Interlaboratory Evaluation of ISO / TS 19021 for Time‐Resolved Fire Effluent Gas Analysis in the ISO 5659 Smoke Chamber Using FTIR Spectroscopy

ISO/TS 19021 specifies a method for time‐resolved quantification of selected fire effluent gases generated in the ISO 5659 single‐chamber smoke test using Fourier Transform Infrared (FTIR) spectroscopy. To support the revision of ISO/TS 19021 and establish updated precision statements, an interlaboratory trial (round‐robin) was organised with 16 laboratories and designed in three steps: (1) assessment of equipment and set‐up conformity to ISO/TS 19021 requirements, (2) qualitative and semi‐quantitative processing of five shared reference spectra, and (3) replicated testing of four common materials under prescribed irradiance and flaming conditions. Step 1 highlighted deviations that can materially influence performance, including insufficient minimum detection limits for some target gases and heterogeneous calibration descriptions. Step 2 demonstrated strong agreement on major species in spectra dominated by target gases (e.g., CO, CO 2 , HCl), but also revealed practical limitations: only five laboratories could fully reprocess externally supplied spectra due to software import constraints, and reported numerical values below the ISO/TS 19021 quantification capability (≤ 15 μL/L for most gases; ≤ 300 μL/L for CO 2 ) were not robust for quantitative comparison. Step 3 data were analysed in accordance with the ISO 5725 series to estimate repeatability and reproducibility for smoke metrics and gas concentrations at defined times and maxima. Comparison with historical datasets indicates consistency for several measurands while confirming that interlaboratory variability increases markedly at low concentrations and for species detected by a limited subset of laboratories. These findings support targeted clarifications in ISO/TS 19021 regarding quantification limits, spectral interpretation, and harmonised reporting.