Flash fires. Explosions. Flames. Arc flashes.

They're all potential dangers associated with various professions. And those who are at risk of these hazards should be wearing FR, or flame-resistant, clothing to stay safe. In this post, we'll take a closer look at FR clothing, the industries where professionals should be wearing it, and more. This post also takes a deep dive into FR layering to meet safety requirements, when layering is necessary, and when it is not. Here's a closer look at everything you need to know about FR clothing:

Industries That Commonly Utilize FR Clothing

Two obvious professions are firefighters and electricians, as they may come into contact with arc flashes and direct flames. However, some other industries that require flame-resistant workwear may surprise you. They include the following:

  • Chemical manufacturers
  • Plastic manufacturers
  • Pulp and paper workers
  • Oil and gas workers
  • Welders
  • Nuclear energy workers
  • Environmental and property restoration
  • Utility workers

Arc Flash and Arc Rating: What You Need to Know

Arc ratings are determined by Hazard/Risk Category (HRC) and are measured from 1-4. A rating of one represents the lowest level of protection needed. This means the threat of flames, fire, and arc flashes is lower based on the nature of the job. A rating of four signifies the highest rating or protection level for the most hazardous jobs. As you might expect, layering FR clothing offers more protection / a higher arc rating.

How is an Arc Flash Rating Calculated?

Arc ratings are measured as calories per square centimeter (cal/cm2), and the rating system is used to classify FR workwear based on four categories. Similar to the HRC method discussed above, Category 1 is the lowest risk while Category 4 is the highest. Category 1 PPE must meet arc ratings of 4 cal/cm2, while Category 4 equipment must be 40 cal/cm2. This is according to National Fire Protection Association (NFPA) standard 70E and validated by OSHA via a 2014 rule.

How to Layer FR Clothing

Layering FR clothing increases the overall protection level of the user. However, there are times when layering is appropriate and times when it's not safe or necessary. Inherently, layering most clothing traps heat, and when a worker is already operating in a hot environment or around flames, this can pose the threat of heat stress or other heat-related illnesses.

Why Should You Layer FR Clothing?

Aside from achieving higher arc protection - the majority of FR clothing is rated at HRC2 or less - there are a few other reasons where it makes sense to layer FR protective clothing, such as:

  • For warmth: If you're regularly working outdoors and in changing climates, it's common sense to know that the more layers of clothing you have on, the warmer your body will be.
  • Moisture management: In order to stay comfortable on the job, you need to keep your attire dry. "Breathable" FR clothing can help moisture vapor and heat escape to help keep you dry and more comfortable. It can also help resist moisture in rainy environments - all while keeping you properly protected from heat and burns.
  • Compliance: When it comes to staying safe in your work environment, layering can make a big difference in meeting required safety standards or specific arc ratings.

How to Layer FR Clothing Properly

There are several things to keep in mind if you're planning to layer FR apparel such as the fit of the FR garments, the protective qualities of the fabric, and the ability to move freely with multiple layers.

  • Make sure the base or primary FR garment fits snugly to your body: This ensures that you'll receive proper protection, and any additional garments should be sized accordingly to fit over it.
  • Make sure your primary layer does not melt: The primary layer is arguably the most important one, being that it's the closest layer to your body. You want to make sure it's made of fabric that won't melt and stick to your body, causing burns.
  • Ensure you're comfortable and mobile: If you layer up and find that your mobility is restricted or you're too hot, it's going to impact the work that you're doing. While staying safe is important, you should be layered in a way that allows you to move, while remaining as safe as possible. Outer layer or secondary FR clothing and coveralls should be breathable and ideally use ANSI-sizing—these factors allow for enhanced movement and help prevent overheating.

When Doesn't Layering Make Sense?

There are a few instances when it doesn't make sense to layer. For instance, if you're working in a lower-risk environment and one FR garment will adequately cover you, then there's probably no need to layer your protective clothing. This could cause unnecessary heat stress.

Additionally, even if you do require PPE with a higher arc rating, this usually isn't for a task that's going to take you all day. In most cases, it might be necessary for a short period of time or for one particular task. Noting this, you might have to layer clothing when it's time to carry out this specific task to stay properly protected. Then, you can remove layer(s) accordingly. You want to layer enough to stay protected, but not too much where you're not as mobile or more likely to overheat.

The Do's and Don'ts of FR Layering

In addition to the information that we've covered in this section, there are more do's and don'ts worth sharing, such as:

  • Don't roll up your FR shirt or coverall sleeves: Part of the reason why it's important to wear FR clothing is to protect your body from potential burns. Rolling up your sleeves will expose your arms, leaving them susceptible to injury. Typically, when working around flames, or environments with the threat of flames, as much of the body should be covered as possible.
  • Do explore lightweight and breathable FR clothing options: Remember, mobility and comfort are important for productivity and safety. FR clothing has advanced to the point these days where it's more lightweight than ever before, allowing workers to stay cooler for longer without sacrificing protection levels or arc ratings.
  • Don't unbutton or unzip FR clothing: Oftentimes, workers unzip or unbutton their clothing to release heat, but this can be extremely dangerous. Just as you shouldn't be rolling up your sleeves, you also shouldn't be unbuttoning or unzipping your FR shirts and coveralls. This can expose parts of your body to burns and excess heat. This is where lightweight and breathable, outer layer FR clothing comes in handy—especially FR garments with a high moisture vapor transmission rate (MVTR). FR garments with a high MVTR help prevent heat stress by allowing heat and moisture vapor to escape the garment as you work.
  • Do tuck in your shirt: If your shirt isn't tucked into your pants, heat and flames can actually go right underneath it and potentially lead to bodily harm and injury.
  • Do know how to properly layer FR clothing: Remember that when you're layering, FR clothing only offers added protection when covering existing (primary) FR clothing. For example, if you're wearing FR coveralls over non-FR-rated pants, you won't be adding enhanced protection to your lower body. In short, layering non-FR clothing with FR clothing does not increase arc ratings or enhance safety levels to the point needed for flame protection.
  • Don't wear a non-FR underlayer: Some professionals think that as long as they're wearing an FR outer layer, that they're OK to wear a non-FR underlayer. This isn't the case. As comfortable as a standard shirt might be, you want to be sure that any base layer is flame resistant and can offer protection against burns and melting. If your secondary (outer layer) flame-resistant clothing catches fire and spreads, the non-fire-retardant clothing underneath will quickly burn and cause bodily harm.
  • Do rely on your safety team for insight: Your safety manager or on-site safety specialist should be able to answer any of your questions pertaining to FR clothing and layering. In particular, they should know the arc rating needed to safely operate on-site or the level needed to perform a specific task.

Outer FR Layering: What You Need to Know

It's important to note that the primary FR is the inner most layer of FR clothing. The outer layer FR is the outermost layer worn over the top of your primary FR. Just as how you want to ensure your primary FR is flame resistant, you want to do the same with the outer layer FR. This won't just offer an enhanced level of protection, but it will also help you stay safe from burns if the outer layer catches fire. Wearing an FR outer layer can also help keep any inner layers in good shape and last longer.

Flame resistant workwear is important for professionals in a lot of industries and job settings. However, it’s equally important to properly wear it. Make sure you know the ins and outs of FR layering, arc ratings, and more of what can keep you safe on a job site that poses the risk of sparks or flames.

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