The Difference Between AR and FR

There’s a new acronym in the world of PPE and it has been causing confusion, both among folks new to the subject as well as those long familiar with FR (Flame Resistant) clothing. The letters “AR” stand for Arc Rated, and made their debut in the recent revision of NFPA 70E. The short explanation of the difference is that all AR clothing is flame resistant (FR), but not all FR clothing has been Arc Rated.

In both cases, and indeed with all applications for FR clothing, the primary purpose of the clothing is to resist ignition (as tested by ASTM D-6413, also known as Vertical Flame Test). If flammable clothing is ignited by an arc flash, flash fire, molten metal, etc., the hazard to the wearer instantly becomes much greater. A clothing fire will last much longer than the initial hazard, typically deeply burn the victim over a much larger body surface area, and is more likely to result in airway and lung damage.

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