Flame Retardants Frequently Asked Questions
The European Flame Retardants Association EFRA - The European Flame Retardants Association
Chemistry making a world of difference
Compiled and edited by Adrian Beard, Clariant, fire test photos by Ralf Baumgarten taken at Siemens Brandversuchshaus in Frankfurt- Hoechst and BayerIndustryServices Fire Test Laboratory in Leverkusen. We thank the teams of Knut Bauer and Michael Halfmann for their help and technical assistance.
Cover photos: Candles are a common cause of ignition for domestic fires. The stereo shown on the front cover is engulfed in flames after 7 minutes when ignited with a small flame - see the photo on the back cover. Contents
Flame Retardants Frequently Asked Questions
Flame Retardants - General Aspects 2
General Fire Safety 4
Fire Safety Standards and Regulations 8
Flame Retardants and other Safety Technologies 12
Flame Retardant types and applications 14
Brominated Flame Retardants (BFRs) 16
Flame Retardants based on Phosphorus Compounds (PFRs) 18
Mineral flame retardants 20
Nitrogen-containing Flame Retardants 22
Other Flame Retardants - Borates, Stannates, ... 24
Flame Retardants - Health and the Environment 26
Recycling and Waste Management of Flame Retardants 32
Common Abbreviations for Flame Retardants 35
Literature and Further Reading 36
EFRA Members 37
1 Flame Retardants Frequently asked Questions
Flame Retardants - General Aspects
What are flame retardants?
Flame retardants are chemicals which are added to combustible materials to render them more resistant to ignition. They are designed to minimise the risk of a fire starting in case of contact with a small heat source such as a cigarette, candle or an electrical fault. If the flame retarded material or an adjacent material has ignited, the flame retardant will slow down combustion and often prevent the fire from spreading to other items. Since the term “flame retardant” describes a function and not a chemical class, there is a wide range of different chemicals which are used for this purpose. Often they are applied in combinations. This variety of products is necessary, because the materials and products which are to be rendered fire safe are very different in nature and composition. For example, plastics have a wide range of mechanical and chemical properties and differ in combustion behaviour. Therefore, they need to be matched to the appropriate flame retardants in order to retain key material functionalities. Flame retardants are thus necessary to ensure the fire safety of a wide range of materials including plastics, foam and fibre insulation materials, foams in furniture, mattresses, wood products, natural and man-made textiles. These materials are e.g. used in parts of electrical equipment, cars, airplanes and building components.
2 tronic equipment where the accel- litres of petrol? Flame retardants erating processor power, electronic can be applied to many different sophistication but at the same time flammable materials to prevent a miniaturisation, result in a concen- fire or to delay its start and propa- tration of energy and an increase in gation by interrupting or hindering risks of local overheating or other the combustion process. They thus electrical fire risks. Flame retardants protect lives, property and the en- can prevent an increase in fire risk vironment. Flame retardants con- from the growing number of con- tribute to meeting high fire safety sumer and electronic goods in hom- requirements for combustible ma- es and offices. Flame retardants terials and finished products pre- protect modern materials such as scribed in regulations and tests. Al- technical plastics, building insula- though fire safety can be achieved tion, circuit boards and cables from by using non-combustible materials igniting and from spreading a fire. in some cases or by design and en- gineering approaches, the use of Once a fire starts in a room of a flame retarded materials often house, it can develop rapidly, if it meets the functionality and aesthet- spreads to items other than that ic requirements of the consumer as first ignited. Once a number of well as offering the most econom- items are burning, the temperature ical approach. in the room will rise, and may reach "flash over" point, when hot burn- ing gases cause effectively the whole Examples: room to catch light, often violently. Once this occurs, escape from the Metal casings for electrical equip- room is impossible, and spread of ment afford fire safety, but pose the fire to other rooms is very likely. electrical risks, as well as being Flame retardants act both by pre- heavier, more expensive and less venting the initial start of a fire by design flexible than modern plas- impeding ignition and by delaying tics. the spread of the fire, thus increas- ing escape time, and perhaps pre- An increasing use of plastics in venting "flash over". cars, trains and aeroplanes offers lower weight and so improved fuel economy, but necessitates What are the benefits of flame retar- flame retardants to ensure fire dants? safety.
Most people do not realise that their Mineral fibres for building insul- television set, sofa, mattress and ation are not flammable, but may Why do we need flame retardants? computer are all made essentially not offer the same energy perfor- from plastics (originally made from mance, structural characteristics Both our homes and offices contain crude oil), and without the inclusion or flexibility of application as poly- an increasing potential "fire load" of flame retardants many of these mer foams. of flammable materials because of products can be set alight by just a the development of electrical and short circuit or cigarette and be- Even where non-flammable mate- electronic equipment, and of rising come a burning mass in just a few rials such as steel are used, flame levels of comfort (furniture, carpets, minutes. Did you know for example, retardant intumescent coatings can toys, magazines and papers ...). that a regular TV set contains in its provide valuable heat protection for The potential causes of fires also combustible plastics an energy con- these to limit or delay mechanical tend to increase, especially in elec- tent which is equivalent to several deterioration in the case of fire.
3 Flame Retardants Frequently asked Questions
General Fire Safety
How large is the number of victims from fires?
Statistics show that generally between 10 and 20 fire deaths per 1 000 000 inhabi- tants are reported in the major industrial countries of the world. The number of severely injured people is estimated at ten times this figure, i.e. 100 to 200 per 1 000 000 inhabitants per year. Every day in Europe there are about 12 fire victims and 120 people severely injured. About 80 % of all fire deaths occur in residential buildings. The people most at risk are the very young and the elderly because they are least able to escape in the event of a fire.
www.flameretardants.eu/pdf/0602/fire_stat0602.pdf and World Fire Statistics www.genevaassociation.org
4 What is the most common cause of death in fires?
The most common cause of death in fires is to be overcome by gas or smoke: In the UK, around 50 % of people die this way, while 25 % of deaths are due to burns and 20 % are attributed to both burns and being overcome by gas or smoke. 5 % of fire deaths cannot be speci- fied. Accidental fires in the home have far higher casualty levels than any other location.
Why are fire gases toxic?
Fires gases are toxic, because in all Besides these volatile gases, some fires toxic products are formed from more complex products are formed the incomplete combustion of or- like polycyclic aromatic hydrocar- ganic materials like plastics, wood, bons (PAHs) or halogenated dioxins textiles and paper. The component and furans (PXDD/F). These pro- which usually dominates the toxicity ducts are formed in much lower of fire effluents is carbon monoxide quantities and are not relevant for (CO), which is responsible for over acute toxic effects but they can have 80 % of all people killed by fire gas- long term health effects. However, es. One striking example is the Düs- because they are higher molecular seldorf Airport fire in 1996: here, all weight substances, they are mostly 17 fire deaths were due to CO poi- adsorbed to soot which reduces soning. By delaying the combustion their toxic potential. The polycyclic of treated materials and the spread aromatic hydrocarbons are typical of the fire, flame retardants signifi- products from incomplete combus- What is the economic damage cantly reduce the emissions of toxic tion of organic materials and they caused by fire? gases. dominate the long-term toxicity of Besides CO, many other toxic com- soot. The conclusion from many The total economic damage is esti- ponents can be formed in a fire: studies carried out on this subject mated at about 25 billion € per year Hydrogen cyanide (HCN) may be is that although the substances in Europe. In Germany alone, com- formed from plastics like polyur- emitted from fires are very variable, pensation costs covered by insur- ethane and polyamide as well as depending on fire conditions, the ance companies amount to 1.5 bil- from natural products which con- toxicity is above all a function of the lion € per year and there are about tain nitrogen like wool and leather. quantity of material burned. 200 major fire incidents with dam- Irritant fire gas components are ages in excess of 0.5 million €. hydrogen chloride (HCl) evolving from plastics like PVC and acrolein www.flameretardants.eu/pdf/ www.gdv.de, www.nfpa.org (USA) released from natural products like babrauskas_summary.pdf wood. However, compared to the toxic potential of CO, which is pre- www.flameretardants.eu/pdf/ sent in large quantities in all fires, prison_mattress.pdf the other fire gas components usu- www.sp.se/fire/Eng/Research/ ally only play a minor role. Fire_LCA_study_TV.pdf
5 Flame Retardants Frequently asked Questions
Does the presence of flame retar- release. The impact of flame retar- dants increase the toxicity of dants on smoke or fire gases also smoke? depends on the proportion of flame retarded material to the total fire This is a concern which is often load. Room fire tests which com- raised. It is based on the fact that pared a room with non flame retar- some flame retardants act by im- ded materials to a room with flame peding the combustion reactions retarded items (TV cabinet, busi- in the gas phase and therefore lead ness machine housing, upholstered to incomplete combustion which chair, electrical cables, electrical in turn means a smoky fire. circuit board) revealed: However, large scale studies have demonstrated that the toxic hazards The total quantities of toxic gases from a fire are more dependant on released by the FR products was how much is burning under which one third that for the non FR. conditions of temperature and ven- tilation rather than what is burning. Total smoke production was not Two cases can be considered: significantly different.
1. The flame retarded (FR) material "Because the total quantities of is subject to the primary ignition material consumed in the full- source: if this is a small flame or room tests with FR products are other low energy source like a cig- much lower than with non FR pro- arette butt, the presence of flame ducts, the total carbon monoxide retardants in the material may cause [the dominant toxic fire gas] emis- it to smoulder and smoke some- sions are thus around half with what, but will severely impede igni- the flame retarded products, sig- tion and in most cases no fire will nificantly reducing the fire haz- develop. If burning is sustained, the ard." release of heat and the spread of (Source: Babrauskas V. et al. (1988) flames will be severely hindered by Fire Hazard Comparison of Fire-Retar- flame retardants allowing people ded and Non-Fire-Retarded Products. more time to escape from the fire. NBS special publication SP 749. NIST, The most significant reduction in USA) toxic gases from fires is achieved by actually preventing the fire, or Therefore, it is clear that because preventing it from spreading from flame retardants reduce the number one item to a whole room. and extent of fires, they can signi- ficantly reduce both the total levels 2. The flame retarded material is of such toxic gases in a given fire not the first item ignited but is invol- and the total emissions from all ved in a fire that is already develop- fires. This has been investigated ing: In this case flame retardants and proven for television sets and cannot prevent the ignition of the upholstered furniture in life cycle material and it will eventually be assessment studies (www.sp.se/fire). thermally degraded or burn. How- Please see the EFRA website for ever, flame retardants will reduce detailed information and references. the rate of flame spread and heat
6 fully developed fire temperature
initiation of fire
time start of fire flash over after < 10 min
How does a fire develop?
A fire can basically be split into three fire. The fire spreads, heats up the oped fire, where temperatures up phases, the initiating fire, the fully surroundings and once the materi- to 1 200 °C can be reached. The fire developed fire and the decreasing als in the room have formed enough will later decrease as the available fire. The fire starts with an ignition flammable gases and are sufficiently fire load is consumed by the fire or source (for example a match) set- hot, flashover takes place and the if the fire occurs in a totally closed ting combustible material (for ex- whole room is engulfed in the fire. room the fire can die because of ample an upholstered armchair) on This is the start of the fully devel- oxygen deficiency.
The fundamental parameters go- paper - on the other hand, there are verning a fire are: materials which are difficult to ignite Heat but once ignited will release a large Combustibility: Will a material amount of energy like diesel fuel or Heat transfer burn? many plastics. In addition, in all fires secondary effects occur. These Ignitability: If it is combustible, do not primarily determine the Heat transfer Fire how and when will it ignite? course of the fire, but cause most of the fire deaths or damage to ma- Spread of flame: Once ignited, terials. These effects are: Fuel Air Mixing of fuel and air how quickly will the flames spread? Smoke development Fire Triangle (according to Emmons) Heat release: What will be the Fire gas toxicity What are the parameters governing rate and total amount of heat a fire? released? Corrosivity and contamination by soot (more relevant to ma- The fire triangle indicates where On the one hand, there are mater- terials than to humans and par- flame retardants can interfere in the ials that are easily ignitable but have ticularly sensitive for electronic combustion process. a relatively small energy content like equipment)
7 Flame Retardants Frequently asked Questions
Fire Safety Standards and Regulations
What is the role of fire safety regulations?
Fire safety regulations aim at preventing fires and saving lives and property. Fire safety regulations exist for building, transportation (road and rail vehicles, aircraft and ships), electrical engineering & electronics as well as for furnishings and textiles. One example for the benefits of fire safety regulations is the introduction of the United Kingdom Furniture and Furnishings (Fire Safety) Regulations in 1988. The strict requirements on the fire performance of upholstered furniture which these regulations stipulated were often met by using flame retardants. Taking into account changes in smoking habits and increased installation of smoke alarms, these regulations were estimated to be saving more than 230 lives and 4 200 injuries per year by 2002 (see graph on opposite page). A study carried out for the French association of Burns Victims (ABF) indicates that a fire safety requirement for furniture would save, in the long term, 210 lives/year and result in net economic benefits of over 700 million €/year
“Preliminary Legal and Socio-Economic Study for the Projected Decree on Fire Safety Standards for Upholstered Furniture”, C. Chevalier for Association des Brûlés de France, July 2005 www.acfse.org/research2.htm
8 total deaths per million population related to smoke from burns from first ignition in upholstery 20 18 16 14 12 10 8 6 4 2 deaths per million population year 0 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Source: “International Fire Statistics and the Potential Benefits of Fire Counter-Measures”, A. Emsley et al., University of Surrey, UK, 2005. Available at www.cefic-efra.org
What are fire safety requirements? In Europe, the two fields where national requirements are still used, Fire safety requirements are contain- building and railways, are being ed in regulations, technical guide- harmonised in the framework of the lines, safety standards and approval European Union. However in the procedures. Today, they cover field of upholstered furniture, the finished products rather than single national regulations of the UK and materials and allow their classifi- Ireland provide the highest levels cation by the use of specific fire of fire safety. tests. Fire safety requirements are In continental Europe efforts to becoming more and more introduce such strict requirements international: on a European level still continue.
Requirement Examples
General safety EU General Product Safety Construction Products regulations Directive 2001/95/EC Directive 89/106/EC
Product standards IEC 60065 for television sets EN 13162 ... 13171 for and other audio / video thermal insulation products for buildings
Fire test standard UL 94 flammability standard Single Burning Item Test, EN 13823
9 Flame Retardants Frequently asked Questions
What is the role of fire tests?
The role of fire tests is to determine formance is determined. Fire tests requirements defined in the tests. the fire risk of materials and finished were developed to simulate the The sample size can vary from a products used in applications like ignition behaviour of materials or small strip of material (e.g. 12.7 cm building, transportation, electrical even real fire events, which are x 1.27 cm; for the UL 94 test) up to engineering and furniture. They are thought to be particularly harmful boards of 1.5 x 1.5 m2 (SBI-Test), the basis upon which a material's to humans and property. The individual furniture items or even flammability or a product's fire per- products have to meet fire safety complete furnished rooms.
Recent improvements in fire safety standards
In 2006, the United States adopted posed rulemaking for fire safety of Improved standards for furniture a federal regulation requiring strict upholstered furniture and for bed- and mattresses have recently been mattress fire safety for all mattres- clothes. developed: in Sweden, 2002, fire ses sold in the USA from July 2007 requirements for mattresses for (flame resistance and limited heat In Europe, the companies Philips, high risk health institutions and emission). The US Consumer Pro- Panasonic, Finlux and Sony volun- prisons (standard SS 876 00 10); in duct Safety Commission estimates tarily announced in 2004 that all France, 2006, revised fire safety that 240-270 lives and 1 150 - 1 330 their TV sets sold in Europe will in standards for seats in public places injuries per year will be saved, and future be ignition resistant (Article AM 18, Norme NF D calculate a net benefit to society of (www.acfse.org). Unlike generally 60013). US$ 820 million/year. The USA has in Europe, TV sets sold on the US also issued advance notice of pro- market are already ignition resistant.
10 Transportation Are there ways to meet fire safety levels without using flame retar- - Automotive: FMVSS 302 dants? (Federal Motor Vehicle Safety Standard, USA) Yes, there are: safety standards and - Railways: Different national fire tests do not prescribe how to tests and pending new harmo- reach the necessary fire perform- nised European tests ance. For example, a manufacturer (EN TS 45545) can choose a non-combustible ma- - Aircraft: Various Bunsen burner terial like steel for an equipment tests, OSU (Ohio State Univer- housing, or engineering design ap- sity) heat release and kerosene proaches are stipulated in some burner seat tests standards which waive the need for fire proof materials if certain safety distances are kept from potential What are the most important fire Electrical Engineering &