Plastics in fire - Revision history

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← Older revision		Revision as of 18:13, 2 November 2026
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	== How plastics burn ==		== How plastics burn ==
	Solid plastics do not burn directly. When heated, they undergo [[pyrolysis]]: the large molecules break down into smaller ones, which escape as combustible gases. Pyrolysis needs no oxygen, but the burning of the gases does.<ref name="VR-3.1" /> Burning becomes self-sustaining when the flame feeds enough heat back to the surface to keep producing these gases, a loop of heat, gas release and flame.<ref name="BH-110">Beyler and Hirschler (2002), p. 1-110.</ref> The SFPE Handbook sums this up in one phrase: polymers cannot burn if they do not break down.<ref name="BH-124" />		Solid plastics do not burn directly. When heated, they undergo [[pyrolysis]]: the large molecules break down into smaller ones, which escape as combustible gases. Pyrolysis needs no oxygen, but the burning of the gases does.<ref name="VR-3.1" /> Burning becomes self-sustaining when the flame feeds enough heat back to the surface to keep producing these gases, a loop of heat, gas release and flame.<ref name="BH-110">Beyler and Hirschler (2002), p. 1-110.</ref> The SFPE Handbook sums this up in one phrase: polymers cannot burn if they do not break down.<ref name="BH-124" />

			[[File:fse-plastics-in-fire-v1.svg\|thumb\|upright=1.5\|alt=Cross-section of a plastic slab with a flame above; arrows show heat going down, gases rising and burning, and heat returning.\|Burning of a plastic is a feedback loop: heat from the flame decomposes the solid into combustible gases, which burn and heat the surface again. Based on Beyler and Hirschler (2002), p. 1-110, and Van Rossum (2027), §3.1.]]

	The products of decomposition depend on the polymer. Polyethylene and polypropylene form very little of their original building block, the monomer, and instead release up to about 70 different small molecules, mostly hydrocarbons.<ref name="BH-124" /> PMMA decomposes almost entirely back to its monomer and burns at a very steady rate. For this reason it is a favourite material in fire research.<ref name="BH-125">Beyler and Hirschler (2002), p. 1-125.</ref> PVC first loses its chlorine as hydrogen chloride gas, nearly completely, between about 500 and 550 K by a process called chain stripping. In commercial PVC compounds the stabilisers delay this, so that hydrogen chloride is not released until above 520 K and the main stage starts at about 600 K.<ref name="BH-126" />		The products of decomposition depend on the polymer. Polyethylene and polypropylene form very little of their original building block, the monomer, and instead release up to about 70 different small molecules, mostly hydrocarbons.<ref name="BH-124" /> PMMA decomposes almost entirely back to its monomer and burns at a very steady rate. For this reason it is a favourite material in fire research.<ref name="BH-125">Beyler and Hirschler (2002), p. 1-125.</ref> PVC first loses its chlorine as hydrogen chloride gas, nearly completely, between about 500 and 550 K by a process called chain stripping. In commercial PVC compounds the stabilisers delay this, so that hydrogen chloride is not released until above 520 K and the main stage starts at about 600 K.<ref name="BH-126" />
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	The rate at which a plastic releases heat matters even more than its energy content. The heat release rate is the main variable that determines how much a material adds to the hazard of a fire in a room.<ref name="J-38" /> In the cone calorimeter, at an irradiance of 40 kW/m² and a thickness of 6 mm, polypropylene reached a peak heat release rate of 1500 kW/m², high-density polyethylene 1400 kW/m² and polystyrene 1100 kW/m².<ref name="BH-124" /> PMMA reached 670 kW/m², PVC 180 kW/m² and PTFE only 13 kW/m². For comparison, values from other sources quoted in the same table are 450 kW/m² for cotton and 310 kW/m² for wool.<ref name="BH-124" /> The handbook warns that the temperature at which a polymer starts to decompose does not on its own predict its fire performance.<ref name="BH-124" />		The rate at which a plastic releases heat matters even more than its energy content. The heat release rate is the main variable that determines how much a material adds to the hazard of a fire in a room.<ref name="J-38" /> In the cone calorimeter, at an irradiance of 40 kW/m² and a thickness of 6 mm, polypropylene reached a peak heat release rate of 1500 kW/m², high-density polyethylene 1400 kW/m² and polystyrene 1100 kW/m².<ref name="BH-124" /> PMMA reached 670 kW/m², PVC 180 kW/m² and PTFE only 13 kW/m². For comparison, values from other sources quoted in the same table are 450 kW/m² for cotton and 310 kW/m² for wool.<ref name="BH-124" /> The handbook warns that the temperature at which a polymer starts to decompose does not on its own predict its fire performance.<ref name="BH-124" />

			[[File:fse-plastics-in-fire-v2.svg\|thumb\|upright=1.5\|alt=Two bar charts: heat of combustion of plastics and red oak, and peak heat release rate in the cone calorimeter for plastics.\|Net heat of complete combustion (left) and peak heat release rate in the cone calorimeter at 40 kW/m² (right) for common plastics. Based on Tewarson (2002), p. 3-108, and Beyler and Hirschler (2002), p. 1-124.]]

	In large fires, the heat released per square metre of burning surface can be estimated from two material properties. The first is the mass loss rate per unit area. The second is the chemical heat of combustion, the heat actually released per gram of material lost in a real fire. The chemical heat release rate is the product of the two:<ref name="T-110">Tewarson (2002), p. 3-110.</ref>		In large fires, the heat released per square metre of burning surface can be estimated from two material properties. The first is the mass loss rate per unit area. The second is the chemical heat of combustion, the heat actually released per gram of material lost in a real fire. The chemical heat release rate is the product of the two:<ref name="T-110">Tewarson (2002), p. 3-110.</ref>
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	The values in ''Introduction to Fire Safety Engineering'' are pre-flashover values, for burning with excess oxygen.<ref name="VR-6.2" /> The NUREG-1805 values come from small-scale tests of turbulent flaming combustion compiled by Klote and Milke.<ref name="KM">Klote and Milke (2002), as cited in Iqbal and Salley (2004), p. 18-4.</ref> In both sources, polystyrene and polyurethane produce roughly 8 to 15 times as much soot per kilogram as wood (calculated). A fire that is smothered, for example by a sprinkler, burns less completely and produces even more soot per kilogram of fuel.<ref name="VR-6.2" />		The values in ''Introduction to Fire Safety Engineering'' are pre-flashover values, for burning with excess oxygen.<ref name="VR-6.2" /> The NUREG-1805 values come from small-scale tests of turbulent flaming combustion compiled by Klote and Milke.<ref name="KM">Klote and Milke (2002), as cited in Iqbal and Salley (2004), p. 18-4.</ref> In both sources, polystyrene and polyurethane produce roughly 8 to 15 times as much soot per kilogram as wood (calculated). A fire that is smothered, for example by a sprinkler, burns less completely and produces even more soot per kilogram of fuel.<ref name="VR-6.2" />

			[[File:fse-plastics-in-fire-v3.svg\|thumb\|upright=1.5\|alt=Bar chart of soot yield: wood 0.015, PMMA 0.022, polypropylene 0.059, ABS 0.105, polystyrene 0.164, flexible polyurethane foam 0.188 kg/kg.\|Soot (particulate) yield of wood and plastics in well-ventilated flaming combustion. Based on Klote and Milke (2002), as cited in Iqbal and Salley (2004), p. 18-4.]]

	== Toxic gases ==		== Toxic gases ==

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FSE wiki: Split an over-long sentence (style check) (written by Claude Opus 5.5)

← Older revision		Revision as of 23:57, 1 November 2026
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	The [[heat of combustion]] of the hydrocarbon plastics is thus about two and a half times that of wood, while chlorine and fluorine lower it. PVC releases about as much heat per kilogram as oak, and PTFE much less.<ref name="T-108" /> ''Introduction to Fire Safety Engineering'' lists a net heat of combustion of 18 MJ/kg for PVC roofing, the same as for beech wood.<ref name="VR-4.4">Van Rossum (2027), §4.4.</ref> In a real fire, combustion is not complete, so the heat actually released is lower than these values.<ref name="VR-4.4" />		The [[heat of combustion]] of the hydrocarbon plastics is thus about two and a half times that of wood, while chlorine and fluorine lower it. PVC releases about as much heat per kilogram as oak, and PTFE much less.<ref name="T-108" /> ''Introduction to Fire Safety Engineering'' lists a net heat of combustion of 18 MJ/kg for PVC roofing, the same as for beech wood.<ref name="VR-4.4">Van Rossum (2027), §4.4.</ref> In a real fire, combustion is not complete, so the heat actually released is lower than these values.<ref name="VR-4.4" />

	The rate at which a plastic releases heat matters even more than its energy content~~, because the~~ heat release rate is the main variable that determines how much a material adds to the hazard of a fire in a room.<ref name="J-38" /> In the cone calorimeter, at an irradiance of 40 kW/m² and a thickness of 6 mm, polypropylene reached a peak heat release rate of 1500 kW/m², high-density polyethylene 1400 kW/m² and polystyrene 1100 kW/m².<ref name="BH-124" /> PMMA reached 670 kW/m², PVC 180 kW/m² and PTFE only 13 kW/m². For comparison, values from other sources quoted in the same table are 450 kW/m² for cotton and 310 kW/m² for wool.<ref name="BH-124" /> The handbook warns that the temperature at which a polymer starts to decompose does not on its own predict its fire performance.<ref name="BH-124" />		The rate at which a plastic releases heat matters even more than its energy content. The heat release rate is the main variable that determines how much a material adds to the hazard of a fire in a room.<ref name="J-38" /> In the cone calorimeter, at an irradiance of 40 kW/m² and a thickness of 6 mm, polypropylene reached a peak heat release rate of 1500 kW/m², high-density polyethylene 1400 kW/m² and polystyrene 1100 kW/m².<ref name="BH-124" /> PMMA reached 670 kW/m², PVC 180 kW/m² and PTFE only 13 kW/m². For comparison, values from other sources quoted in the same table are 450 kW/m² for cotton and 310 kW/m² for wool.<ref name="BH-124" /> The handbook warns that the temperature at which a polymer starts to decompose does not on its own predict its fire performance.<ref name="BH-124" />

	In large fires, the heat released per square metre of burning surface can be estimated from two material properties. The first is the mass loss rate per unit area. The second is the chemical heat of combustion, the heat actually released per gram of material lost in a real fire. The chemical heat release rate is the product of the two:<ref name="T-110">Tewarson (2002), p. 3-110.</ref>		In large fires, the heat released per square metre of burning surface can be estimated from two material properties. The first is the mass loss rate per unit area. The second is the chemical heat of combustion, the heat actually released per gram of material lost in a real fire. The chemical heat release rate is the product of the two:<ref name="T-110">Tewarson (2002), p. 3-110.</ref>

Daan: New FSE wiki article: Plastics in fire (written by Claude Opus 5.5)

2026-11-01T22:56:30Z

New FSE wiki article: Plastics in fire (written by Claude Opus 5.5)

New page

'''Plastics in fire''' describes how synthetic polymer materials, such as polyethylene, polystyrene, polyurethane foam and PVC, behave when they are heated and burn. In the classification of the SFPE Handbook, plastics are polymers that can be deformed only partly reversibly. Thermoplastics soften and may melt when heated, while thermosets change irreversibly and do not melt.<ref name="BH-111">Beyler and Hirschler (2002), p. 1-111.</ref><ref name="BH-112">Beyler and Hirschler (2002), p. 1-112.</ref> Like wood, a plastic burns only after heat has broken it down into combustible gases.<ref name="VR-3.1">Van Rossum (2027), §3.1.</ref><ref name="BH-124">Beyler and Hirschler (2002), p. 1-124.</ref>

Plastics matter in fire safety because they are everywhere in buildings and vehicles and because many of them burn intensely. Polyethylene and polypropylene release more than 43 kJ of heat per gram when burnt completely, about two and a half times as much as wood.<ref name="T-108">Tewarson (2002), p. 3-108.</ref> Many plastics also produce much more soot than wood and so reduce visibility faster.<ref name="VR-6.2">Van Rossum (2027), §6.2.</ref> Plastics that contain nitrogen release hydrogen cyanide, and PVC releases hydrogen chloride.<ref name="P-100">Purser (2002), p. 2-100.</ref><ref name="BH-126">Beyler and Hirschler (2002), p. 1-126.</ref> Their behaviour varies widely, however: some plastics burn fiercely, while others such as PVC and PTFE have a very low peak heat release rate in standard tests.<ref name="BH-124" />

== Types of plastics ==
Polymers are large molecules built from repeating units. The SFPE Handbook classifies them by their physical properties into elastomers, plastics and fibres. Elastomers, or rubbers, can be stretched to several times their length and recover almost completely. Plastics can be stretched by 100 to 200 per cent before they break, and their deformation is only partly reversible.<ref name="BH-111" /> Plastics are further divided into thermoplastics, which soften on heating without permanent change, and thermosets, which undergo irreversible changes when heated.<ref name="BH-111" />

The chemical composition gives a better indication of how a plastic behaves in fire. The main polymers containing only carbon and hydrogen are the polyolefins polyethylene (PE) and polypropylene (PP), and the styrenics such as polystyrene (PS). Polystyrene is widely used as a foam and for injection-moulded products.<ref name="BH-111" />

Oxygen-containing plastics include poly(methyl methacrylate) (PMMA), used for its transparency, and polyesters such as polyethylene terephthalate (PET) and polycarbonate.<ref name="BH-111" /> Nitrogen-containing polymers include nylons, polyurethanes (PU) and polyacrylonitrile; polyurethanes are mainly used as flexible and rigid foams and as thermal insulation.<ref name="BH-111" /> Poly(vinyl chloride) (PVC) contains chlorine. Together with polyethylene and polypropylene it is one of the three most widely used synthetic polymers, both as a rigid and as a flexible, plasticised material.<ref name="BH-112" /> Fluorine-containing polymers such as polytetrafluoroethylene (PTFE) are very inert to heat and chemicals.<ref name="BH-112" />

== How plastics burn ==
Solid plastics do not burn directly. When heated, they undergo [[pyrolysis]]: the large molecules break down into smaller ones, which escape as combustible gases. Pyrolysis needs no oxygen, but the burning of the gases does.<ref name="VR-3.1" /> Burning becomes self-sustaining when the flame feeds enough heat back to the surface to keep producing these gases, a loop of heat, gas release and flame.<ref name="BH-110">Beyler and Hirschler (2002), p. 1-110.</ref> The SFPE Handbook sums this up in one phrase: polymers cannot burn if they do not break down.<ref name="BH-124" />

The products of decomposition depend on the polymer. Polyethylene and polypropylene form very little of their original building block, the monomer, and instead release up to about 70 different small molecules, mostly hydrocarbons.<ref name="BH-124" /> PMMA decomposes almost entirely back to its monomer and burns at a very steady rate. For this reason it is a favourite material in fire research.<ref name="BH-125">Beyler and Hirschler (2002), p. 1-125.</ref> PVC first loses its chlorine as hydrogen chloride gas, nearly completely, between about 500 and 550 K by a process called chain stripping. In commercial PVC compounds the stabilisers delay this, so that hydrogen chloride is not released until above 520 K and the main stage starts at about 600 K.<ref name="BH-126" />

Thermoplastics may melt and flow before they decompose. This can improve or worsen fire safety. A plastic that flows away from the heat source may avoid ignition or further fire growth, but plastic that flows towards the heat source can make the fire worse.<ref name="BH-123">Beyler and Hirschler (2002), p. 1-123.</ref> Polyethylene melts and flows readily, while high-quality cast PMMA flows only slightly.<ref name="BH-123" /> Many standard fire tests let a melting material flow away from the heat source and are therefore unsuitable for assessing the hazard of materials that drip or flow.<ref name="BH-123" /> Thermosets cannot melt, so they undergo no notable physical change before they decompose.<ref name="BH-112" />

Some plastics form a char, a carbon-rich solid residue. A char layer reduces the amount of combustible gas and protects the material below from heat, so it slows down burning.<ref name="BH-123" /> Char is not always an advantage, however: the char itself can keep burning as sustained smouldering combustion.<ref name="BH-123" />

== Heat release ==
The energy content of plastics varies widely. It depends mainly on the elements in the polymer: plastics made of carbon and hydrogen only release the most heat, while oxygen, chlorine and fluorine lower the value. The SFPE Handbook gives the following net heats of complete combustion, measured in an oxygen bomb calorimeter:<ref name="T-108" />

{| class="wikitable"
! Material !! Net heat of complete combustion (kJ/g)
|-
| Polyethylene || 43.6
|-
| Polypropylene || 43.4
|-
| Polystyrene || 39.2
|-
| Expanded polystyrene || 35.6 to 38.1
|-
| Nylon || 30.8
|-
| Rigid polyurethane foams || 25.0 to 28.0
|-
| Flexible polyurethane foams || 23.2 to 27.2
|-
| Poly(methyl methacrylate) || 25.2
|-
| Poly(vinyl chloride) || 16.4
|-
| Polytetrafluoroethylene || 6.2
|-
| Red oak (for comparison) || 17.1
|}

The [[heat of combustion]] of the hydrocarbon plastics is thus about two and a half times that of wood, while chlorine and fluorine lower it. PVC releases about as much heat per kilogram as oak, and PTFE much less.<ref name="T-108" /> ''Introduction to Fire Safety Engineering'' lists a net heat of combustion of 18 MJ/kg for PVC roofing, the same as for beech wood.<ref name="VR-4.4">Van Rossum (2027), §4.4.</ref> In a real fire, combustion is not complete, so the heat actually released is lower than these values.<ref name="VR-4.4" />

The rate at which a plastic releases heat matters even more than its energy content, because the heat release rate is the main variable that determines how much a material adds to the hazard of a fire in a room.<ref name="J-38" /> In the cone calorimeter, at an irradiance of 40 kW/m² and a thickness of 6 mm, polypropylene reached a peak heat release rate of 1500 kW/m², high-density polyethylene 1400 kW/m² and polystyrene 1100 kW/m².<ref name="BH-124" /> PMMA reached 670 kW/m², PVC 180 kW/m² and PTFE only 13 kW/m². For comparison, values from other sources quoted in the same table are 450 kW/m² for cotton and 310 kW/m² for wool.<ref name="BH-124" /> The handbook warns that the temperature at which a polymer starts to decompose does not on its own predict its fire performance.<ref name="BH-124" />

In large fires, the heat released per square metre of burning surface can be estimated from two material properties. The first is the mass loss rate per unit area. The second is the chemical heat of combustion, the heat actually released per gram of material lost in a real fire. The chemical heat release rate is the product of the two:<ref name="T-110">Tewarson (2002), p. 3-110.</ref>
<math display="block">\dot{Q}''_\mathrm{ch} = \dot{m}'' \, \Delta H_\mathrm{ch}</math>

{| class="wikitable"
! Symbol !! Description !! Unit
|-
| <math>\dot{Q}''_\mathrm{ch}</math> || chemical heat release rate per unit area of burning surface || kW/m²
|-
| <math>\dot{m}''</math> || mass loss rate per unit area || g/(m²·s)
|-
| <math>\Delta H_\mathrm{ch}</math> || chemical heat of combustion || kJ/g
|}

The SFPE Handbook applies this relation to the steady mass loss rates expected in large, well-ventilated fires.<ref name="T-110" /> For polyethylene, the expected mass loss rate is 26 g/(m²·s) and the chemical heat of combustion 38.4 kJ/g, so the heat release rate is 26 × 38.4 = 998 kW/m². Polystyrene gives 36 × 27.0 = 972 kW/m².<ref name="T-110" /> PVC, by contrast, gives only 16 × 5.7 = 91 kW/m², and FEP Teflon 7 × 4.1 = 28 kW/m².<ref name="T-110" /> For PVC, the chemical heat of combustion is only about a third of its heat of complete combustion, while for polyethylene it is close to 90 per cent (calculated).<ref name="T-108" /><ref name="T-110" /> The relation describes a fire that is not limited by its air supply; in a ventilation-controlled fire, combustion is less complete.<ref name="T-110" />

Plastics have changed the fire load of everyday objects. A study for the Netherlands Institute for Public Safety notes that modern cars, with their high plastic content, have a greater fire load and a higher heat release rate than older steel models. In indoor car parks this leads to very high temperatures and dense black smoke.<ref name="NIPV-11">Van der Graaf et al. (2021/2023), p. 11.</ref> ''Introduction to Fire Safety Engineering'' notes for the same reason that the design fire curves for cars in Dutch car park standards may be less conservative in some situations.<ref name="VR-8.6">Van Rossum (2027), §8.6.</ref>

== Smoke and soot ==
Plastics are major producers of smoke. The production of [[soot]] depends on the fuel and on the combustion conditions: plastics produce relatively much soot, wood much less, and ethanol very little.<ref name="VR-6.2" /> The soot yield is the mass of soot produced per mass of fuel burnt. Two sources give the following values for well-ventilated flaming combustion:

{| class="wikitable"
! Material !! Soot yield, ''Introduction to Fire Safety Engineering'' (kg/kg) !! Particulate yield, NUREG-1805 (kg/kg)
|-
| Wood || 0.015 || 0.015 (red oak)
|-
| Poly(methyl methacrylate) || – || 0.022
|-
| Polypropylene || – || 0.059
|-
| Acrylonitrile-butadiene-styrene (ABS) || – || 0.105
|-
| Poly(vinyl chloride) || 0.14 || –
|-
| Polystyrene || 0.16 || 0.164
|-
| Expanded polystyrene || 0.195 || –
|-
| Polyurethane || 0.23 || 0.188 (flexible foam), 0.118 (rigid foam)
|}

The values in ''Introduction to Fire Safety Engineering'' are pre-flashover values, for burning with excess oxygen.<ref name="VR-6.2" /> The NUREG-1805 values come from small-scale tests of turbulent flaming combustion compiled by Klote and Milke.<ref name="KM">Klote and Milke (2002), as cited in Iqbal and Salley (2004), p. 18-4.</ref> In both sources, polystyrene and polyurethane produce roughly 8 to 15 times as much soot per kilogram as wood (calculated). A fire that is smothered, for example by a sprinkler, burns less completely and produces even more soot per kilogram of fuel.<ref name="VR-6.2" />

== Toxic gases ==
All fires produce carbon monoxide, but some plastics add specific toxic gases. [[Hydrogen cyanide]] is always present to some extent when nitrogen-containing materials burn, such as acrylics, polyurethane foams, melamine, nylon and wool. High concentrations are likely in large post-flashover fires.<ref name="P-100" /> PVC releases hydrogen chloride as it decomposes, and acid gases such as hydrogen chloride are among the most important irritants in smoke.<ref name="BH-126" /><ref name="P-91">Purser (2002), p. 2-91.</ref> PTFE produces carbonyl fluoride, a highly toxic lung irritant.<ref name="P-87">Purser (2002), p. 2-87.</ref> In vehicle fires, the burning plastic parts already create severely toxic smoke, which seriously limits the possibilities for escape.<ref name="RISE">RISE (2020), as cited in Van der Graaf et al. (2021/2023), p. 30.</ref>

The SFPE Handbook compares the toxicity of the smoke of material classes with a potency factor, where 1 corresponds to a typical lethal exposure dose of about 500 g·m<sup>−3</sup>·min.<ref name="P-98">Purser (2002), p. 2-98.</ref> In non-flaming decomposition, most materials have a factor close to 1. Nitrogen-containing materials that release much hydrogen cyanide at low temperatures, such as polyacrylonitrile and rigid polyurethane foam, reach 3 to 8.<ref name="P-98" />

In early, well-ventilated flaming fires, wood and cotton are the least toxic, with a factor of 0.2. Plastics containing only carbon, hydrogen and oxygen have a factor of about 0.4, and PVC and fire-retarded materials about 1.<ref name="P-98" /> After flashover, the potency of all materials rises. For nitrogen-containing materials it ranges from about 2.5 for flexible polyurethane foam to about 11 for polyacrylonitrile, and PVC is suggested to reach about 2.5.<ref name="P-98" />

== Flame retardants ==
A [[flame retardant]] is added to a plastic to change the way it decomposes and burns, and its effect depends on chemistry and timing. In thermal analysis, the overlap between the decomposition stages of the polymer and of the additive indicates how effective an additive is.<ref name="BH-115">Beyler and Hirschler (2002), p. 1-115.</ref> The mechanisms and likely effectiveness of flame retardants can therefore be predicted well from thermal decomposition data.<ref name="BH-124" /> In one example from the SFPE Handbook, a bromine compound in ABS worked together with antimony oxide, because the antimony bromide formed could evaporate. The same compound was ineffective with iron oxide, whose bromide does not evaporate, and with zinc oxide, whose bromide evaporates before the polymer starts to break down.<ref name="BH-124" />

Flame retardants involve a trade-off. Many treatments increase the yield of toxic gases per gram of material but greatly reduce the rate at which the material burns, so that the overall fire hazard falls.<ref name="J-38">Janssens (2002), p. 3-38.</ref> In full-scale tests with upholstered chairs, fire-retarded covers increased the time before conditions became untenable through asphyxiant gases by about 1.5 minutes.<ref name="P-140">Purser (2002), p. 2-140.</ref> The handbook concludes that some modern materials and fire retardant systems may present toxic or environmental problems, but give considerable overall benefits if they reduce the number of fires and slow fire development.<ref name="P-140" />

== Plastics in buildings and regulation ==
[[Building regulations]] can limit the use of combustible linings through reaction-to-fire classes. In New Zealand, lining materials are classified by the time to flashover in a full-scale room test. Exposed polyurethane foams reach flashover within two minutes and fall into the worst class, Group Number 4, which is not acceptable in occupied spaces.<ref name="CVM2C-141">Ministry of Business, Innovation and Employment (2013), p. 141.</ref> Some plastic-containing products cannot be judged with small-scale tests. The New Zealand commentary names metal-faced [[sandwich panel]]s and foil-faced combustible insulation as products for which the small-scale correlation does not work.<ref name="CVM2C-141" />

== Limits and common misconceptions ==
A common misconception is that all plastics behave alike in a fire. The data above show that peak heat release rates in the cone calorimeter range from 13 to 1500 kW/m², and heats of combustion from 6.2 to 43.6 kJ/g.<ref name="BH-124" /><ref name="T-108" /> PVC is an example of a plastic with a low heat release rate but an important release of hydrogen chloride.<ref name="BH-124" /><ref name="BH-126" />

A second misconception is that a single property, such as the limiting oxygen index or the decomposition temperature, describes fire performance. The SFPE Handbook notes that the oxygen index technique has fallen into disrepute and that thermal decomposition data alone cannot predict fire performance.<ref name="BH-124" /> Toxicity data are also limited: the handbook calls the database of toxic potency tests very poor, especially for post-flashover conditions.<ref name="P-98" /> Values for soot yield and toxicity depend strongly on the fire conditions, and the same material gives different results in well-ventilated and in smothered fires.<ref name="VR-6.2" /><ref name="P-98" />

== See also ==
* [[Euroclass system]]
* [[Fire resistance test]]
* [[Combustibility]]
* [[Cone calorimeter]]

== Notes ==
<references />

== References ==
* Beyler, C. L., & Hirschler, M. M. (2002). Thermal decomposition of polymers. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 1-110–1-131). National Fire Protection Association; Society of Fire Protection Engineers.
* Iqbal, N., & Salley, M. H. (2004). ''Fire Dynamics Tools (FDTs): Quantitative fire hazard analysis methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program'' (NUREG-1805). U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation.
* Janssens, M. (2002). Calorimetry. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 3-38–3-62). National Fire Protection Association; Society of Fire Protection Engineers.
* Ministry of Business, Innovation and Employment. (2013). ''Commentary for Building Code clauses C1–C6 and Verification Method C/VM2''.
* Purser, D. A. (2002). Toxicity assessment of combustion products. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., & J. M. Watts Jr. (Eds.), ''SFPE handbook of fire protection engineering'' (3rd ed., pp. 2-83–2-171). National Fire Protection Association; Society of Fire Protection Engineers.
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[[Category:Materials & Fire Testing]]