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Gas species and thermal measurements preceding backdraft events in a 2/5th scale compartment



Ryan Falkenstein-Smith, Thomas Cleary


This report documents real-time and time-averaged temperature, global and local equivalence ratios, and oxygen, carbon dioxide, and carbon monoxide concentration measurements made at various positions in an isolated 2/5th scale compartment prior to a backdraft event. The compartment was subjected to methane, propane, and propylene fires of different sizes and fuel flow times. Backdrafts were observed to vary depending on the fuel source. Gas mixture composition measurements obtained before an anticipated backdraft were obtained through various gas analysis techniques, including an enhanced phi meter, a gas analyzer equipped with one paramagnetic and two non-dispersive infrared sensors, and a Gas Chromatograph/Mass Spectrometer System. Measurements and the influence of transient compartment conditions, including opening configuration, spark igniter location, fire size, and fuel flow time, are discussed in detail. The likelihood of backdraft under these compartment configurations is typically improved with a higher spark igniter location and fire size, smaller compartment opening, and shorter fuel flow time.
Technical Note (NIST TN) - 2185
Report Number


Backdraft, Gas Species Concentrations, Global Equivalence Ratio, Local Equivalence Ratio, Reduced-Scale Enclosure, Real-time Measurements, Time-averaged Measurements.


Falkenstein-Smith, R. and Cleary, T. (2001), Gas species and thermal measurements preceding backdraft events in a 2/5th scale compartment, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online],, (Accessed May 25, 2024)


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Created January 1, 2001, Updated November 29, 2022