A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable material catches fire immediately on exposure to flame. The degree of flammability or combustibility in air depends largely upon the volatility of the material - this is related to its composition-specific vapour pressure, which is temperature dependent. The quantity of vapour produced can be enhanced by increasing the surface area of the material forming a mist or dust. Take wood as an example. Finely divided wood dust can undergo explosive combustion and produce a blast wave. A piece of paper (made from wood) catches on fire quite easily. A heavy oak desk is much harder to ignite, even though the wood fibre is the same in all three materials. Common sense (and indeed scientific consensus until the mid-1700s) would seem to suggest that material "disappears" when burned, as only the ash is left. In fact, there is an increase in weight because the combustible material reacts (or combines) chemically with oxygen, which also has mass. The original mass of combustible material and the mass of the oxygen required for combustion equals the mass of the combustion products (ash, water, carbon dioxide, and other gases).

Antoine Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794),
CNRS (

conservation of mass In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass can ...

. Lavoisier used the experimental fact that some metals gained mass when they burned to support his ideas.

Definitions

Historically, ''flammable'', ''inflammable'' and ''combustible'' meant ''capable of burning''. The word "inflammable" came through French from the Latin ''inflammāre'' = "to set fire to," where the Latin preposition "in-" means "in" as in "indoctrinate", rather than "not" as in "invisible" and "ineligible". The word "inflammable" may be erroneously thought to mean "non-flammable". The erroneous usage of the word "inflammable" is a significant

safety hazard A hazard is a potential source of harm. Substances, events, or circumstances can constitute hazards when their nature would allow them, even just theoretically, to cause damage to health, life, property, or any other interest of value. The probabi ...

. Therefore, since the 1950s, efforts to put forward the use of "flammable" in place of "inflammable" were accepted by linguists, and it is now the accepted standard in American English and British English. Antonyms of "flammable" or "inflammable" include: ''non-flammable'', ''non-inflammable'', ''incombustible'', ''non-combustible'', ''not flammable'', and ''fireproof''. ''Flammable'' applies to ''combustible'' materials that ignite easily and thus are more dangerous and more highly regulated. Less easily ignited less-vigorously burning materials are ''combustible''. For example, in the United States

flammable liquid A flammable liquid is a liquid which can be easily ignited in air at ambient temperatures, i.e. it has a flash point at or below nominal threshold temperatures defined by a number of national and international standards organisations. The Occupat ...

s, by definition, have a flash point below —where combustible liquids have a flash point above .

Flammable solids Dangerous goods, abbreviated DG, are substances that when transported are a risk to health, safety, property or the environment. Certain dangerous goods that pose risks even when not being transported are known as hazardous materials ( syllabi ...

are solids that are readily combustible, or may cause or contribute to fire through friction. Readily combustible solids are powdered, granular, or pasty substances that easily ignite by brief contact with an ignition source, such as a burning match, and spread flame rapidly. The technical definitions vary between countries so the United Nations created the Globally Harmonized System of Classification and Labeling of Chemicals, which defines the flash point temperature of flammable liquids as between 0 and and combustible liquids between and .

Flammability

Flammability is the ease with which a combustible substance can be ignited, causing

fire Fire is the rapid oxidation of a material (the fuel) in the exothermic chemical process of combustion, releasing heat, light, and various reaction products. At a certain point in the combustion reaction, called the ignition point, flames a ...

combustion Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel (the reductant) and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Combus ...

or even an explosion. The degree of difficulty required to cause the combustion of a substance is quantified through fire testing. Internationally, a variety of test protocols exist to quantify flammability. The ratings achieved are used in

building code A building code (also building control or building regulations) is a set of rules that specify the standards for constructed objects such as buildings and non-building structures. Buildings must conform to the code to obtain planning permiss ...

insurance Insurance is a means of protection from financial loss in which, in exchange for a fee, a party agrees to compensate another party in the event of a certain loss, damage, or injury. It is a form of risk management, primarily used to hedge ...

requirements, fire codes and other regulations governing the use of building materials as well as the storage and handling of highly flammable substances inside and outside of structures and in surface and air transportation. For instance, changing an

occupancy Within the context of building construction and building codes, "occupancy" refers to the use, or intended use, of a building, or portion of a building, for the shelter or support of persons, animals or property. A closely related meaning is t ...

by altering the flammability of the contents requires the owner of a

building A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and fu ...

to apply for a building permit to make sure that the overall

fire protection Fire protection is the study and practice of mitigating the unwanted effects of potentially destructive fires. It involves the study of the behaviour, compartmentalisation, suppression and investigation of fire and its related emergencies, as we ...

design basis of the facility can take the change into account.

Testing

A fire test can be conducted to determine the degree of flammability. Test standards used to make this determination but are not limited to the following: *

Underwriters Laboratories The UL enterprise is a global safety science company headquartered in Northbrook, Illinois, composed of three organizations, UL Research Institutes, UL Standards & Engagement and UL Solutions. Established in 1894, the UL enterprise was founded as ...

br>UL 94 Flammability Testing
* International Electrotechnical Commission IEC 60707, 60695-11-10 and 60695-11-20 *

International Organization for Standardization The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...

ISO 9772 and 9773. * National Fire Protection Associationbr>NFPA 287 Standard Test Methods for Measurement of Flammability of Materials in Cleanrooms Using a Fire Propagation Apparatus (FPA)

NFPA 701: Standard Methods of Fire Tests for Flame Propagation of Textiles and Films

NFPA 850: Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations

Furniture flammability

Flammability of furniture is of concern as cigarettes and candle accidents can trigger domestic fires. In 1975, California began implementing

Technical Bulletin 117 ''California Technical Bulletin 117'' (TB 117) is a California fire safety law, first implemented in 1975. It has recently been updated as a Technical Bulletin 117-2013. The law requires fabric to pass a smoldering test. The test exposes fabrics an ...

(TB 117), which required that materials such as

polyurethane Polyurethane (; often abbreviated PUR and PU) refers to a class of polymers composed of organic units joined by carbamate (urethane) links. In contrast to other common polymers such as polyethylene and polystyrene, polyurethane is produced from ...

foam used to fill furniture be able to withstand a small open flame, equivalent to a candle, for at least 12 seconds. In polyurethane foam, furniture manufacturers typically meet TB 117 with additive halogenated organic

flame retardant The term flame retardants subsumes a diverse group of chemicals that are added to manufactured materials, such as plastics and textiles, and surface finishes and coatings. Flame retardants are activated by the presence of an ignition source and ...

s. No other U.S. states had similar standards, but because California has such a large market, manufacturers meet TB 117 in products that they distribute across the United States. The proliferation of flame retardants, and especially halogenated organic flame retardants, in furniture across the United States is strongly linked to TB 117. When it became apparent that the risk-benefit ratio of this approach was unfavorable and industry had used falsified documentation (i.e. see

David Heimbach David M. Heimbach (September 29, 1938 – August 7, 2017) was an American surgeon and a professor emeritus of the University of Washington. He gained notoriety as the "star witness" for the flame retardant industry. In 2014 he surrendered his medic ...

) for the use of flame retardants, California modified TB 117 to require that fabric covering upholstered furniture meet a smolder test replacing the open flame test. Gov.

Jerry Brown Edmund Gerald Brown Jr. (born April 7, 1938) is an American lawyer, author, and politician who served as the 34th and 39th governor of California from 1975 to 1983 and 2011 to 2019. A member of the Democratic Party, he was elected Secretary of ...

signed the modified TB117-2013, which became effective in 2014.

Examples of flammable substances

Flammable substances include, but are not limited to: *

Gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organi ...

Petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...

/ a complicated mixture of hydrocarbons that includes isomers of octane, C₈H₁₈ *

Ethanol Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...

/ CH₃CH₂OH *

Rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, an ...

Isopropyl alcohol Isopropyl alcohol (IUPAC name propan-2-ol and also called isopropanol or 2-propanol) is a colorless, flammable organic compound with a pungent alcoholic odor. As an isopropyl group linked to a hydroxyl group ( chemical formula ) it is the s ...

/ CH₃CH(OH)CH₃ * Methanol / CH₃OH *

Wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

Acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...

/ CH₃COCH₃ *

Paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...

Nitromethane Nitromethane, sometimes shortened to simply "nitro", is an organic compound with the chemical formula . It is the simplest organic nitro compound. It is a polar liquid commonly used as a solvent in a variety of industrial applications such as in ...

/ CH₃NO₂

Examples of nonflammable liquids

Water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

* Carbon tetrachloride

Classification of flammability

The US Government uses the Hazardous Materials Identification System (HMIS) standard for flammability ratings, as do many US regulatory agencies, and also the US National Fire Protection Association (NFPA). The ratings are as follows:

Codes

Flammability

For existing buildings, fire codes focus on maintaining the occupancies as originally intended. In other words, if a portion of a building were designed as an apartment, one could not suddenly load it with flammable liquids and turn it into a gas storage facility, because the fire load and smoke development in that one apartment would be so immense as to overtax the

active fire protection Active fire protection (AFP) is an integral part of fire protection. AFP is characterized by items and/or systems, which require a certain amount of motion and response in order to work, contrary to passive fire protection. Categories of active fi ...

as well as the

passive fire protection Passive fire protection (PFP) is components or systems of a building or structure that slows or impedes the spread of the effects of fire or smoke without system activation, and usually without movement. Examples of passive systems include floo ...

means for the building. The handling and use of flammable substances inside a building is subject to the local fire code, which is ordinarily enforced by the local fire prevention officer.

Combustibility

Combustibility is a measure of how easily a substance bursts into flame, through

. This is an important property to consider when a substance is used for construction or is being stored. It is also important in processes that produce combustible substances as a by-product. Special precautions are usually required for substances that are easily combustible. These measures may include installation of

fire sprinkler A fire sprinkler or sprinkler head is the component of a fire sprinkler system that discharges water when the effects of a fire have been detected, such as when a predetermined temperature has been exceeded. Fire sprinklers are extensively use ...

s or storage remote from possible sources of ignition. Substances with low combustibility may be selected for construction where the fire risk must be reduced, such as apartment buildings, houses, or offices. If combustible resources are used there is greater chance of fire accidents and deaths. Fire resistant substances are preferred for building materials and furnishings.

Code definitions

For an

Authority Having Jurisdiction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and co ...

, combustibility is defined by the local code. In the

National Building Code of Canada The National Building Code of Canada is the model building code of Canada. It is issued by the National Research Council of Canada. As a model code, it has no legal status until it is adopted by a jurisdiction that regulates construction. History T ...

, it is defined as follows: *''Combustible: A material that fails to meet acceptance criteria o
CAN/ULC-S114, Standard Method of Test for Determination of Noncombustibility in Building Materials
'' :This leads to the definition of noncombustible: *''Non-combustible: means that a material meets the acceptance criteria o
CAN4-S114, "Standard Method of Test for Determination of Non-Combustibility in Building Materials
. BS 476-4:1970 defines a test for combustibility in which a technician heats three specimens of a material in a furnace. Combustibile materials are those for which any of the three specimens either: * Makes the temperature reading from either of two thermocouples rise by 50 degrees Celsius or more above the initial furnace temperature * Flame continuously for 10 seconds or more inside the furnace Otherwise, the material is classified as non-combustible.

Fire testing

Various countries have tests for determining noncombustibility of materials. Most involve the heating of a specified quantity of the test specimen for a set duration. Usually, the material must not support combustion and must not lose more than a certain amount of mass. As a general rule of thumb, concrete, steel, and ceramics - in other words inorganic substances - pass these tests, so building codes list them as suitable and sometimes even mandate their use in certain applications. In

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, for instance, firewalls must be made of

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

Combustible dust

A number of industrial processes produce combustible dust as a by-product. The most common being

wood dust Sawdust (or wood dust) is a by-product or waste product of woodworking operations such as sawing, sandpaper, sanding, Milling (machining), milling, Plane (tool), planing, and Router (woodworking), routing. It is composed of small chippings of ...

. Combustible dust has been defined as: ''a solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition, which presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations.''United States Occupational Safety and Health Administration (2009
"Hazard Communication Guidance for Combustible Dusts"
OSHA 3371-08, Occupational Safety and Health Administration, U.S. Department of Labor In addition to wood, combustible dusts include metals, especially magnesium, titanium and aluminum, as well as other carbon-based dusts. There are at least 140 known substances that produce combustible dust. While the particles in a combustible dusts may be of any size, normally they have a diameter of less than 420 μm.I.e. they can pass through a U.S. No. 40 standard sieve. , the United States Occupational Safety and Health Administration has yet to adopt a comprehensive set of rules on combustible dust. When suspended in air (or any oxidizing environment), the fine particles of combustible dust present a potential for explosions. Accumulated dust, even when not suspended in air, remains a fire hazard. The National Fire Protection Association (U.S.) specifically addresses the prevention of fires and dust explosions in agricultural and food products facilities in NFPA Code section 61, and other industries in NFPA Code sections 651–664.E.g. NFPA 651 (aluminium), NFPA 652 (magnesium), NFPA 655 (sulphur) Collectors designed to reduce airborne dust account for more than 40 percent of all dust explosions. Other important processes are grinding and pulverizing, transporting powders, filing silos and containers (which produces powder), and the mixing and blending of powders. Investigation of 200 dust explosions and fires, between 1980 to 2005, indicated ''approximately 100 fatalities and 600 injuries.'' In January 2003, a polyethylene powder explosion and fire at the West Pharmaceutical Services plant in

Kinston, North Carolina Kinston is a city in Lenoir County, North Carolina, United States, with a population of 21,677 as of the 2010 census. It has been the county seat of Lenoir County since its formation in 1791. Kinston is located in the coastal plains region of ...

resulted in the deaths of six workers and injuries to 38 others. In February 2008 an explosion of sugar dust rocked the Imperial Sugar Company's plant at

Port Wentworth, Georgia Port Wentworth is a city in Chatham County, Georgia, United States. The 2020 population was 10,878, more than double the population of 5,359 at the 2010 census. Port Wentworth is part of the Savannah metropolitan area. History The Georgia General ...

, resulting in thirteen deaths. Non-combustible material – A non-combustible material is a substance that does not ignite, burn, support combustion, or release flammable vapors when subject to fire or heat, in the form in which it is used and under conditions anticipated. Any solid substance complying with either of two sets of passing criteria listed in Section 8 of ASTM E 136 when the substance is tested in accordance with the procedure specified in ASTM E 136 is considered to be non-combustible.

Categorization of building materials

Image:Steinwolle 1600dpi roxul rxl80.jpg, DIN4102 A1 noncombustible rockwool Image:Tu braunschweig din4102 smoke density test.jpg, DIN4102 A2

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywal ...

fireproofing Fireproofing is rendering something (structures, materials, etc.) resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a ...

plaster Plaster is a building material used for the protective or decorative coating of walls and ceilings and for moulding and casting decorative elements. In English, "plaster" usually means a material used for the interiors of buildings, while "re ...

leavened with polystyrene beads Image:Toilet flange.jpg, DIN 4102 B1 (difficult to ignite/often self-extinguishing) Silicone caulking used as a component in

firestop A firestop or fire-stopping is a form of passive fire protection that is used to seal around openings and between joints in a fire-resistance-rated wall or floor assembly. Firestops are designed to maintain the fire-resistance rating of a wall ...

ping

piping Within industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid. Industrial process piping (and accompa ...

penetration Image:Palletts at inniskillin vineyard.jpg, DIN 4102 B2: Timber, normal combustibility Image:Polyurethane foam at inniskillin 2.jpg, DIN 4102 B3: Polyurethane foam (easy to ignite = many

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...

bonds usually) Materials can be tested for the degree of flammability and combustibility in accordance with the Germa
DIN
4102. DIN 4102, as well as its British cousi
BS
476 include for testing of

systems, as well as some of its constituent materials. The following are the categories in order of degree of combustibility and flammability: A more recent industrial standard is the European EN 13501-1 - Fire classification of construction products and building elements—which roughly replaces A2 with A2/B, B1 with C, B2 with D/E and B3 with F. B3 or F rated materials may not be used in building unless combined with another material that reduces the flammability of those materials.

Important characteristics

Flash point

A material's flash point is a metric of how easy it is to ignite the vapor of the material as it evaporates into the atmosphere. A lower flash point indicates higher flammability. Materials with flash points below are regulated in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

OSHA OSHA or Osha may refer to: Work * Occupational Safety and Health Administration, a federal agency of the United States that regulates workplace safety and health * Occupational Safety and Health Act (United States) of 1970, a federal law in the Un ...

as potential workplace hazards.

Vapor pressure

* The

vapor pressure Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phas ...

of a liquid, which varies with its temperature, is a measure of how much the vapor of the liquid tends to concentrate in the surrounding atmosphere as the liquid evaporates. Vapor pressure is a major determinant of the flash point, with higher vapor pressures leading to lower flash points and higher flammability.

Notes

References

External links

{{Wiktionary, flammable, inflammable
Videos showing flammability of cables based on jacket rating

Fire Performance of Ageing Cable Compounds, NFPA Treatise by Dr. Perry Marteny

CAN4-S114 CAN/ULC-S114 Abstract

iBMB/TU Braunschweig Governmental Lab for Testing Building Materials

* ttp://www.astm.org/Standards/E136.htm ASTM E136 Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750°C abstract
"Combustible Dust: Agricultural Related Fires and Explosions Increasing, but Preventable"
Division of Occupational Safety and Health, N.C. Department of Labor
Combustible Dust: A Major Hot Work Hazard"
Division of Occupational Safety and Health, N.C. Department of Labor Fire protection Fire prevention Thermodynamics Explosion protection

Definitions

Flammability

Testing

Furniture flammability

Examples of flammable substances

Examples of nonflammable liquids

Classification of flammability

Codes

Flammability

Combustibility

Code definitions

Fire testing

Combustible dust

Categorization of building materials

Important characteristics

Flash point

Vapor pressure

See also

Notes

References

External links