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Class 4 - Flammable solids, substances liable to spontaneous combustion, substances which, in contact with water, emit flammable gases

Class 4.1 / 4.2 / 4.3

Class 4 is divided into three division as follow:

Division 4.1 – Flammable solids; Self-Reactive Substances; Polymerizing Substances; and Solid Desensitized Explosives

  • Solids which, under conditions encountered in transport, are readily combustible or may cause or contribute to fire through friction
  • Self-reactive substances and polymerizing substances which are liable to undergo a strongly exothermic reaction
  • Desensitized explosives which may explode if not diluted sufficiently

Division 4.2 – Substances Liable to Spontaneous Combustion 

  • Which are liable to spontaneous heating under normal conditions encountered in transport, or to heating up in contact with air and being then liable to catch fire
  • Following types of substances are classified in division 4.2: Pyrophoric substances and Self-heating substances

Division 4.3 – Substances which, in Contact with Water, Emit Flammable Gases (Dangerous when wet)

  • By interaction with water, are liable to become spontaneously flammable or to give off flammable gases in dangerous quantities


Disclaimer: this information is provided for convenience only. Please consult International Associations and Local Authorities for more details and latest information.

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