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What Does Flame Resistant (FR) Really Mean, and How Do We Test it in Protective Clothing?

You hear requests for flame resistant (FR) clothing and gloves all the time…but what does that really mean? What is an end user with this request expecting from you?

Have you ever been in a situation where it seems impossible, and even like a liability, to label a product as FR when there are no standards written around the product directing you how to make this claim? We have some examples of this conundrum and have experienced inquiries about them from many customers. For example, you want to label gloves as FR–what’s the standard specification for this? Or, the end user doesn’t have an arc or flash fire hazard, but they want “flame resistant clothing” —what’s the minimum testing that should be performed to call something “flame resistant”?

While the truth is that there are no standard specifications to specifically label clothing “flame resistant”*, there are some qualities that materials/products for protection from heat and flame should have:

1. The material/product should not melt and drip (which would indicate a propensity to stick to a person’s skin)

2. It should resist ignition.

3. It should self-extinguish in exposure to the thermal hazard for which it is designed.

Flame resistance is defined by NFPA 2113 (a standard from the U.S. based National Fire Protection Association) as “the property of a material whereby combustion is prevented, terminated, or inhibited following the application of a flaming or nonmelting source of ignition, with or without subsequent removal of the ignition source”. There’s a problem with applying this definition though, and the issue is not necessarily present within the scope of NFPA 2112/2113, but with the broader term “flame resistant” and it’s meaning in the industry.  What’s the “ignition source”? Isn’t the behavior of the material dependent upon the ignition source? Firefighter turnout gear is flame resistant. So is arc rated and flash fire rated clothing. Does that mean you could wear something that is arc rated into a structural fire and have the same level of protection? Not necessarily.

Most flame resistant materials were developed in the 1950s for the US space program and NASA.  At that time, there were only a few small-scale flame testing methods.  These small-scale flame methods survived the test of time and are still used today (like ASTM D6413), but they alone are inadequate to characterize flame resistance without setting many parameters.  This is why large-scale methods came about in the 1990s.  Flash fire manikin testing using ASTM F1930 and ISO 13506 and arc flash testing  (ASTM F1959ASTM F2621IEC 61482-1-1IEC 61482-1-2)  took industry knowledge of thermal hazards to a new level.

There are certainly plenty of test methods available to evaluate the behavior of a material when exposed to heat and flame. If there is no specification written to cover the product or material you’re concerned about, we recommend always using vertical flame testing, oven testing, and one large-scale test (either arc or flash fire), at a minimum, to have an understanding of the material response in a harsh exposure.

The specific hazard must be considered when making testing decisions and for end users making purchasing decisions, as well as the market the product is intended to be sold in.  How do we, as an industry, shift the focus away from the term “FR” and into specific hazards and standards that can be backed with test data and proper categorizations? Educate the end user, the market, and get to work voicing concerns and creating solutions at standards committees and with peers as our industry advances and evolves.

Have comments or want to tell us what FR testing means to you? We want to hear from you!

*ASTM F2302-08 was a standard with minimum requirements to label clothing FR. This standard has been wit

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