In 2012, the National Fire Protection Association (NFPA) updated its terminology in relation to personal protective equipment. Moving forward, PPE designed to withstand electric arc flash hazards is no longer always referred to as Flame Resistant (FR) but instead considered Arc-Rated (AR). This has led to some confusion as there are important differences between arc-rated vs flame resistant clothing.
What to Know
The most important thing to remember when dealing with arc-rated vs flame resistant terminology is that all arc-rated clothing is flame resistant but not all flame resistant clothing is arc-rated. To understand why, let’s look at the two primary ways these clothes protect you: by resisting ignition and insulating from heat.
Whether a piece of clothing is flame resistant depends on the fabric’s ability to resist ignition or quickly self-extinguish after the ignition source is removed. In the event of a flash fire or arc flash, it is critical that the clothing being worn does not catch fire, melt, or continue to burn after the initial hazard as this greatly increases the severity of injuries sustained in an accident. All FR clothing must pass a Vertical Flame Test which measures its response to heat and flame.
As the name implies, arc-rated clothing fabric is subjected to a series of arc flashes to determine how much energy it can block before it is likely to cause the wearer a 2nd degree burn 50% of the time. This amount is known as the Arc Thermal Protective Value (ATPV). However if the fabric breaks open prior to reaching the ATPV the arc rating it is labeled as the Energy breakopen threshold (Ebt).The EBT is the amount of energy a material can withstand before the fabric breaks open and exposes skin or lower layers of clothing to the hazard. The ATPV and EBT are measured in calories of heat energy per square centimeter (cal/cm²). The higher the arc rating value, the greater the protection.
According to all current standards for arc flash protection clothing must be flame resistant to qualify for arc rating. This makes the difference between arc-rated vs flame resistant clothing clear: Equipment rated FR may not provide sufficient protection for workers in environments where arc flash hazards exist. These employees must wear the appropriate level of AR PPE in order to lessen the chances of serious injury or even death.
Workrite provides a wide variety of arc-rated safety equipment to meet your needs. Take a look through our online store or contact us and we’ll help ensure you have the required protection to help keep your workers as safe as possible.