Thermal hazards, cautions

The PSM Standard requires that the following information be contained within the PSI element-physical data, reactivity data, corrosivity data, thermal and chemical stability data, and hazardous effects of potential inadvertent mixing of different materials. The standard does not specifically define what is to be included in any of these data categories, the level of detail required, or the method of compilation.41 It does, however, stipulate that an MSDS can be used to compile the data to the extent that it contains the information required. In 1996, OSHA issued a Hazard Information Bulletin cautioning that MSDSs do not always contain information about hazards from mixing or blending chemicals (OSHA, 1996). 

When YBa2Cus07 x is heated to 1000°C in a flowing atmosphere containing H2, [CAUTION The H2 should be diluted with 10 volumes of Ar to reduce the hazard of an explosion. A 10-turn 5-cm-diameter coil of glass tubing should be inserted next to the H2 tank to prevent flashback of the tank. The thermal analyzer must be purged completely so there are no dead volumes of air and the exit gas must be exhausted carefully.] reduction to BaO, Y2Os and Cu occurs (10)(25)... 

Unlike organic peroxides (see section 2.3 in Chapter 2), metal alkyls do not in general decompose violently if subjected to heat. Thermal decomposition of metal alkyls usually occurs in a slow, non-hazardous manner. However, there are a few exceptions. For example, diethylzinc and trimethylaluminum can decompose violently at elevated temperatures. Extreme caution must be exercised to insure that these neat products are not subjected to high temperatures. 

In conducting an investigation of thermal hazards, particularly of the thermal runaway, certain cautions must be mentioned. As discussed previously, the Semenov Theory holds for many liquids, but solids must be treated quite differently. Because the Semenov Theory is easier to apply than the theories available for solids, it is often tempting to apply the Semenov Theory to solids as well as liquids. Major errors can arise ... 

The word asphalt has been carelessly used in that it is not adequately differentiated from thermally degraded materials, especially coal tar and derivatives. It is essential to differentiate asphalt from these materials which contain known carcinogens and health hazards. For this reason, the use of cracked asphalts must be treated with caution. 

Caution. Under no circumstances should perchlorate salts be used in any of the reactions involving neat triflic acid. The anhydrous hot perchloric acid thus produced represents an extremely explosive hazard, especially in contact with transition metal complexes. Addition of anhydrous diethyl ether to such solutions would represent an additional explosive hazard. Trifluoromethanesulfonic acid, its salts, and its complexes are extremely stable thermally, and no explosive hazards are known. However, consideration should be given to the thermal stability of other components of the complex before any new reactions are attempted at elevated temperatures. 

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