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Layering Guide for FR Clothing: The Inner Layer

Tyndale's Layer 1 Performance T-Shirt (M010T)

This is the second post in a series covering how to layer FR clothing properly during colder months. Subsequent topics will include: FR outer layers for warmth and insulation, and a final, waterproof FR layer.

In our previous post on cold stress, we discussed the hazards workers face outdoors during winter months. But do you really understand the risks you and your colleagues face if you mix FR and non-FR layers of clothing together? Today, advancements in cold weather FR apparel are making safety and compliance easier than ever.

With an increase in regulation surrounding the use of personal protective equipment (PPE) and FRC, comes a higher risk of pairing incorrect clothing together in an effort to simply stay warm. In this post and the next two, we share tips and advice for layering proper flame resistant clothing together to not only keep you warm, but also safe and compliant with industry regulations and company requirements.

So how do you avoid cold stress like hypothermia, frostbite and trench foot? The first step is to look at your first layer of clothing or the inner layer that is worn against your skin.

What to Avoid Wearing

When you wear cotton against your skin, it holds moisture from sweat then contributes to too much cooling of your body. Sweat from hard work can be trapped in certain types of clothing. When the work stops, moisture against the skin has a negative effect on comfort.

Wearing synthetic undergarments, like Under Armour, beneath your FR is dangerous. Non-FR clothing will ignite and continue to burn when exposed to flame or electric arc. Synthetic fabrics, like polyester, nylon, acetate and others can melt to your skin.

Consequently, wearing an FR outer layer over a non-FR inner layer does not provide adequate protection. Wearing a bulky FR jacket over a non-FR shirt simply provides the wearer a false sense of security. When wearing a non-FR layer under FRC, the inner layer may ignite under certain conditions. Generally, a non-FR t-shirt risks ignition during an electric arc at an energy level approximately 4 cal higher than the garment’s arc rating. Given the inherent variability in arc flash and other hazards, wearing only FR inner layers is a practical solution.

Keeping that in mind, workers and safety managers typically look at a standard (i.e. NFPA 70E) for protective ratings in terms of one protective garment even though the standard clearly suggests layering garments to achieve required Hazard Risk Category (HRC) and Arc Thermal Protective Value (ATPV) ratings.

What You Should Wear

Extreme outdoor adventurers know that moisture management is critical for staying warm in cold weather. If you work hard and sweat, non-moisture-wicking fabrics will hold the water against your skin and can make you uncomfortably cold. Moisture-wicking garments worn next to your skin help regulate your body temperature by moving perspiration and moisture away from your skin, allowing it to dry quickly. Staying dry is not only a matter of comfort, but also essential in avoiding hypothermia, or other types of cold stress, in winter weather.

By choosing FRC that offers wicking and fast-drying capabilities, or by changing your inner layer between jobs, you can keep the layer of clothing next to your skin dry. When your inner-most layer of FR is dry, you will be much warmer and more comfortable.

Inner Layer Options

Some FR options workers have now that were not previously available include FR treated knits, such as sweatshirts, mock turtlenecks and Henleys. In general, knit garments allow more movement than woven fabrics (i.e. canvas, denim, twill). Below are some examples of FR inner layers available from Tyndale!

FR Base Layers

Contact your Tyndale sales manager today to add these products to your program! Stay tuned for information on FR outer layers for warmth and insulation and, if needed, how to add a final layer of waterproof FR clothing.

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