By Jeffrey Stull
Protective hoods have become an integral part of the firefighting ensemble. Minimum performance specifications for hoods exist in the NFPA 1971 Standard. Intended as an interface item of protective clothing, separate hoods are typically constructed of knitted material with a face opening to fit around the breathing apparatus mask and "bib" extensions of the material to remain tucked under the firefighter's coat.
In NFPA 1971, protective hoods have a lower thermal insulation requirement than garments (a TPP rating of 20, compared to the minimum 35 required for garments), but still have to meet all of the flame and heat resistance requirements typically associated with garment materials. As a consequence, protective hoods are heavy single ply or double ply materials using Nomex, PBI, P84, Basofil, Kevlar, and FR rayon fibers.
Here are the main things to consider when selecting fire hoods.
Owing to their knit constructions, hoods are typically "one size fits all" but must be carefully selected to fit properly with the other equipment, primarily the SCBA facepiece. Because hoods are repeatedly stretched over the facepiece and the wearer's head, some hoods quickly lose their shape and can fail to properly protect the firefighter. NFPA 1971 has attempted to address this requirement with a test for measuring the hood face opening size after repeated donnings and doffings of the hood on a manikin headform.
Features for hoods are relatively simple. These usually consist of: the type of face opening (some hoods are designed to accommodate specific respirator facepieces); the length of the sides, front, and back (sometimes referred to as "bibs"); and ventilation areas. Some heavyweight hood materials use mesh materials in the ear region to permit easier communication, but this feature also reduces protection. One style of hood uses mesh on the top of the hood (sitting underneath the helmet) to provide a means for heat to escape.
Some of the reluctance to use hoods has been due to resistance by some firefighters to the idea of total encapsulation of the body. Many more traditional firefighters claim that they use their ears as "early warning" sensors to detect excessive heat and know when to leave. Unfortunately, the sensitivity of ears to heat also makes them very vulnerable to high heat. Hoods have repeatedly demonstrated their effectiveness in covering those exposed portions of the face not covered by other elements of the ensemble.
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Jeffrey O. Stull is a FireRescue1 columnist and president of International Personnel Protection, Inc., which provides expertise on the design, evaluation, selection and use of personnel protective clothing, equipment and related products to end users and manufacturers. They are considered amongst the leading experts in the field of personal protective equipment.