Classification of self-heating

A classification of self-heating chemicals is introduced in the present chapter. Treatments of gas-permeable oxidatively-heating substances are made in Chapters 7 anti 8. 

A broad classification of self-heating chemicals into the two large groups, f.e., the TD type and the AC type... 

A classification of self-heating chemicals is introduced in Chapter 3. 

In Chapter 3, a classification of self-heating chemicals, except gas-permeable oxidatively-heating substances, is introduced. Treatments of gas-permeable oxidatively-heating substances are made in Chapters 7 and 8. Self-heating chemicals are divided into two large groups, i.e., the thermal decomposition or TD type and the autocatalytic reaction or AC type. The TD type is subdivided into liquid chemicals, for each of which the Semenov equation is applied to calculate the Tc, and, solid (powdery, in reality) chemicals, for each of which the F-K equation is applied to calculate the Tc. On the other hand, the AC type is subdivided into high explosives of the true AC type and powdery chemicals of the quasi-AC type. 

Reaction conditions (i) and (ii) resemble the Semenov classifications of stable and unstable behaviour. For (iii), the reaction conditions are called parametrically sensitive. With absolute control of system parameters, any degree of self-heating can be produced and a complete range of maximum temperature excesses attained up to the adiabatic flame temperature. Physically such exact control is impossible and althou in the laboratory we should expect to see occasional temperature rises of the order of 100 K, repeatable non-explosive temperatures will be practically bounded by the steady-state limits. For simple systems, therefore, stationary-state treatments are still of great value. First, they impose a stability bound, inasmuch as conditions stable under stationary-state theory always remain stable under... 

The simple model (Fig. 20) can be criticized because it cannot readily be quantified. However, it does account for a wide range of properties, such as the tendency for the partial molar heat capacity and the viscosity -coefficient to become more negative with increase in ion size (Fortier et al., 1974a McDowell and Vincent, 1974 Kay, 1968 1973). Kay has collated conductance and viscosity data and shown how these lead to a classification of ionic properties (Fig. 21). The effects of added salts on the self-diffusion of ions is consistent with the Frank-Wen structural model (Hertz et al., 1974). It is noteworthy that in D20, which is argued to be more... 

To classify a self-heating substanee or mixture, test method N.4, as deseribed in Part III, subsection 33.3.1.6 of the UN Recommendations on the Transport of Dangerous Goods, Manual of Tests and Criteria, should be performed. Classification is according to decision logic 2.11. 

The classification procedure for self-heating substanees or mixtures need not be applied if the results of a screening test can be adequately correlated with the elassifieation test and an appropriate safety margin is applied. Examples of screening tests are ... 

Surfactant additives have been studied intensively in recent years because of the self-reparability or self-assembly of their micro structures after degradation by mechanical or extensional stresses. This ability has led to many studies of their applications in DHC recirculation systems. Classifications of surfactant DR As and their self-assembly nature are described. Also discussed in this section are the main research results on microstructures, rheological properties, HTR of surfactant DR solutions, and approaches to enhance heat transfer coefficients. Significant field tests around the world are reviewed. 

Broaden the application to cover reactive hazards resulting from process-specific conditions and combinations of chemicals. Additionally, broaden coverage of hazards from self-reactive chemicals. In expanding PSM coverage, use objective criteria. Consider criteria such as the North American Industry Classification System (NAICS), a reactive hazard classification system (e.g., based on heat of reaction or toxic gas evolution), incident history, or catastrophic potential. 

Many of these classes are self-explanatory, but some require definition. For example, the term controlled refers to supersaturation control. The term classifying refers to the production of a selected product size by classification in a fluidized bed of crystals. In a circulating-liquor crystallizer the crystals remain in the crystallization zone only the clear mother liquor is circulated, e.g., through a heat exchanger. In the circulating-magma crystallizer the crystals... 

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