Arc ratings are values that indicate the arc performance of a material or system of materials and are expressed in calories per centimeter squared. This value may be either Arc Thermal Performance Value (ATPV) or Breakopen Threshold Energy (EBT), depending on whether or not sufficient energy was transmittied through the material to cause a second degree burn in human tissue before the material broke open. Arc Rating s are statistical calculations based on evaluation of a minimum of 20 data points generated in arc testing. With advances in test methods and testing methodology , new data is constantly being generated.
This specification provides performance requirements for clothing worn by electric utility workers and other personnel working around energized parts. In addition to non-thermal requirements, the standard requires the fabric to be flame-resistant; that is, to not ignite and continue to burn after exposure to an ignition source. Flame resistance is measured using FTM 5903.1 Vertical Flame test (max. 2 sec afterflame and 6 in. char length). The standard is currently being revised to include the requirement of reporting an Arc Rating. The Arc Rating is either the Arc Thermal Performance Value (ATPV) or Arc Breakopen Value (EBT) as measured by ASTM F1959 Arc Thermal Performance Test.
This standard applies to flame-resistant waterproof materials used in rainwear. Garments can be made from coated or laminated fabrics. The fabrics must be flame-resistant as determined by ASTM D-6413 Vertical Flame test (max. 2 sec afterflame and 6 in. char length). The standard also requires the Arc Thermal Performance Value (ATPV) to be reported, and requires a minimum Arc Break Open Threshold (EBT) of 5 as measured by ASTM F1959 Arc Thermal Performance Test. The standard is currently being revised to include a fabric flammability test more suitable to coated fabrics.
This standard applies to Fire Service station uniforms made from 100% cotton and flame-resistant fabrics. Recently revised to exclude vertical flammability testing, this standard requires that fabrics do not shrink more than 15% after being tested in a 500°F oven for 5 minutes. This is the only thermal requirement of this standard. Garments are subject to 3rd party testing and inspections. In the past, NFPA 1975 was often used by industries beyond the Fire Service to specify industrial FR garments. However, with the elimination of vertical flammability testing, this standard is no longer adequate for industrial FR garments.
This standard is used by the Forest Service and Fire Departments involved in forest, field and other natural fires (in contrast to structural fires). Garments that meet this standard must pass vertical flammability tests (maximum 2 sec afterflame and 4 in. char length). Fabrics must not melt, drip, separate or ignite, nor shrink more than 10% after being tested in a 500°F oven for 5 minutes. Fabrics must have a minimum Radiant Protective Performance Value of 7. Garments are subject to 3rd party testing and inspections.
This is the first US standard that specifically addresses the need for industrial flame-resistant uniforms. This standard requires FR fabrics to pass a comprehensive battery of thermal tests, including
- Vertical flammability (2 sec after flame and 4 in. char length)
- Thermal Protective Performance (TPP) test (minimum TPP of 6 acl/cm2 spaced and 3 cal/cm2 in contact)
- Thermal Stability Test (fabric must not melt or drip, separate or ignite after 5 minutes in a 500°F oven)
- Thermal Shrinkage Test (less than 10% after 5 min in a 500°F oven)
- ASTM F1930 Thermal Mannequin Test (maximum 50% body burn after 3 sec flash fire)
This standard is not yet finalized, and therefore the thermal performance requirements will probably change. Once published, this standard is likely to form the basis of future laws and regulations for FR clothing in the petroleum, chemical and other industries with a hazard of flash fire. Third party testing and certification is being discussed as a component of this standard.
This standard, also under development, will serve as a User's Guide for industrial flame-resistant clothing. It addresses topics such as purchasing, cleaning, repairs, storage, decontamination, retiring garments, and proper use procedures. This standard will require that garments be certified to NFPA 2112.
NFPA 70E addresses electrical hazard threats that are present in the workplace. NFPA 70E requires that the employer shall document the incident energy exposure of the worker when it has been determined that the worker will be performing tasks within the flash protection boundary
NFPA bases incident energy exposure levels on the working distance of the employee's face and chest areas from a prospective arc source for the specific task to be performed. Flame Resistant Clothing and Personal Protective Equipment shall be used by the employee, and an adequate level of protection based upon the incident energy exposure associated with the specific task shall be worn.
- Installing conductors and other electrical equipment on industrial substations or buildings, residential or commercial
- Connecting the installations to a supply of electricity
- Installing other outside conductors
- Installations in ships, watercraft, railway rolling stock, aircraft, or automotive vehicles other than mobile homes and RVs
- Installations in underground mines
- Installations of railways for operation of rolling stock
- Installations of communication equip. under control of communication utilities
- Installations under the control of electric utilities
| Category | NFPA 70E Requirements |
| Movement and Visibility | When flame resistant, flame retardant, or treated clothing is worn to protect an employee, it shall cover all ignitable clothing and shall allow for movement and visibility |
| Body Protection | - Employees shall wear clothing resistant to flash flame wherever there is possible exposure to an electric arc flash. - Such clothing can be provided as shirt and trousers, or as coveralls, or as a combination of jacket and trousers, or, for maximum protection, as coveralls and jacket. |
| Outer Layers | Garments worn as outer layers over FR clothing, such as jackets or rainwear, shall also be made from flame resistant material. |
| Underlayers | Meltable synthetic fibers shall be avoided in fabric underlayers (underwear) next to the skin. Garments worn as underlayers that neither ignite nor melt and drip in the course of an exposure to the electric arc and related thermal hazard may provide additional thermal protection. |
| Coverage | Clothing shall cover potentially exposed areas as completely as possible |
| Care and Maintenance | - All personal protective equipment shall be maintained in a sanitary and reliable condition. - Individual protection items will normally be used in conjunction with one another as a system to provide appropriate |
| Layering |
- FR and natural fiber garments shall be permitted to be used for a layered system for added protection. - A typical layering system may include an undershirt, a shirt and trouser and coverall. - Specific tasks may call for specific protection systems. |
NOMEX® is an aramid fiber manufactured by DuPont. For clothing applications, it is offered as NOMEX® IIIA, a blend of 93% NOMEX®, 5% KEVLAR®, and 2% static dissipative fiber. NOMEX® is inherently flame resistant and this property cannot be degraded by laundering. NOMEX® is unaffected by most acids, except for some strength loss after long exposure to hydrochloric, nitric, and sulfuric. It has generally good resistance to alkalis. NOMEX® has excellent resistance to mildew, aging and abrasion. Natural (undyed) NOMEX® is not white and will yellow with exposure to sunlight. Accordingly, some lighter dyed shades will discolor rapidly. These lighter shades are available in solution dyed form.
Excel-FR: Excel-FR is the latest advance in flame-resistant protection available only from industry leader Bulwark. Excel-FR has set a new standard for consistent quality with its state-of-the-art continuous finishing process. Excel-FR is yet another example of Bulwark's heritage of innovation and uncompromising commitment to wearer safety. It comes in 100% cotton fabric with a range of weights from 6.5 oz. to 14.75 oz. The Excel-FR offers unbeatable protection in foundries, flame cutting and welding, electrical industries. All Excel-FR apparel is permanently treated to guarantee flame resistance for the life of the garment.
Excel-FR ComforTouch: offers the same protection of Excel-FR with a difference of feeling; the Cotton’s comfort of 88% and the Nylon’s durability of 12% provides long-lasting protection for nearly all work environments involving ferrous metals, as well as electrical utilities and the chemical, oil, gas and petrochemical industries. Naturally, Excel-FR ComforTouch flame resistance is engineered to last for the life of the garment.
PBI GOLD is a synthetic polybenzimidazole fiber made by Celanese Advanced Materials, Inc. which may be used alone or in blends. PBI Gold® is a 60% KEVLAR® aramid/40% PBI blend fabrics offered by PGI DIFCO and Southern Mills for career apparel applications. PBI TriguardTM is a blend of 20% PBI, 30% LENZING FR® and 50% Micro Twaron®. PBI fiber has excellent resistance to most acids and alkalis. PBI has good resistance to mildew and aging. Prolonged exposure to sunlight will cause darkening and loss of tensile strength. PBI fiber has fair abrasion resistance, but the PBI Gold® blend has very good abrasion resistance.
VINEX® FR-9B® is a blend of 85% vinal (a synthetic fiber composed of vinyl alcohol units with acetal crosslinks) and 15% FRR rayon, offered in the U.S. by Westex, Inc. Its primary use is in resisting molten aluminum splash. Almost exclusively in the aluminum casting industry, where its unique ability to shed molten aluminum is valued. VINEX® (also known as FR-9B®) is inherently flame resistant, and this property cannot be degraded by laundering. VINEX® is highly resistant to a wide variety of most common acids and alkalis with no observed loss of fabric strength. However, concentrated nitric acid will degrade the fabric. VINEX® does not provide personal chemical protection to the wearer. Where chemical exposure is a hazard, appropriate specialized barrier garments should be selected. Resistant to most organic solvents. Chlorine bleach will not damage the fiber, but will result in discoloration of the shade. Relatively poor resistance to mildew, aging and sunlight. Abrasion resistance is fair.