REACTIVITY LIMITS OF ALUMINUM AND HALOHYDROCARBON MIXTURES - DETERMINATION BY THE ASTM CHETAH PROGRAM

The CHETAH program has been successfully used to assess potential hazards of binary mixtures of aluminium with several halogenated compounds. From this thermochemical evaluation, conducted on more than 2000 mixtures, it was possible to distinguish mixtures with very low reactivity from mixtures with high reactivity delimited by two well defined concentrations of Al. These two concentration limits, analogous to flammability limits, can be considered as upper and lower reactivity limits. The CHETAH evaluation, carried out on mixtures with the highest reactivity values, in the presence of different amounts of an 'inert' compound (heptane), gives a triangular reactivity diagram similar to that frequently used in flammability characterization of combustible gases and vapours.