If you are returning for Part 2, welcome back! If you haven’t had the chance to read Part 1 yet, take time to go back and read it first! Without knowing the overall importance of fire resistant clothing within our industry, what you are about to read might not strike as much of a chord with you. As a quick recap from Part 1, a few things that have been proven:
- Synthetic materials, in the majority of athletic wear, have a low melting point and a high likelihood of worsening burns in the event of a post-crash fire;
- The use of flight suits made of fire resistant fibers coupled with undergarments made of natural fibers offers a high level of protection from fires;
- And finally, in order to increase our protection to the highest level we need to layer undergarments made of fire resistant fibers beneath our flight suits. In addition to the coupling of fire resistant undergarments with a flight suit, items such as natural fiber socks, fire resistant gloves, sturdy boots, and a properly worn helmet can all work together to protect us in the incident of a post-crash fire.
Let’s think about a usual day for those of us in the air medical industry. Better yet, let’s make it a day off work. You have a dinner engagement tonight with friends, one that requires no specific level of dress. You’re free to pick any outfit out of your closet that you want. Let’s look at three possible options: a well-worn pair of sweat pants and a comfortable hooded sweatshirt; denim pants with a classy shirt; and lastly, a formal sport jacket joined with pressed slacks. Which do you choose and why? Do you pick based on comfort, quality, durability, stylish appearance, or maybe you have your own reasons for picking one over the other. If you chose the sweats, what traits make those worn-in sweats so sought after? They are lightweight, soft, and fit perfectly for their intended purpose of lounging around. It is very easy to see that comfort, style, and durability are major factors in choosing our apparel. They are also huge factors toward non-compliance with PPE policies and procedures.
One of the top reasons for PPE non-compliance is lack of comfort. However, by choosing an appropriate fire resistant fiber, matched with a high quality manufacturing process, a consumer can have comfort, style, and function. Fire resistant clothing’s intended purpose is to keep us safe from a post-crash flash fire. Beyond that, our uniform within HEMS acts as a walking billboard for our respective companies or agencies. Our PPE has to appear professional, wash well, and stand up to the rigors and harsh environments that it will be subjected to; all the while being a garment that we will choose to wear based on our desire to be comfortable.
There is a plethora of fire resistant garment manufacturers on the market. They all differ just like any other clothing manufacturer. The clothing from one vendor may be more comfortable than another, or one company may make a product that is more durable than their competitor. Let’s start simple; it all begins with what fiber is used. There are many fire resistant fibers on the market. In this article I am going to examine two differing types of materials – Nomex® and Lenzing FR®. This by no means is an exhaustive list. There are numerous blends of fibers on the market offering differing levels of protection. Some may outperform others in areas such as comfort, durability, flash fire protection, or heat transfer.
Nomex® is a trademarked flame resistant fiber. It first became commercially available in 1967. When its fibers are exposed to heat the material has a unique ability to absorb the energy, allowing for valuable time to evacuate from direct flame. 5 After many years of Nomex® being the leader in fire resistant materials, DuPont created a new product, Nomex® IIIa. This product was created in part to offer increased protection from flash fires. Another feature enhancement of Nomex® IIIa is its addition of Kevlar, and an antistatic material, woven into the Nomex® fibers. The Nomex® IIIa product offers increased durability, as well as superior comfort over its predecessor, yet works very similarly to the original Nomex® product. The fibers within Nomex® IIIa will expand when exposed to flame and heat in order to create a barrier between the wearer and the source of flame. 7
We now know that the Nomex® IIIa serves the purpose of being a protective fiber, but let’s review it for what we really consider when purchasing a garment: comfort and durability. With Nomex®, DuPont reports it to feel like any other normal piece of clothing. Even during daunting and hazardous tasks such as those we would be exposed to in the HEMS industry, it is reported to be comfortable. When it comes to durability, the life of a garment plays a very vital role in whether a garment can be economically feasible for an organization or individual. Let’s consider for example, if a fire resistant shirt cost $100 and has a life expectancy of approximately one year. The average work week consists of around three shifts per week, meaning there would be need to own a minimum of three shirts. Would your organization or you personally be able to afford this annual recurring cost? Would that change if the life expectancy of that garment was 3 or 5 years? DuPont claims that their Nomex® products last, on average, two to three times longer than normal textiles and can be washed an average of 125 times, making them a much more feasible and economic choice. 7
The second fire resistant material I want to discuss is Lenzing FR®. This is a cellulose fiber from the Beachwood tree. One significant benefit of this product is that it not only offers excellent protection from flame impingement onto skin, it also provides tremendous improvements when it comes to reducing heat stress on the wearer. 4 Within our workplaces, we will typically be wearing these fire resistant garments all day long and within temperature extremes that include heat. A product such as this, that offers breathability, temperature control, and moisture wicking abilities, will reduce potential heat related illnesses. When compared to other fibers such as aramids like Nomex® and Modacrylic, Lenzing FR® was able to outperform them by maintaining much lower body temperatures. 6 Another benefit to this product, as well as with Nomex®, is that the fire resistant properties are inherent within the fibers themselves. This allows the garments to not lose their protective properties when they are cleaned. The fire resistant properties are only limited by the life of the garment itself. The basic principle behind how Lenzing FR® works is when the material is exposed to heat or flame, the degradation of the material causes a protective barrier to be formed on the surface of the garment. Without getting into too much chemistry, there are two significant heating points that cause degradation of Lenzing FR®. In order for this protective barrier to occur, certain agents within the fibers must decompose prior to the cellulose fibers within the garment. 8
There are no right or wrong answers when someone asks what is the best type of fire resistant material. The “best” product is in the eye of the beholder or on the body of the wearer. It depends on what specifically you are looking for with your garment. Are you searching for comfort or is durability more important to you? Is heat protection during a flash fire worth sacrificing in order to double or triple your overall life of the garment? I think that there are key factors as to what are the most important traits of fire protective garments, but I will let you decide what is the most essential to you. No matter what we place at the top of our list, the reason that you’re reading this article is that you have a vested interest in your safety and how to improve upon it. Even if you have the most expensive fire resistant garments on the market, if you wear them incorrectly they will be of no use to you.
Looking back to Part 1, we have established that layering of fire resistant garments provides the best protection in the event of a flash fire. This includes the use of fire resistant underwear, long undergarment pants, long-sleeve undergarment shirts, pants, shirts, flight suit (either two piece or one piece) and outerwear should the need arise in the climates of your operation. In addition to these, I cannot overstress the importance of a good leather pair of boots, a well fitted helmet with visors, and appropriate gloves.
One of the best places to look when determining the proper way to wear these items is U.S. military standards. Documents such as the Air Force Instruction 36-2903, Army Regulation 670-1, and Army Regulation 95-1 offer direction pertaining to proper wear of a flight suit, garments to wear under a flight suit, and appropriate accessories that can be worn as well. Base layers are required to be made of 100% cotton or fire resistant fibers from an approved list. During the course of in-flight operations, the wearer of a flight uniform is to have his suit zipped up to no lower than the middle of their name tag and their sleeves are to be completely pulled down. In addition to the undergarments and flight suit, direction is also given for the use of fire resistant gloves as well as cotton or wool socks. 1, 2, 3 Beyond these standard regulations, there is a general consensus within the military aviation industry that when sizing for a flight suit, the wearer needs to account for about a quarter inch gap between their undergarments and the flight suit. The gap between the garments is to account for the absorption of heat and energy from flash fires causing the fire resistant fibers to swell; this allows for the suit to not constrict too tightly around the wearer. Also, these suits are not meant as a fashion statement, but rather for life safety purposes. Though it may make you look like a 1950s car club president, wearing your collar in an upright positon during in-flight operations will offer more fire resistant surface area against your body than when it is in its typical turned-down position.
As a conclusion to this 2-part series, let’s look at a quick summary. First, the use of athletic apparel, usually polyester based, can prove to be detrimental to our health as HEMS providers in the event of a post-crash flash fire. These types of garments have significantly lower melting points compared to others fabrics and will drip rather than burn or self-extinguish. With the threat of rotor-craft post-crash fires being as high as it is, we must be proactive in the use of proper PPE. Layering a Nomex® flight suit with natural fibers can improve outcomes, but layering that same flight suit with fire resistant undergarments and other accessories such as gloves, socks, and a helmet will provide the maximum amount of protection. Choosing those garments isn’t an easy task, and must be closely evaluated and carefully considered by the wearer. Comfort lies solely in the individual consumer – what is considered comfortable for one person may be considered unwearable to another. Selecting proper fire resistant materials involves being educated on the varying fibers available as well as their use by manufacturers in their clothing lines. Comfort, durability, and function are only a few benchmarks to examine when you’re shopping for these items. Finding an undergarment that you enjoy wearing is essential, but more importantly, it is paramount that you evaluate your entire PPE ensemble and wear it in the way that it was meant to be worn. By following small standards such as keeping your flight suit zipped, sleeves down, and layering with proper fabrics you will drastically improve your chances of surviving one of the greatest threats to providers within the HEMS industry.
- “Air Force Instruction 36-2903.” www.afpc.af.mil. 12 Aug 2014. Web. 16 Feb 2016. PDF.
- “Army Regulation 95-1.” www.gensale.net. 3 March 2006. Web. 16 Feb 2016. PDF.
- “Army Regulation 670-1.” http://fas.org. 3 March 2005. Web. 16 Feb 2016. PDF
- “Lenzing FR.” www.lenzing-fibers.com. Web. 24 Feb 2016.
- “Nomex® History.” DuPont. 2007. Web. 24 Feb 2016.
- “Performance Test.” www.lenzing-fibers.com. Web. 24 Feb 2016.
- “Protection Against Fire Hazards with Nomex® IIIA.” DuPont. 2016. Web. 24 Feb 2016.
- “Thermal and Sorption Study of Flame-Resistant Fibers.” Lenzing Berichte. 2011. Web. 26 Feb 2016. PDF.
Darrin is a certified flight paramedic who is currently working within the critical care transport environment for a national air medical provider. Along with serving as a clinical provider he also has the opportunity to serve as an educator for both his peers as well as the public. Darrin has had the privilege of serving for several emergency response organizations including those providing firefighting, dive rescue/recovery, hazardous materials response, district level disaster response, hospital based EMS, municipal based Fire/EMS, tactical medicine, and private for-profit critical care transport. He has not only served as an operational member of these teams, but has also had the opportunity to of instruct on topics specific to each discipline. Darrin holds a Bachelor’s of Science degree focused on Homeland Security and Public Safety.