Class 4 has three divisions. Flammable solids, spontaneously combustible solids, and Solids that are dangerous when they get wet.
Division 4.1 also includes self-reactive substances and de-sensitized explosives. By definition, a flammable solid is readily combustible by a brief contact with an ignition source. They may cause fire through friction, particularly, during transport and being readily combustible, they may also contribute to a fire.
Examples of Division 4.1 are sulfur, magnesium, naphthalen
آی-ویدئو