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Mechanical properties and off gassing characteristics of new and legacy SCBA facepieces

Published

Author(s)

Richard Kesler, Constandinos Mitsingas, Adam G. Quiat, Tonghun Lee, Daniel Madrzykowski, Gavin Horn

Abstract

In today’s structure fires, evolving fire loads and higher heat release rates mean that fires grow larger and faster than ever before. Firefighting personal protective equipment (PPE) can be subjected to these severe thermal conditions repeatedly during firefighting operations. The self-contained breathing apparatus (SCBA) is a critical component of PPE that isolates the firefighter from hot and potentially toxic gases and particulate, present as byproducts of combustion. In recent years, changes in NFPA standards have resulted in the introduction of new SCBA facepiece designs and materials. However, the facepiece lens is still often considered the “weak-link” of the firefighting ensemble. SCBA facepiece lenses from two editions of the NFPA 1981 standard around which significant new tests were introduced were exposed to repeated thermal loads similar to those that could be encountered on a fireground (5 kW/m2 for 5 minutes for 100 cycles, and 10 kW/m2 for 1.5 minutes for 10 cycles). Samples from subsets of these SCBA were subjected to quasistatic tensile tests and dynamic impact testing and compared to samples from new, unexposed facepieces. Identical facepiece samples were subjected to the NFPA 1981 Lens Radiant Heat Test that was introduced in the 2013 version of the standard, which drove much of the change in facepiece design. Finally, facepiece lenses were tested for potential off-gassing that was proposed to be the result of polycarbonate decomposition from typical fireground thermal loads, due to the concern that these gasses could be inhaled by the firefighter wearing the SCBA facepiece. Statistically significant differences were found between facepieces certified to different versions of NFPA 1981. Those lenses certified to the 2013 edition had higher tensile strength and absorbed more energy but were more brittle than the 2007 edition materials. Exposure to repeated thermal loads resulted in changes to the tensile strength, strain to failure, maximal load
Citation
Grant/Contract Reports (NISTGCR) - 18-019
Report Number
18-019

Keywords

Facepiece, firefighting, SCBA
Created December 11, 2018, Updated January 28, 2019