Step 3 is by far the most important step! There a 4 steps to a basic risk assessment: Trying to figure out when arc flash PPE should be worn is not as straight forward as you might think.īut I’ve got a nice way you can approach it. Not every garment will pass both so remember this one thing.Īll arc rated clothing is flame resistant but not all flame resistant clothing is arc rated. Then once it passes that test it can be sent to see if it passes the AR tests (from ASTMF 1506). In order to even send a material to be tested for an arc rating, it must first meet the requirements of FR clothing standard (ASTM D-6413). What’s the Difference Between AR & FR?Īll arc rated garments are flame-resistant, in fact, that’s the barrier to entry. It’s the amount of incident energy that would result in a 50% chance that breakopen occurs. The breakopen threshold energy (EBT) is similar to the ATPV… What is EBT Rating?Īnother factor in performance testing your arc flash gear is determining when it will break open.īreak open is defined as a hole that’s either has an area of 16 mm2 or an opening of 25 mm in length. This means the skin under your clothing is exposed to about 1.2 cal/cm2. Well… now there is a 50% chance that you will experience the onset of a second-degree burn. So… let’s say you are in an arc flash that is has an incident energy of 8 cal/cm2.Īnd you are wearing clothing that is rated 8 cal/cm2 (because the ATPV was 8). Yup, sounds crazy but this is how it works. The value is determined by the amount of incident energy required to transfer enough heat through the material to create a 50% probability that the person wearing the ppe will experience the onset of a second degree burn. The arc thermal performance value (ATPV) is the material’s ability to withstand the incident energy. We call that the arc flash incident energy. When you are performance testing arc flash apparel you expose the material to a certain amount of heat energy. Usually, it’s the arc thermal performance value or ATPV Rating. Whichever one comes first dictates the number that goes on the equipment’s tag.
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