Quantification of Elevated Hydrogen Cyanide (HCN) Concentration Typical in a Residential Fire Environment Using Mid-IR Tunable Diode Laser

Shruti Ghanekar; Gavin P Horn; Richard M Kesler; Rajavasanth Rajasegar; Jihyung Yoo; Tonghun Lee

doi:10.1177/00037028231152498

Quantification of Elevated Hydrogen Cyanide (HCN) Concentration Typical in a Residential Fire Environment Using Mid-IR Tunable Diode Laser

Appl Spectrosc. 2023 Apr;77(4):382-392. doi: 10.1177/00037028231152498. Epub 2023 Mar 9.

Authors

Shruti Ghanekar^{1

2}, Gavin P Horn^{2

3}, Richard M Kesler^{2

3}, Rajavasanth Rajasegar¹, Jihyung Yoo⁴, Tonghun Lee¹

Affiliations

¹ Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL, USA.
² Fire Safety Research Institute, UL Research Institutes, Champaign, IL, USA.
³ Illinois Fire Service Institute, University of Illinois Urbana-Champaign, Columbia, MD, USA.
⁴ Department of Automotive Engineering, Hanyang University, South Korea.

Abstract

A versatile portable tunable diode laser based measurement system for measuring elevated concentrations of hydrogen cyanide (HCN) in a time-resolved manner is developed for application in the fire environment. The direct absorption tunable diode laser spectroscopy (DA-TDLAS) technique is employed using the R11 absorption line centered at 3345.3 cm^-1 (2989.27 nm) in the fundamental C-H stretching band (ν₁) of the HCN absorption spectrum. The measurement system is validated using calibration gas of known HCN concentration and the relative uncertainty in measurement of HCN concentration is 4.1% at 1500 ppm. HCN concentration is measured with a sampling frequency of 1 Hz, in gas sampled from 1.5 m, 0.9 m, and 0.3 m heights in the Fireground Exposure Simulator (FES) prop at the University of Illinois Fire Service Institute, Champaign, Illinois. The immediately dangerous to life and health (IDLH) concentration of 50 parts per million (ppm) is exceeded at all the three sampling heights. A maximum concentration of 295 ppm is measured at the 1.5 m height. The HCN measurement system, expanded to measure HCN simultaneously from two sampling locations, is then deployed in two full-scale experiments designed to simulate a realistic residential fire environment at the Delaware County Emergency Services Training Center, Sharon Hill, Pennsylvania.

Keywords: HCN; TDLAS; Tunable diode laser spectroscopy; absorption spectroscopy; hydrogen cyanide; mid-IR; mid-infrared; residential fires; toxic gas exposure.