(54bx) Analysis of Combustible Dust Flash Fires on Personal Protective Equipment Fabrics

Combustible dust flash fires present unique hazards to fabrics utilized in personal protective equipment (PPE) garments. NFPA 484 (2015) Standard for Combustible Metals states that “Testing has shown that the 84 kW/m² heat flux used in the NFPA 2112 Standard on Flame-Resistant Clothing for Protection of Industrial Personnel Against Short-Duration Thermal Exposures from Fire garment-equipped mannequin flash fire test is only 25 percent to 32 percent of an iron dust flash fire heat flux” and suggests that garments designed to comply with NFPA 1971 Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting or ASTM F2621 Standard Practice for Determining Response Characteristics and Design Integrity of Arc Rated Finished Products in an Electric Arc Exposure may be more appropriate but that there are “no test data to substantiate their performance for metal dust fires.”

In addition to radiative heat transfer from the flame, combustible dust flash fires also produce high-temperature solid particles that may adhere to fabrics and produce significant and prolonged heat transfer to the garment. While this additional heat transfer unique to combustible dust flash fires may be significant, the prescriptive performance requirements of PPE fabrics required by standards are based primarily on flammable gas-fueled flash fires, and have not been thoroughly evaluated for combustible dust flash fires. Therefore, these standards may not be directly applicable.

In this study, in an effort to analyze the additional hazards that combustible dusts flash fires pose on PPE fabrics, various PPE fabrics are exposed to combustible dust flash fires using a custom flash fire apparatus. Organic and metal dusts are dispersed using an injection system similar to a standard Siwek 20-L combustion chamber, and subsequently ignited into a flash fire directed at the PPE fabric. The performance of the PPE fabric is evaluated using heat flux measurements and compared to a flash fire from a flammable liquid mist.