Part of 2012). These nucleophiles include amines, alcohols, carboxylic acids, thiols, water, ureas and urethanes (Aneja 2002). 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. 1985 and Levin et al. Based on this data, the HCN recovery fraction was calculated for both materials. This is true of ALL polyurethane foam since it is an organic material, just like wood or cotton fabric. The samples tested included both commercial rigid polyurethane foam and polyisocyanurate foam. Elemental analysis of the polymer and the char showed that 80% of the nitrogen in the polymer was lost when heated at 370C, but only 0.6% was recovered as HCN when burned at 600C. Google Scholar, Allan D, Daly J, Liggat JJ (2013) Thermal volatilisation analysis of TDI-based flexible polyurethane foam. It is inexpensive and easy to install, however, it is a severe fire risk and requires a thermal barrier to make it safe. (2006) and also Garrido and Font (2015). These fires are large, relative to the enclosure, and produce greater volumes of effluent, affecting occupants over a much wider part of any building. Cite this article. The authors noted a primary depolymerisation of the foam which would release volatile TDI and leave the polyol precursors in the condensed phase. California Privacy Statement, Short chains with high functionality results in highly cross-linked polyurethane polymers which is characteristic of rigid foams. Foams Under Laboratory Conditions, Fire Research Note, No 1039. Only the SSTF has a heated reaction zone which replicates the hot layer. Humans may react differently than animals exposed to toxic materials. (2007). These polyols will fragment and volatilise as the temperature increases, leaving behind a char (>600C). In contrast to the relativelywell-defined effects of asphyxiants, the effects of exposure to irritants are more complex. I recently purchased a memory foam (polyurethane) mattress and was looking online to see how long they take to "air out". Most polyurethanes are cross-linked to some degree and decompose without melting. The amount of nitrogen recovered from the char (8%) at 600C is of a similar order to the results reported by Purser and Purser (2008a) in the steady state tube furnace suggesting that the amount of nitrogen in the polyurethane foam converted into HCN when the material is allowed to smoulder first before flaming is similar to that of steady under-ventilated flaming. EN 2826. At high concentrations nitric oxide is rapidly oxidised in air to form nitrogen dioxide, however, at the concentrations found in fire gases, most of the nitric oxide remains unoxidised. This char can decompose further, leaving behind a residue at >800C, to produce simple organic fragments and some polycyclic aromatic hydrocarbons (PAHs). According to Tim Rodrique, the director of the DFS, investigators suspect that the fires were caused by the exothermic reaction that results from the mixing of the two chemicals used to make . 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. This agrees with the fact that oxidation of NH3 and HCN to NO (and NO2, although it was not analysed in these experiments) would occur more readily during well-ventilated burning. The test room was 2.43.03.0m with a door (dimensions not specified) and a 1 to 2kg slab of foam in the centre of the room. 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). NBSIR 832719. the sum of each of the concentrations multiplied by the exposure time, for each product; upper respiratory tract irritants are believed to depend on the concentration alone (Purser 2007). Relation of LC Again, above 600C the compound and any yellow smoke present was decomposed into smaller volatile fragments. 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. Free of VOCs and HAPs. Ureas and urethanes decompose between 160 and 200C. polyurethane foam production and up to a point the amount of water added will be inversely proportional to the density of the foam. Fire Sci Rev 5, 3 (2016). 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. Memory foam is a type of polyurethane foam. The effects range from tears and reflex blinking of the eyes, pain in the nose, throat and chest, breath-holding, coughing, excessive secretionof mucus, to bronchoconstriction and laryngeal spasms (Purser 2008b). This range of functional groups and their ratios in the polymer are a large contributing factor to the wide range of properties that polyurethane materials can possess. Furniture, upholstery and curtains Early work by Woolley et al (1975) indicated that the decomposition of polyurethanes up to around 600C resulted in the volatilisation of fragmented polyurethane and subsequent release into a nitrogen rich yellow smoke, containing partially polymerised isocyanates and droplets of isocyanate from the foam. The polyisocyanurate, on the other hand, produced slightly more HCN than the rigid foam (17mgg1 vs 12mgg1). In the gas phase, isocyanates, amines and yellow smoke will begin to decompose at >600C into low molecular weight nitrogen containing fragments (such as benzonitrile, aniline and hydrogen cyanide (HCN)). The open cone calorimeter replicates the early well-ventilated stage of flaming where a fire would be too small to produce enough toxicants to cause harm except in very small enclosures. The steady state tube furnace produced a CO yield that was closer to what would be expected for under-ventilated conditions. This was enough to cause deaths both during and post-exposure. The most notable and abundant of these was hydrogen cyanide which increased in yield from 700 to 1000C. Additionally, a polyol-rich residue is left behind that begins to fragment and volatilise between 300 and 600C. The difficulty of replicating the conditions of fully developed under-ventilated flaming on a bench-scale is caused by several practical problems. However, there is verylittle literature available regarding the yields of isocyanates produced by the combustion of polyurethane foams. Acrolein and formaldehyde are formed especially from cellulosic materials under non-flaming decomposition conditions, but products of vitiated combustion contain other organic irritants. Google Scholar, Schartel B, Hull TR (2007) Development of fire-retarded materials - interpretation of cone calorimeter data. Polyurethane foam, when burnt, gives off: Sulfuric acid Cyanide gas Ethane Phosphine. In many studies (such as those by Stec and Hull (2011), Purser and Purser (2008a) and Blomqvist et al. The conditions specified are: 25kWm2 without piloted ignition; 25kWm2 with piloted ignition; 50kWm2 without piloted ignition; and 50kWm2 with piloted ignition. 1982), the authors exposed male Fisher 344 rats in a 200L exposure chamber to the fire effluent from the flaming and non-flaming combustion of both materials. 2013). (1999) tested both rigid and flexible polyurethane foams using a bespoke smoke chamber apparatus to assess the toxicity of the flaming combustion products of the materials to rats. Med Sci Law 21:60. . 11, a conical heater used as a fire model is enclosed in a heat resistant glass chamber (400mm high with 300300mm base) so that the air flowaround the specimen may be controlledby diluting the oxygen content with nitrogen. (1991a) compared a number of test methods. The severity of the effects increases with dose (Hartzell 1993). FIRE INVESTIGATOR REVIEWS Flashcards & Practice Test | Quizlet (2007). The use of 13C labelling by Chambers et al. Investigations by Woolley et al. At high concentrations these acids can cause pulmonary oedema and death (Paul et al. TNO Report. Fire Res 1:p1121. (2003) used a cone calorimeter to assess the yields of amines, aminoisocyanates and isocyanates from the flaming combustion of a flexible polyurethane foam. The authors tested a rigid polyurethane foam using a NBS cup furnace (as described in Levin et al. Fire and Polymers II: Materials and Tests for Hazard Prevention 599:p498517, Chun BH, Li X, Im EJ, Lee KH, Kim SH (2007) Comparison of Pyrolysis Kinetics between Rigid and Flexible Polyurethanes. Journal of Fire Sciences 8:p6379, BS 6853 (1999) Code of practise for fire precautions in the design and construction of passenger carrying trains. While it is evident that the HCN yield increases as a fire becomes more under-ventilated, the link between the nitrogen content of the fuel and the yield of HCN is less clear. (2007)), the sample is raised to a fixed furnace temperature, which is further increased in the gas phase during flaming combustion. The average CO yield expected from under-ventilated flaming is ~200mgg1 for polyurethane materials. True. 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. That smell comes from volatile organic compounds, or VOCs, chemicals used in the mattress manufacturing process. In air, the resulting decomposition fragments can be oxidised into CO, CO2, H2O and nitrogen oxides at high temperatures. In the case of flaming combustion, one of the most important factors relating to the toxic product yield is the fuel/air ratio which, as defined earlier, can be expressed as an equivalence ratio (). DiNenno et al., eds.). Equation HCN analysis was performed using infrared (IR) spectroscopy using a short path-length gas cell, which is a questionable method for the quantification of HCN due to its poor IR absorption, high potential for interferences and a poor limit of detection. Does the foam give off toxic fumes if burned? Journal of Applied Polymer Science 63:p4774, Rein G, Lautenberger C, Fernandez-Pell AC (2006) Application of Genetic Alogorithms and Thermogravimetry to Determine the Kinetics of Polyurethane Foam in Smoldering Combustion. 6). As polyurethane foams have very low thermal inertia, application of heat or a small flame can be enough to ignite them. This equation only relates to lethality, or cause of death. Self-addition reaction of two isocyanates to produce a uretidione, Self-addition reaction of three isocyanates to produce a isocyanurate ring, Reaction of two isocyanates to produce a carbodiimide. In China and Japan, there are specific restrictions on the use of materials with high fire toxicity in high risk applications such as tall buildings, while an increasing number of jurisdictions permit the alternative performance based design approaches to fire safety. Farrar DG, Galster WA (1980) Biological end-points for the assessment of the toxicity of products of combustion of material. Fire and Materials 31:p495521, Bott B, Firth JG, Jones TA (1969) Evolution of toxic gases from heated plastics. When a liquid fuel gives off enough vapors so that it can be ignited and burn, has reached its? Combustion Science and Technology 183(7):p627644, Saunders JH (1959) the Reactions of Isocyanates and Isocyanate Derivatives at Elevated Temperatures. 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. Experimental data reported a 28% recovery of DAT which supports the proposed decomposition mechanism. The resulting substituted urea can then react with another isocyanate to produce a biuret linkage (Scheme4). More recent work by Shufen et al. Journal of Analytical and Applied pyrolysis 108:p143150, Hartzell G (1993) Overview of Combustion Toxicology. Cookies policy. volume5, Articlenumber:3 (2016) 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). MDI is a diaromatic diisocyanate compound that boils at 208C and is primarily used in the production of rigid foams. Interflam Conference Proceedings. The authors noted that the yields of the toxicantsproduced an atmosphere in the tests which fell well below their Immediately Dangerous to Life and Health (IDLH) values. In a compartment fire, the reactions of under-ventilated flaming occur in both the flame zone and in the hot upper layer. The half-scale ISO 9705 experiments showed a wider range of ventilation conditions up to ~2.0. (2011) Aerospace series - Burning behaviour of non-metallic materials under the influence of radiating heat and flames - Determination of gas components in the smoke; ABD 0031 Fire-Smoke-Toxicity (FST) Test Specification (Airbus Industries); Boeing BSS 7239, Test method for toxic gas generation by materials on combustion. The most widely used fire-test apparatus, stipulated in smoke regulations in most countries of the developed world, is the smoke density chamber as described inISO 56592 2012, andshownschematically in Fig. 2012). (such as polyurethane foam) burn slower (have a lower (HRR) than higher-density materials (cotton padding) of similar makeup. The three-compartment test consisted of a 2.43.72.4m burn room, a 2.44.62.4m corridor and a 2.43.72.4m target room where samples would be taken. What does polyurethane foam give off when burned? Fumes Tiny particles are produced from heating, volatilization, and condensation of metals (examples: zinc oxide fumes from welding of galvanized metal). New memory foam smell? The fire toxicity of polyurethane foams - Fire Science Reviews 1982) to that of a large scale test room. TDI is primarily used in the production of flexible foams, which are used in the furniture and interior industries. Polyol fragments in the gas phase will also begin to decompose at >800C to produce simple organic fragments and PAHs. Full-scale fires simultaneously involve different fire stages in different places, which are changing with time. It has been suggested that the reproducibility problems arise from the single point measurement (the tip of the probe may be in the centre of the plume, below it, or if mixing is more efficient, the upper layer may be recirculated through the flame), or the timing of the effluent sampling may cause instabilities (for example an initial proposal to sample after 8min was replaced by a proposal to sample when the smoke density reached its maximum). Fire Safety Science - Proceedings of the First International Symposium, p1111-1122, Markets and Markets report (2011) Methylene Diphenyl Diisocyanate (MDI), Toluene Diisocyanate (TDI) and Polyurethane Market (2011 2016): Markets and Markets CH 1596, July 2011, Marsh ND, Gann RG (2013) Smoke Component Yields from Bench-Scale Fire Tests: 4. Centre for Fire and Hazard Science, University of Central Lancashire, Preston, PR1 2HE, UK, Sean Thomas McKenna&Terence Richard Hull, You can also search for this author in (1985) when a flexible polyurethane foam was first heated at a temperature below its auto-ignition temperature, followed by flaming combustion of the remaining char and residue at a higher temperature. 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. Additionally, the self-addition of isocyanates to produce isocyanurates (v in Fig. The Steady state tube furnace apparatus, ISO/TS 19700. During flaming combustion, many fire retarded flexible polyurethane foams showed similar or slightly higher toxic potency than the non-fire retarded foams in both well-ventilated and under-ventilated conditions. However, a non-standard modification of the apparatus has been described, enclosing the fire model in a controlled ventilation chamber, in an attempt to replicate oxygen-depleted conditions. Further fragmentation of these molecules led to the production of HCN, acetonitrile, acrylonitrile and a range of olefinic fragments. This makes foam mattresses very harmful. Refer to MSDS. Preliminary calculations suggested that 27% of the TDI should be recovered as DAT. Its widespread availability has encouraged its adaptation to toxic gas generation and assessment. It can be used for testing samples 100100mm and up to 50mm thick, in both the horizontal and vertical orientation. At 650C, the yield of HCN from the CMHR-PUF increased up to ~2.0 where it reached a peak of 14mg of HCN per gram of polymer burned. The average well-ventilated yield of HCN was found to be 4mgg1, while it was 9mgg1 for under-ventilated conditions. Polyurethane. . The toxic hazards associated with fire and the inability of victims to escape from fire atmospheres may be considered in terms of major hazard factors: heat, smoke and toxic combustion products (Hartzell 1993). However, when the TDI was unable to enter the pyrolysis zone, the slower, irreversible decomposition to diaminotoluene (DAT) would occur. Do memory foam mattresses give off toxic fumes? When polyurethane foam is burned, it gives off a wide variety of potentially harmful substances. (1999) used the controlled atmosphere cone calorimeter, but argues correctly,in the authors' opinion,that an instantaneous effective global equivalence ratio The non-flaming decomposition of non-fire retarded polyurethane foams in air is generally quite well understood and comparable to the inert atmosphere decomposition, in terms of both products and mechanisms. National Bureau of Standards, Gaithersburg MD, Barbrauskas V, Singla V, Lucas D, Rich D (2015) Letter to the Editor- Questions about the conclusions in Blais and Carpenter 2013. The authors acknowledged that the lower nitrogen recovery fraction for the flexible foam could be due to fuel nitrogen being lost as isocyanates, which are known to escape into the effluent plume, while for rigid foams they are more likely to be trapped in the burning solid (Woolley & Fardell 1977). The calculations showed that, for both the rigid polyurethane and the polyisocyanurate, hydrogen cyanide is the major toxicant in smouldering, well-ventilated and under-ventilated flaming. Springer Nature. Work by Ravey and Pearce (1997) on the decomposition of a polyether based flexible polyurethane foam suggested that up to 360C the decomposition of the foam was achieved by two main mechanisms. STM wrote the manuscript and produced all of the images used in figures. Polymer Degradation and Stability 93:p20582065, Tewarson A (2002) SFPE Handbook of Fire Protection Engineering, 3rd ed. The authors noted that the total concentrations of CO and HCN during flaming combustion were greater than the sum of those from the individual materials. Is Polyurethane Foam Toxic, And Should You Avoid it? - The Safe Parent STM would like to acknowledge the University of Central Lancashire for provision of a studentship. Isocyanates also react with themselves in various ways to produce dimers, trimers and completely new functional groups. For the purpose of estimating toxicity in fires, fire growth has been classified into a number of stages (ISO 19706 2011): Although on some occasions smouldering (oxidative pyrolysis) can generate toxicologically significant quantities of effluent (for example smouldering cotton, or polyurethane foam), typicallythe rate of reaction, and hence the amount of toxic species generated will be small, so it is unlikely to affect anyone outside the immediate vicinity.

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