ABSTRACT
Flammable solids Hazard Class 4 is composed of flammable solids (Table 6.1). Additionally, some pyrophoric and water-reactive liquids are included under 4.2 Spontaneously Combustible and 4.3 Dangerous When Wet divisions because there are no such categories for just spontaneously combustible or dangerous when wet liquids. Flammable solids can be categorized into five groups according to the hazards of the materials: flammable metals, spontaneous combustibles, intensely burning or difficult-to-extinguish flash point solids, and water reactives. Solid materials may take on many different physical forms (not to be confused with physical states), including fine powder, filings, chips, and various-sized solid chunks (Photo 6.1). The smaller the solid particle, the more dangerous it becomes in terms of flammability and potential explosiveness. This is because the smaller the particle, the more surface area that is created to react.
