Page 22 - OHS, September 2020

PPE: ELECTRICAL SAFETY
equipment that are capable of generating an arc flash, like high- voltage switching and grounding gear, panel boards, switchboards, motor control centers, motor starters, metal clad switchgear, transformers and meters. If you are an electrical maintenance worker, industrial electrician, or machine operator, you should look for clothing that is 70E rated.
A portion of the standard addresses safety-related work practices including gloves, sleeves footwear, head protection, face and eye protection as well as protective apparel. A key part of the standard establishes CAT categories, formally hazard-risk categories (HRCs), which define the level of arc rating needed by clothing to perform specific hazardous tasks where the potential for an arc flash exists. The standard identifies a specific category for each type of work normally performed by electrical workers.
NFPA 2112. The NFPA 2112 Standard on Flame-Resistant Clothing for Protection of Industrial Personnel Against Short- Duration Thermal Exposures from Fire provides criteria for clothing materials in terms of flash fire. The purpose of this standard is to “provide minimum requirements for the design, construction, evaluation, and certification of flame-resistant garments for use by industrial personnel, with the intent of providing a degree of protection to the wearer and reducing the severity of burn injuries resulting from accidental exposure to hydrocarbon flash fires.”
This standard is for clothing used as protection against industrial flash fire hazards, typically seen in petrochemical and oil and gas industries. A flash fires is characterized as sudden, intense fire in short duration but severe in potential danger. All flash fire clothing that is compliant with NFPA 2112 has to meet extremely stringent requirements and must be tested and certified by a third party. The garment must defy melting, dripping or after-flame burning.
It must also achieve a 50 percent or less predicted body burn, which means that the garment will pass the test if it records less than 50 percent of a second- and third-degree body burn in a three- second flash fire. These numbers were determined by looking at survival rates when humans suffer second- or third-degree burns over more than half of their body. Unlike the 70E which is expressed in calories, the 2112 data is expressed as a percent body burn, and the lower the number, the better the protection.
Note: NFPA 2112 does not apply to protective clothing for electrical flashes, technical rescue or any firefighting operations or hazardous materials emergencies.
Compliance within Standards
As discussed, NFPA 2112 is a clothing standard for protection against industrial flash fire hazards, and NFPA 70E is for clothing protecting against the thermal hazards of an electric arc. The hazards are somewhat similar, but when selecting FR clothing, it is important to recognize that compliance with one standard does not necessarily mean compliance with the other.
NFPA 2112 refers to compliance both within the fabric itself and the finished garment, the product must be tested and certified by a third party. The requirements to be listed a 2112-certified garment are far more stringent, and if the garment passes, the manufacturers must label the product with the certification organization’s mark (think of the Underwriters Laboratory stamp that you see on a number of household products in the marketplace). If you are
purchasing a product that is NFPA 2112 certified, you can be assured that it is using compliant materials and that the finished product is compliant as well.
The requirements for NFPA 70E are based solely on the fabric alone and not necessarily the finished product. Furthermore, NFPA 70E is a self-declaration standard. This means that a manufacturer can test products themselves, either in-house or out-of-house, and declare themselves compliant and label products as such. However, the regulations for 70E say that the clothing must still be able to be worn following an arc event, so some manufacturers will test and certify the garment as a whole.
Key Tests
Below are the criteria each garment or fabric must have in order to be certified to either standard. In the graphic below, you will see the requirements for each garment to prove that it has been tested and certified.
For the 70E Standard, the garment must comply with the following criteria:
■ ASTM D7138 (thread melting resistance). Thread used in garments must be of flame-resistant fiber and not melt at 500 degrees Fahrenheit.
■ ASTM D6413 (vertical flame resistance). When exposed to flame for 12 seconds, garment fabrics must self-extinguish (after flame) in two seconds or less, exhibit damage (char length) of six inches or less, not melt or drip and meet these standards after 25 wash and dry cycles.
■ ASTM F1959—Arc Testing. Determines how much heat a certain fabric will block from an electric arc before the onset of second degree burns for the wearer (ATPV or EBT values reported in cal/cm2).
For the 2112 Standard, the garment must comply with the following criteria:
■ ASTM D7138 (thread melting resistance). (same as above).
■ ASTM D6413 (vertical flame resistance). When exposed to flame for 12 seconds, garment fabrics must self-extinguish (after flame) in two seconds or less, exhibit damage (char length) of four inches or less, not melt or drip and meet these standards after 100 industrial laundering cycles.
■ ASTM F2894 (heat resistance). When exposed to 500 degrees Fahrenheit for five minutes, garment fabrics must not ignite, melt, drip or separate and not shrink more than 10 percent.
■ ASTM F2700 (heat transfer performance). When exposed to combined convective and radiant heat at 2.0 cal/cm2/sec, garment fabrics must have an HTP rating of 3.0 cal/cm2 or greater (contact) and 6.0 cal/cm2 or greater (spaced).
■ ASTM F1930 (instrument manikin test). Under simulated flash fire condition, predicted second- and third-degree total body injury is no more than 50 percent of total body surface area covered by sensors (less head, hands and feet).
■ Label Print Durability Test. Garment labels must remain legible and in place after 100 industrial laundering cycles.
Read the Labels
Unfortunately, despite the existence and promotion for using standards to qualify clothing in the workplace, often there is still incorrect information provided to end users. Some tests are used to
18 Occupational Health & Safety | SEPTEMBER 2020
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