Bulwark UniversityTechnical Articles

Whether it is appropriate to attach non‐FR embroidery and emblems to flame resistant protective garments is always a difficult question to address. The only comment of the consensus standards writing organizations, such as NFPA and ASTM, is that nothing on an article of clothing may increase the extent of wearer injury in case of garment ignition. ASTM in Standard F‐1506, Standard Performance Specification for Flame Resistant Textile Materials for Wearing Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards states in an appendix item that, "Logos, name tags, and other heraldry should be limited in number and surface area".

No OSHA or military standards address this area. SFI, the race driver's association, has not addressed this issue. However, identification and personalization are clearly safety issues in themselves that must be addressed by end users.

In the final analysis, the end user of the garment must weigh the benefits of identification and personalization against the potential risk from using non‐flame resistant materials. Common sense in the size, placement, and number of these materials is the best solution.

Treated flame resistant natural fiber fabrics such as 100% cotton and cotton blends wick moisture which adds to wearer comfort. They also absorb liquids and therefore provide no protection from chemical substances. NOMEX fiber exhibits very good resistance to many chemicals and NOMEX fabrics are often used when wearers are exposed to minor splashes of chemicals. In these cases the hazard is limited to a concern for the durability of the fabric. However, NOMEX fabric also does not provide personal chemical protection to the wearer. Large chemical exposures can easily penetrate the open weave fabric and reach the wearer's skin.

Heavier weights of fabric or different fabric constructions may provide very slight improvements in chemical penetration time. Nevertheless, specially designed laminated or coated fabrics are required for use in protective apparel where barrier protection against hazardous chemical penetration is required.

Bulwark offers a line of disposable chemical splash FR coveralls, lot number KDE4SB. This covering garment cannot be worn alone and must be worn over flame resistant protective clothing for thermal protection. It can be worn to provide limited protection against chemical exposure while performing specific tasks, such as transferring chemicals. If full time protection is needed, then one of the specialty chemical resistant garments will be required.

According to NFPA 70E section 130.7 (C) (12) (a), layering of non-melting flammable garments is permitted to be worn under FR garments for added protection. However, the system arc rating of the innermost FR layer must be sufficient to prevent breakopen and ignition of the flammable under layer.

If Table 130.7 (C) (9) is used to determine the HRC category, only FR layers within the layered system are used to determine system arc rating. Arc ratings of individual layers cannot simply be added together. Any garment worn as the outer layer, including rainwear, must be FR.

Meltable fibers such as acetate, nylon, polyester, polypropylene, and spandex cannot be used in under layers next to the skin except that an incidental amount of elastic is permitted in socks and underwear.

Because of changes to the 2009 Edition of NFPA 70E, we can no longer advise our customers to simply add individual single layer arc ratings together to arrive at a system arc rating for layered garments. Annex M.3.1 of the 2009 Edition of NFPA 70E states that the total system arc rating cannot be determined by adding the arc ratings of the individual layers... The only way to determine the total system arc rating is to conduct a multilayer arc test on the combination of all the layers assembled as they would be worn.

Bulwark is currently conducting a series of layered arc tests to determine the total system arc rating of various combinations of shirts over T-shirts and base layer fabrics, coverall fabrics over shirts and pants, and outerwear over shirts, pants and coveralls. This information will be communicated to the market as soon as it is available.

Wearers are often concerned about possible allergic reactions from wearing flame resistant garments. They are also concerned about taking these garments home, having them in the closet with other clothing, and laundering them with the family wash. Extensive testing has shown that the fabrics used in Bulwark flame resistant garments are not harmful by either contact or ingestion.

Industrial laundries are equipped to launder all types of fabrics and degrees of soiling. If cleaning is the responsibility of the wearer, having these garments in the home is not harmful to others. If they are not soiled with contaminants that should not be washed together with the family laundry, they may be mixed in wash loads without concern. If they are soiled with flammable contaminants, of course they should be washed separately.

The majority of Bulwark garments are made from either durable flame resistant 100% cotton or blends of 88% cotton/12% nylon or NOMEX IIIA. NOMEX IIIA is a blend of 93% NOMEX, 5% KEVLAR, and 2% proprietary static dissipative fiber. NOMEX is a DuPont registered trademark for its family of aromatic polyamide (aramid) fibers. NOMEX is chemically inert, and DuPont states that based on more than 30 years experience the fabric poses minimal risk to human health and the environment.

Durable flame resistant cotton and cotton blend fabrics have been extensively tested for skin irritation, contact hypersensitivity, and toxicology from ingestion. All of these tests have shown no irritation or contact sensitivity caused by the flame-retardant finish.

Finally, Bulwark and its predecessor companies have manufactured garments from various flame resistant fabrics for more that 35 years. During this time hundreds of direct cutting and sewing operators have handled millions of yards of fabric. There has never been an occupational injury or illness linked to these fabrics.

Bulwark is confident that the flame resistant garments we provide are safe to wear and are not hazardous to the families of employees.

Research shows that flame resistant garments are no more hazardous than any other apparel in hazardous areas where static electricity is a concern.

The generation of static electricity on clothing depends on a number of factors: the relative humidity, the fabrics involved, the use of grounding devices, and the task being performed. Under standard environmental conditions, synthetic fabrics such as polyester or NOMEX absorb less moisture and retain more static than natural fiber fabrics. NOMEX IIIA contains 2% static dissipative fiber to control nuisance static. NOMEX does not require moisture in the atmosphere to conduct static electricity. However, NOMEX garments alone without other engineering controls will not address the hazards associated with static.

Natural fabrics such as cotton used in Bulwark Excel-FR and Excel-FR ComforTouch garments have less static buildup in high humidity conditions because they absorb water from the atmosphere. This water conducts and helps distribute the static charge. However, since absorbed water is actually conducting the charge and not the cotton fiber itself, cotton fabric is ineffective at dissipating static charges at low levels of relative humidity (<20% RH). These garments will dissipate static in high humidity, but not under low humidity conditions.

Static electricity in the workplace can be either a nuisance in the form of garment cling, or a hazard from sparking in a flammable atmosphere. The primary hazard from static charges is the stored energy on the body of an ungrounded person. Most flammable vapor/air mixtures can be ignited with spark energies in the range of 0.15 to 2 millijoules (.001 joule, a unit of electrical energy). The ungrounded human body can store energies as high as 40 millijoules while clothing can hold less than 5% of that amount. The contribution of clothing to static charge buildup is very small as long as wearers do not don or remove items of clothing in a hazardous area.

Donning or removing any garments can generate static charge on the fabric through triboelectric generation by friction and cause charge separation between the layers of clothing. Increased charge on the fabric and charge separation increases the likelihood of spark generation from the fabric surface. Testing of a Bulwark vest showed a 5X increase in static charge to the wearer when the vest was removed compared to the charge present while the vest was being worn. Therefore the action of donning or removing garments can increase the charge on the human body and provide a source of spark energy.

Concerns have been raised about whether the use of conductive components in protective garments for electrical workers, such as metal snap fasteners on shirts or coveralls, diminishes protection from electric arcs.

In general, the concern about conductive components in garments for these workers is a misinterpretation of OSHA 1910.269, Final Rule on Electrical Protective Clothing. This rule is designed to prevent the use of items that are expected to contribute to the severity of wearer injury in case of an accident. OSHA had in mind such things as dangling gold chains or bracelets that might contact energized parts.

Mr. Charles Davis, Director of OSHA Compliance Programs, was asked this question: "Are metal zippers in linemen's clothing a concern for employers to whom the paragraph 1910.269(l)(iii) applies?" The reply was: "The metal in a metal zipper is not expected to contribute to the severity of injury sustained by an employee in the event an electric arc occurs. Therefore, provided the surrounding material meets the Apparel Standard, the metal zipper will be acceptable under paragraph 1910.269(l)(iii)."

Similarly, ASTM International Standard F 1506-02a Performance Specification for Flame Resistant Textile Materials for Wearing Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc and Related Thermal Hazards states in Note 4 to section 6.1.1, "Fasteners or closures used (in a manner in which they can come in contact with the skin) should be covered with a layer of fabric between the fastener or closure and the skin". F 1506 is referenced in National Fire Protection Association Standard NFPA 70E (Standard for Electrical Safety in the Workplace).

Based on specifications for wearing apparel for electrical workers and interpretations of OSHA rules, conductive components are allowed as long as they are covered so that they cannot contact the wearers' skin.

There has been much discussion about the use of DEET insect repellent because of concern about West Nile Virus. DEET (chemical name, N, N‐diethyl‐meta‐toluamide) is the active ingredient in many insect repellent products. It is used to repel biting pests such as mosquitoes and ticks. Products containing DEET currently are available to the public in a variety of liquids, lotions, sprays, and impregnated materials (e.g., wristbands). DEET is designed for direct application to human skin to repel insects, rather than kill them.

DEET is the active ingredient in the most successful & popular insect repellents and is HIGHLY flammable, especially in concentrated form. Products such as Deep Woods Off contain about 26% DEET, which is the most you can buy over the counter. However, 100% DEET spray is available on the Internet.

The best advice is to spray the product ONLY on skin and never on clothes. Since full strength DEET is highly flammable, if an individual exposed to the hazard of electric arc or garment ignition sprayed his or her clothing and there were an accident, there is a significant risk that the clothing will ignite and continue to burn. In this scenario the DEET is serving as a fuel source.

Any insect repellent should be applied to the skin only and not to flame resistant garments.


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Our Experts

Derek Sang

Derek Sang

Derek Sang has been involved with the Flame Resistant Clothing market from the service, manufacturing and garment sides for over 15 years.

Read Full Bio Denise Statham

Denise Statham

In her current position as Bulwark’s Technical Manager, Denise is responsible for the evaluation of new fabrics and related technologies, representing Bulwark on pertinent NFPA and ASTM technical committees.

Read Full Bio