Flame
- Flammables – which are gases, aerosols, liquids, or solids that will burn or ignite under certain conditions
- Self-Reactives – heating alone, without air, may cause fire or explosion
- Pyrophorics – in small amounts, may ignite within 5 minutes after contact with air
- Self-Heating – which may catch fire only in large amounts and after long periods of time when exposed to air
- Emitters of flammable gas
- Organic peroxides – which, when heated, may cause fire or explosion; may be sensitive to impact or friction; and may react dangerously with other chemicals