Saving lives with arc-resistant and flame-resistant apparel
Arc-resistant and flame-resistant (FR) personal protective equipment (PPE) clothes are the first and the last line of defense against serious injury.
Let there be no doubt that recent technological advances in manufacturing have helped craft safer apparel for use in a hazardous work environment. Arc-resistant and flame-resistant (FR) clothes are perfect examples of such garments. In almost all instances of arc flash, these clothes are the first and the last line of defense against serious injury.
Not long ago, workers in the power sector were exposed to serious risks from arc flash because their clothes were unable to properly absorb the sudden burst of electrical energy. Considering that an arc flash can generate heat up to 35,000 °F, clothes made from 100% natural fiber cannot protect a worker. As a result, there were more than 600 fatalities every year from electrical accidents involving potential arc components in the United States alone.
Despite safety measures in a modern workplace, arc flash incidents remain a serious threat because they occur due to common human errors while working around energized electrical equipment. In some cases, even low-voltage electric components can discharge energy that can cause serious injuries including hearing loss, eye injuries, and lung damage.
Under such circumstances, both arc-rated and flame-resistant clothes can prevent workers from an unforeseen dangerous event. However, it is important to understand how and why these clothes protect workers as well as the subtle differences between arc-rated and flame-resistant garments.
Flame-resistant (FR) clothing is a special type of garment, which protects a person from catching fire when exposed to combustion and high temperature. Unlike traditional clothes, FR clothes do not burn indefinitely. Once the heat source is removed or as soon as the person loses contact with the source, the cloth stops burning. This gives a person enough time to escape from the hazard and can help reduce injuries.
Most FR clothes are made from specific materials that have excellent qualities for resisting heat. Clothes made of Nomex, chemically altered cotton, and Kevlar do not conduct heat, which means the burning process decreases instantly. Since second-degree and third-degree burns are the result of melted garments, flame-resistant clothes protect workers from undesirable consequences.
While such clothes are beneficial, it does not mean they will not catch fire. It also means that flame-resistant garments will burn if they’re exposed to a heat source for long periods of time.
What is arc-resistant apparel?
Most FR clothes are categorized according to an arc rating. The rating indicates how much protection the cloth offers to the wearer. The value of the arc rating is expressed as calories per square meter. The higher the value of the arc, the more suitable the apparel against arc flash and flames.
A rating of 4 calories per centimeter square is suitable for Category I hazard. Similarly, 8, 25, and 40 calories per cm square are recommended for Category II, III and IV hazards, respectively. Starting from 2015, the arc flash personal protective equipment (PPE) category is used to define protective gear suitable for corresponding work environments. The PPE scale also is based on the same levels, between 1 and 4, as defined by arc rating.
The difference between flame-resistant and arc-resistant apparel
Garments with an arc rating are tested for exposure to electric art. If the garment does not have an arc rating, it may be flame-resistant up to a certain extent, but it is not arc-resistant. In other words, not all flame-resistant clothes are tested for arc resistance.
All arc-resistant apparels are also flame resistant. This means that any garment that has an arc rating will protect against fire and high temperatures. Similarly, any flame-resistant clothing that has an arc rating is designed to protect against exposure to electric arc.
ATPV and Ebt Values
ATPV and Ebt values indicate arc rating. Therefore, clothing manufacturers generally put the arc thermal performance value (ATPV) value or energy breakopen threshold (Ebt) value on a flame-resistant cloth.
The ATPV indicates the person exposed to an electric arc has a 50% chance of getting burned if exposed to the same number of calories of heat. In an unfortunate incident, the garment will not break open if the number of calories of heat is less than the designated ATPV.
The Ebt rating is measured differently. The Ebt value indicates the garment will break open if exposed to the same number of calories, but the skin will not burn.
If the difference seems confusing, remember clothes with an Ebt rating are often more insulative than they are strong. In contrast, clothes with an ATPV value are much stronger than their insulation.
Irrespective of the difference, it must be noted all types of flame-resistant and arc-resistant fabrics will break open at some point if exposed to high temperatures for an extended period. In such a situation, the inner layer will be exposed to the heat, resulting in additional injuries.
Overall, arc rating, fiber makeup, fabric weight, and the type of construction method will determine the level of safety.
Selecting FR and arc-resistant clothes
Almost all clothing manufacturers put an arc rating on the label. If the cloth is flame-resistant and it doesn’t have an arc rating, it means the garment will increase protection against high temperatures, but it is not suitable against an arc flash. For increased safety, workers should wear multiple layers of arc-resistant apparel.
FR clothing doesn’t need to be bulky and ugly. These days, there are many stylish clothes. For added protection, workers can cover their clothes with arc-resistant clothes to feel safer. It also is a good idea to use baggy and loose-fitted clothes because they do not transfer heat as quickly as tight-fit clothing.
If the top layer is burned or damaged, subsequent layers will help stop the heat and flames from burning the skin and inflicting serious injuries. It is important to put on full protective clothes and gear for the best possible protection against potential hazards.
– DEP is a CFE Media and Technology content partner.