In-situ measurement of water-vapor in fire environments using a real-time tunable diode laser based system

Shruti Ghanekar, Rajavasanth Rajasegar, Nicholas Traina, Constandinos Mitsingas, Richard M. Kesler, Gavin P. Horn, Robin Zevotek, Stephen Kerber, Tonghun Lee

Research output: Contribution to journalArticlepeer-review


A robust tunable diode laser absorption spectroscopy (TDLAS) based system is developed and deployed to make real-time water-vapor concentration measurements in quasi-controlled live-fire experiments conducted in firefighter training props. This system targets the 1392.5 nm (7181.15 cm−1) water-vapor absorption line while employing a multi-tier detection sensitivity scheme that allows for measurements at multiple locations in fire environment through varying smoke obscuration levels. Temperature-corrected absorbance values are compared to HITRAN simulations to quantify water-vapor concentration. Upon validation in laboratory setting, the impact of firefighter hose stream application on water-vapor concentration is studied. Comparative effects of training structures (metal, concrete and drywall-lined) and fuel-loads (pallet/straw, lightweight furnishings and pallet/straw/oriented-strand-board (OSB)) on water-vapor concentration are characterized. Despite small increase in water-vapor concentration due to suppression, the post-suppression concentrations are found to be comparable or lower than the corresponding maximum pre-suppression concentrations in all scenarios except the metal structure. Irrespective of the structure, highest temperature and water-vapor concentrations are measured with pallet/straw/OSB fuel-load. Under identical fuel-loads, the drywall structure scenarios generate highest water-vapor concentration. Peak water-vapor concentrations are measured post-suppression in typical training structures (near-floor and crawling levels), but prior to suppression in the structure/fuel package combination that simulated a typical residential fire scenario.

Original languageEnglish (US)
Article number103114
JournalFire Safety Journal
StatePublished - Mar 2021


  • Absorption spectroscopy
  • Fire suppression
  • Near-infrared
  • Smoke obscuration
  • Training fires
  • Tunable diode laser
  • Water-vapor measurement

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Safety, Risk, Reliability and Quality
  • Physics and Astronomy(all)


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