The Effectiveness of PBI and Nomex Flight Suits in Jet Fuel Fires

Pilots and their crew engage in some of the most dangerous activities in the work force. They risk their lives every single time they take to the skies, flying tens of thousands of feet above solid ground. But the danger doesn’t only come from the height; equipment failures, flash fires, and severe weather are only some of the various kinds of dangers they face. To protect themselves from possible injury, it is imperative that flight personnel have the safest equipment possible, especially their flight suit. Oftentimes the fight suit will be the first, and last, line of defense from different conditions and can be the de facto life saver.

For such a ubiquitous item, the flight suit is sold in many variations. From style to make to material, flight suits run the full gamut of design. But there are two materials that stand out from the rest. PBI and Nomex flight suits are often considered to be the industry leaders, providing superior protection to their wearers. These suits contain fire resistant fibers that are melded with the regular material of the suit, providing serious protection from heat, as well as being comfortable, versatile, and breathable. It is vital that Air Force employees have access to these materials due to the jet fuel and flames they can be exposed to. Because of its unique structure, PBI and Nomex suits prevent not just fire injuries, but also wounds that are incurred from burnt clothing. The suits’ design allows for a durable, yet secure outfit.

There have been multiple tests performed on these two fabrics to determine which one offers better protection. In environments as unpredictable as many of the Air Force personnel are, it is of utmost importance to have the best bodily defenses. Various studies have looked at how flammable the suits are, as well as the mechanical and comfort features of them. The majority of the research found that PBI suits worked better than those made from Nomex. In one experiment in which the suits were exposed to JP-4 fuel fires, the PBI suits were 21 percent less damaged. Participants also rated them higher in categories such as comfort and mechanics.

In the tests involving actual fires, the PBI and Nomex suits were put on mannequins and then drenched with 25 gallons of jet fuel. Upon being set alight, temperature and intensity readings were taken by placing sensitive strips on each of the mannequins. The data was carefully recorded, further demonstrating that the PBI suits were far outperforming Nomex flight suits in protection capabilities.

Although the PBI suits were declared better overall, there were times where the Nomex suits outperformed the PBI flight suits. The Nomex flight suits demonstrated stronger abrasion resistance, or less likelihood to tear from repeated friction, than the PBI suits. Despite weighing the same, the Nomex material tends to be a thinner fabric, when compared to the PBI material. Though Nomex could claim these victories, it could not stem off further advances of the PBI suits. The PBI suits were also determined to have better breathability and moisture retention, making it a far better choice for both comfort and fire resistance. Finally, the PBI flight suits kept better times when exposed to jet fuel. When set aflame, the PBI material kept had a one-second heat and glow time, as compared to the nine-second heat and glow time of the Nomex suits. The seemingly minimal eight-second disparity can mean the difference between life and death, injury and fatality.

If PBI performed so well against Nomex, why isn’t it the dominant material in the flight suit industry? There is a simple answer to the question: cost. PBI costs quite a bit more to manufacture than Nomex, and since Nomex can adequately meet the Defense Forces’ needs, there is no reason to spend the extra money on PBI.