ISO DIS 19702

Description / Abstract: This International Standard specifies requirements and makes recommendations for sampling systems for use in small and large-scale fire tests, for the selection of parameters and use of the FTIR instrument itself and for collection and use of calibration spectra.

The primary purpose of the methods is to measure the concentrations of chemical species in fire effluents which may 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 characterisation studies;

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

d. characterise 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 International Standard specifies principles of sampling and methods for the individual analysis, in fire effluents, of airborne concentrations 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).

In most common cases, a wide concentration range is covered by an FTIR instrument. Generally, it is in the range from few μL/L to thousands of μL/L for HCl, HBr, HF, SO2, NOx, HCN and up to few percent for CO, CO2 and H2O. This list is only indicative and many other species could be added [20]. Although not specifically defined in this International Standard, as they were not specifically studied in the SAFIR project [6], the method presented is also suitable for analysis of other gaseous species, including e.g. hydrogen fluoride (HF) and sulphur dioxide (SO2) with appropriate sampling methods.

Calibration methods are provided in this International Standard. Guidance is also given on the recommended cleaning, servicing and operating checks and procedures to be carried out on the FTIR instrument which is considered essential to maintain 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.

Conformance with this International Standard implies that:

• The sampling procedure used is in accordance with current internationally accepted "best practice" for the applications described.

•The analytical procedure has been carried out with due regard to the restraints imposed by the nature of the fire effluent atmosphere and the limitations of the FTIR methodology itself.

This International Standard only provides general recommendations for the sampling and analysis of fire effluents, based on best practice as determined from a wide variety of small- and large-scale standard and ad hoc fire test studies. The Standard may not be wholly applicable for use in specific published fire test methods where FTIR may be 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 may be published within the standard test procedures and should be followed. However if such specific requirements have not been published, ISO 19702 may be used as a basis for acceptable results.