As we learned in previous How It’s Tested episodes, ASTM F1506 establishes minimum performance requirements for flame resistance, arc rating, and mechanical durability, using two main tests and a series of smaller test to identify fabrics that comply.
In this post, we’re concentrating on one of the two main tests – ASTM F1959, the Standard Test Method for Determining the Arc Rating of Materials for Clothing, also known as “The Arc Rating Test.” In short, The Arc Rating Test allows us to be sure that arc rated fabrics – protecting wearers against arc flash hazards on the job – have been tested to the arc flash standard.
More specifically, it is the official method for determining how much arc flash protection a fabric or fabric system provides to the wearer. There are two ways to achieve an arc rating: Arc Thermal Performance Value (ATPV) and Energy to Breakopen Threshold (EBT) – click here to learn more about the difference between the two.
Check out our video below, featuring Tyndale’s Vice President of Technical, Scott Margolin, which provides an overview of ASTM F1959 and shows the test in action:
As shown in the video, the test is performed by placing three pieces of fabric one foot away from an arc and this is done seven times, providing 21 data points. If you look at an arc rating report, you’ll see red dots on the bottom horizontal axis and the upper horizontal axis:
From there, find the point where the black line (which is the computer-generated average of the data points) intersects with the 50% reading on the vertical axis. Then draw a straight line down from that point of intersection to the horizontal access to find the arc rating for that fabric – and any garment ever made from it. If applicable, the arc rating can then be used to identify the NFPA 70E PPE Category (CAT, formerly known as Hazard Risk Category or HRC) for a garment made from this fabric.
Have a flash fire hazard instead? Check back soon and keep an eye on your inbox or the How It’s Tested hub – we’ll be diving into the standards and test methods for flash fire protection starting in our next episode!