Flame resistant vs. flame retardant
Resistance depends on fabric structural strength & self-extinguishing properties
As you read this article you are quite possibly at work or someplace other than your home. It’s also very likely that you drove to whatever location you are currently at. I would wager one of the first things you did when you entered your car was to apply your seat belt. Have you ever stopped and thought about why? I would suppose you would answer that “it is the law “or “you will be ticketed if you don’t have it on” and that’s very true, but you might also answer that it’s a safety measure in the event you are in an accident. And, if you are in an accident, seatbelts have been proven to greatly enhance your survivability chances.
If we apply this same logic to FR clothing, you will see there is little difference between a seat belt and FR clothing. The law requires that you must wear flame-resistant clothing when in an environment with potential thermal hazards such as arc flash and/or flash fire. While most of us have never experienced an arc flash or flash fire first hand, it has been proven that these events do occur more commonly than you might think and FR clothing has been proven to greatly enhance your survivability chances should you be exposed to one of these hazards.
Workers push back
Let’s look at the commonalities of wearing a seat belt and wearing FR clothing. Both are required by law; you will be fined or ticketed for not complying. Both vehicle accidents and industrial thermal hazard events can, and do, occur more often than we would like. Lastly, we know that seat belts and FR clothing greatly increase our chances of surviving these vehicle accidents and thermal events. In today’s world we would not consider driving without wearing a seat belt, yet workers constantly push back on wearing FR clothing and believe they can only be comfortable wearing non-FR clothing. It is important to take the time to educate your workers on why FR clothing could save their life and how non-FR clothing could take their life.
Thermal events such as arc flash and flash fire are very quick and violent. Electrical arc flashes typically last less than a few milliseconds while flash fires last for only for a few seconds. Injury can be incurred from the exposure of energy and flame, but it’s the ignition and continuation of burning from non-FR clothing that will most likely affect the severity of injuries. Even if the non-FR clothing is extinguished, it can reignite due to absorption of heat and energy.
Importance of fabric structural strength
FR clothing is made from flame-resistant fabric. Many people confuse flame resistant with flame retardant. Flame-retardant products are designed to slow down ignition or combustion. Common flame-retardant products are carpets, drapes, and furniture. They take time to ignite allowing us time to escape a fire.
Flame-resistant products are designed to self-extinguish. All fabrics wishing to be termed as “flame resistant” must pass an ASTM vertical flame test. The fabric is suspended over a vertical flame for 12 seconds and is then removed from the flame. The fabric must self-extinguish in two seconds or less and have a minimal length six inches or less if being used for arc flash protection or four inches or less if being used for flash fire protection.
The important thing here is to understand the test involves igniting the fabric so, by default, flame-resistant fabrics can and do ignite. Their protection value is in the structural strength of the fabric, the threshold before ignition and its self-extinguishing properties. It requires more energy to ignite flame-resistant clothing than non-flame-resistant clothing and flame-resistant clothing will extinguish very quickly while non-flame-resistant clothing will continue to burn long after the event is over, again adding to the severity of a person’s injuries. Due to the violent nature of momentary thermal events, structural strength is important. FR clothing is designed to resist break open much more than non-FR clothing, thereby reducing injury though ignition of non-FR undergarments.
Lessen chances of serious burns
Flame-resistant clothing is designed to mitigate or lessen injury. It is not designed to always prevent injury. The test standard for arc rating a fabric is ASTM F1959. This test gives the fabric a rating that tells us which point we would experience the onset of no more than a second degree burn. For flash fire the test standard for fabrics is ASTM F1930. This test gives the fabrics a rating of a pass or fail test. In this test, a coverall is placed on a mannequin and exposed to three seconds of flame. If it is determined the mannequin received third- and second-degree burns on less than 50 percent of the body then the fabric passes. So we can see from the test methods that injury can occur if wearing flame-resistant clothing, but by wearing non-flame resistant clothing our potential severity of injury is much greater.
Another area to be aware of when considering the dangers of wearing non-flame resistant clothing is copper, which melts at roughly 1,900 degrees. Non-FR clothing can ignite when exposed to temperature exceeding 350 degrees to 400 degrees. Super slow motion videos of arc flash events have shown that copper shrapnel and vaporized copper can travel beyond 10 feet. So the worker does not need to be right next to an arc flash to incur an injury.
In summary, in a momentary thermal event such as arc flash or flash fire, the difference between life and death may very well hinge on the decision to wear FR clothing or non-FR clothing in daily activities. With FR garments, it simply makes sense to click it.