Meaning of Hazard Diamond

Meaning of Color and Numbers on NFPA 704 ( Diamond)

(National Fire Protection Association)

Symbol and Number Meaning Example
Blue-0
Does not pose a health hazard. No precautions are necessary.
water
Blue-1
Exposure may cause irritation and minor residual injury.
acetone
Blue-2
Intense or continued non-chronic exposure may result in incapacitation or or residual injury.
ethyl ether
Blue-3
Brief exposure may cause serious temporary or moderate residual injury.
chlorine gas
Blue-4
Very brief exposure may cause death or major residual injury.
sarin, carbon monoxide
Red-0
Will not burn.
carbon dioxide
Red-1
Must be heated in order to ignite. Flash point exceeds 90°C or 200°F
mineral oil
Red-2
Moderate heat or relatively high ambient temperature is required for ignition. Flash point between 38°C or 100°F and 93°C or 200°F
diesel fuel
Red-3
Liquids or solids that readily ignite at most ambient temperature conditions. Liquids have a flash point below 23°C (73°F) and boiling point at or above 38°C (100°F) or flash point between 23°C (73°F) and 38°C (100°F)
gasoline
Red-4
Rapidly or completely vaporizes at normal temperature and pressure or readily disperses in air and readily burns. Flash point below 23°C (73°F)
hydrogen, propane
Yellow-0
Normally stable even when exposed to fire; not reactive with water.
helium
Yellow-1
Normally stable, but may become unstable elevated temperature and pressure.
propene
Yellow-2
Changes violently at elevated temperature and pressure or reacts violently with water or forms explosive mixtures with water.
sodium, phosphorus
Yellow-3
May detonate or undergo explosive decomposition under the action of a strong initiator or reacts explosively with water or detonates under severe shock.
ammonium nitrate, chlorine trifluoride
Yellow-4
Readily undergoes explosive decomposition or detonates at normal temperature and pressure.
TNT, nitroglycerine
White-OX
oxidizer
hydrogen peroxide, ammonium nitrate
White-W
Reacts with water in a dangerous or unusual way.
sulfuric acid, sodium
White-SA
simple asphyxiant gas
Only: nitrogen, helium, neon, argon, krypton, xenon