FR clothing stands for Flame Resistant, referring to the material in the garment being able to self-extinguish itself once the ignition source (such as an arc flash fire) is removed.
FR clothing is worn by people who are exposed to these types of hazards:
And FR clothing is absolutely necessary for any workers who come in contact with energized electrical equipment.
Each piece of FR clothing has an ATPV (Arc Thermal Performance Value), which is a rating of the arc burn protection capability of each garment. To determine the rating, the higher the number, the more protection it offers.
To determine which ATPV is best for your FR clothing, an arc flash hazard analysis should be performed to determine the potential incident energy in the work environment.
Hazard Risk Categories (HRC) are specified in the NFPA 70E safety standard (CSA Z462 in Canada), based on specific job tasks. The five categories go from Category 0, which allows untreated 100% cotton, to Category 4, that requires FR clothing plus a double layer switching coat and pants.
The latest edition of NFPA 70E stipulates that all garments for HRC 1 through 4 must be flame resistant. Older editions of the standard have allowed for "layering" solutions using 100% cotton, non-FR T-Shirts worn under rated FRC.
As for untreated material, cotton is the material of choice. Unlink polyester blends and nylon, cotton will simply burn off and not melt into the skin – which will happen during the intense heat of an arc flash explosion. As a rule of thumb, roughly 90% of all electrical trade workers fall into Categories 1 and 2 – requiring FR clothing with an ATPV rating of 8 or higher.
Some of the protective fabrics for FR clothing include:
This FR clothing technology provides all the benefits of FR cotton, including higher ATPV ratings and softer, more comfortable fabric. Tecasafe Plus is "inherently" Flame Resistant, combining the best features of all fabric options (a blend of three inherently FR fibers, combining the best attributes of flame resistance, strength, and comfort).
Whereas Dupont is the sole manufacturer of Nomex fiber, CXP Nomex from Milliken is manufactured using a patented process in which traditional Nomex IIIA fiber is combined with Kevlar using a special weave for a noticeably softer, more comfortable wear than traditional Nomex (yet retaining all the protective quality levels).
Westex produces both products, and both are FR Cotton and FR treated for the life of the FR clothing — but there are significant differences. While Indura is chemically treated 100% cotton Indura Ultra Soft consists of 88% FR Cotton and 12% Nylon woven together to make the garment more durable and comfortable. This is an important factor, as it increases the lifetime of the garment through industrial laundering while also increasing the garments’ ATPV or Arc Rating.
(It should be noted that although there is nylon in the Indura Ultra Soft, and nylon is meltable, it is a very small amount that is blended or woven tightly on the inside of the fabric and the combination produces maximum protection.
The cleaning/washing and maintenance of FR clothing should be left to the professionals. Chlorine bleach and hydrogen peroxides found in some detergents can degrade the FR clothing properties of your PPE. In addition, there is always the danger of flammable materials and soils building up on the surface of the clothing, creating a potentially flammable situation. All styles of FR clothing offer superior protection, but it is absolutely critical to select the correct hazard rating for the job at hand. For additional information on the NFPA 70E Standard, see www.nfpa.org, or purchase online the CSA Z462 standard from our website: https://www.electricityforum.com/arc-flash/index.html