How outer shell fabrics are your first line of defense
Discomfort used to be a price you paid for protection, but here’s how that changed
Sponsored by TenCate Protective Fabrics
By Robert Avsec for FireRescue1 BrandFocus
Heat stress and its physiological impact on a firefighter while wearing and working in their structural firefighting protective ensemble, PPE, has been garnering more attention in recent years in our efforts to improve firefighter safety. PPE manufacturers are constantly searching for new ways to keep firefighters safe from the external threats (e.g., thermal, mechanical, liquid) while at the same time lessening the impact of heat stress on the firefighter inside the garment.
I had the opportunity to speak with Jordan Davis, end use market manager for emergency response for TenCate Protective Fabrics, to learn more about TenCate’s latest fabric innovation, Enforce Technology, that’s been developed by TenCate scientists and engineers.
According to Davis, when he works with fire department leaders and their firefighters to discuss PPE buying decisions, he focuses on three things:
- The health and safety of the firefighter wearing the PPE (which historically has been linked to thermal protection)
- The gear’s performance (e.g., comfort, flexibility, breathability)
- The gear’s durability (Fire departments have a fiduciary responsibility to purchase gear that not only does the above, but also lasts).
From there, according to Davis, there are always three other conversations that take place regarding what a fire department is looking for or needs from their PPE:
- Protection from exposure to toxic materials on the fire scene
- Protection while working on non-fire emergency call (e.g., motor vehicle extrication, technical rescue)
- Protection from heat stress and its impact on the firefighter (e.g., sudden cardiac events, heat exhaustion, heat stroke)
“That seems to set the stage pretty well for what they need to accomplish with their buying decision, and it helps them realize that what they're really involved in is a balancing act,” said Davis. “How do we select an ensemble that addresses all of these factors the best way that we can and stay within our budget?”
Davis went on to say, “And that philosophy is really the underpinning of how we go about our research and development process. Can we engineer those properties into a fabric that will help us address those factors in the best way possible for our client fire departments?”
OUTER SHELL PERFORMANCE
NFPA 1971: Standard on Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting, addresses the level of performance every PPE manufacturer needs to build into their ensemble elements. Until recently, those performance measures for the outer shell (fabric) have focused on protecting the firefighter inside from flame impingement and mechanical injuries (e.g., cuts or scrapes).
That outer shell (the first layer) was also designed to work in conjunction with the moisture barrier (second layer) and the thermal barrier (third layer) to protect the firefighter from external heat and fluid hazards (e.g., body fluids, hydraulic fluid).
But meeting those requirements has often resulted in PPE that firefighters found to be stiff and hard to move in when new; they also complained of how long it took to “break in” that new turnout gear. So, with that kind of feedback, manufacturers like TenCate went “back to the drawing board.”
And back to the drawing board for TenCate meant focusing its scientists and design engineers on developing an outer shell fabric that was lighter and that moved better. The result was Enforce Technology that not only improved comfort for firefighters, but also helps reduce work effort by not having a stiff outer shell impeding their movement. And all while still providing thermal and abrasion protection that’s compliant with NFPA 1971 requirements.
According to Davis, having a lighter and more flexible outer shell that moves with you is more than just an advancement in firefighter comfort.
“It also means that the firefighter wearing the garment is not working harder because they’re working against their turnout gear,” said Davis. “Less effort means less exertion and less exertion means less buildup of body heat. And that buildup of body heat is where the effects of heat stress start.”
THE TENCATE DIFFERENCE
What makes TenCate different when it comes to developing technologies like Enforce, and creating fabrics that better meet the needs of the fire service, is that they own the process.
“We’re unique in that we have the technology and the capability to own the entire process,” said Davis. “We're buying raw fibers from PBI from DuPont, from other suppliers, and we're taking those [raw fibers] all the way through the process to make our own yarns.”
TenCate then uses those yarns to weave their own fabrics, fabric that will become the outer shell for firefighter protective garments. TenCate then takes those fabrics and finishes them and dyes them before sending them on to manufacturers who will cut, sew and sell them.
“We have a lot of control within that process and we see every step in it,” said Davis.
PPE PERFORMANCE STARTS IN THE YARN
The outer shell of firefighter PPE begins as fibers, which are turned into yarns, and then the yarns are woven into fabrics. The most common fibers used in creating yarn for outer shell fabrics are staple fibers and filament fibers.
“Spun yarns [where more than one fiber is spun together into a yarn] have better abrasion resistance characteristics,” said Davis. “Fabrics made with filament yarns [where a continuous fiber is used in the spinning process] have a higher tear strength and they also have a better feel to them which is why you see filament yarns used in fabrics for thermal barriers. It feels better on the skin.”
According to Davis, Enforce is a hybrid yarn that combines the best features of a spun yarn with those of a filament yarn for a synergistic effect.
“Both our Pioneer and Agility lines of firefighter PPE are the first to use our new Enforce Technology,” said Davis. “With that, we’re able to create an outer shell that’s lighter and more comfortable for the firefighter—right off the bat—while still having a high degree of thermal and abrasion protection.”
Turnout gear fabrics using Enforce Technology, and its innovative twill weave, ensure a range and ease of movement that firefighters want and need to remain on the job and in the action. And that turnout gear is as much as ten percent lighter than gear made using legacy fabrics.
“These benefits are enhanced even further when combined with a TenCate cutting edge thermal liner utilizing Coolderm Technology and Nomex Nano liner," added Davis. "Coolderm allows your turnouts to perform like high-end active wear- actively pulling sweat off of the body and promoting evaporative cooling. "
Add Nomex Nano to the thermal liner batting to improve flexibility even more, decrease bulk by up to 40%, increase breathability by up to 13%, increase wickability, and decrease dry-times.
If you're looking to provide better heat stress management for your firefighters, then here's a formula Davis recommended.
You take TenCate lightweight outer shells with Enforce, combine them with a pro-quality thermal liner with Coolderm Technology’s active moisture wicking, add in a layer of Nomex Nano in the thermal liner batting and you have a set of turnout gear that revolutionizes heat stress management.
Put all of that together and you have turnout gear that protects the firefighter on the inside from external hazards while at the same time making it easier for that firefighter to move and work. And that makes for a protective ensemble that can reduce the impact of heat stress on that firefighter as well.