Fire effluents

LUNDGREN STRIDH Chemical Analysis of Fire Effluents... 

The amount of hydrocarbons present in the fire effluents have been measured in two different ways 1) amount of non-burnt hydrocarbons 2) soot was separated from gas with a glassfilter and latei extracted with cyclohexane. After the porous filter an absorbent glass-tube was connected with either charcoal or Tenax GC as the absorbent. Charcoal tubes were later extracted with carbon disulfide for analysis and Tenax tubes directly thermally desorbed t( a gas chromatograph and a mass spectrometer. 

Results from thermally desorbed samples taken from the fire effluents of the different materials in the full scale fire experiments are presented in Table VI. The different species of hydrocarbons have been grouped together and presented in three different cathegories T< M and R representing Trace. Medium and Rich concentration. In this way it is possible to get an idea of the amount of contribution of different species of hydrocarbons to the fire effluents of each material. These results agree well in principle with results obtained by other researchers (6. 7). 

Table VI. Organic Species found in the Fire Effluents from the Fullscale Fire Test NT-FIRE 025 for the Different Materials...

A comparison of results for fire effluents from full scale and small scale fire tests has to be done in steps. A full scale fire is a developing event where temperature and major constitutions changes continously. A small scale fire test either take one instant of that developing stage and try model that or try to model the development in a smaller scale. On a priority one level rate of heat release, temperature, oxygen concentrations and the ratio of C02/C0 concentrations have to be similar for a comparison. The full scale fire experiments reaches a temperature of 900 C at the moment of flashover, while the small scale fire tests are reaching temperatures just above 400 °C for NT-FIRE 004 and the cone experiments. For the DIN 53436-method the temperature was set to 400 °C. 

Keeping in mind the somewhat different approach for the production of fire effluents in the different methods used, one will find that the results presented in Table VII do not differ dramatically much from each other. The results for the cone calorimeter are however distinctly higher than the corresponding values for the other methods. 

Direct reading instruments may be used in the studies of fire effluents from different small scale testing methods. Moisture and high concentrations do create problems that has to be considered. Such problems may be overcome by using a dilution system such as the EPM 797-system. The instruments used must be fast responding since in certain situations the whole event is over within 1 minute. This also requires proper attention in the design of the sampling line. 

ISO 11907-1 1998 Plastics - Smoke generation - Determination of the corrosivity of fire effluents - Part 1 Guidance... 

Impact on the environment may result from both unwanted fires, improper control of fire effluent or improper use of suppression system agents. Environmental considerations impact decisions on whether to provide protection for a hazard, and whether this protection should be provided automatically or manually. Scenarios to be considered include uncontrolled fires, potential hazardous situations, firefighting training, and fixed or mobile vehicle suppression system discharge testing. 

There are essentially two different experimental configurations that are used for quantifying the attenuation of light in fire effluents. The test methods that are based on these two configurations are referred to as static and dynamic, respectively. Different units have been used to report the results of these two types of tests. 

Various methods and instruments are available for measuring gas concentrations in fire effluents, e.g., gas detector tubes, ion-selective electrodes, GC/MS (gas chromatography/mass spectrometry), and Fourier Transform Infrared (FTIR) spectroscopy. An extensive review of the methods is provided in ASTM E 800 and ISO 19701. 

ISO TS 19700 Fire Tests—Controlled Equivalence Ratio Method for the Determination of Hazardous Components of Fire Effluents. International Organization for Standardization, Geneva, Switzerland. 

Additional goals become relevant, in particular with respect to the protection of larger properties not subjected to direct fire influences, such as corrosion induced by the fire effluents. Hereby, the long-term corrosion damage to the building and to equipment (industrial machinery as well as electrical and electronic installations) is of great interest. 

Estimation of Fire Effluent Toxicity from Chemical Composition Data.460... 

General Requirements for Bench-Scale Generation of Fire Effluents.466... 

In contrast to the well-defined effects of asphyxiant toxicants, the effects of exposure to irritants are much more complex. Incapacitating irritants and smoke can cause death indirectly by preventing escape from fire. Most irritant fire effluents produce signs and symptoms of both sensory and upper... 

The effect of fire effluents on human life cannot be measured directly for legal and ethical reasons. It may be estimated from the effect on animals either directly, using animal exposure, or indirectly from tables of concentrations leading to a particular effect (such as the limit below that causing irreparable damage, death, or incapacitation of 50% of the population, etc.). In each case, the data rely on the untested assumption that effects on animal subjects (usually rats) may be simply... 

Exposure to toxic fire effluents can lead to a combination of physiological and behavioral effects of which physical incapacitation, loss of motor coordination, disorientation are only a few. Furthermore, survivors of a fire may experience postexposure effects, complications, and burn injuries, leading to death or long-term impairment. The major effects, such as incapacitation or death, may be predicted using existing rat lethality data, as described in ISO 1334431 or more recently, based on the best available estimates of human toxicity thresholds as described in ISO 13571,5 by quantifying the fire effluents in different fire conditions in small-scale tests, using only chemical analysis, without animal exposure. 

Toxicities are expressed as the effluent generated from burning lg of material in 200L of air, based on an established standard.40 Organoirritants in the fire effluent (measured as the difference in C02 before and after passing over the secondary oxidizer) were considered collectively using an organic yield of 10 mg L 1 to result in incapacitation, as described by Purser.6... 

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