CLASS 4 – DIVISION 4.1 - FLAMMABLE SOLIDS

 

This division is comprised of flammable solids, self-reactive and related substances, solid desensitized explosives, and polymerizing substances.

 

Division 4.1 substances are assigned to UN Packing Groups II or III. 

  • Flammable solids are solids that, under conditions encountered in transport, are readily combustible or may cause or contribute to fire through friction.  They can also be a powder or paste.  An added danger can be from toxic combustion products.

  • Self-reactive and related substances are substances that are liable to undergo a strong exothermic reaction (heat release.) Decomposition can be initiated by heat, contact with catalytic impurities (e.g. acids, heavy metal compounds, bases), friction or impact. The rate of decomposition increases with temperature and varies with the substance. Decomposition, particularly if no ignition occurs, may result in the evolution of toxic gases or vapours. Some self-reactive substances may decompose explosively, particularly if confined. Some may burn vigorously. All self-reactive substances are assigned to one of twenty generic UN entries.

  • Solid desensitized explosives are Class 1 explosives which are wetted with sufficient water, alcohol, or plasticizer to suppress their explosive properties. Desensitized explosives may explode if not diluted sufficiently.

  • Polymerizing Substances are substances which, without stabilization, are liable to undergo a strongly exothermic reaction resulting in the formation of larger molecules or resulting in the formation of polymers under conditions normally encountered in transport.

PACKING GROUPS

  • Packing group II: Assigned to readily combustible solids (other than metal powders) if the burning time is less than 45 seconds and the flame passes the wetted zone or assigned to powders of metal or assigned to metal alloys if the zone of reaction spreads over the whole length of the sample in 5 minutes or less.

  • Packing group III: Assigned to readily combustible solids (other than metal powders) if the burning rate time is less than 45 seconds and the wetted zone stops the flame propagation for at least 4 minutes or assigned to metal alloys if the reaction spreads over the whole length of the sample in more than 5 minutes but not more than 10 minutes.

Commonly transported Division 4.1 materials

  1. Azodicarbonamide formulations

  2. Camphor

  3. Celluloid

  4. Cerium

  5. Desensitized explosives, solid

  6. Ferrocerium (flint spark lighters, strikers, ferro rods) 

  7. Firelighters

  8. Matches

  9. Metaldehyde

  10. Metal powders

  11. Naphthalene (moth balls, urinal cakes)

  12. Nitrocellulose with water, alcohol, nitrogen, pigment, or plasticizer

  13. Phospherous

  14. Sulphur

  15. Table tennis balls (celluloid)

  16. Wetted ammonium picrate

  17. Wetted dinitrophenol