It’s a name that literally goes hand-in-hand with turnout gear.
More than 40 years ago, DuPont scientist Dr. Wilfred Sweeny – continuing research that had extended for more than a decade – made the discoveries leading to the final development of a product called high temperature nylon, or HT-1. Today it’s known simply as Nomex.
First made commercially available in turnout coats in the mid-1960s, the fiber is found throughout modern personal protective equipment (PPE) ensembles worn by emergency crews worldwide. The fire-resistant fiber is now woven into everything. It is used as threads or blended with other fibers and is found in the reinforcement of outer shells of turnout gear, as well as in the fabrics of pants and coats and gloves – and in liners and the ubiquitous Nomex protective hoods.
“Nomex is the baseline. It’s the standard that everything is measured against,” said Dr. Richard H. Young, senior research chemist with DuPont Advanced Fiber Systems in Richmond, Va. Young has been with DuPont 23 years and has spent all of them working with Nomex.
“You might not see it, but it’s a key part in every garment firefighters wear,” Young said. “All of these are materials that contain Nomex.”
Before the days of DuPont’s discovery, traditional turnout coats were made from rubber or cotton-duck outer shells with neoprene moisture barriers and flannel thermal liners. The cotton outer shells were usually wet down before firefighters entered a burning building.
Cotton Breaks Down
“Cotton will give you thermal protection, but if it does ignite, that’s where the problem is,” Young said. “Cotton breaks down at 285 to 300 degrees, but skin breaks down sooner than that. Nomex was the first garment that didn’t dry out and ignite. A Nomex garment had a consistent performance whether it was wet or dry.”
At DuPont, Sweeny and others were charged with developing a high-melting fiber, and what came out of that work was HT-1. Traditional synthetic fibers such as Nylon and Polyester are “melt-spun,” according to Young, but Nomex, which does not have a melting point, is “solution-spun.”
Melt-spun fibers are produced by melting the raw material and then extruding the fibers. Solution-spun fibers, because they don’t melt, are extruded from material that is liquified using a solvent.
Slow To Catch On
Traditional synthetic fibers and nylon fibers melt at around 500 degrees, Young said. Although Nomex does not melt, he said it will break down around 700 to 800 degrees.
“Suddenly, here was a miracle fiber that didn’t burn,” he said. “That’s what makes it so good for apparel. Until someone had developed a high-temperature material, no one thought of it.”
But getting the product into the hands of firefighters was easier said than done.
In 1965, DuPont partnered with Georgia-based textile maker Southern Mills, Inc. (now TenCate Southern Mills) and New Hampshire-based gear maker Globe Manufacturing Company (Globe Firefighter Suits) to develop turnout coats. Globe introduced the first Nomex coat in 1966, but had few initial takers, said Don Welch, now Globe’s president.
The coat was 10 times the price of traditional turnout coats, Welch said, and it was bulky and heavy – the Nomex itself was nearly twice the weight it is now.
“Everything about the coat was Nomex,” said Pat Freeman, Globe’s technical service manager who has been with the company for nearly 30 years. “The outer shell, the substrate, the corduroy collar – all of it was Nomex.”
Cleveland Steps Up
It took four years before the company received its first Nomex order – from the city of Cleveland in 1970. Welch said the use of Nomex evolved to primarily the coat’s outer shell and then moved predominantly to thermal liners, though it is still also used in the outer shells. Over time the gear became lighter, more breathable, more ergonomic and more flexible.
“The garment design has also come a long way,” Welch said. “It’s a combination of design and materials that are more advanced.”
In the early 1980s, he said, cotton still was the most widely used outer shell, even though it didn’t meet the National Fire Protection Association standard for bunker gear that was established in the mid-1970s. The standard, known as NFPA 1971, called for an outer layer of flame-resistant fabric that would not be destroyed through charring, separating or melting when exposed to 500 degrees Fahrenheit for five minutes.
“The standard,” Welch said, “moved our customers from cotton to Nomex.”
In the early 1980s, Globe became the first company to sell only garments that met the NFPA standards for fire resistance, according to Freeman.
Driving The Standard
“The NFPA standards have moved us so much further,” she said. “Nomex was ahead of the standard, but Nomex also drove the standard.”
The development of Nomex was a huge innovation for the fire service, said Bruce Varner, the chief of the Santa Rosa (Calif.) Fire Department since 2004 and a recognized safety advocate who has served on a number of NFPA committees that set standards for PPE.
“Nomex represented the single most significant change in firefighter protective clothing in decades, increasing the protection of individuals and reducing the weight of the garments,” said Varner, who previously served as deputy chief of the Phoenix (Ariz.) Fire Department, where he was also one of the country’s first fire department safety officers. He later served as chief of the Carrollton (Texas) Fire Department for a dozen years.
“GORE-TEX and the other products from [W.L. Gore & Associates] have improved the breathablity,” he said. “Many different fibers have become available that have improved upon the insulative values. Weight and performance have also been improved.”
Another DuPont synthetic fiber well-known for its high strength-to-weight ratio is Kevlar. It has been blended with Nomex to improve the strength of outer shells and thermal liners.
Late last year, Interspiro, Inc., which makes self-contained breathing apparatus (SCBA), offered a Kevlar/Nomex protective SCBA hose cover as an option after a report that a burning ember caused a hose failure on one of its units.
As with any number of fire service innovations – even those four decades old – there can be critics. There are those who say the improved turnout gear is “too good,” that it allows firefighters to feel a false sense of security and get themselves into dangerous situations they might not otherwise encounter.
“There’s always that debate, is there too much protection,” said DuPont’s Young. “Nomex helps you get the job done, but your biggest tool is your brain. You’ll still feel the heat on your hands and face. You’ve got to listen to your body.”
Gear-makers, such as Globe, also hear that concern, according to Freeman, who offers a rhetorical question: should the manufacturers’ response be to build gear to a lesser standard?
“As firefighters, you have to understand the limitations of your gear and your body,” she said. “I can’t envision making [PPE] less protective.”
Varner agrees. “I will go back to comments that I made in the 1980s,” he said. “If you want to expose parts of your body to feel the heat, there are much more sensitive parts than your ears. Accountability, crew integrity, strong command, safety and situational awareness are the keys to protecting firefighters, not wearing a lower level of protection.”
Efforts continue to develop the next generation of materials and technologies for turnout gear. Young said the future points toward more lightweight garments, with increased breathability, as well as low-friction liners using a Nomex filament.
“That low friction gives you mobility, flexibility,” he said. “The garment manufacturers are doing more to make Nomex more comfortable. They’re making it more everyday wear, trying to make it lighter and more efficient so you can do more things.”
Varner sees additional possibilities down the road for PPE. “If we had a crystal ball we might be able to see what the next real generation of protection would look like,” he said. “There are just now fibers that grow when exposed to heat that will help to protect firefighters in emergency conditions.”
DuPont officials are reluctant to talk about the kinds of new fibers that might be on the horizon. “We are always working on new products,” said Katherine Meyer, a company spokeswoman, “but nothing commercially ready or available at this point.”
Still – more than 40 years after its development – Nomex continues to be a workhorse fiber for the industry. That’s because of its inherent properties for thermal protection and durability.
“Every fire department still has that Nomex garment in the closet that just won’t wear out,” Dupont’s Young said. “Manufacturers continue to develop new products using Nomex because it has proven its value.”