Fabric Selection

Selecting FR and AR Fabrics 

One of the greatest risks employees face in industrial environments is operating under conditions where the potential for arc flash and flash fire injuries is high. In these environments, it is important that workers utilise the proper PPE to keep themselves safe in the workplace. Flame resistant (FR) and arc rated (AR) workwear is an essential component of PPE for personnel working in an environment where contact with intense heat, arc flash or flash fire is likely. Workers exposed to flammable liquids, open flame, high-energy electric components or combustible dusts are at high risk for serious and sometimes fatal injuries due to arc flash or flash fire. In addition to adhering to safety standards, understanding proper care for FR/AR apparel is equally important. Precautions must be taken when laundering and mending garments to ensure the apparel retains its protective qualities. 

Selecting the right FR/AR fabric is a complex problem. It requires careful consideration of workplace hazards, industry standards and worker comfort. It is crucial to prioritise protection first, ensuring fabrics meet required certifications for the specific hazards present. Then factors such as comfort, durability and maintenance should be evaluated to select fabrics that are both safe and practical for the intended use. FR/AR fibres and fabrics have particular properties, which either provide benefits or shortcomings. Fabric manufacturers blend fibres in an attempt to balance these individual properties to maximise fabric performance. Blended fabrics combine the protective qualities of different fibres to offer enhanced comfort, durability and performance in hazardous environments. These blends often incorporate inherent FR aramid fibres (Nomex® and Kevlar®) or Modacrylics alongside materials like treated Cotton or other synthetics to improve softness, breathability and moisture management. Blending creates fabrics that have a combination of properties that would be difficult to achieve using inherent or treated fibres alone, for example being lightweight and durable.  

Overarching criteria that must be considered when selecting a fabric, is that not all FR fabrics are AR. Arc rated fabric is a specific type of flame resistant fabric that has undergone arc flash testing, whereas not all FR fabrics have been subjected to this additional testing to determine their specific protection against electric arcs. While all AR fabrics provide FR protection, FR fabric without an arc rating only protects against flame: not the thermal energy of an arc flash. 

In Summary

• FR clothing must pass the vertical flame test, ASTM D6413.
• AR clothing is governed by ASTM F1506. This standard requires that a fabric must be FR before it can be arc rated (via ASTM F1959) and used for arc flash protection. So all AR fabrics are both FR and AR.
• But not all FR clothing has been arc rated.

The key to specifying a quality FR/AR fabric for any protective garment is to analyse the hazards employees face. If protection is equal, choosing a fabric becomes a matter of comfort, user preferences and consensus standards performance.

All FR and AR fabrics must meet one or more of:

• NFPA 2112
• CGSB 155.20
• NFPA 70E

1. Does the fabric meet the hazard requirements.
2. How does the fabric perform in laboratory evaluation.
3. How does the fabric perform in the real world over time.
4. Does the fabric demonstrate performance and longevity characteristics important to the end user.
5. Will employees want to wear it. 

Aramid Fibres

Aramid fibres (meta-aramid and para-aramid) are a man-made class of synthetic, high-performance fibres with molecules characterised by relatively rigid polymer chains linked through powerful hydrogen bonds that effectively transfer mechanical stress. The term aramid is short for 'aromatic polyamide'. Aromatic polyamides were first applied commercially as meta-aramid fibres in the 1960s, with para-aramid fibres being developed in the 1970s. The first commercial aromatic polyamide was produced by DuPont™ and branded Nomex®. Thanks to its strength and heat resistance combined with tactile characteristics that were close to normal textiles, Nomex® was quickly adopted for a number of uses including protective apparel, insulation and more.

In addition to Nomex®, other leading brands of aramid fibres include DuPont™ Kevlar®, Kermel, Protex® Modacrylic and Teijin Twaron®, Technora® and Teijinconex®. Aramid fibres are renowned for their high tensile strength. Aside from their resistance to abrasion and piercing, they also have high resistance to organic solvents and intense heat. They have no melting point and only begin to degrade at extremely high temperatures. They also have low flammability.

FR and AR garments made with premium materials deliver superior heat, flame, arc flash and flash fire protection while providing lightweight, comfortable solutions that meet or exceed industry standards for PPE protection.

Links

DuPont™ Nomex®

DuPont™ Kevlar®

Protex® Modacrylic

TEIJIN

Kermel Polyamide-Imide Fibre (Meta-Aramid)

Since its foundation, Kermel has designed the best protective solutions so that professionals can fight electric arc and fire with the highest levels of safety.

Kermel is a leading European solution provider of textile innovations made from its heat and flame resistant fibres; yarns, fabrics, knits, FR protective clothing are adapted to specific needs of end users.

Fire suits for firefighters, together with protective clothing for public order squads, police, military and industrial uses are some of the most popular applications chosen for total protection.