NFPA 704

"NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response" is a standard maintained by the U.S.-based National Fire Protection Association. First "tentatively adopted as a guide" in 1960,[1] and revised several times since then, it defines the colloquial "fire diamond" or "safety square" used by emergency personnel to quickly and easily identify the risks posed by hazardous materials. This helps determine what, if any, special equipment should be used, procedures followed, or precautions taken during the initial stages of an emergency response.

NFPA 704
fire diamond
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasolineHealth code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentineReactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorusSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond


Flammability (red): no hazard codeHealth (blue): no hazard codeReactivity (yellow): no hazard codeSpecial hazards (white): no codeNFPA 704 four-colored diamond

The four divisions are typically color-coded with red on top indicating flammability, blue on the left indicating level of health hazard, yellow on the right for chemical reactivity, and white containing codes for special hazards. Each of health, flammability and reactivity is rated on a scale from 0 (minimal hazard) to 4 (severe hazard). The latest version of NFPA 704 sections 5, 6, 7 and 8 for the specifications of each classification are listed below. The numeric values in the first column are designated in the standard by "Degree of Hazard" using Arabic numerals (0, 1, 2, 3, 4), not to be confused with other classification systems, such as that in the NFPA 30 Flammable and Combustible Liquids Code, where flammable and combustible liquid categories are designated by "Class", using Roman numerals (I, II, III).[2]

Health (blue)
0 Poses no health hazard, no precautions necessary and would offer no hazard beyond that of ordinary combustible materials (e.g. wood, paper)
1 Exposure would cause irritation with only minor residual injury (e.g. acetone, sodium bromate, potassium chloride)
2 Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury (e.g. diethyl ether, ammonium phosphate, iodine)
3 Short exposure could cause serious temporary or moderate residual injury (e.g. liquid hydrogen, sulfuric acid, calcium hypochlorite, hexafluorosilicic acid)
4 Very short exposure could cause death or major residual injury (e.g. hydrogen cyanide, phosgene, methyl isocyanate, hydrofluoric acid)
Instability/reactivity (yellow)
0 Normally stable, even under fire exposure conditions, and is not reactive with water (e.g. helium, N2)
1 Normally stable, but can become unstable at elevated temperatures and pressures (e.g. propene)
2 Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water (e.g. white phosphorus, potassium, sodium)
3 Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked (e.g. ammonium nitrate, cesium, hydrogen peroxide)
4 Readily capable of detonation or explosive decomposition at normal temperatures and pressures (e.g. nitroglycerin, chlorine dioxide, nitrogen triiodide, manganese heptoxide)
Special notice (white)
The white "special notice" area can contain several symbols. The following symbols are defined by the NFPA 704 standard.
OX Oxidizer, allows chemicals to burn without an air supply (e.g. potassium perchlorate, ammonium nitrate, hydrogen peroxide).
W Reacts with water in an unusual or dangerous manner (e.g. caesium, sodium, sulfuric acid).
SA Simple asphyxiant gas (specifically nitrogen, helium, neon, argon, krypton, xenon). The SA symbol shall also be used for liquefied carbon dioxide vapor withdrawal systems and where large quantities of dry ice are used in confined areas.[2]
Non-standard symbols (white)
These hazard codes are not part of the NFPA 704 standard, but are occasionally used in an unofficial manner. The use of non-standard codes may be permitted, required or disallowed by the authority having jurisdiction (e.g. fire department).
Corrosive; strong acid or base (e.g. sulfuric acid, potassium hydroxide)
Acid or alkaline, to be more specific
BIO or Biohazard symbol.svg Biological hazard (e.g. flu virus, rabies virus)
POI Poisonous (e.g. strychnine, alpha-Amanitin)
RA, RAD or Radiation warning symbol2.svg Radioactive (e.g. plutonium, cobalt-60)
CRY or CRYO Cryogenic (e.g. liquid nitrogen)

See also


  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: Uses authors parameter (link)
  2. ^ a b "NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response". 2017.

External links


1,4-Dichlorobenzene (1,4-DCB, p-DCB, or para-dichlorobenzene, sometimes abbreviated as PDB or para) is an organic compound with the formula C6H4Cl2. This colorless solid has a strong odor. The molecule consists of a benzene ring with two chlorine atoms (replacing hydrogen atoms) on opposing sites of the ring.

It is used as a disinfectant, pesticide, and deodorant, most familiarly in mothballs in which it is a replacement for the more traditional naphthalene because of naphthalene's greater flammability (though both chemicals have the same NFPA 704 rating). It is also used as a precursor in the production of the chemically and thermally resistant polymer poly(p-phenylene sulfide).


2-Methylhexane (C7H16, also known as isoheptane, ethylisobutylmethane) is an isomer of heptane. It is structurally a hexane molecule with a methyl group attached to its second carbon atom. It exists in most commercially available heptane merchandises as an impurity but is usually not considered as impurity in terms of reactions since it has very similar physical and chemical properties when compared to n-heptane (straight-chained heptane).

Being an alkane, 2-methylhexane is insoluble in water, but is soluble in many organic solvents, such as alcohols and ether. However, 2-methylhexane is more commonly considered as a solvent itself. Therefore, even though it is present in many commercially available heptane products, it is not considered as a destructive impurity, as heptane is usually used as a solvent. Nevertheless, by concise processes of distillation and refining, it is possible to separate 2-methylhexane from n-heptane.

Within a group of isomers, those with more branches tend to ignite more easily and combust more completely. Therefore, 2-methylhexane has a lower Autoignition temperature and flash point when compared to heptane. Theoretically 2-methylhexane also burns with a less sooty flame, emitting higher-frequency radiation; however, as heptane and 2-methylhexane differ by only one carbon atom, in terms of branching, both burn with a bright yellow flame when ignited.

Compared to n-heptane, 2-methylhexane also has lower melting and boiling points. A lower density of liquid is found in 2-Methylhexane than heptane.

On the NFPA 704 scale, 2-methylhexane is listed as a reactivity level-0 chemical, along with various other alkanes. In fact, most alkanes are unreactive except in extreme conditions, such as combustion or strong sunlight. At the presence of oxygen and flame, 2-methylhexane, like heptane, combusts mostly completely into water and carbon dioxide. With UV-light and mixed with halogens in solvents, usually bromine in 1,1,1-trichloroethane, a substitution reaction occurs.

302 Acid

302 Acid is a music group from Washington, D.C., United States, formed by Doug Kallmeyer and Justin Mader in 2002. It currently includes Doug Kallmeyer (strings, samples, projections), Justin Mader (samples, projections).

Video projections are a component of their live performances, and their music has improvisatory elements. Notable in the sound is Kallmeyer's use of an electric double bass.

The group released an EP entitled Ailanthus Altissima on the Hackshop Records label in 2004, and subsequently a full-length album 302 acid0005 on the Nottingham-based Em:t Records label in 2005. The title of the latter release is in accord with em:t's naming conventions, but the work contained in the release is actually titled Even Calls. A limited CD-R of their performance at the Big Chill music festival was also released by Em:t. The group is currently working on a new album. The group has toured in the U.S., Canada, and the U.K., and has performed several live radio broadcasts.

The group took their name from an NFPA 704 hazard placard for hydrochloric acid that can be frequently seen when traveling the Washington Metro system.


β-Tocotrienol is a tocotrienol, a member of vitamin E family.

Chromium(III) sulfide

Chromium(III) Sulfide is the inorganic compound with the formula Cr2S3. It is a brown-black solid. Chromium sulfides are usually nonstoichiometric compounds, with formulas ranging from CrS to Cr0.67S (corresponding to Cr2S3).

Dangerous goods

Dangerous goods, abbreviated DG, are items or substances that when transported are a risk to health, safety, property or the environment. Hazardous materials (abbreviated as HAZMAT or hazmat) are substances, solids, liquids, or gases that can harm people, other living organisms, property, or the environment, more specifically.

Hazardous materials are often subject to chemical regulations. Hazmat teams are personnel specially trained to handle dangerous goods, which include materials that are radioactive, flammable, explosive, corrosive, oxidizing, asphyxiating, biohazardous, toxic, pathogenic, or allergenic. Also included are physical conditions such as compressed gases and liquids or hot materials, including all goods containing such materials or chemicals, or may have other characteristics that render them hazardous in specific circumstances.

In the United States, dangerous goods are often indicated by diamond-shaped signage on the item (see NFPA 704), its container, or the building where it is stored. The color of each diamond indicates its hazard, e.g., flammable is indicated with red, because fire and heat are generally of red color, and explosive is indicated with orange, because mixing red (flammable) with yellow (oxidizing agent) creates orange. A nonflammable and nontoxic gas is indicated with green, because all compressed air vessels are this color in France after World War II, and France was where the diamond system of hazmat identification originated.

Ethyl nitrite

The chemical compound ethyl nitrite is an alkyl nitrite. It may be prepared from ethanol.

It is used as a reagent with butanone to yield the dimethylglyoxime end product.

Ethyl nitrite is the main ingredient in a traditional ethanol-based South African remedy for colds and flu known as Witdulsies and sold in pharmacies. It is known as a traditional Afrikaans remedy and may have Dutch roots, as the same remedy is apparently made by the Germano-Dutch Amish people in the USA. However FDA has blocked over-the-counter sales of this same remedy, known in the USA as sweet nitrite or sweet spirit of nitre since 1980. Its use has been associated with fatal methemoglobinemia.

Flammability limit

Mixtures of dispersed combustible materials (such as gaseous or vaporised fuels, and some dusts) and air will burn only if the fuel concentration lies within well-defined lower and upper bounds determined experimentally, referred to as flammability limits or explosive limits. Combustion can range in violence from deflagration through detonation.

Limits vary with temperature and pressure, but are normally expressed in terms of volume percentage at 25 °C and atmospheric pressure. These limits are relevant both to producing and optimising explosion or combustion, as in an engine, or to preventing it, as in uncontrolled explosions of build-ups of combustible gas or dust. Attaining the best combustible or explosive mixture of a fuel and air (the stoichiometric proportion) is important in internal combustion engines such as gasoline or diesel engines.

The standard reference work is still that elaborated by Michael George Zabetakis, a fire safety engineering specialist, using an apparatus developed by the United States Bureau of Mines.

Hydrogen safety

Hydrogen safety covers the safe production, handling and use of hydrogen - particularly hydrogen gas fuel and liquid hydrogen. The main concern in working with hydrogen is flammability.

Hydrogen possesses the NFPA 704's highest rating of 4 on the flammability scale because it is flammable when mixed even in small amounts with ordinary air; hydrogen gas and normal air can ignite at as low as 4% air due to the oxygen in the air and the simplicity and chemical properties of the reaction. However, hydrogen has no rating for innate hazard for reactivity or toxicity. The storage and use of hydrogen poses unique challenges due to its ease of leaking as a gaseous fuel, low-energy ignition, wide range of combustible fuel-air mixtures, buoyancy, and its ability to embrittle metals that must be accounted for to ensure safe operation. Liquid hydrogen poses additional challenges due to its increased density and the extremely low temperatures needed to keep it in liquid form.

List of highly toxic gases

Many gases have toxic properties, which are often assessed using the LC50 (median lethal dose) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or permanent injury), and/or exposure limits [Threshold limit value|TLV], TWA or STEL) determined by the ACGIH professional association. Some, but by no means all, toxic gases are detectable by odor, which can serve as a warning. Among the best known toxic gases are carbon monoxide, chlorine, nitrogen dioxide and phosgene.


NFPA may refer to:

National Fire Protection Association

NFPA 704, National Fire Protection Association Fire Diamond

National Food Processors Association

National Fluid Power Association

Non-Fossil Purchasing Agency

Non-functioning pituitary adenoma


Nonadecane is an alkane hydrocarbon with the chemical formula CH3(CH2)17CH3, simplified to C19H40.


Pentadecane is an alkane hydrocarbon with the chemical formula C15H32.


A placard is a notice installed in a public place, like a small card, sign, or plaque. It can be attached to or hung from a vehicle or building to indicate information about the vehicle operator or contents of a vehicle or building. It can also refer to paperboard signs or notice carried by picketers or demonstrators.

Silver hexafluorophosphate

Silver hexafluorophosphate, sometimes referred to "silver PF-6," is an inorganic compound with the chemical formula AgPF6.

Sodium metatitanate

Sodium metatitanate is a chemical compound with the chemical formula Na2Ti3O7.

Sodium methoxide

Sodium methoxide is a chemical compound with the formula CH3ONa. This colorless solid, which is formed by the deprotonation of methanol, is a widely used reagent in industry and the laboratory. It is also a dangerously caustic base.

Table (information)

A table is an arrangement of data in rows and columns, or possibly in a more complex structure. Tables are widely used in communication, research, and data analysis. Tables appear in print media, handwritten notes, computer software, architectural ornamentation, traffic signs, and many other places. The precise conventions and terminology for describing tables vary depending on the context. Further, tables differ significantly in variety, structure, flexibility, notation, representation and use. In books and technical articles, tables are typically presented apart from the main text in numbered and captioned floating blocks.

Tert-Butyl hydroperoxide

tert-Butyl hydroperoxide (tBuOOH) is an organic peroxide widely used in a variety of oxidation processes, for example Sharpless epoxidation. It is normally supplied as a 69–70% aqueous solution.

Flammability (red)
0 Materials that will not burn under typical fire conditions (e.g. Carbon tetrachloride), including intrinsically noncombustible materials such as concrete, stone, and sand. Materials that will not burn in air when exposed to a temperature of 820 °C (1,500 °F) for a period of 5 minutes.
1 Materials that require considerable preheating, under all ambient temperature conditions, before ignition and combustion can occur (e.g. mineral oil, ammonia). Includes some finely divided suspended solids that do not require heating before ignition can occur. Flash point at or above 93.3 °C (200 °F).
2 Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur (e.g. diesel fuel, paper, sulfur) and multiple finely divided suspended solids that do not require heating before ignition can occur. Flash point between 37.8 and 93.3 °C (100 and 200 °F).
3 Liquids and solids (including finely divided suspended solids) that can be ignited under almost all ambient temperature conditions (e.g. gasoline, acetone). Liquids having a flash point below 22.8 °C (73 °F) and having a boiling point at or above 37.8 °C (100 °F) or having a flash point between 22.8 and 37.8 °C (73 and 100 °F).
4 Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily (e.g. acetylene, propane, hydrogen gas). Includes pyrophoric substances. Flash point below room temperature at 22.8 °C (73 °F).

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