How do they test FR workwear?

Every day, workers around the world are risking their lives as they are exposed to the risk of flash fire, electrical arc flash and molten metal splash. In the split second when such a dangerous situation does occur, providing the right FR clothing can make the difference between avoiding a disaster involving serious injury, or death.

In a matter of seconds, a momentary electric arc, flash fire or molten metal splash exposure can surround a worker with searing temperatures that will ignite everyday non-flame-resistant workwear instantaneously. Worse yet, non-flame-resistant workwear continues to burn even after the source of ignition has subsided. In fact, the majority of severe and fatal burn injuries are due to the ignition of non-flame-resistant work clothes - not by the actual exposure to the heat source itself.

Using flame-resistant clothing can provide the necessary thermal protection to shield workers at the moment of exposure. Once the source of ignition is removed, flame-resistant garments will self-extinguish, greatly limiting the severity of a burn. In many cases, they can mean the difference between a minor accident and a tragic fatality.

With the growing need for standard FR workwear on many worksites there are many reasons to check the quality and safety of the materials and fabrics used to construct many existing workwear products. The following tests analyse fabrics through standard tests used to certify and categorise the safety ability of FR materials.

What is the definition of FR - flame retardant and flame resistant?

It is the ability of a fabric or material to not combust when exposed to flame and also to self-extinguish once an ignition source (flame) is removed.

What are the types of fibres used in FR (fabrics)?

Inherent: flame resistance is an essential characteristic of the fibres from which a fabric is made. This characteristic cannot be washed or worn out, eg, Nomex and Tecasafe Plus.

Chemically treated: a chemical treatment is applied to the raw material that changes the original level of FR, and will reduce over time due to chemical being washed out of fabric eg, Proban (Banwear and Ultra-Soft).

How is FR tested and measured?

Exposure energy

Is expressed in calories/cm², 1 cal/cm² is equivalent to the exposure of the tip of a finger to a lit match in one second.
An exposure energy of 1-2 cal/cm² will cause a second-degree burn on human skin.

Arc rating

Is the measurement of the maximum exposure energy resistance demonstrated by a material (or a layered system of materials) prior to break open, or at the onset of a 2nd degree skin burn, typical non FR workwear can ignite at ratings as low as 2 cal.

Arc thermal performance value

ATPV is the exposure energy on a material that results in a sufficient heat transfer through the material for a 50% probability of the onset of a 2nd degree burn. An ATPV rating is assigned to FR clothing to indicate the level of protection provided. The higher the rating (cal/cm²) the greater the protection.

Hazard risk category

HRC is a rating range directly related to ATPV. There are 5 HRCs ranging from 0 to 4, with a hazard risk of 0 presenting the least risk and a hazard risk of 4 being the greatest level of risk.