So you are looking to get some arc flash or fire resistant clothing for yourself or for some people that work with you and want to know what to watch out for?  I hope that this article will be useful and will give you good ideas on how to select the proper FR clothes.  We get asked most of these questions once in a while and decided that it would be best to put the general answers out there for everyone to see…

• Don’t want to read the entire thing but still wish to get some basic guidelines for choosing the correct fire resistant/arc flash clothing?  Skip to the bottom for the summary to get at least the basics.

Keep in mind – this is just general information and it is up to you to actually make sure that your clothing provides adequate protection.  We are trying to make it a little easier for you to ask the right questions and look for important qualities, but your safety is still your own responsibility.

Below you will find information differentiating and describing:

• Basic fire resistant clothing
• Arc flash rated clothing
• Flash fire rated clothing
• Heat resistant FR clothing

What level of protection is needed?

First of all, you should determine what type of FR protection you really need.  FR clothing actually is not a one-solution-to-all-problems type of deal.  Some people view FR as flame retardant, fire resistant and consider that all FR clothing is also flash fire or arc flash rated clothing.  That is not really the case.

Clothing that could increase the intensity of injury in case of an accident vs. clothes with basic natural flame retardant properties. Polyester is very dangerous when heat or flame hazards are present – it burns rather easily and melts when it burns, sticking to skin and making injuries much more severe than if the person wore 100% cotton.  Wool, on the other hand is normally somewhat resistant to heat and light flame (that is why it is frequently used in fire blankets that can effectively smother a smaller flame).  Similar observations can be made about some materials used in rainwear – PVC coated fabrics normally have a resistance to light fire.  But this doesn’t mean that these materials are necessarily safe for all occasions – a flame from a cigarette lighter is in a completely different league from a fireball created by a flash fire or an arc flash explosion, and so is the FR clothing that protects from it.

FR treated clothing and clothes made of inherently fire resistant clothing materials (most commonly used).

Regular FR Clothes

If your job demands that you wear fire resistant clothing, without requiring anything more specific, then this will likely be what you need.  There are a variety of fabrics available for these: FR treated cotton or blends of cotton with other fibers, Nomex, some Aramid fibers (like Kevlar or Modacrylic), and a variety of blends of various fibers that are labeled under special brand names (Indura, Indura UltraSoft, Protera, Tecasafe, Nomex IIIA, etc).  These are frequently used in applications that have sparks and possible contact with hot objects.

You can find a lot of FR treated cotton clothing for welding (often in green color), those are often coated with chemicals that suppress fire and often wash out as the garment is laundered multiple times.  Though keep in mind that not all treated cottons lose their FR properties after laundering, and it isn’t even bad in some cases – garments with a limited number of washes are normally cheaper and if you know that the garment will have holes and be thrown out after a few weeks and just a few washes, then this might be a good way to go.

Arc flash rated clothing has to be labeled as compliant with certain standards and provide a calorie rating.  If it does not have at least a calorie rating, then it is better to assume that it is not arc flash clothing.  There are different ASTM standards that apply to various types of arc flash PPE.  ASTM F1506 is the standard that dictates the requirements of arc flash uniforms and suits.  ASTM F1891 describes the requirements of arc flash rainwear.  There are other standards that apply to face shields, hand protection and even fall protection that is suitable for use in applications with arc flash hazards present.  Other requirements are also put on arc flash clothing since arc flashes such as no exposed metals parts, so make sure that your arc flash garments do not have uncovered metal snaps, buttons or zippers.

Arc Flash Rated Clothing

The main difference between an arc flash and a regular fire is that the arc flash takes place for an extremely short duration of time, but in that time it can reach a temperature that is hotter than the surface of the Sun.  Thus, due to the rapid jump in temperature, it creates a shock wave and appears as an explosion.  After the moment it is gone, but it is capable of igniting anything that is flammable around it – so if there is a person wearing regular cotton or other regular fabrics, the clothing remains on fire and continues to burn the individual.  FR treated or inherently fire resistant clothing, on the other hand, self-extinguishes almost immediately.  Additionally, some fabrics are able to absorb the heat better than others, without passing all the temperature of the initial blast to the skin of the individual.  Do you need an entire arc flash suit that covers you from head to toe for a high-risk task?  Read more about arc flash suits here to find information on the components and common features and differences.  Want to see what an arc flash might look like?  Check it out here: What is an Arc Flash.

Flash Fire Rated Work Clothing

Flash fire clothing is a different class of clothes that protect from heat and fire.  Flash fires are different from arc flashes.  They are caused by an ignition of a mixture of air and a flammable substance – could be flammable solids (like dust), gases or liquid mists.  A flash fire last longer than an arc flash, but normally does not reach such a high temperature.  The flash fire standard for regular uniform-style clothing is NFPA 2112, flash fire rainwear normally gets rated to ASTM F2733.  Look for these standards in FR clothing specifications to make sure that it provides sufficient protection.  A flash fire test conducted on Nasco Sentinel rainwear can be seen in this video - What a Flash Fire looks like.  Watching this you can get an idea of what the exposure and intensity may be in a flash fire accident.

Heat Resistant Clothing - Aluminized, Leather and Carborized

Another type of FR clothing that is frequently used in applications that have a constant high risk of exposure to hot objects like molten metals or kilns is, basically, fire resistant clothing with above-average insulation and sometimes reflective properties.  Metal smelters and kiln operators are always exposed to extremely high heat and need more than a garment that protects in case of an accident – they need a clothing that literally allows them to do their job.  Aluminized clothing is commonly used in such applications – it helps reflect radiant heat and is normally able to withstand physical contact with very hot objects without damaging and immediately transferring the heat to the inside.  Another type of specialty clothing has to do with high insulation and maximum temperature – welders that have excessively large amounts of splatter land on them might want to consider using higher-end materials instead of regular FR cottons or aramids.  Fire resistant clothing made of carborized fibers is usually able to withstand extremely high temperatures and also provides very good insulation.  This makes dealing with molten splatter easier since it does not easily burn holes in the garment and keeps the heat out for longer than almost anything else of the same thickness.  If you are curious for more information about high heat clothing, please read more in the aluminized and high temperature resistant clothing.

Additional standards exist for various types of fire fighting safety gear including requirements for station uniforms, structural fire fighting suits, wildland fire fighting clothing.

Things to look for and avoid:

• In applications that have flash fire or arc flash hazards, it is normally a good idea to avoid putting any flammable materials into your outside pockets – especially cigarette lighters and other objects that can ignite and burn well.  That is why arc flash suits often have no outside pockets.
• Manufacturers laundering instructions should be followed to preserve FR properties and to maximize fabric life.
• Make sure that you have proper undergarments – a polyester T-shirt or underwear can be a hazard even underneath an FR coverall.  You can find 100% cotton undergarments or even use fire resistant underwear (it is available).
• Don’t put on regular winter clothing or rainwear over a fire resistant coverall and expect that you are protected.
• Use fire resistant, arc rated or flash fire winter clothing or rainwear for warmth or dryness.
• Use fire resistant/arc flash high visibility vests instead of regular polyester ones if there are fire hazards.
• Watch for what you wear on your head – polyester or acrylic hats burn and melt even if the rest of the body is safely covered in expensive Nomex.

If you want to learn more about FR clothing:

It might be beneficial to get an understanding of the different fire resistant fabrics to learn what might work better for you.  The different FR materials vary in softness, thickness, calorie ratings, breathability, durability, laundry requirements, useful life-time, best-fit applications, etc.  You can see a somewhat basic chart showing some properties of widely used FR fabrics on ArcFlashFRClothing.com in its FR Fabrics guideline.

Summary:

Basic fire resistant clothing – normally does not have any calorie ratings and does not claim to comply with any official standards.  However, it is widely used in applications like welding where regular clothing might catch on fire.  Do not use this if you need arc flash or flash fire protection.

Arc flash clothing – make sure that it is calorie rated at a sufficient level for your task and that it complies with ASTM F1506 or ASTM F1891.  Call your supplier if you are not sure that the garments you plan to use are compliant with the necessary ASTM standards.  As a side note – garments that have a limited number of wash cycles normally are not suitable for arc flash protection.  Also watch out for uncovered metal parts on the outside – those are also usually deal-breakers (uncovered metals snaps or zippers).

Flash fire clothing – check to make sure that it complies with NFPA 2112 or ASTM F2733 to ensure that it is suitable for protection from flash fires.

by Andy K
from Legion Safety Products
Published February 9, 2012