Industry Standards and Fabric Types Influence the Selection of Flame-Resistant Apparel

To aid in the selection and implementation of PPE in areas at risk for arc flash or flash fire, industry standards from the National Fire Protection Agency (NFPA) provide guidelines and reference charts relating environmental risks to the appropriate level of protection required. However, the variety of flame-resistant (FR) fabric choices and garment types available, combined with the diverse range of environmental elements that may be present and differing severities of hazards, can make proper selection a difficult task. Understanding industry standards and the FR fabric options is essential in determining the proper FR apparel for an application environment.

FR apparel is designed for continuous wear in designated areas where intermittent exposure to flame or heat is possible. Ordinary work apparel will ignite and continue to burn if exposed to an ignition source such as flame or electric arc. Conversely, FR garments are intended to resist ignition and prevent the spread of flames, diverting them away from the immediate area of high heat impingement.

FR apparel also is designed to self-extinguish almost immediately upon removal of the ignition source. By reducing the length of time the wearer is exposed to flame, FR garments reduce the extent of the burn injury. FR clothing additionally resists breaking open and does not melt or drip when exposed to flame, maintaining a barrier that insulates the wearer from heat.

Hot Hazards

Arc flash is an explosive blast of flame, debris, sound and force that occurs due to the passage of substantial electric current through ionized air. While an arc flash event usually lasts under 1 second, it can reach up to 35,000 degrees F and send molten metals at high velocity. Arc flash is the cause of up to 80 percent of all electrical injuries, often due to ignition of clothing and subsequent burns. Each year, more than 2,000 employees are admitted to burn centers with severe burns due to the ignition of clothing that resulted from arc flash incidents.

A flash fire is a sudden, intense fire caused by the ignition of flammable solids, liquids or their vapors, gases or dust. It is characterized by high temperature – creating a heat flux of approximately 84 kW/m2 – and a duration of typically 3 seconds or less, as well as considerable shock waves and a rapidly moving flame front. This flame front can be a combustion explosion, spreading with unusual speed. Witnesses may see the flame race across the surface of a flammable liquid or through a cloud of dust or gas.

While commonly used in areas with the potential of arc flash and flash fire, FR apparel also may be required in welding and other environments prone to sparks and slag, as well as the presence of molten metals or close proximity to open flames.

Industry Standards

Under OSHA’s Genderal Duty clause, it is the employer’s responsibility to identify risks and hazards in the workplace, as well as to seek out appropriate protective garments and equipment for the protection of workers. In making this hazard risk assessment, the employer must consider the risks present and also the most appropriate means of addressing those risks. FR protective apparel can be an important part of an action plan to address these concerns in environments with ignition risks.

The potential need for FR apparel also is addressed in 1910.269, the final rule on electrical protective equipment. This applies to electric utilities and co-generation plants where maintenance is performed on existing facilities. It states that the employer “shall ensure that each employee who is exposed to the hazards of flames or electric arc does not wear clothing that, when exposed to flames or electric arcs, could increase the extent of the injury that would be sustained by the employee.”

To meet OSHA’s need to further address electrical hazards in the workplace, the National Fire Protection Association (NFPA) developed the NFPA 70E standard, containing detailed instruction on electrical safety-related work practices and procedures for safeguarding employees during activities such as operation, maintenance and demolition of exposed energized electrical conductors or circuit parts. NFPA 70E states that “employees shall wear flame-resistant clothing wherever there is a possible exposure to an electric arc flash,” and it provides comprehensive, multi-step instructions on how to protect electricians and maintenance employees from electric arc hazard. This includes Table 130.7(C)(9), used to determine the hazard/risk category (HRC) – a term for categories of clothing and PPE recommendations based on the expected arc energy, as well as the risk of arc in the particular job, task or equipment.