1
Introduction Frequent accidents are known to occur in a fireworks industry. Accidents during processing, storage, and transportation have been reported [1]. This is because fireworks mixtures are energetic compounds susceptible to explosive degradation on ignition, impact, and friction. These mixtures decompose at low temperatures and the decomposition mechanism is yet to be explored. Inadequate knowledge on exothermic hazards and reactive nature of these chemicals is yet another reason for explosive incidents, causing casualties and material loss. Fireworks Industries in India can be categorized as small scale and unorganized with almost no opportunity for sophistication
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