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Thermal Performance of Self-Contained Breathing Apparatus Facepiece Lenses Exposed to Radiant Heat Flux

Published

Author(s)

Anthony D. Putorti Jr., Nelson P. Bryner, George C. Braga, Amy E. Mensch

Abstract

Fire fighters are exposed to highly variable thermal environments including elevated temperatures, convective heat flux, and radiant heat flux, which can put a significant burden on personal protective equipment. Thermally degraded and melted self- contained breathing apparatus (SCBA) facepieces have been identified as a contributing factor in certain fire fighter fatalities and injuries in the United States. At the current time, SCBA facepieces are tested at less severe thermal conditions than other components of a fire fighter’s ensemble and equipment. In order to better understand the level of thermal performance of the SCBA facepiece lens, facepieces were exposed to radiant heat dominated thermal environments. In these experiments, SCBA facepieces were exposed to radiant heat fluxes of 2 kW/m2 to 15 kW/m2 from a natural gas fired radiant panel apparatus. The facepieces were mounted on a headform and instrumented with thermocouples to measure the temperatures of the exterior lens surface, the interior lens surface, inside the facepiece, on the headform, and in the airway of the headform during exposure. Heat flux to the headform was also measured during the exposures. Airflow through the mouth and respiratory system was simulated using a breathing apparatus, with the air to the mask supplied by an SCBA, at an average flow rate of 40 LPM at 24 breaths/min. The pressure inside the facepiece was measured during the experiments. During the experiments, the facepiece lenses sustained various degrees of thermal damage, ranging from no visible damage to the formation of crazing, bubbles, holes, and protuberant deformations. The maximum temperatures measured on the exterior of the lenses were approximately 290 °C, while the maximum airway temperatures were approximately 55 °C. An incident radiant heat flux of 15 kW/m2 was determined to be a useful test criterion for determining the performance of SCBA facepiece lenses. Measurement of internal facepi
Citation
Technical Note (NIST TN) - 1785
Report Number
1785

Keywords

SCBA, self-contained breathing apparatus, lens, performance metrics, radiant heat flux, respirator, radiant panel
Created March 5, 2013, Updated November 10, 2018