Calorimetry accelerators

The microanalytical methods of differential thermal analysis, differential scanning calorimetry, accelerating rate calorimetry, and thermomechanical analysis provide important information about chemical kinetics and thermodynamics but do not provide information about large-scale effects. Although a number of techniques are available for kinetics and heat-of-reaction analysis, a major advantage to heat flow calorimetry is that it better simulates the effects of real process conditions, such as degree of mixing or heat transfer coefficients. 

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... 

ABAQUS, description, 123 Accelerating-rate calorimetry advantages and disadvantages, 428-429 experimental procedure, 429-430 hazard evaluation on MDl, 43lr isothermal decomposition studies, 431-432,433/ use in assessment of hamrds of chemicals, 428... 

Reactivity (instabiiity) information Acceleration rate calorimetry Differential thermal analysis (DTA) Impact test Thermal stability Lead block test... 

Accelerating Rate Calorimetry. This is a heat-wait-search technique (see Fig. 5.4-62). A sample is heated by a pre-selected temperature step of, typically, 5 C, and then the temperature of the sample is recorded for some time. If the self-heating rate is less than the calorimeter detectability (typically 0.02 "C) the ARC will proceed automatically to the next step. If the change of the sample temj)erature is greater than 0.02 °C, the sample is no longer heated from outside and an adiabatic process starts. The adiabatic run is continued until the process has been completed. ARC is usually carried out at elevated pressure. 

Townsend, D., "Accelerating Rate Calorimetry," I. Chem. Eng. Symp. Series, 68 (1981). 

Snee, T. J., "Incident Investigation and Hazard Evaluation Using Differential Scanning Calorimetry and Accelerating Rate Calorimetry," J. Occupational Accidents, 8 (1987). 

ARC Accelerating Rate Calorimeter Accelerating Rate Calorimetry... 

Special Studies High Sensitivity Calorimetry A- DESIREEV UNDESIRED dT/dt ATadiab Kinetics, EA, A Sample size 1- 50 ml, pW/g sensitivity Shelf life studies by accelerated aging Combine with low adiabatic to confirm solids low self-heating rate studies... 

Chemical reactivity test data produced by employers or obtained from other sources (e.g., differential scanning calorimetry, thermogravimetric analysis, accelerating rate calorimetry). 

The PSI element of both the OSHA PSM Standard and the EPA RMP regulation can be improved by requiring the inclusion of all existing information on chemical reactivity. Examples of such information are chemical reactivity test data, such as DSC, thermogravimetric analysis (TGA), or accelerating rate calorimetry and relevant incident reports from the plant, the corporation, industry, and government. OSHA and EPA should require the facility to consult such resources as Bretherick s Handbook of Reactive Chemical Hazards,Sax s Dangerous Properties of Industrial Materials, and computerized tools (e g., CHETAH, The Chemical Reactivity Work Sheet). 

Testing includes screening (e.g., literature research, mixing calorimetiy, thermodynamic calculations, estimation of heats of reaction, DSC, flash point calculations), quantitative assessment (e g., accelerated rate calorimetry, specialized calorimetry), and scaleup (vent size packaging [VSP], modeling, reaction calorimetry). 

In this context, the term adiabatic refers to calorimetry conducted under conditions that minimize heat losses to the surrounding environment to better simulate conditions in the plant, where bulk quantities of stored or processed material tend to minimize cooling effects. This class of calorimetry includes the accelerating rate calorimeter (ARC), from Arthur D. Little, Inc., and PHI-TEC from Hazard Evaluation Laboratory Ltd. 

See ACCELERATING RATE CALORIMETRY, ASSESSMENT OF REACTIVE CHEMICAL HAZARDS, CALORIMETRY, HEAT FLOW CALORIMETRY... 

See also ACCELERATING RATE CALORIMETRY, SELF-ACCELERATING DECOMPOSITION TEMPERATURE... 

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