Understanding key and common PPE definitions and how these apply to your industry is one of the most important steps when determining the correct PPE. As global safety experts, CHARNAUD is well equipped to guide you when it comes to making the right choice for the safety of your employees.

Knowing your PPE

In order to select and procure the correct PPE which is suited to protect against the hazard, one must first understand the meanings of common and important terms. Some terms carry very specific definitions, while others can be easily confused if one does not fully understand them. This blog sets out a list of industry-related terms and their definitions in order to educate our customers to make the best choices when it comes to purchasing PPE from CHARNAUD.

Arc Rating

Arc Rating can refer to both fabrics and garments. A fabric which is arc rated (AR) has undergone a series of tests in line with the standard ASTM F 1959. Depending on the results of the tests, the fabric will achieve an arc rating, which is always referred to as cal/cm² (calories-per-square-centimetre). Although a garment may be made from arc rated fabric, this does not mean the complete garment is arc rated. To ensure that the arc rating of a garment is the same as the fabric it’s made from, it has to undergo testing as well. When a garment is tested, its arc rating should be the same as the fabric it’s made from.

Knowing the arc rating of a garment is especially important for electrical workers, and that is why all SURVIVE-ARC® garments have their arc rating prominently displayed on the garment.

Read next: The Differences Between ATPV and EBT Ratings in Arc Flash PPE

Arc Thermal Performance Value (ATPV) and Energy Breakopen Threshold (EBT)

Arc Thermal Performance Value (ATPV) is the incident energy on a material that results in a 50% probability that sufficient heat transfer through the fabric or garment ensemble is predicted to cause the onset of second-degree burn injury based on the Stoll Curve, expressed in cal/cm².

Energy Breakopen Threshold (EBT) is the incident energy on a material that results in a 50% probability of breakopen. Breakopen is defined as any open area of at least 1.6 cm² (0.5 in.²)’
SURVIVE-ARC® offers a range of garments for electrical workers which offer protection from head to foot and are both ATPV and EBT rated.


A calorie is a unit that measures energy. Although it is more commonly associated with food, it is no less relevant when it comes to PPE. A calorie is the amount of energy needed to raise one kilogram of water by 1 degree Celsius.
As the end-user, it is important that you know the calorie rating of the PPE you are wearing as this will let you know whether what you are wearing is sufficient to protect you against the hazard. All CHARNAUD SURVIVE-ARC® garments have their calorie rating prominently displayed in an easy-to-read format.

Stoll Curve

The Stoll Curve is an empirical prediction model to measure the onset of second-degree skin burn injury. Second-degree skin burn tests are not conducted on human subjects; instead, a copper calorimeter (measuring device) is used to determine the human skin response to thermal energy. When a garment or fabric undergoes thermal testing, the results of the test will be compared against the Stoll Curve and the point at which the Stoll Curve is breached will be identified. The point at which the heat transfer crosses the Stoll Curve line is the exact point in time, and the specific temperature at which a second-degree skin burn injury will begin on human skin.

Heat Flux

Heat flux measures the rate of energy transfer during the thermal testing of a fabric or garment. The rate is calculated by dividing the amount of energy that is transmitted by the size of the area and by time: KW/m² [cal/cm²s].

Flash Fire

Flash fire is a short duration fire and is spread by a dispersion of fuel such as gas, dust or ignitable liquid vapours. People working in the oil and gas industries and wildland firefighters are more likely to experience flash fires and therefore need to ensure they are suitably protected against flash fire hazards. CHARNAUD’s FIRE-SAFE® offers a full and extensive range of permanently flame resistant PPE to protect against the hazards of flash fires.

Flame Resistant and Flame Retardant

A material which is flame resistant (FR) or has flame resistant properties, will not combust even when a flaming or non-flaming ignition source is applied to the material. The FR properties of the material mean that combustion is prevented, inhibited or terminated after the ignition source has been applied. A material only becomes flame resistant once the substrate has been treated with a flame retardant chemical, or if the polymer used in the production of the synthetic fibre is in itself, flame resistant.

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TO ensure that you are dressed in head-to-toe in the best PPE, ensure that you invest in gear from CHARNAUD. Contact us for more information on our PPE.

Now Read: 5 Interesting, Yet Terrifying, Facts About Arc-Flashes