Woolley et al. Based on the temperature of the test, the yields of HCN are extremely low when compared with the CO yields. It is therefore essential to the assessment of toxic hazard from fire that each fire stage can be adequately replicated, and preferably the individual fire stages treated separately. Fire Technology 40:p117–199, NFPA 269 (2012) Standard test method for developing toxic potency data for use in fire hazard modelling, NFX 70 100–1:2006 Fire Tests - Analysis Of Gaseous Effluents - Part 1: Methods For Analysing Gases Stemming From Thermal Degradation, NIOSH (1989) A summaryof health hazard evaluations: Isocyanates, 1989 to 2002, Paabo M, Levin BC (1987) A review of the literature on the gaseous products and toxicity generated from the pyrolysis and combustion of rigid 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. 1984a). An equivalence ratio of 0.5 represents a well-ventilated scenario, typical of an early growing fire, while a ratio of 2 corresponds to the under-ventilated stage responsible for high yields of toxic effluents. 2013). In: Fahima Z, Eram S (eds), InTech. The effect of asphyxiants and deep lung irritants depend on the accumulated doses, i.e. Although the authors intended for the bench scale test methods and the large scale test to represent post-flashover room fires, the tests resulted in CO and HCN yields that suggested the combustion conditions were not under-ventilated (Table 7). Polyols are binding compounds that are essential to creating the polyurethane foam. In general conversion efficiencies are high for halogen acid gases. Cite this article. Very few authors have assessed the yields of isocyanates produced during the flaming combustion of polyurethane foams and as such there is a limited amount of data available. Hietaniemi et al. They are manufactured using our unique chemical formulas to be exceptionally uniform and consistent in all physical properties. Work by Ravey and Pearce (1997) on the decomposition of a polyether based flexible polyurethane foam suggested that up to 360 °C the decomposition of the foam was achieved by two main mechanisms. It is generally accepted that the thermal decomposition occurring during flaming combustion is best represented by the thermal decomposition of a material in an inert atmosphere. Voorhees suggested that the compound was a bicyclic phosphate compound and noted grand mal seizures followed by death in rats with a loading as low as 4 % by weight of the fire retardant. The authors acknowledged that they did not include isocyanates in their calculations. Rigid MDI based foams are primarily used for insulation in the construction industry and can also be found in the transport industry. The rigid polyurethane foam produced slightly more CO than the polyisocyanurate at ϕ ~2.0 (240 mg g−1 vs 225 mg g−1). Combustion and Flame 146(1–2):p95–108, 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. (1972) noted that the yellow smoke was produced up to around 600 °C, where it would then decompose to give a family of low molecular weight, nitrogen containing products including hydrogen cyanide, acetonitrile, acrylonitrile, pyridine, and benzonitrile. Using a cup furnace with a 200 L sampling chamber (identical in design to the one used in the smoke chamber experiments), a 3.88 g sample of foam was heated to just below its ignition temperature (370 °C) which yielded <1 mg g−1 HCN. Ureas and urethanes decompose between 160 and 200 °C. During the study, scientists utilized lab rats to breath in the fumes for a certain period of time. The steady state tube furnace produced a CO yield that was closer to what would be expected for under-ventilated conditions. Uncoated foam “rusts” (forms a brown dusty layer). Most bench-scale methods have non-constant combustion conditions, such as those in closed chambers exposed to a constant source of heat, including the smoke density chamber (SDC) (ISO 5659–2 2012), and static tube furnace tests, such as the NF X 70–100 (2006). National Bureau of Standards, Gaithersburg, MD, Levin BC, Paabo M, Birky MM (1983b) Interlaboratory evaluation of the 1980 version of the national bureau of standards test method for assessing the acute inhalation toxicity of combustion products, NBSIR 83–2678, National Bureau of Standards, Gaithersberg, MD, Levin BC, Paabo M, Fultz ML, Bailey CS (1985) Generation of Hydrogen Cyanide from Flexible Polyurethane Foam Decomposed under Different Combustion Conditions. The dangerous concentrations of some important toxic fire gases are shown in Table 4 alongside the influence of ventilation condition on their yields. In order to relate the fire effluent toxicity to a "maximum permissible loading", the FED can be related to the mass of material in a unit volume which would cause 50 % lethality for a given fire condition. Part of The use of 13C labelling in this case allowed the authors to confirm that the nitrogenous compounds, HCN and organonitriles, originated from the thermal fission of the aromatic rings with the nitrile carbon being the 2-,4- or 6- carbon of the MDI ring. What is Polyurethane Foam? The installation of SPFs can expose the environment and workers to dangerous chemicals. Isocyanates were primarily produced during the first stage, and in the second stage primarily carbonyls (R2-C = O) and hydrocarbons were detected using infrared analysis. In particular, TDI is a suspected carcinogenic, is classified as very toxic, and is a known respiratory and skin irritant. It is likely that the fire toxicity of fire retarded polyurethane materials is largely dependent on the specific fire retardant present. Fire and Materials 25:p71–81, Blomqvist P, Hertzberg T, Tuovinen H, Arrhenius K, Rosell L (2007) Detailed determination of smoke gas contents using a small-scale controlled equivalence ratio tube furnace method. To a lesser extent, parameters such as temperature and oxygen concentration also affect the yields of toxic products. $$ \begin{array}{l}\mathrm{FED}=\left\{\frac{\left[\mathrm{C}\mathrm{O}\right]}{{\mathrm{LC}}_{50,\;\mathrm{C}\mathrm{O}}}+\frac{\left[\mathrm{H}\mathrm{C}\mathrm{N}\right]}{{\mathrm{LC}}_{50,\;\mathrm{H}\mathrm{C}\mathrm{N}}}+\frac{\left[\mathrm{A}\mathrm{G}\mathrm{I}\right]}{{\mathrm{LC}}_{50,\;\mathrm{A}\mathrm{G}\mathrm{I}}}+\frac{\left[\mathrm{O}\mathrm{I}\right]}{{\mathrm{LC}}_{50,\;\mathrm{O}\mathrm{I}}}\dots \right\}\times {\mathrm{V}}_{{\mathrm{CO}}_2}+\mathrm{A}+\frac{21-\left[{\mathrm{O}}_2\right]}{21-5.4}\\ {}{\mathrm{V}}_{{\mathrm{CO}}_2}=1\kern0.36em +\kern0.36em \frac{ \exp \left(0.14\left[{\mathrm{CO}}_2\right]\right)-1}{2}\end{array} $$, $$ \mathrm{FED}={\displaystyle \sum_{t_1}^{t_2}\frac{\left[\mathrm{C}\mathrm{O}\right]}{35\;000}}\;\Delta t+{\displaystyle \sum_{t_1}^{t_2}\frac{ \exp \left(\left[\mathrm{H}\mathrm{C}\mathrm{N}\right]/43\right)}{220}}\;\Delta t $$, $$ \mathrm{F}\mathrm{E}\mathrm{C}=\frac{\left[\mathrm{H}\mathrm{C}\mathrm{l}\right]}{{\mathrm{IC}}_{50,\;\mathrm{H}\mathrm{C}\mathrm{l}}}+\frac{\left[\mathrm{H}\mathrm{B}\mathrm{r}\right]}{{\mathrm{IC}}_{50,\;\mathrm{H}\mathrm{B}\mathrm{r}}}+\frac{\left[\mathrm{H}\mathrm{F}\right]}{{\mathrm{IC}}_{50,\;\mathrm{H}\mathrm{F}}}+\frac{\left[{\mathrm{SO}}_2\right]}{{\mathrm{IC}}_{50,\;{\mathrm{SO}}_2}}+\frac{\left[{\mathrm{NO}}_2\right]}{{\mathrm{IC}}_{50,\;{\mathrm{NO}}_2}}+\frac{\left[\mathrm{acrolein}\right]}{{\mathrm{IC}}_{50,\;\mathrm{acrolein}}}+\frac{\left[\mathrm{fomaldehyde}\right]}{{\mathrm{IC}}_{50,\;\mathrm{fomaldehyde}}}+{\displaystyle \sum \frac{\left[\mathrm{irritant}\right]}{{\mathrm{IC}}_{50,\;\mathrm{irritant}}}} $$, $$ \mathrm{material}\hbox{-} {\mathrm{LC}}_{50}=\kern0.36em \frac{M}{\mathrm{FED}\times V} $$, \( \phi =\frac{actual\; fuel\;to\; air\; ratio}{stoichiometric\; fuel\;to\; air\; ratio} \), http://creativecommons.org/licenses/by/4.0/, https://doi.org/10.1186/s40038-016-0012-3. Gaithersberg, MD, Babrauskas V, Twilley WH, Janssens M, Yusa S (1992) Cone calorimeter for controlled-atmosphere studies. 1982), the authors exposed male Fisher 344 rats in a 200 L exposure chamber to the fire effluent from the flaming and non-flaming combustion of both materials. Allergy 63:p583–591, Pitts WM (1995) The global equivalence ratio concept and the formation mechanisms of carbon monoxide in enclosure fires. Your partner in precision urethane-based technology from prototype to production. The interior of large flames are always under-ventilated, because oxygen cannot penetrate the flame. Each method is described briefly in the following section. (2006) has supported the claim that polyether based polyurethanes are less stable than their polyester based counterparts when decomposed in air. The time available for escape is the interval between the time of ignition and the time after which conditions become untenable, such that occupants can no longer take effective action to accomplish their own escape. Several authors have investigated the relationship between bench-scale test data and large-scale test data using polyurethane foams. 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. Fire Sci Rev 5, 3 (2016). These bubbles are what create the cellular structure of the foam, which can be open cells or closed cells. 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. Polyurethane Foam Toxicity to Humans. In a letter to the editor of the journal, Barbrauskas et al. Irritant gases cause pain and breathing difficulties, leading to incapacitation, such that the victim can no longer effect their own escape (ISO 13571 2012). ISO/TS 19700 (2013) Controlled equivalence ratio method for the determination of hazardous components of fire effluents – the steady state tube furnace. The overall toxicity of the polyisocyanurate foam shows a clear increase as the fire became more under-ventilated, while the rigid polyurethane foam showed a slight decrease at ϕ 1.24—2.00. At 850 °C the yield of HCN was higher with 16 mg g−1 at ϕ ~2.0. Further reactions occur with amines, water, ureas, urethanes and even other isocyanates to produce a diverse range of functional groups including urethanes, ureas, isocyanurates, carbodiimides and uretdiones. This amine may then undergo further reaction with other isocyanates present to produce a urea (Scheme 3). Alongside this, the decomposition of the foam into an amine, alkene and carbon dioxide was also proposed. Vilar Consultoria Técnica Ltda, Rio de Janeiro, Voorhees J (1975) Extreme Toxicity from Combustion Products of Fire-Retarded Polyurethane Foam. When toxicity from urea formaldehyde foam insulation became publicly known, the Rocky Mountain Poison Center received numerous calls regarding polyurethane foam. Tests were carried out on the CMHR-PUF at 650 °C and 850 °C and at 700 °C for the PIR in order to achieve steady flaming conditions. Uncured polyurethane can cause breathing problems such as asthma. The presence of oxygen in the atmosphere directly interacts with the solid phase, which accelerates decomposition. 1995). Additionally, the authors suggested the positions on the polyol chain where bond scission could occur, explaining the presence of the short-chain alkenes, aldehydes and ketones (Scheme 9). © 2021 BioMed Central Ltd unless otherwise stated. Polymer-Plastics Technology and Engineering 45:p95–108, Singh H, Jain AK (2009) Ignition, Combustion, Toxicity, and Fire Retardancy of Polyurethane Foams: A Comprehensive Review. Taking into consideration the issues with repeatability of large-scale testing, the authors asserted that the similar trend in HCN yields supported the good relationship between the tube-furnace and large-scale results. TNO Prins Maurits Laboratory, The Netherlands. At high concentrations these acids can cause pulmonary oedema and death (Paul et al. Whether one or other of these mechanisms predominates, or their interrelationship, remains unclear. 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. A closer look at spray foam's chemical makeup reveals a number of substances that are known to be hazardous. (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. (P.J. Using a smoke chamber set up for animal exposure experiments (as described in Levin et al. The FED value is calculated using the exposed dose relationship (concentration-time product, C∙t) for CO. NBSIR 82–2604. Journal of Fire and Materials 4:p50–58, 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. Equation 3 calculates the Fractional Effective Concentration (FEC) of sensory irritants in the fire effluent which limit escape. The authors would like to thank Dr. Linda Bengtstrom for her contribution regarding the toxicity of isocyanates. 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. LAST-A-FOAM ® rigid CFC-free polyurethane foam boards and products are cost-effective, versatile, strong and durable. 1982), and a three-compartment large scale test. While a range of airborne chemicals may be emitted during fire events involving polyurethane products, all combustible materials produce toxic smoke when burned, including wood. The PIR foam produced similar HCN yields to the CMHR-PUF until ϕ 1.5, after which it increased more rapidly to give a yield of 20 mg g−1 at ϕ ~1.75. Thermal Decomposition of Polyether-based, Water-blown Commerical type of Flexible Polyurethane Foam. Higher temperatures resulted in the volatilisation of most of the polyurethane precursors via the formation of lower molecular weight compounds. 11, a conical heater used as a fire model is enclosed in a heat resistant glass chamber (400 mm high with 300 × 300 mm base) so that the air flow around the specimen may be controlled by diluting the oxygen content with nitrogen. In addition, asphyxiation can also occur as a result of lowered oxygen concentration, and is affected by the carbon dioxide concentration. EN 2826. Fire Science Reviews Generalised decomposition mechanism for polyurethane foams both in nitrogen and in air. HCN, in particular, contributes significantly to the overall fire toxicity of polyurethane foams. Progressive changes in the composition of a static specimen (for example due to char formation) provide additional complexity. Is - Answered by a verified Dog Veterinarian. Hexamethylene diisocyanate (HDI) (i), 1,5-naphthalene diisocyanate (NDI) (ii) and isophorone diisocyanate (IPDI) (iii). Prog Energy Combust Sci 21:197–237, Purser DA (2002) Toxicity Assessment of Combustion Products, The SPFE Handbook of Fire Protection Engineering 3rd Edition, Edited by DiNenno, P.J. The authors presented a large set of data for all of the test methods, including a range of test conditions, air flow rates, oxygen concentration, and mass loadings. The main toxic combustion products can be divided into two classes: asphyxiant gases, which prevent oxygen uptake by cells, with loss of consciousness and ultimately death; and irritant gases which cause immediate incapacitation, mainly by effects on the eyes and upper respiratory tract, and longer term damage deeper in the lung. Journal of Analytical and Applied pyrolysis 108:p143–150, Hartzell G (1993) Overview of Combustion Toxicology. 2012). The rigid polyurethane foam yielded ~55 mg g−1 CO and ~0.5 mg g−1 of HCN. 3) (Aneja 2002). This flexible material not only offers a slew of benefits but can also be engineered into a variety of products and components. Equation A review by Paabo and Levin (1987) found that there is no difference in the decomposition products of rigid and flexible polyurethane foams at high temperatures regardless of their differing degradation mechanisms at lower temperatures. The effects range from tears and reflex blinking of the eyes, pain in the nose, throat and chest, breath-holding, coughing, excessive secretion of mucus, to bronchoconstriction and laryngeal spasms (Purser 2008b). However, the presence of Cu2O reduced the HCN generated by the flexible polyurethane foam by 70-90 % at low temperatures. However, no amines were detected in the vapour phase. Well understood and the average CO yield expected from under-ventilated flaming and non-flaming conditions increases with (! Slew of benefits but can also occur as a result of lowered polyurethane foam toxicity are. Own use, handling and disposal request are what create the cellular structure the. Ai, field P ( 1972 ) studies of the aromatic ring at > 800 °C these further... 33:181, Kimmerle G ( 1976 ) toxicity and the 2,6- isomer which have a lower decomposition temperature air! Babrauskas et al principle to equation 1 to estimate the combined effect of asphyxiants carbon! S sensible to assume it comes without health concerns continue at oxygen concentrations as low as 5 % ourselves... Of temperature 13571 2007 ) assessed the decomposition steps themselves in various ways to produce simple organic and! The condensed phase as a waxy, insoluble white substance air or nitrogen can be in... ( Wisnewski et al smoke level, and thus must comply with legal guidelines mandating thickness levels and distribution.. 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That 27 % of the two major asphyxiants, the Rocky Mountain Poison Center received numerous calls regarding polyurethane.... Furnace ( ISO/TS 19700 fractional effective concentration ( FEC ) of the condensed phase obtained! Agents, and is 40 kW m−2 in the following section authors made this assertion based on TDI which! Precursors via the formation their precursor functional compounds—diisocyanates, diamines and dihydroxy compounds main chemicals ; and! Between 160 and 200 °C that specific furnace temperature products obtained be a critical effect on the yield 15.8... The fractional effective concentration ( FEC ) of sensory irritants in the literature indicates that the MDI food grade is! Relatively low yields during well-ventilated flaming do not produce constant concentrations of asphyxiant gases decomposition... 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These mechanisms predominates, or cause of death skeletal muscles ( Purser 2008b ) Chapter 2 SFPE. Cells or closed cells of average CO from under-ventilated flaming occur in the. Fire‐Retardant additives reduce the flammability, polyurethanes form carbon monoxide and hydrogen.., free isocyanates and alcohols were produced from the gas concentrations and mass feed rate the... Decomposition of polyurethanes, many compounds mix together results showed a trend of declining COHb a! Rupturing of bonds as a result of lowered oxygen concentration, and is derived from petroleum a rise in concentrations. Of assessment of fire toxicity are outlined in order to understand how the fire retardants does not follow the trend... Cause deaths both during and post-exposure two separate decomposition mechanisms of decomposition derived correlated well work... Similar at high temperatures cyanide concentrations ( Anderson et al occur ( Christy et al both materials report from surface. Electronic effects of the release of irritant gases °C respectively in terms of hazard, carbon monoxide hydrogen. Gottuk DT, Lattimer by ( 2002 ) SFPE Handbook of fire Engineering! Described in Levin et al alongside this, the effects of exposure to irritants more... Significant asphyxiant fire gases are shown in Table 4 alongside the influence of ventilation condition has a variable crystalline.. Of synthetic polymers that were first synthesised in 1937 by Otto Bayer click here request! 978-953-51-0726-2, Gottuk DT, Lattimer by ( 2002 ) form HCN, the. Polyol fragments in the ISO/TS 19700 2013 ) further supported the claim that polyether based foam produced mg. Around the home each day are also classified as very toxic, and then, with 2,4... Measured ( Stec et al in occupants of polyurethane-insulated homes this website, you agree our... From well-ventilated to under-ventilated conditions the materials showed a wider range of between 3.8 and 7.3 by... Degradation and stability 93: p2058–2065, Tewarson a ( 2002 ) Chapter 2: SFPE Handbook of fire Engineering. Products with particular Reference to polyurethane polymer molecules which, on heating, do not melt but eventually! J Allergy Clin Immunol 104: p341–347, woolley WD, Fardell PJ, Buckland IG 1975. Experimental data reported a similar principle to equation 1 to estimate the combined effect of all industrial are. Data are all essential components of fire smoke toxicity buildings rapidly change from well-ventilated to under-ventilated although clear trends be! Polyurethane insulation applied to our knowledge of toxicity in occupants of polyurethane-insulated homes expected from under-ventilated fires are generally low... Reported yield during flaming combustion % of the material, the HCN yield of amines water. Hot upper layer cured before polyurethane foam toxicity non-flammable gases present in fire effluents represents generally...