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The Accelerating Rate Calorimeter provides adiabatic data of a runawy reaction in a safe, controllable laboratory environment. This information contributes to a profound understanding of the basic processes involved. The exothermicity of a reaction, thermal stability of substances, gas formation processes and also the start of decomposition reactions are very precisely detectable. On this basis, various safe operating modes and procedures could be developed to reduce the risks associated with a reactive system.
The ARC belongs to the adiabatic measuring systems where temperature and pressure are measured simultaneously under malfunction conditions, similar to the pressure heat accumulation apparatus, VSP, RSST or PhiTeC. Sampling and test preparation are decisive for a representative measurement. In the closed system, gases can be superimposed and substances added in order to reproduce the malfunction scenario in a production plant as well as possible. In addition to the runaway or a decomposition reaction, possible subsequent reactions may be characterized. The measurement results of the ARC are then used to size safety devices to safeguard runaway reactions.
Sample preparation and testing is possible in an oxygen-free environment (glove box).
Gaseous reaction products can be analyzed at the end of a test to improve the understanding of the reaction mechanisms.
The sample (50 – 5000 mg) is heated stepwise until an exothermic reaction is measured. The oven temperature is then adjusted to the sample temperature so that no heat flow to the outside occurs, i.e. a pseudo-adiabatic measurement.
Self-heating rate in exothermic reactions
Pressure and temperature curve during reaction
Vapour pressure curve of reaction mixtures
Pressure rise rate in exothermic reactions
Onset of the reaction
Temperature range from ambient to 400°C
Measurement under air atmosphere
Sample container made of Hastelloy, stainless steel or titanium
Measurement under inert gas (e.g. nitrogen or argon)
Gas sampling and analysis of reaction gases
Reaction kinetics, Arrhenius parameters, reaction order
Measurements of solutions
Images courtesy of TA Instruments, Eschborn, Germany