"NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response" (Scots: Staundart Seestem for the Identification o the Hazards o Materials for Emergency Response) is a staundart mainteened bi the U.S.-based National Fire Protection Association. First "tentatively adoptit as a guide" in 1960,[1] an revised several times syne then, it defines the colloquial "fire diamond" uised bi emergency personnel tae quickly an easily identify the risks posed bi hazardous materials. This helps determine whit, if ony, special equipment should be uised, procedures follaed, or precautions taken during the ineetial stages o an emergency response.

NFPA 704
"fire diamond"
Flammability code 3: Liquids an solids that can be ignited unner awmaist ae ambient temperature condeetions. Flash pynt atween 23 an 38 °C (73 an 100 °F). E.g., gasoline)Health code 1: Exposur would cause irritation but anly minor residual injury. E.g., turpentineReactivity code 2: Unnergangs violent chemical chynge at elevatit temperatures an pressurs, reacts violently wi water, or mey form explosive mixturs wi watter. E.g., phosphorusSpecial hazard W: Reacts wi watter in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond


Flammability (reid): no hazard codeHealth (blue): no hazard codeReactivity (yellae): no hazard codeSpecial hazards (white): no code 

The fower diveesions are teepically colour-codit wi reid indicatin flammability, blue indicatin level o heal hazard, yellae for chemical reactivity, an white conteenin codes for special hazards. Each o heal, flammability an reactivity is ratit on a scale frae 0 (na hazard) tae 4 (severe risk). The latest version o NFPA 704 sections 5, 6, 7 an 8 for the specifications o each clessification are leetit ablo. The numeric values in the first column are designatit in the staundart bi "Degree of Hazard" uisin Arabic numerals (0, 1, 2, 3, 4), nae tae be confused wi ither clessification seestems, sic as that in the NFPA 30 Flammable an Combustible Liquids Code, whaur flammable an combustible liquid categories are designatit bi "Cless", uisin Roman numerals (I, II, III).[2]

Flammability (reid)
0 Materials that will nae burn unner teepical fire condeetions (e.g. Carbon tetrachloride), includin intrinsically noncombustible materials sic as concrete, stane an saund (Materials that will nae burn in air when exposed tae a temperatur o 820 °C (1,500 °F) for a period o 5 minutes)
1 Materials that require considerable preheatin, unner aw ambient temperatur condeetions, afore igneetion an combustion can occur (e.g. mineral ile). Includes some finely dividit suspendit solits that dinna require heatin afore igneetion can occur. Flash pynt at or abuin 93.3 °C (200 °F).
2 Must be moderately heatit or exposed tae relatively heich ambient temperatur afore igneetion can occur (e.g. diesel fuel) an multiple finely dividit suspendit solits that dinna require heatin afore igneetion can occur. Flash pynt atween 37.8 an 93.3 °C (100 an 200 °F).
3 Liquids an solits (includin finely dividit suspendit solits) that can be ignitit unner awmaist aw ambient temperatur condeetions (e.g. petrol, acetone). Liquids haein a flash pynt ablo 22.8 °C (73 °F) an haein a bylin pynt at or abuin 37.8 °C (100 °F) or haein a flash pynt atween 22.8 an 37.8 °C (73 an 100 °F).
4 Will rapidly or completely vaporise at normal atmospheric pressur an temperatur, or is readily dispersed in air an will burn readily (e.g. acetylene, propane, liquid hydrogen). Includes pyrophoric substances. Flash pynt ablo ruim temperatur at 22.8 °C (73 °F).

Health (blue)
0 Poses na heal hazard, na precautions necessar an wad offer na hazard yont that o ordinary combustible materials (e.g. wid, paper)
1 Exposur wad cause irritation wi anly meenor residual injury (e.g. acetone, sodium bromate)
2 Intense or continued but nae chronic exposur coud cause temporary incapacitation or possible residual injury (e.g. diethyl ether, ammonium phosphate)
3 Short exposur coud cause serious temporary or moderate residual injury (e.g. liquid hydrogen, carbon monoxide, calcium hypochlorite)
4 Very short exposur coud cause daith or major residual injury (e.g. hydrogen cyanide, phosgene, methyl isocyanate, hydrofluoric acid)

Instability/reactivity (yellow)
0 Normally stable, even unner fire exposur condeetions, an isba reactive wi watter (e.g. helium, N2)
1 Normally stable, but can acome unstable at elevatit temperaturs an pressurs (e.g. propene)
2 Unnergangs violent chemical chynge at elevatit temperaturs an pressurs, reacts violently wi watter, or mey form explosive mixturs wi watter (e.g. white phosphorus, potassium, sodium)
3 Capable o detonation or explosive decomposition but requires a strang ineetiatin soorce, must be heatit unner confinement afore ineetiation, reacts explosively wi watter, or will detonate if severely shocked (e.g. ammonium nitrate, chlorine trifluoride)
4 Readily capable o detonation or explosive decomposeetion at normal temperaturs an pressurs (e.g. nitroglycerin, chlorine azide, chlorine dioxide, nitrogen triiodide)

Special notice (white)
The white "special notice" aurie can conteen several seembols. The follaein seembols are defined bi the NFPA 704 staundart.
OX Oxidizer, allaes chemicals tae burn withoot an air supply (e.g. potassium perchlorate, ammonium nitrate, hydrogen peroxide).
Reacts wi watter in an unuisual or dangerous manner (e.g. caesium, sodium, sulfuric acid).
SA Semple asphyxiant gas. Speceefically leemitit tae the follaein gases: nitrogen, helium, neon, argon, krypton an xenon.[2]
Non-staundart seembols (white)
Thir hazard codes are nae pairt o the NFPA 704 staundart, but are occasionally uised in an unoffeecial manner. The uise o non-staundart codes mey be permittit, required or disallaed bi the authority haein jurisdiction (e.g. fire depairtment).
Corrosive; strang acid or base (e.g. sulfuric acid, potassium hydroxide)
Acid or alkaline, tae be mair speceefic
BIO or   Biological hazard (e.g. flu virus, rabies virus)
POI Pushionous (e.g. strychnine, alpha-Amanitin)
RA, RAD or   Radioactive (e.g. plutonium, cobalt-60)
CRY or CRYO Cryogenic (e.g. liquid nitrogen)


  1. Dr. W. H. L. Dornette, Miles E. Woodworth (1969). "Proposed Amendments on Revisions to the Recommended System for the Identification of The Fire Hazards of Materials / NFPA No. 704M — 1969" (PDF). National Fire Protection Association. Retrieved 2016-03-04.CS1 maint: uises authors parameter (link)
  2. 2.0 2.1 "NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response". 2012. Archived frae the oreeginal on 2014-11-09. Unknown parameter |deadurl= ignored (help)