| 1. |
- Blomqvist, Per, et al.
(författare)
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Characterisation of fire generated particles : BRANDFORSK project 700-061, FireTechnology, SP Report 2010:01
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Characterisation of fire generated particlesThe present project has examined the question of distribution patterns of important chemical compounds between gas phase and particle phase. It has also, in some cases, addressed the question of the distribution of individual particle-associated species between the different size-ranges of particles produced in a fire. The chemical compounds studied were hydrogen chloride (HCl), polycyclic aromatic hydrocarbons (PAHs), and isocyanates.The steady-state tube furnace, ISO/TS 19700, was chosen as the physical fire model in order to study the production of particles from different types of fire exposure. Three different fire types were investigated: oxidative pyrolysis, well-ventilated flaming fires and vitiated post flashover. Two materials were chosen for investigation, PVC-carpet and wood board, based on their prevalence fire exposure scenarios and their chemical composition. The particle production from the two materials investigated varied both concerning the amounts produced and the particle size distributions. The production of particles on a mass basis was generally significantly lower from the wood board compared with the PVC-carpet. The tests with the PVC-carpet showed that relatively large particles are produced from all combustion conditions examined. The tests made with the wood board show preferably predisposition towards the production of small-sized particles during flaming combustion.The analysis of PAHs in the tests with the PVC-carpet showed that volatile PAHs were dominate during all types of combustion. However, when the toxicity of the individual species was taken into account, the relative importance between volatile and particle associated PAHs changed. From the tests with the wood board material (OSB) it was noted that the highest yields of total PAHs were found from under ventilated conditions, and the volatile part of the total PAH dominated for this material as well. The yields found from the well-ventilated tests were very low. Toxicity weighted data showed that the particle associated part dominated the toxicity both for under ventilated and well-ventilated conditions.A study made of the presence of chlorine on particles showed that it is clear that the major part of the HCl produced during combustion of the PVC-carpet is present in the gas phase. Chlorine was found associated with particulates but these results were, however, inconclusive due to the difficulty in determining the source of the chlorine found in the soot fractions studied.The low polyurethane (PUR) content and the substantial degradation of the PUR in the tests resulted in no or very small amounts of quantifiable isocyanate dimers (i.e. high molecular species). Monoisocyanates such as ICA and MIC dominated in the emitted degradation products. These kinds of monoisocyanates are volatile compounds and almost exclusively present in the gas phase.
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| 2. |
- Gustavsson, Marcus, et al.
(författare)
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Adsorption Efficiency of Respirator Filter Cartridges for Isocyanates
- 2010
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Ingår i: Annals of Occupational Hygiene. - : Oxford University Press (OUP). - 0003-4878 .- 1475-3162. ; 54:4, s. 377-390
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Tidskriftsartikel (refereegranskat)abstract
- In some industries, the temperature and the humidity will vary greatly between different work places, such as outdoor work in arctic or tropical climates. There is therefore a need to test respirator filters at conditions that simulate conditions that are relevant for the industries that they are used in. Filter cartridges were exposed to controlled atmospheres of varying isocyanate concentration, air humidity, and temperature in an exposure chamber. For isocyanic acid (ICA) and methyl isocyanate (MIC), the exposure concentrations were between 100 and 200 p.p.b., monitored using a proton transfer reaction mass spectrometer. ICA and MIC were generated by continuous thermal degradation of urea and dimethylurea. The breakthrough was studied by collecting air samples at the outlet of the filter cartridges using impinger flasks or dry samplers with di-n-butylamine as derivatization reagent for isocyanates followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. For hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), the exposure concentrations were between 4 and 20 p.p.b. and were generated by wet membrane permeation. To reveal the profile of adsorption in different layers of the respirator filters, representative samples from each of the layers were hydrolyzed. The hydrolysis products hexamethylene diamine and isophorone diamine were determined after derivatization with pentafluoropropionic anhydride (PFPA) followed by LC-MS/MS analysis. The two filter types studied efficiently absorbed both ICA and MIC. There was no trend of impaired performance throughout 48-h exposure tests. Even when the filters were exposed to high concentrations (similar to 200 p.p.b.) of ICA and MIC for 96 h, the isocyanates were efficiently absorbed with only a limited breakthrough. The majority of the HDI and IPDI (> 90%) were absorbed in the top layers of the absorbant, but HDI and IPDI penetrated farther down into the respirator filters during 120 h of exposure as compared to 16 h exposure.
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