What Is The Fr Clothing?
Clothing bearing the FR designation (e.g. FR shirts and work trousers) may provide some flame retardancy. There are two different types of FR clothing. They are flame retardant and flame resistant.
Flame retardant clothing consists of fibers that do not easily ignite when exposed to fire. The flame retardancy of clothing can never be washed off over time or diminished by wear. A well-known example of this is Nomex.
Flame-retardant clothing is made from fabrics that self-extinguish if ignited. Clothing in this category is also referred to as FRT, which stands for flame retardant treated.
In fact, both FR and flame retardant garments are self-extinguishing. This is the property you should look for when shopping for a proper flame retardant.
Both types also reduce the risk of burns. If you come into contact with fire, they can prevent the burns from becoming serious.
Still, there are two significant differences between the two. First is the duration of functionality. Second is the ability to resist wear and tear from frequent washing.
Basically, FR fabrics retain their functionality, while FRT fabrics easily lose their functionality with prolonged use. The latter are therefore cheaper and more accessible for different organizations.
How Does Fr Work?
The task of the FR fabrics is to shield you from flames and also potential heat and thus protect you from severe burns.
To better understand how to protect yourself from dangerous fires, you must first understand how fire works. You also need to know its most important components.
“If you know yourself but not the enemy, for every victory you will take defeat.”
-Sun Tzu, The Art of War
The Fire Triangle
A simple model to understand what most fires require in order to ignite is the Fire Triangle (also known as the Combustion Triangle).
The three main components of fire are:
Remove part of this triangle and there will be no fire (or if it is burning, it cannot sustain itself).
Most fire extinguishers remove the “oxygen” portion of the combustion triangle. The result is that the fire “suffocates” due to a lack of air and thus a lack of oxygen.
With the overview of how our enemy works, we can delve deeper into explaining how you can protect yourself from them.
Fire Resistant Fabrics
Fire-resistant fabrics offer a high level of protection against fire hazards because they do not catch fire at normal oxygen pressure.
Because of their durability, they are also more expensive than the fabrics discussed in the next section.
The underlying mechanism for creating fire-resistant fabric is a mixture of oxidized fibers that char (in other words, burn) and then expand, eliminating any oxygen content in the fabric (causing part of the fire triangle to be removed).
This process also offers a higher TPP Index (Thermal Protective Performance).
What is TPP?
This is a way of measuring the thermal output of a fabric when exposed to convective or radiant heat (usually in a fire). A TPP rating is a standardized number, limited to the number of seconds how quickly a person will suffer second-degree burns from exposure to a solid source of thermal energy.
Treated For Fabrics
The term “flame retardant” encompasses a variety of chemicals that are added to manufactured materials (e.g. plastics and textiles), surfaces and coatings.
Flame retardancy is activated by the presence of an ignition source. Its purpose is to prevent or slow down further inflammation (using a variety of physical and chemical methods).
The mechanisms for achieving protection from flames are as follows:
Reduction Of Endothermal Response
High temperatures can lead to endothermic degradation of some compounds. This reaction removes the heat from the substrate, which of course then leads to a cooling of the material.
This process prevents the spread of flames by creating a thermal insulation barrier between those parts of the fabric that have already been burned and those that are still intact.
Dilution Of The Gas Phase
Gases such as carbon dioxide, which are produced by the thermal decomposition of certain substances, dilute combustible gases, lower their oxygen partial pressure and slow their reaction rate.
We return to our combustion triangle (or further down to the more accurate, expanded version, the fire tetrahedron, which adds the chemical chain reaction component).
Most importantly, these fabrics (plus chemicals) are inherently very different from their fire retardant versions, which are built from the ground up not to catch fire.
But it’s a welcome addition to the family. It opens the door to user-friendly and comfortable fabrics (like cotton and other well-known materials) so that wearing them for long periods of time is much more comfortable and beneficial.
What Restrictions Does Fr Clothing Have?
As mentioned in the previous section, there is a measurement of the performance of garments when exposed to open flame.
The 1986 revision of the 1971 NFPA introduced a new method of measuring thermal protection and specified a minimum thermal protection performance (TPP).
However, it is important to remember that the only way to increase a garment’s TPP rating is to increase the insulation, usually by adding heavier fabric components.
The question that needs to be asked is whether the extra seconds of protection gained in the event of a flashover environment is really a good compromise to today’s lighter systems and higher THL (Total Heat Loss) values.
THL and TPP tests are both performed on all three layers of clothing treated as a single layer. This is required because it is not possible to get a valid result by merging values from one level with values from another level.
You can learn more about FR clothing testing in this video by WorkriteFR.
What is the difference?
- TPP (Thermal Protective Performance) – thermal insulation
Thick/heavy garment = higher TPP (protection)
- THL (Total Heat Loss) – breathability
Lighter/thinner garment = higher THL (comfort)
There is an important inverse relationship between TPP and THL in most systems. The respective optimal values are required to achieve both comfort and protection.
But generally, with increasing TPP comes decreasing THL and with increasing THL comes decreasing TPP. The goal is therefore to balance the two values.
You can’t move effectively with a bulky system. Impairing your mobility is therefore not a good system for Operators.
The trade-off of a few seconds in a high-intensity scenario usually doesn’t outweigh the cost of 99.999% of the time you’re in normal conditions.
Garment TPP ratings are a crucial factor. Of course, we are always striving to optimize the benefits compared to the costs in order to continue to achieve optimal results.
Prolonged exposure to heat definitely takes its toll and cannot be easily prevented, even if the garment itself is fireproof and will not catch fire.
In such scenarios, it is important to understand the two different aspects of protecting oneself in such situations.
- The first is active protection. Active protection involves the individual’s response to a threat, moving out of their way to find cover. The second is passive protection.
- Passive protection means that the focus is on the physical or chemical capabilities of the PPE (Personal Protective Equipment) to provide protection. This is where the FR garments score.
Both are integral parts of the pros’ ability to get out safely with minimal or preferably no injury.
No-melt/no-drip, The Comparison
A few words to debunk the myths surrounding this topic.
No-Melt/No-Drip is an exclusive feature of CORDURA® Nylon.
NOT CORRECT. It can be achieved by combining fibers that melt and drain with a quantity of natural fibers sufficient to absorb the melting material.
No-Melt/No-Drip has flame retardant properties.
NOT CORRECT. It’s not even slightly flame retardant. It does not protect your body from the deadly effects of flame and/or heat exposure.
You can find more information about the No-Melt/No-Drip garments in this blog article.
What Is Pyroshell™ Technology?
We have long been fascinated by the flame retardant technology developed by Schoeller.
One of the reasons we are interested in this is that the anatomical fit and comfort of the garments we make is our top priority.
We didn’t want to compromise fit or comfort by offering bulky garments that are unsuitable for missions where the wearer is bound to be on the move.
In fact, the possibilities to manufacture flame retardant clothing that is still comfortable support active protection.
Another reason we love Schoeller technology is that it’s not made from flame-retardant fibers.
What is a flame retardant fiber?
A flame retardant fiber is one that incorporates flame retardancy into its chemical structure. In simple terms, it simply means that the fiber is inherently capable of quenching any flame generated on its surface. This ability to extinguish a flame is the result of a chemical reaction initiated by the heat of the fire to which the fiber is exposed for a period of time.
This technology converts materials that would normally burn when exposed to fire into materials that do not. The result is an FR garment that exceeds all expectations.
Tested in EMPA: “Thermo Man Testing”. We’ve had excellent results testing our pyroshell-made Striker FR BDU with a 3-second flash-over on a Thermo Man dummy in “regular” and not particularly FR or FR WoolPower 200 underwear.
The pyroshell™ appeared to have excellent heat and flame retardant properties, but we didn’t quite understand the underlying principles when we saw it in action.
At this point it seemed unlikely that this substance was not based on a non-inherent FR substance.
On top of that, the garments still had all the fantastic functional elements, like stretch properties and lack of bulk.
In our conversations with developers, we learned what makes pyroshell™ a game-changing technology, one that has redefined the way we design FR systems.
Schoeller simply glued two fabrics together. And “only” by sticking them together did they become flame retardant. That was awesome. It took a fabric (nylon) that would withstand excessive heat under normal conditions and made it very special.
However, as we delved deeper into the technology, we found that it is the middle adhesive layer that best showcases Schoeller’s innovation.
It shows that graphite has been incorporated. It is the presence of graphite in this layer that provides the desired FR qualities.
What is graphite?
Graphite is simply carbon in crystalline form with hexagonally arranged atoms. This makes graphite a good conductor of heat and electricity.
OK, that’s a cool fact, but you might be wondering how does this make up FR combat pants?
When exposed to heat, the graphite swells through the fabric, encasing the material in a non-combustible layer that protects the otherwise flammable fibers from direct heat or flame.
This prevents these substances from catching fire.
In addition, we no longer have to deal with available colors, minimum order quantities, etc. of FR fibers that do not match our preferences and the needs of our customers.
Abrasion resistance and pilling are also a problem of classic flame retardant fibers. A big problem, in fact, because the inherent FR fibers perform poorly in terms of durability.
Thanks to new flame retardant technology like Schoeller’s pyroshell™, which we use in our Striker FR system, we have access to truly outstanding protection against flames.
This technology combines flame protection with thermal insulation and makes no compromises in terms of wearing comfort or other fabric properties.
In this video by Armin, our Head of Development, you can see our Striker FR Combat Uniform.