When you specify or purchase AR/FR garments for workers that have the level of protection you need, you can feel confident the garments will perform in the event of an arc flash or flash fire. The rest of the time, however, many AR/FR garments do not perform. If you think about PPE and workwear as just being protective and functional for the specific hazards they're designed for, you're missing the bigger picture. It's important to remember that workers face a more common, consistent battle to stay safe and compliant in the face of hazards like heat stress. The better you can arm your workers with high-performance PPE, the better they will be able to perform and the more compliant they will be.
The main factors that help determine the performance of AR/FR garments against heat stress are weight, drying rate, moisture-wicking, and breathability. Each of these individual qualities works together to achieve better performance. This article seeks to focus on how the drying rate - as evaluated by the American Association of Textile Chemists & Colorists (AATCC) test methods 200 and 201 - and the weight of the garment contribute to helping overcome heat stress.
The longer a garment is wet, the longer it is uncomfortable. But more critically, the longer a garment is wet, the less moisture it can absorb and then release, affecting the efficiency of the body's natural cooling process: sweating. Once a person's AR/FR gear is saturated with sweat, the body's natural evaporative cooling process stops working efficiently. Trapped sweat not only adds unnecessary weight to the garment, but it hinders what the body needs to do in order to regulate its internal temperature given the hot conditions. So, the quicker a garment dries, the more moisture it will be able to absorb to continue the evaporative cooling cycle.
AATCC 200 is designed to determine "the drying rate of textiles based on the evaporation rate that occurs at their approximate absorbent capacity," which is the maximum amount of liquid the material can hold. AATCC 201 mimics a human wearer as the fabric is placed against a plate that is heated to the same temperature as a human body. These drying rates will vary in the field based on airflow and relative humidity. However, for the purposes of comparing products one-to-one, AATCC 200 and 201 establish a standard procedure. Comparing the rate at which a garment dries - especially AATCC 201 results - can give you an important indication of how it will perform in the field.
The weight of the garment can also contribute to heat stress. When comparing AR/FR workwear at the protection level you need, there are a couple of factors relating to weight that can help you judge how the garment will perform. First, though heavier fabric may have historically meant greater protection, examining the relative protection offered versus the weight of the garment reveals whether the fabric protects your workers as well as or better than other products by shedding extra weight they don't need to carry around. Older technology with a CAT 2 rating can weigh as much as 20-30 percent more than newer performance fabrics also rated CAT 2.
Keeping your workers protected from hazards like arc flash and flash fire should always be the priority when specifying AR/ FR workwear. Ensuring PPE is compliant with all of the regulations your workers are subject to is complex, and ensuring their PPE is being worn compliantly is even more so. A fabric's drying rate and garment weight are two more factors to add to your considerations. By specifying high-performance AR/FR PPE that is more comfortable and helps combat heat stress, you can enable your workers to wear it more compliantly without sacrificing necessary protections.