Content Description

This document specifies requirements and makes recommendations for sampling systems for use in small-scale and large-scale fire tests, for the selection of parameters and use of the FTIR instrument, and for the collection and use of calibration spectra.

The primary purpose of the methods outlined in this document is to measure the concentrations of chemical species in fire effluents which can be used to:

a)       provide data for use in combustion toxicity assessment without requiring biological studies;

b)       allow the calculation of yield data in fire characterization studies;

c)        provide data for use in mathematical modelling of hazard to life from the fire effluent by characterizing the effluent composition generated by physical fire models;

d)       characterize the effluent composition of small-scale physical models and larger-scale fires for comparative purposes;

e)       assist in the validation of numerical fire models;

f)         set the conditions for exposure in biological studies if required;

g)       monitor biological studies where used; and

h)       assist in the interpretation of biological studies where used.

This document specifies principles of sampling and methods for the individual analysis, in fire effluents, of airborne volume fractions of carbon monoxide (CO), carbon dioxide (CO₂), hydrogen cyanide (HCN), hydrogen chloride (HCl), hydrogen bromide (HBr), nitric oxide (NO), nitrogen dioxide (NO₂) and acrolein (CH₂CHCHO).

NOTE            Depending on the optical path length, there can potentially be some saturation of certain spectral lines at high concentration, leading to incorrect volume fractions.

In most common cases, a wide concentration range can be measured by an FTIR instrument. Typically, it is in the range of a few µl/l to thousands of µl/l for HCl, HBr, HF, SO₂, NO_x, and HCN, and up to a few per cent for CO, CO₂ and H₂O. These mentioned species are only indicative, and many other species could be added.^[27] Although not specifically defined in this document, as they were not specifically studied in the SAFIR project,^[18] the method presented is also suitable for analysis of other gaseous species, including e.g. hydrogen fluoride (HF) and sulfur dioxide (SO₂) with appropriate sampling methods.

Calibration methods are provided in this document. Guidance is also given on the recommended cleaning, servicing and operating checks and procedures to be carried out on the FTIR instrument and the sampling systems which are considered essential for maintaining the instrument in a suitable condition for use in fire effluent analysis.

Sampling is considered to be an integral part of the whole FTIR measurement methodology and recommendations are made for the design, maintenance and operation of suitable systems.

This document provides general recommendations for the sampling and analysis of fire effluents based on best practice as determined from a wide variety of small-scale and large-scale standard and ad hoc fire test studies. This document is not necessarily applicable for use in specific published fire test methods where FTIR is specified as a requirement for effluent sampling and analysis in that particular test. In these cases, the specific requirements for the sampling and analysis by FTIR within the published standard test procedures are followed. However, if such specific requirements have not been published, this edition of this document can be used as a basis for acceptable results.

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