Industrial Supply Blog

The Difference Between AR and FR Clothing

Oct 17, 2017 12:39:59 PM


Are you aware of the arc flash hazards in the oil and gas industry? There’s a huge danger of electrical spark hazards in this industry. Electrical workers are at the highest risk of facing this hazard. But maintenance workers and others are also exposed.

Many oil and gas workers wear FR clothing as part of their regular uniform. But sometimes they need to wear AR clothing instead. It’s important for workers to know the difference between AR and FR clothing. The two are not the same.

AR Clothing

AR stands for Arc-Rated. This type of clothing protects employees from electrical arc flash hazards. An arc flash is a violent release of heat and energy that results from an electrical arc. It’s the result of an electrical fault that occurs when one of the following happens:

  • An employee makes accidental contact with electrical systems
  • Conductive dust builds up inside electrical units
  • Corrosion builds up on electrical conduit and wires
  • Tools drop onto or into electrical units
  • Improper work procedures

The purpose of AR clothing is to protect workers from these hazards. AR clothing is designed and tested to resist ignition. So when an oil worker is exposed to an arc flash, he experiences minimal burns and injuries.

Arc flashes can reach temperatures of up to 35,000 degrees Fahrenheit. The pressure from an arc flash can be powerful. It can send molten metal and other projectiles into the face and body of the exposed worker. Arc flashes can result in serious burns and even death.

The video below shows the difference between AR clothing and regular clothing during an arc flash event.

FR Clothing

FR stands for flame-resistant. It’s designed to protect employees from fire-related hazards. Examples of such hazards include flash fires, flames, and embers. FR clothing is not fire proof -- it will ignite if exposed to fire. But it’s designed to self-extinguish. It will not continue to burn once ignited. FR clothing helps to minimize the extent of burn injuries.

Oil and gas workers wear FR clothing during certain phases of production. It’s primarily used during drilling and servicing operations. It should also be worn for hot work.

Check out this post for more information on FR Clothing in the Oil and Gas Industry.


Knowing the Difference

FR Clothing is not the same as Arc-Rated Clothing. They might look the same. But the two are very different, and are not interchangeable..

Think of it this way: FR clothing protects workers from fire-related hazards. AR clothing protects workers from very specific electrical hazards. Both hazards involve heat and flames. But arc flashes and electrical hazards are much more dangerous. That’s why AR clothing has a higher level of protection.

All AR clothing is flame-resistant… but not all FR clothing is arc-rated.

The surest way to tell the difference between the two kinds of clothing it to check the label. OSHA approved AR clothing must say on the label that it is compliant both with NFPA-70E and ASTM Standards.

Take a look at the video below for a quick explanation of how these two types of clothing are different.

A Closer Look at AR Clothing

How do I know if a garment is arc-rated?

If a garment is arc-rated, it will say so on the tag. Ratings are usually found on an internal tag. Sometimes they’re listed on the outside of the garment as well. Double-check the ratings with your supplier before purchasing.

What is ATPV?

ATPV is the Arc Thermal Performance Value. This is the value given to materials to describe their level of protection. ATPV protection ratings are specific to electrical arc discharges. The ratings are expressed in calories per centimeter squared, or cal/cm². The higher the number, the greater the protection.

What are Hazard Risk Categories?

NFPA 70E identifies four hazard risk categories, based on specific job tasks. Category 1 is low-risk work that requires minimal protection. Category 4 is high-risk, and requires 3 or more layers of protection. For arc flash protection, clothing must meet the specified ATPV cal/cm² rating.

Hazard Risk Categories

What level of protection do I need?

It’s up to the employer to determine which hazard risk category its workers fall into. In general, most electrical work is considered to be category 1 and 2. So, electrical workers should be wearing 1-2 layers of FR clothing that has an arc-rating of 8 or higher.

For high voltage and high risk electrical equipment, the hazard category is likely to be a 3 or 4. In that case, workers would need extra protection. Refer to the requirements in the chart above.

Certain electrical equipment requires arc flash warning labels. Anything that is likely to require service, maintenance, adjustment or inspection (while energized) must have a label. The labels must contain the following:

  1. Nominal system voltage
  2. Arc flash boundaries
  3. At least one these:
    1. Incident energy distance
    2. Minimum arc rating for clothing
    3. Site specific level of PPE
Arc flash2.jpgArc Flash.jpg

Arc Flash Hazards in Oil and Gas

The oil and gas industry risks fires and explosions every day. After all, workers in these environments are surrounded by fuel sources. If something were to ignite, it could cause catastrophic consequences.

When it comes to arc flash hazards, oil gas workers risk exposure the same way any other industry does. Electricians working on live equipment face the biggest risk.

But, also prevalent in the oil and gas industry is static electricity. Static electricity could cause an arc if ignited, even by a small electrical spark. The following have been identified as high risk for producing a static electrical discharge:

  • Fuel and storage tanks
  • Propane gas cylinder processing facilities
  • Fracking tanks
  • Fueling operations
  • Natural gas pipelines

Static can build up when liquids move in contact with other materials. This includes when liquids are poured, pumped, stirred, or flow through pipelines.

Preventing an Arc Flash

The best way to protect your employees from an arc flash is to focus on prevention.

OSHA supports the NFPA 70E recommendation that employers should conduct an arc flash site assessment if they meet the following criteria:

  • Electrical equipment is likely to be adjusted or maintained while energized; and
  • Electrical equipment exceeds 50 volts

An arc flash risk assessment is a calculation that determines the thermal incident energy, arc flash boundaries, and PPE requirements for each hazard location. Only a Professional Engineer, or PE, can conduct this study. The engineer should have experience in electrical, power, and short circuit studies. The PE must also be familiar with NFPA 70E.

Other ways you can prevent arc flash hazards include:

  • Use warning labels to indicate arc flash hazards
  • Reduce or eliminate the amount of work done around live equipment
  • Use remote diagnostic and maintenance tools
  • Install devices to reduce energy in addition to containing energy
  • Utilizing properly designed and installed equipment for new and existing installations

For the oil and gas industry, here are some ways to prevent the buildup of static electricity:

  • Grounding containers and storage tanks
  • Bonding containers with bonding straps or wires
  • Dissipate static discharges on polyethylene pipeline
  • Use static-safe floor mats and paints
  • Use spark-resistant tools

For more information on how to avoid arc flash hazards, read through OSHA’s guide on “Understanding Arc Flash.”

Topics: FR Clothing

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