CHETAH programme

The CHETAH programme is the most popular process of quantitatively estimating the risks related to the instability of a compound. It stands for Chemical Thermodynamic and Energy Release Program. This program was developed by the National Institute of Standards (N1ST)2. The 7-0 version is not distributed in France. 

The CHETAH programme is one of many and varied semiquantitative approaches to the estimation of risk. These approaches have proiiferated in recent years in academia, commerce, industry and reguiatory circies. One of the advantages of CHETAH is that it avoids some of the compiexities and uncertainties of more compiex models. 

The CHETAH programme used kcal/mole units whereas kJ/mole is used here. Nevertheless, numerous published documents give results using the old units. This is the reason it was decided to provide these group values in both units to be able to make calculations using both systems for comparative purposes. kJ is therefore retained. 

Oxygen balance plays a role on its own within the CHETAH programme and its interpretation proves to be difficult. Indeed, is it possible that the very similar oxygen... 

Denotes modification of C4 parameters, taking into account C2 and C3 parameters of CHETAH programme. "Unstable compound according to labour regulations. 

The reader will be able to read in Chapter 5 about this compound, and convince himself ttwt the author s estimate makes more sense than that used In the regulations, which is contrary to general observation. On the other hand, the CHETAH programme completely urKlerestimates.this compound. 

Applying the calculation formula given by the CHETAH programme for C4 by replacing AH by AH, which is the enthalpy of reaction defined previously as IR , and apply the same classification criteria as with CHETAH ... 

Calculation of C3.This is defined as in the CHETAH programme and criteria are the same. 

The enthalpy of decomposition, which is rather low compared with criterion C, in the CHETAH programme (see p.117), was determined by DSC and corresponds to 0.76 KJ/g at 230-260°C. In a confined atmosphere the decomposition conditions would be explosive. This reaction has been used many times because of its spectacular aspect. This is why it is called Vesuvius fire by artificers and green volcano by lecturers. These demonstrations should be stopped because of the detonation risks they represent as well as chromium (III) oxide toxicity. 

Frurip, D.J., Freedman, E. and Hertel. G.R.. 1989, A new release of the ASTM CHETAH programme for hazard evaluation versions for mainframe and personal computer, Int Symp on Runaway Reactions. 39-51 (CCPS, AIChE, USA). Benson. S.W., 1976, Thermochemical Kinetics. Methods for the Estimation of Thermochemical Data and Rate Parameters. 2nd edition (Wiley). 

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