You’re facing down a 12-hour outdoor shift and a cover of dense, grey clouds are threatening continuous rainfall. Even though you're dressed to handle the cold, you know that the rain will gradually soak through your layers one by one, which means you’re in for a long and miserable day.

When a wet day looms ahead, rainwear is a godsend. But you need to make sure that the outermost layers that protect you from the rain don't compromise your safety in other ways.

In this article, we'll go over some of the things you need to know about flame-resistant (FR) rainwear.

The Rain Won't Protect You - You Still Need FR Gear

At first blush, flame resistance in the rain might seem redundant. If your task finds you working in a downpour, and likely cold and uncomfortable, the risk of fire may be far from your mind.

It's true that when every surrounding surface is wet, the risk of a conventional fire is low. However, even in inclement weather, conditions that lead to electrical arc flash or flash fire are still present at some worksites.

Since we have to consider both the probability and severity of a potential incident, fire hazards can’t be overlooked in favor of comfort or convenience. Rainwear has its own safety implications – it helps prevent cold stress and even hypothermia – but the main application is simply keeping workers dry and comfortable.

Comfort matters, but overall safety is still the principal priority, one we can’t compromise. Specifically, you have to ensure that the control used for one hazard (rainwear for rain) doesn't create an uncontrolled hazard in another category (fire). Inappropriate outer layers may do just that.

Thankfully, weather and fire hazards can be addressed together in a simple way: flame-resistant rainwear.

Flame-Resistant Ratings

FR rainwear is made from materials that are rated against two different heat-energy hazards: electric arc and flash fire.

The characteristics of each type are sufficiently different that separate ASTM (American Society for Testing and Materials) technical standards have been developed to rate resistance under the respective conditions. ASTM standard F1891 deals with specification for rainwear arc protection, while ASTM F2733 focuses on flash fire. Both ratings should be displayed conspicuously on the garment as applicable.

Depending on probabilities of either or both types of exposure, appropriate protection levels should be selected. An electrical station, for example, should weigh heavily on arc protection, whereas workers at a gas plant might put more emphasis on a higher flash fire rating. Management needs to assess the relative electrical arc and flash fire control requirements to decide which PPE is appropriate for each setting.

(Learn about the Top 3 Arc Flash Clothing Complaints – And How to Solve Them.)

The NFPA standard 70E lays out the framework for rating estimated incident energy exposures from 0-4, which determines the minimum flame resistance rating an item of PPE needs for a given application. The ratings (calories/square centimeter) represent the value of the ATPV (Arc Thermal Performance Value) and EBT (Energy Break-open Threshold) determined by the ASTM D6413 vertical flame test.

Got all that?

In a nutshell, the values represent the heat energy a material can “absorb” before the skin underneath would sustain a second degree burn. You may never be tested on how these standards, associations, and acronyms interact to yield the ratings, but a basic understanding could be useful in diligently selecting proper gear.

Your Outer Layer Needs to be Flame-Resistant

“I have FR clothing underneath,” you might say say. “The rainwear is just on top. Why is this a problem?"

The processes used to make conventional waterproof fabrics include anything from paraffin emulsions to wax, vinyl, derivatives of silicone, or other synthetic materials. Some rainwear products may inherently have a degree of flame resistance, but without the rating you couldn’t really know. Far more likely, the materials will quickly yield to fire, and burn, break open, melt, drip, and shrink on exposure to heat. If so, not only does this offer no protection, but it can stick to any layers underneath and provide ignited fuel, potentially defeating FR clothing layers underneath.

Furthermore, it may be difficult or impossible to remove the rainwear once it has melted, and this could exacerbate injuries in any place materials adhered to exposed skin. Any rescue or medical activity thereafter is complicated as a result.

Garments that melt readily are themselves a hazard, and most conventional rainwear falls into this category. Using flame-resistant rainwear easily addresses the problem, allowing workers to remain both dry and safe on their showery shifts.

Look Beyond the Logo

At a recent safety trade show I attended, I spoke with vendors selling all varieties of flame-resistant PPE, including rain gear. Each one echoed the same cautionary sentiment when it came to fire resistant rain gear: the "FR" on some product’s labeling is no guarantee. Evidently there are manufacturers selling products that sport the reassuring FR logo that would not hold up to a realistic electrical arc or flash fire condition.

When selecting rainwear for your worksite, pay attention to arc and flash ratings, but also purchase from a reputable manufacturer. If you buy cheap, or believe overlooking the hazard posed by conventional rainwear is safe, you’re all wet.

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