Class 4.2 - Substances liable to spontaneous combustion

Substances liable to spontaneous combustion

The heading of Class 4.2 covers:

  • Pyrophoric substances which are substances, including mixtures and solutions (liquid or solid), which even in small quantities ignite on contact with air within five minutes. These are the Class 4.2 substances the most liable to spontaneous combustion; and
  • Self-heating substances and articles which are substances and articles, including mixtures and solutions, which, on contact with air, without energy supply, are liable to self-heating. These substances will ignite only in large amounts (kilograms) and after long periods of time (hours or days).
S Substances liable to spontaneous combustion, without subsidiary risk:
S1 Organic, liquid;
S2 Organic, solid;
S3 Inorganic, liquid;
S4 Inorganic, solid;
S5 Organometallic;
SW Substances liable to spontaneous combustion, which, in contact with water, emit flammable gases;
SO Substances liable to spontaneous combustion, oxidizing;
ST Substances liable to spontaneous combustion, toxic:
ST1 Organic, toxic, liquid;
ST2 Organic, toxic, solid;
ST3 Inorganic, toxic, liquid;
ST4 Inorganic, toxic, solid;
SC Substances liable to spontaneous combustion, corrosive:
SC1 Organic, corrosive, liquid;
SC2 Organic, corrosive, solid;
SC3 Inorganic, corrosive, liquid;
SC4 Inorganic, corrosive, solid;
ADR European Agreement Concerning the International Carriage of Dangerous Goods by Road, ECE/TRANS/257 (Vol. 1), Economic Commission for Europe Inland Transport Committee, UNECE 2017