The authors asserted that fire retarding flexible polyurethane foam did not increase its acute or chronic toxicity when compared to non-fire retarded flexible foam. Both of the materials showed a clear relationship with the HCN yield increasing with . The full size ISO 9705 test resulted in well-ventilated flaming ( 0.260.5) due to the relatively large volume of air and relatively small sample size. \( \phi =\frac{actual\; fuel\;to\; air\; ratio}{stoichiometric\; fuel\;to\; air\; ratio} \). The radiant heat apparatus, smoke chamber and controlled atmosphere cone calorimeter produced much lower CO yields than would be expected for under-ventilated flaming. Fire and Materials 16:p3743, Barbrauskas V, Harris RH, Gann RG, Levin BC, Lee BT, Peakcock RD, Paabo M, Twilley W, Yoklavich MF, Clark HM (1988) Fire hazard comparison of fire-retarded and non-fire-retarded products, Special Publication 749. This value decreased to 18mgg1 at ~2.0. At 1000C the hydrogen cyanide produced accounted for a range of between 3.8 and 7.3% by weight. Summing these contributions generates a fractional effective dose (FED). CO and HCN are the main asphyxiants produced during the combustion of polyurethanes and there have been a large number of studies published regarding their yields. In addition totheir flammability, polyurethanes form carbon monoxide, hydrogen cyanide and other toxic products on decomposition and combustion. During polymerisation, isocyanates undergo a number of distinct reactions. 1982) to that of a large scale test room. Do memory foam mattresses give off toxic fumes? Acrolein and formaldehyde are formed especially from cellulosic materials under non-flaming decomposition conditions, but products of vitiated combustion contain other organic irritants. Aromatic isocyanates are more reactive than aliphatic isocyanates due to the electronic effects of the aromatic ring. While the link between CO yield and equivalence ratio is well established, the yield of HCN in ventilation limited conditions shows more complicated behaviour for polyurethanes. This makes foam mattresses very harmful. This is when flame retardant chemicals were added to the foam or coverings to stop the furniture from burning so ferociously. Will polyurethane melt under heat? - remodelormove.com It is inexpensive and easy to install, however, it is a severe fire risk and requires a thermal barrier to make it safe. 9). Paabo and Levin (1987) reviewed the literature of the toxic product generated by the combustion of rigid polyurethane foams. In some bench-scale apparatus the heat flux is constant, and often insufficient to sustain flaming at such low oxygen concentrations; further, an unknown quantity of fresh air bypasses the fire plume, so the ventilation condition, and hence, remains undefined. The CACC and SDC show reasonable agreement for well-ventilated burning, but fail to replicate the more hazardous under-ventilated fire conditions. When polyurethane foam is burned, it gives off a wide variety of potentially harmful substances. Fire Technology 51:p318, Blomqvist P, Lonnermark A (2001) Characterization of the combustion products in large-scale fire tests: comparison of three experimental configurations. ISO/TS 19700 (2013) Controlled equivalence ratio method for the determination of hazardous components of fire effluents the steady state tube furnace. Fire Safety Science Proceedings of the ninth international symposium. Google Scholar, Allan D, Daly J, Liggat JJ (2013) Thermal volatilisation analysis of TDI-based flexible polyurethane foam. Fire Hazards Of Polyurethane Foam - Klausbruckner PDF CORE - Aggregating the world's open access research papers 4 1985 and Levin et al. The half-scale ISO 9705 experiments showed a wider range of ventilation conditions up to ~2.0. As the availability of oxygen becomes lower in proportion to the amount of fuel, the yields of certain toxic gases will increase. Oxygen depletion can be lethal if the oxygen concentration falls below tenable levels (~6%). This can result from exposure to radiant and convected heat; visual obscuration due to smoke; inhalation of asphyxiant gases; and exposure to sensory/upper-respiratory irritants. However, the presence of Cu2O reduced the HCN generated by the flexible polyurethane foam by 70-90% at low temperatures. p 111711128. (PDF) The fire toxicity of polyurethane foams - ResearchGate Thermal Decomposition of Polyether-based, Water-blown Commerical type of Flexible Polyurethane Foam. P.J. Polyurethane and other organic foam materials are finding increased use on vessels because of their excellent insulating properties and light weight. . Three Massachusetts Home Fires Linked to Spray-Foam Installation The increased yield of HCN for the CMHR-FPUR between 650C and 850C is likely due to the increased fragmentation of nitrogenous organic compounds in the flame, similar to the behaviour during non-flaming combustion in air reported by Woolley et al. Toxicology 115:7, Henneken H, Vogel M, Karst U (2007) Determination of airborne isocyanates. A large number of studies have been performed over the last 50years to understand the thermal decomposition of polyurethane materials, and as a result of this the mechanism of their decomposition in inert-atmospheres is fairly well understood. While several authors work has focused primarily on the nitrogenous products of decomposition, other publications have focused on the production of other compounds such as carbon monoxide. A more recent review, by Levchik and Weil (2004), assessed the decomposition, combustion and fire-retardancy of polyurethanes. Since serious fires involving the use of these materials have occurred on several ships, the United States Coast Guard has issued a Navigation and Vessel Inspection Circular No. 1982), a developmental method (SwRI/NIST method) which used a radiant heater on the sample which lead into a 200 L exposure chamber, a cone calorimeter (ISO 5660 2002), a furniture calorimeter (as described in Babrauskas et al. Since then, Blais and Carpenter (2015) investigated a flexible polyurethane foam with and without a chloro phosphate (tris-dichloro-propyl phosphate TDCPP) fire retardant using a smoke box (ISO 56592 2012) to assess the toxicity. Therefore, in certain conditions, polyurethanes foams can reach their auto-ignition temperature and ignite which will significantlyalter the effect the decomposition mechanisms and resulting products. Elemental analysis of the polymers showed that the CMHR-FPUR contained 8.22% nitrogen by weight and the PIR contained 6.15% nitrogen by weight. Faster. Isocyanate structure also affects the reactivity of the isocyanate group. Conversely, nitric oxide gas at low concentrations(~20 ppm) has been used to aid breathing in the treatment of respiratory disorders (Kavanagh & Pearl 1995). The Purser model, presented in equation1, uses \( {\mathrm{V}}_{{\mathrm{CO}}_2} \) a multiplication factor for CO2 driven by hyperventilation, therefore increasing the FED contribution from all the toxic species, and incorporates an acidosis factor A to account for toxicity of CO2 in its own right (ISO 13344 1996). Others, such as the NF X 70100, and the ISO/TS 19700 SSTF use the furnace temperature setting to ensure a consistent radiant heat flux. However, in the field of combustion toxicity testing, this under-ventilated burning is the most difficult to create using bench-scale apparatus. The products generated in the flame zone then pass through the heated furnace tube, maintaining a high temperature, as in the upper layer of a compartment fire. This char can decompose further, leaving behind a residue at >800C, to produce simple organic fragments and some polycyclic aromatic hydrocarbons (PAHs). (3) Polyurethane foam mattresses, dubbed "solid gasoline", can give off toxic fumes that may be linked to short- and long- term health conditions. The higher flammability of these new furniture products took people by surprise, and has been blamed for an increased number of serious fires and a tripling of fire deaths over 20years (Fig. At this temperature around one third of the compounds mass was lost as volatile products, and the regenerated alcohol products were mainly present in the residue of the sample. The standard specifies four test conditions, but fails to link them to particular fire scenarios. Draeger tubes), conventional or Fourier transform infrared spectroscopy (FTIR) gas analysis, despite significant problems of reproducibility. But the amount & rate of release are affected . Journal of Fire and Materials 4:p5058, Farrar DG, Hartzell GE, Blank TL, Galster WA (1979) Development of a protocol for the assessment of the toxicity of combustion products resulting from the burning of cellular plastics, University of Utah Report, UTEC 79/130; RP-75-2-1 Renewal, RP-77-U-5. In the UK, the rapid rise in fire deaths, in particular those from smoke toxicity, between the late 1950s and the early 1980s has been attributed to the rapid growth in low cost polyurethane foam furniture, with superior comfort and lower cost than the natural fillings that preceded it. Bench-scale methods used for generating toxic effluents from polyurethane foams have met with controversy. Equation Early work by Voorhees (1975) identified what they described as extreme toxicity of the combustion products of a phosphate fire retarded polyurethane foam. p 102-120. The yields of CO and HCN at varying and temperature are presented in Table5. The authors intended to compare the HCN yields for the non-flaming and flaming combustion of the foam in a smoke chamber apparatus (as described in Levin et al. 2012). Equation Material composition, temperature and oxygen concentration are normally the most important. The authors noted that the polyester polyols were more stable than the polyether polyols, with the latter fragmenting at a lower temperature (300400C). At a CO concentration of 10 ppm, impairment of judgement and visual perception occur; exposure to 100 ppm causes dizziness, headache, and weariness; loss of consciousness occurs at 250 ppm; and 1000 ppm results in rapid death. The relativelyhigh yields of CO from under-ventilated fires are held responsible for most deaths through inhalation of smoke and toxic gases. The average combined yield of isocyanates recovered was 0.869mgg1 and the average yield of amines and aminoisocyanates was 0.321mgg1. The toxic effect of carbon monoxide is characterised by a lowered oxygen-delivery capacity of the blood, even when the partial pressure of oxygen and the rate of blood flow are normal. Recent work by Allan et al. The authors noted that the yields of CO during the well-ventilated testing were higher than expected for both materials, and attributed this to the possible presence of gas phase free radical quenchers, such as halogens or phosphorous containing flame retardants, which would reduce the conversion of CO to CO2 (Schnipper & Smith-Hansen 1995). Preliminary calculations suggested that 27% of the TDI should be recovered as DAT. 6 Sources of Toxic Chemicals (VOCs) in Your Home The yields of toxic products followed the expected trend of being higher in the under-ventilated conditions. It has been designed to generate data for input to fire hazard assessments, using the methodology in ISO 13344 (1996) and ISO 13571 (2012), particularly in relation to the ISO fire stages. Some methods have proved incapable of properlyreplicating the most toxic under-ventilated fire condition, where the yields of carbon monoxide and hydrogen cyanide are greatest, while other methods have shown good correlation with large scale test data. Polyurethane foam, when burnt, gives off: Sulfuric acid Cyanide gas Ethane Phosphine. For the range of materials investigated, the authors also noted that those containing fire retardants (including the CMHR-PUF and PIR) resulted in a higher recovery fraction of fuel N as HCN. Both types of foam yielded very similar products at temperatures above 600C. The authors noted no significant difference in the range of yields of isocyanates detected in either well- or under-ventilated conditions with a range of 1.0-1.6mgg1. The polyisocyanurate, on the other hand, produced slightly more HCN than the rigid foam (17mgg1 vs 12mgg1). Cyanide gas. The flexible foam produced ~175mgg1 of CO and 5mgg1 of HCN. These processes occur at around 300C with the precursor chemicals including TDI, MDI, HDI, polyols (both polyether and polyester-polyols) and aromatic amines. These substances can include carbon dioxide, carbon monoxide, formaldehyde, aldehydes, and other volatile organic compounds (VOCs), as well as soot and particulates. At ~2.0 the CMHR-FPUR resulted in 8% and 11% nitrogen recovered as HCN for 650C and 850C respectively. At >800C these compounds further fragment into simple molecules (such as HCN, CO, CH4 and CH2O) and PAHs. After the initial stages of inert-atmosphere thermal decomposition where the polymer precursors are reformed and volatilised, the decomposition products tend to fragment into smaller molecules. Isocyanurate rings are the most thermally stable in an inert atmosphere and decompose between 270 and 300C. Avar G, Meier WU, Casselmann H, Achten D (2012) Polymer Science: A Comprehensive Reference, Polymer Science: A Comprehensive Reference, 10, p411-441. eff, should be used, rather than an averaged local equivalence ratio, based on the oxygen supply to the chamber, because, in some experiments, substantial secondary flaming occurred outside the test chamber, such that the amount of oxygen available to combustion exceeded the amount that was fed to the enclosed chamber. CO also combines with myoglobin in the muscle cells, impairing diffusion of oxygen to cardiac and skeletal muscles (Purser 2008b). Before you take it for a test drive, make sure to give your new mattress time to off-gas in a well-ventilated environment. CORE - Aggregating the world's open access research papers Similarly, Busker et al. 6). 1984a). Further fragmentation of these molecules led to the production of HCN, acetonitrile, acrylonitrile and a range of olefinic fragments. Whether one or other of these mechanisms predominates, or their interrelationship, remains unclear. Polyether polyols are more resistant to hydrolysis, but less stable to oxidation, while for polyester polyols it is the opposite. Most fire deaths and injuries actually occur in residential fires, although assessment of fire toxicity is currently focused on areas where escape is restricted, such as aeroplanes, railway carriages, and passenger ships, which include requirements to quantify the fire toxicity of internal components. Full-scale fires simultaneously involve different fire stages in different places, which are changing with time. Additionally, a polyol-rich residue is left behind that begins to fragment and volatilise between 300 and 600C. STM would like to acknowledge the University of Central Lancashire for provision of a studentship. Equation2 represents the generally accepted case that there are only two significant asphyxiant fire gases, CO and HCN. Burning foam will emit mainly carbon monoxide, carbon dioxide and small traces of other toxic gases, such . There is some contradiction the literature as to the effect fire retardants have on the overall toxicity of polyurethane foams. Intermediate between these two approaches are those that can produce quasi-steady combustion conditions, such as the cone calorimeter (ISO 56601 2002) with non-standardised controlled atmosphere attachment (CACC), and the fire propagation apparatus (FPA) (ISO 12136 2011). Aromatic diisocyanates, which are commonly used in the production of polyurethanes, have a slightly more complicated chemistry compared to monoiscyanates due to the electronic effects of two isocyanate groups. ISBN 978-953-51-0726-2, Gottuk DT, Lattimer BY (2002) SFPE Handbook of Fire Protection Engineering, 3rd ed. Syntheticpolymeric materials may be divided into thermoplastics and thermosets. Other common diisocynates include hexamethylene diisocyanate (HDI), 1,5-naphthalene diisocyanate (NDI) and isophorone diisocyanate (IPDI) (Fig. In general conversion efficiencies are high for halogen acid gases. Prog Energy Combust Sci 21:197237, Purser DA (2002) Toxicity Assessment of Combustion Products, The SPFE Handbook of Fire Protection Engineering 3rd Edition, Edited by DiNenno, P.J. The overall toxicity of polyurethane materials followed a similar trend to their HCN yields; with flexible foams generally being the least toxic, rigid foams being slightly more toxic and polyisocyanurate foams being the most toxic. Additionally, the amount of CO generated for both materials began to taper off at 1.2-2.0 as the available oxygen becomes so low that the generation of CO becomes limited, while the yield of HCN continues to increase with equivalence ratio and temperature. They also asserted that the toxicity of the fire retarded foam was less than or equal to wood on a mass/mass basis and that wood contributes significantly more to residential fires in terms of fire smoke toxicity. Combustion and Flame 146(12):p95108, Rogaume T, Bustamante-Valencia L, Guillaume E, Richard F, Luche J, Rein G, Torero JL (2011) Development of the Thermal Decomposition Mechanism of Polyether Polyurethane Foam Using Both Condensed and Gas-Phase Release Data. Biuret and allophanate bonds will decompose first between 100 and 125C. (1981) reported similar data by analysing the inert-atmosphere pyrolysis of a series of biscarbamates to act as model compounds representing polyurethane foams. In others, under reduced oxygen concentrations, the fuel lifts from the surface, but ignition does not occur (Christy et al. Polyurethane Fume Exposure And Your Health: What You Need To Know TNO Prins Maurits Laboratory, The Netherlands. Farrar DG, Galster WA (1980) Biological end-points for the assessment of the toxicity of products of combustion of material. However, from a fire toxicity perspective it is generally assumed that heat and other gases will have already prevented survival, while other toxicants such as CO or HCN, will be present in lethal quantities further from the fire where the oxygen depletion would not be considered harmful. The detection of the amino MDI derivative in the tar further supports the literature reports of a secondary decomposition mechanism where isocyanates trapped in the condensed phase are converted irreversibly into their amine derivatives. For any larger fire there will always be a significant yield of CO, HCN (from nitrogen containing materials), hydrocarbons and smoke. The methods of assessment of fire toxicity are outlined in order to understand how the fire toxicity of polyurethane foams may be quantified. Furniture, upholstery and curtains Suggested points of chain scission on a polyether polyol resulting in aldehydes, ketones and alkenes (Allan et al. Biurets are the result of the reaction of isocyanates with substituted-urea functional groups and allophanates are formed in small amounts (unless catalysed) by the reaction of isocyanates with urethanes. This prompted the authors to perform further studies in order to understand why allowing the foam to smoulder increased the yield of HCN during flaming combustion. When the black char was burned at 600C, it yielded 14.95mg of HCN (65mg per gram of char) and the yellow oil yielded 21mg per gram of oil. The strain of two electronegative atoms (N and O) results in electron density being pulled away from the carbon atom, giving it a strong partial positive charge. Since 2004, by law, the U.S. requires all mattresses to be fireproof to a specific temperature point and ever since the toxicity levels in foam memory mattresses have increased. Polyurethane. UPDATED 8/16/2011 The Massachusetts Division of Fire Safety (DFS) is investigating the causes of three house fires that were ignited while insulation contractors were installing spray polyurethane foam. 1982), and a three-compartment large scale test. The danger of using urethane products is when the foam burns. Several authors have investigated the relationship between bench-scale test data and large-scale test data using polyurethane foams. Relation of LC This can be explained by the fragmentation of nitrogen containing organics in the flame and in the effluent, as suggested bystudies of the inert-atmosphere decomposition of polyurethane materials. This results in relativelyhigh yields of CO and HCN during under-ventilated flaming and relatively low yields during well-ventilated flaming. Fumes Tiny particles are produced from heating, volatilization, and condensation of metals (examples: zinc oxide fumes from welding of galvanized metal). In a 12-square-foot area, urethane was totally burned off, but the rest suffered more minor damage. 12, feeds the sample (typically around 25g of pellets or granules) into its hot zone at a fixed rate, under a controlled air supply, inside a horizontal silica tube of diameter 48mm, allowing adequate mixing of fuel and oxidant. A detailed understanding of the thermal decomposition chemistry of polyurethane foams is necessary in order to relate the toxicants generated during bothflamingand non-flaming combustion of the polymer to its structure. Journal of Fire Sciences 8:p6379, BS 6853 (1999) Code of practise for fire precautions in the design and construction of passenger carrying trains. Both may be present in fire effluent, for example from PVC or halogenated flame retardants, and since the damage caused by the acidity (the concentration of H+ ions) is independent of the specificanion (Cl or Br), the discussion on HCl is also applicable to HBr. I. NBSIR 822532. Similarly to the trend reported by Stec and Hull (2011) in well-ventilated conditions, this can be attributed to gas phase free radical quenching in the material by the chlorine present in both the CMHR-PUF and PIR (2.53% and 3.56% chlorine by weight, respectively). 50 The toxic product generation during flaming combustion of polyurethane foams is reviewed, in order to relate the yields of toxic products and the overall fire toxicity to the fire conditions. The authors noted a primary depolymerisation of the foam which would release volatile TDI and leave the polyol precursors in the condensed phase. The Steady state tube furnace apparatus, ISO/TS 19700. The authors acknowledged that they did not include isocyanates in their calculations. Heat, smoke and irritant gases may impair escape, increasing the risk of a lethal exposure to asphyxiant gases, andcan sometimes lung damage causes death in those managing to escape. Polyurethane is widely used, with its two major applications, soft furnishings and insulation, having low thermal inertia, and hence enhanced flammability. Although these temperatures can provide a good general idea of which bonds will be likely to break down with heating, the steric and electronic effects of the attached groups can affect the strength of the bonds and thus the temperature at which the bond will decompose. The formation of the toxicant in question was the result of an unusual reaction of the polyol in the foam, trimethylol propane, with the phosphate fire retardant in the gas phase. 4)). The presence of both amines and water in the decomposition products of polyurethane foams are discussed in later sections. CEN/TS 455452 (2009) Railway applications - Fire protection on railway vehicles Part 2: Requirements for fire behaviour of materials and components, Chambers J, Jiricny J, Reese CB (1981) The Thermal Decomposition of Polyurethanes and Polyisocyanurates. As with all foams, memory foam compresses under pressure. HCN, in particular, contributes significantly to the overall fire toxicity of polyurethane foams. Michal (1982) reported a similar trend at a fixed air flow rate. . Their analysis indicated that, above 600C, the high temperature decomposition of MDI generated a large number of volatile fragments, including benzene, toluene, benzonitrile and toluonitrile. False True. The average CO yield expected from under-ventilated flaming is ~200mgg1 for polyurethane materials.
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