Selecting the Most Appropriate FR Fabric and/or Fibre

Selection of the 'perfect' FR fabric and/or fibre is a complex process. Each FR fabric or fibre has particular properties which either provides benefits or shortcomings. Fabric manufacturers blend fibres in an attempt to balance these individual properties to maximise fabric performance. It is important that Corporations be aware of each fibre’s properties to ensure that garments selected meet the specific requirements of a given application.

When reviewing fabrics and fibres, Corporations should consider thermal protection, static resistance, comfort, durability, stability, employee acceptance and appearance, ease of care and maintenance, colour availability and initial and ongoing cost. There also needs to be recognition of special hazards such as electric arc, flash fire and molten metal and chemical splash. These particular hazards may require additional evaluation and/or PPC program investment to ensure employees are provided with the correct and hopefully 'perfect' protection.

Corporations should follow three basic steps when undertaking proper evaluation of different FR fabric types. They are;

  1. Identify the potential hazard - different hazards have different characteristics, which is why test results do not directly correlate to each other. Test results for electric arc flash should not be substituted for test results for flash fire.

  2. Identify industry consensus standards for the exposure - for example, NFPA 70E and ASTM F1959 and F1506 have been developed for electric arc flash environments while NFPA 2112 and ASTM F1930 have been developed for flash fire environments.

  3. Ensure testing has been conducted at independent laboratories - this will ensure that scientifically valid data is being assessed. There is no substitute for information generated at an independent laboratory. The leading independent testing laboratories for electric arc flash performance are Kinectrics and KEMA Powertest and for flash fire performance, the University of Alberta.

About Aramid Fibres

Aramid fibres (meta-aramid and para-aramid) are man-made high-performance fibres with molecules characterised by relatively rigid polymer chains. These molecules are linked by strong hydrogen bonds that transfer mechanical stress very efficiently, making it possible to use chains of relatively low molecular weight. 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 1960s and 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 world leading brands of aramid fibres include DuPont™ Kevlar®, Kermel®, Teijinconex®, Twaron® and Technora®. 

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 fire. They have no melting point and only begin to degrade at extremely high temperatures. They also have low flammability.

Aramid fibres share some general characteristics that distinguish them from other synthetic fibres, namely:

These unique characteristics derive from the combination of having stiff polymer molecules with strong crystal orientation as well as close interaction between the polymer chains due to the hydrogen bonds. The hydrogen bonds are aligned, for the most part, along the fibre axis, which gives them remarkable strength and flexibility.

When considering PPE for military, fire departments or the police, their personnel require the highest levels of protection, as well as comfort and wearability. They need superior thermal protection and flame resistance and resistance to tears and abrasions. What's more, they want comfort that comes with lighter weight materials, greater flexibility and increased breathability. Firefighter turnout gear made from aramid fibres meet ever-more stringent requirements in terms of protection, thermal insulation and wearing comfort. The wearer is not only protected against heat and flame, but also against hazards associated with electric arc and flash fire.

Police and Special Forces also face increasingly threatening or violent situations. Aramid fibres provide protection, not only against heat and flame but also against bullets, slashing and stabbing.

In short, aramid fibres provide the key benefits of inherent flame resistance, superior heat insulation, dimensional stability, no burning, melting or adherence to human skin and are strong, light, durable and comfortable.  

Key Determinants for Blended Fabrics

To widen the specification of high-performance FR fabrics, principal or lead fibres such as Nomex®, FR Cotton, Kermel® and Kanecaron/Protex®, are often blended with one or a number of other high-performance fibres such as:

Some of the world's leading and technically blended FR apparel fabrics, used in the construction of the ArcFlashWear premium range, include: