Combustibility and flammability
The quantity of vapour produced can be enhanced by increasing the surface area of the material forming a mist or dust.
Finely divided wood dust can undergo explosive flames and produce a blast wave.
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.
The burning of a solid material may appear to lose weight if the mass of combustion gases (such as carbon dioxide and water vapor) are not taken into account.
Lavoisier used the experimental fact that some metals gained mass when they burned to support his ideas (because those chemical reactions capture oxygen atoms into solid compounds rather than gaseous water).
[7][8] This system is used internationally to evaluate and sort substances in industrial applications, workplaces and products distributed to consumers.
In 1975, California began implementing Technical Bulletin 117 (TB 117), which required that materials such as polyurethane foam used to fill furniture be able to withstand a small open flame, equivalent to a candle, for at least 12 seconds.
[12] In polyurethane foam, furniture manufacturers typically meet TB 117 with additive halogenated organic flame retardants.
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) 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.
Substances with low combustibility may be selected for construction where the fire risk must be reduced, such as apartment buildings, houses, or offices.
A non-combustible material[17] 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.
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.
[19][b] As of 2012[update], the United States Occupational Safety and Health Administration has yet to adopt a comprehensive set of rules on combustible dust.
[22] When suspended in air (or any oxidizing environment), the fine particles of combustible dust present a potential for explosions.
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,[23] and other industries in NFPA Code sections 651–664.
[20]: 105–106 In January 2003, a polyethylene powder explosion and fire at the West Pharmaceutical Services plant in Kinston, North Carolina resulted in the deaths of six workers and injuries to 38 others.
Materials with flash points below 100 °F (38 °C) are regulated in the United States by OSHA as potential workplace hazards.
[28] Once the flame point of a material is reached, it produces enough fuel vapors or oils to support continuous burning.
In the U.S. other agencies have also developed building codes that specify combustibility ratings such as state and/or county governing bodies.
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.
DIN 4102, as well as its British cousin BS 476 include for testing of passive fire protection systems, as well as some of its constituent materials.
