Arc Thermal Performance Value
Energy Break open Threshold

Thanks zog, I would like to see some information...

Arc Thermal Performance Value (ATPV) is defined as the arc incident energy required causing the onset of second-degree burn and is represented in cal/cm2. This rating is the result of a testing procedure (ASTM F-1959) that measures the amount of thermal protection a FR fabric would give a wearer if the person were exposed to an electric arc.

Alternatively the material may have an EBT (Energy Break-open Threshold) rating. EBT is defined as the average of the 5 highest incident energy exposure values below the Stoll curve where the specimen did not exhibit break-open. EBT is reported when ATPV cannot be measured due to FR fabric break open.

Great Explanation Zog!

Here is an article which explains the differences in a little more detail.

http://www.americanchronicle.com/articles/view/130732