Choosing the right flame-resistant PPE
Flame-resistant (FR) clothing is essential for anyone who works on job sites or with equipment that comes with potential fire, combustion or electrical hazards.
Flame-resistant (FR) clothing is an essential protection measure for anyone who works on job sites or with equipment that comes with potential hazards like fire, combustion, or electrical arcs. There are many different factors involved in choosing the right kind of FR clothing and there are basics everyone should know.
What is flame-resistant clothing?
Flame resistance refers to the ability of cloth and other materials to self-extinguish. This means that, when the ignition source such as a flame or electric arc is removed, flame-resistant clothing stops burning. This prevents the fire from propagating and eliminates the risk of either burning clothing or high thermal temperatures from coming in direct contact with the skin. While FR clothing is also designed to resist catching fire in the first place, it is not “fireproof” and will ignite and continue to burn if the source of ignition is strong enough and remains in contact with the fabric.
Who should wear flame-resistant clothing?
Anyone who works in environments where there is the risk of injuries from heat, fire or electricity should wear flame-resistant clothing. There are three primary types of hazards that people of various professions come into contact with:
- Electric arc: A risk for electricians, electric utility workers, and those who come in contact with energized electrical equipment
- Flash fire: This hazard is a risk for those at pharmaceutical or chemical plants, refinery workers and others who work with flammable materials
- Combustible dust explosion: A risk for those who work where fine dust is generated, such as at paper, food processing, paint and metal processing plants
The Occupational Safety and Health Administration (OSHA) has specific guidelines that stipulate that employers should ensure employees do not wear clothing that “when exposed to flames or electric arcs, could increase the extent of injury that would be sustained by the employee.”
What types of flame-resistant clothing are there?
Flame-resistant clothing is rated by its arc thermal performance value (ATPV) and energy break-open threshold (EBT). The ATPV describes a fabric’s insulating value, or the maximum energy in calories per cm squared (cal/cm2) resulting from an arc flash that a fabric can be exposed to and prevent the wearer from becoming burned.
The EBT describes the maximum amount of energy a fabric can be exposed to before it breaks open to a size of 0.5 in2. Both the ATPV and EBT of a flame-resistant fabric are measured, and the lower of the two values becomes the fabric’s arc rating. The higher the arc rating, the better the protection.
There are various kinds of fabric that have been developed over the years to provide flame-resistant protection. Most are a blend of different flame-resistant fibers and other materials, such as cotton and nylon, that have been treated with flame-retardant chemicals. Some common types of inherently flame-resistant fibers are:
- Nomex: A type of fiber developed by DuPont in the 1960s, it creates durable and breathable fabrics that are inherently flame-resistant and are used in a wide variety of FR clothing – including those worn by firefighters. It is often used both alone and in combination with other fibers.
- Kevlar: Also developed by DuPont, these fibers are renowned for their strength in addition to their flame-resistant properties. It is lighter and thinner than Nomex and retains its strength even in extreme temperatures. However, it usually comes with a hefty price tag and so is often used as part of a mix rather than alone.
- Modacrylic: The most common type of inherently FR fiber, it has been commercially produced since 1949 and is almost always used in blends. The fiber is easily dyed, resists wrinkling, and is quick to dry, making it perfect for use in uniforms and other work clothing.
Choosing the right flame-resistant clothing
Flame-resistant clothing is typically selected by an employer based on a hazard analysis that considers potential energy exposures in a particular working environment. The results of this analysis are then usually applied to a safety standard. The NFPA 70E personal protective equipment (PPE) categories (formerly Hazard Risk Category) are primarily used in the United States. There are four PPE categories; Category 1 being of the lowest hazard and Category 4 the highest, each with specific clothing requirements based on the job.
For instance, a single layer of clothing with a minimum arc rating of 4 cal/cm2 is required in low-risk Category 1. This means that workers must wear FR clothing on the upper and lower body, but a long-sleeve shirt and pants or coveralls is enough to provide sufficient protection. Yet in high-risk Category 4, the minimum arc rating for clothing is 40 cal/cm2, and an arc-rated flash suit hood and gloves, or rubber insulating gloves, are also required in addition to other PPE such as eye protection and leather footwear.
Older editions of NFPA 70E allowed for clothing to be layered with 100% cotton to provide sufficient protection, but this has been rescinded from the latest edition. However, it’s still recommended that those who require flame-resistant PPE avoid undergarments that contain synthetic fibers like nylon and polyester, which could potentially burn or melt beneath FR clothing when exposed to significant heat.
Flame-resistant clothing is essential in protecting the safety of workers, which should be of the utmost importance to both employers and the workers themselves. Performing correct risk assessments, choosing the right flame-resistant clothing, and making sure that it is worn properly, ensure that workers are sufficiently protected and can focus on the task at hand.