Minute concentration measurements of simple hydrocarbon gases are demonstrated using near-infrared supercontinuum laser absorption spectroscopy. Absorption-based gas sensors, particularly when combined with optical fiber components, can significantly enhance diagnostic capabilities to unprecedented levels. However, these diagnostic techniques are subject to limitations under certain gas sensing applications where interference and harsh conditions dominate. Supercontinuum laser absorption spectroscopy is a novel laser-based diagnostic technique that can exceed the above-mentioned limitations and provide accurate and quantitative concentration measurement of simple hydrocarbon species while maintaining compatibility with telecommunications-grade optical fiber components. Supercontinuum radiation generated using a highly nonlinear photonic crystal fiber is used to probe rovibrational absorption bands of four hydrocarbon species using full-spectral absorption diagnostics. Absorption spectra of methane (CH4), acetylene (C2H2), and ethylene (C2H4) were measured in the near-infrared spectrum at various pressures and concentrations to determine the accuracy and feasibility of the diagnostic strategy. Absorption spectra of propane (C3H8) were subsequently probed between 1650 nm and 1700 nm, to demonstrate the applicability of the strategy. Measurements agreed very well with simulated spectra generated using the HITRAN database as well as with previous experimental results. Absorption spectra of CH4, C2H2, and C2H4 were then analyzed to determine their respective measurement accuracy and detection limit. Concentration measurements integrated from experimental results were in very good agreement with independent concentration measurements. Calculated detection limits of CH4, C2H2, and C2H4 at room temperature and atmospheric pressure are 0.1%, 0.09%, and 0.17%, respectively.

Simultaneous measurements of light hydrocarbon species based on near-infrared (near-IR) supercontinuum laser absorption spectroscopy (SCLAS) are demonstrated. SCLAS is a broadband absorption diagnostic technique that provides significant advantages over existing absorption diagnostic techniques. Coupled with a fast spectrum analysis strategy, accurate measurements of multiple hydrocarbon concentrations can be made concurrently. Methane (CH4), acetylene (C2H2), ethylene (C2H4), and their mixtures were probed near ambient temperature and pressure conditions. Light hydrocarbons are found in many fuel and energy applications, and a sensor that can accurately and simultaneously probe multiple species’ concentrations and temperature would greatly enhance measurement versatility. Absorption spectra of the three hydrocarbon species were measured between 1.5 and 1.7 μm in this study. These spectra can be very convoluted, where broad absorption features interfere with neighboring features, be it from the same or different species. Species concentrations and temperatures were resolved using a spectrum analysis strategy based on linear regression. Experimental results showed good agreement with test conditions even in the presence of significant spectral overlap.

Abstract. This paper describes an experimental investigation of the impact of structure geometry, fire location, and closed interior doors on occupant tenability in typical single family house geometries using common fuels from twenty-first century fires. Two houses were constructed inside a large fire facility; a one-story, 112 m 2 , 3-bedroom, 1-bathroom house with 8 total rooms, and a two-story 297 m 2 , 4-bedroom, 2.5-bathroom house with 12 total rooms. Seventeen experiments were conducted with varying fire locations. In all scenarios, two bedrooms had doors remaining open while the door remained closed in a third bedroom immediately adjacent to the open door bedrooms. Temperature and gas measurement at the approximate location of a crawling or crouching trapped occupant (0.9 m from the floor) were utilized with the ISO 13571 fractional effective dose (FED) methodology to characterize occupant tenability up to the point of firefighter intervention. The FED values for the fire room were higher for heat exposure than for toxic gases, while target rooms reached highest FED due to CO/CO 2 exposure. The closed interior door decreased FED significantly, with the worst case scenario resulting in a 2% probability of receiving an incapacitating dose compared to the worst case scenario for an open bedroom of 93% probability of receiving an incapacitating dose. In fact, in 7 of the 17 experiments, the closed interior door resulted in a less than 0.1% chance of an occupant receiving an incapacitating dose prior to firefighter 'intervention.'

Abstract. This paper describes experimental investigations of fire service ventilation and suppression practices in full-scale residential structures, including a one-story, 112 m 2 , 3 bedroom, 1 bathroom house with 8 total rooms and a two-story 297 m 2 , 4 bedroom, 2.5 bathroom house with 12 total rooms. The two-story house featured a modern open floor plan, two-story great room and open foyer. Seventeen experiments were conducted varying fire location, ventilation locations, the size of ventilation openings and suppression techniques. The experimental series was designed to examine the impact of several different tactics on tenability: door control, vertical ventilation size, and exterior suppression. The results of these experiments examine potential occupant and firefighter tenability and provide knowledge the fire service can use to examine their vertical ventilation and exterior suppression standard operating procedures and training content. It was observed that door control performed better at controlling the thermal exposure to occupants than did fully opening the door. Additionally, the impact of increased vertical ventilation area was minimal, and only slightly reduced the thermal exposure to occupants in a few non-fire rooms. In the two-story structure, the non-fire rooms on the second floor consistently had larger thermal fractional effective rate (FER) values (approximately 2.59 the thermal risk to oocupants) than did the non-fire rooms on the first floor. Water application was also shown to reduce the thermal risk to occupants 60 s after water application 1/3rd the original values on second floor rooms of the two-storry structure and by at least 1/5th of the original values on the first floor rooms of both structures. Data also showed that the impact of front door ventilation on the toxic gases exposure was minimal, as the toxic gases FER actually increased after front door ventilation for several experiments. However, after vertical ventilation there was a 30% reduction in the toxic gases exposure rate in two of the one-story structure experiments.

Ignition by electrostatic discharge of clean flammable gas, such as natural gas, being released to the atmosphere during blowdown operations is unlikely. However, the presence of foreign material in the form of solid particles or liquid droplets changes the risk level significantly. The discharge of a flammable gas stream with a cloud of foreign material poses a potential electrostatic hazard, even if the piping system and associated equipment is otherwise bonded and grounded. The foreign material may be capable of accumulating sufficient electrostatic potential to ignite the flammable gas. There have been several documented incidents where ignition has occurred during a flammable gas blowdown. In some instances, gas lines were being cleaned, while in others, the blowdown was completed as a safety measure for another process. This article will focus on a case study where a stream of flammable gas was ignited during a blowdown and an obvious ignition source (other than electrostatic discharge) was not present, but foreign material was observed. © 2018 American Institute of Chemical Engineers Process Saf Prog 38: e12024, 2019