FR Clothing: Leaving Hazards in the Dust

On Feb. 7, 2008, a combustible dust explosion ripped through the Imperial Sugar Co. refinery in Port Wentworth, Ga., killing 14 employees and injuring dozens. The incident triggered $8 million in proposed OSHA fines, a Senate hearing, a renewed call for an OSHA standard and widespread concerns about combustible dust hazards. It also prompted Imperial Sugar to make some changes in its facilities and procedures — including outfitting all workers in fire-resistant (FR) clothing.

“Post-event, we have required all employees and visitors to the manufacturing areas to wear fire-resistant clothing. It's a blanket requirement and one that is we believe quite conservative,” says Ron Allen, who joined Imperial Sugar as senior director of environmental, health, safety and quality in March 2009. “It's probably unusual for a manufacturer of dry product to require fire-resistant clothing plant-wide for all employees.”

Approximately 700 Imperial Sugar workers — about 400 in the rebuilt Port Wentworth facility, as well as 300 at the company's Grammercy, La., plant — must wear FR garments. All contractors and site visitors must don the protective clothing as well.

Imperial Sugar provides combinations of FR pants, shirts and coveralls. The uniforms are rated for 100 washes, and the garments carefully are monitored so they do not exceed that wash requirement. Electricians and welders wear a higher performing fabric to protect them from arc flash.

Scott Margolin, international technical director at Westex Inc., acknowledges that in the event of a combustible dust incident, some fatalities may be unavoidable because of explosions, entrapment or sustained fire. But “vastly more people” often are involved in the flash fire portion of the event, he says.

“If it doesn't ignite your clothes, you're probably going to live. And if it does, you're probably not,” Margolin says. “FR clothing can make a huge contribution to worker safety in that area.”

FR BASICS

FR clothing is designed to protect workers from arc flash and flash fire, two hazards that can cause serious injury or death. In an arc flash, the amount of energy released is “quite significant,” with temperatures reaching between 10 and 20,000 degrees Fahrenheit, explains Dan Bowen, technical marketing specialist for Dupont Personal Protection.

“Even though the duration of an arc flash is usually fairly short, on the order of less than 1 second, the amount of intense heat will cause anything combustible to burst into flames almost immediately,” Bowen says. “There's been a tremendous amount of people injured and killed by arc flash events that suffer badly because the clothing they were wearing caught on fire.”

Bowen explains that workers' clothing plays a big role in the extent of their injuries in the event of an arc flash, especially if they are wearing a synthetic blend such as polypropylene or nylon blends.

“The challenge with those fabrics is not only will they ignite, but they'll burn vigorously because they're plastic,” Bowen says. “They are highly flammable. They melt, they burn, they drip. They make a bad matter much worse.”

When FR clothing is exposed to a heat source and that heat source is then removed, the garment will not continue to burn, Bowen explains. “That's not to say these things are fire proof. It's not like wearing cement or steel — they will undergo a physical change — but as soon as the heat source is gone, that fabric won't burn. It's designed to provide protection for the worker from that burn injury.”

Margolin adds that if a worker's street clothes ignite, the fire and subsequent burn injuries will spread to areas of the body where the arc itself never touched.

“As silly as this sounds, you're literally better off naked because the body burn injury you would suffer is going to be limited to the areas of the body where the arc hits. [If] your garments ignite, that fire is going to spread very rapidly,” he says. “As soon as the shirt ignites, you're shifting from survivable or no injury with FR clothing, to potentially or probably fatal injury [without FR clothing] within seconds.”

FR clothing also provides protection through insulation, shielding the body from the heat of the event.

“The analogy that I like to make is you wouldn't wear a windbreaker out into a blizzard, would you?” Margolin says. “If you know it's 55 degrees out, you can put a windbreaker on and you're going to okay. If it's 55 degrees out, you're not going to wear that same lightweight jacket — you're dressing appropriately to that hazard, in this case cold.”

MISCONCEPTIONS

As with any PPE, workers and safety professionals must have a full understanding of the equipment to properly and safely use it. Misconceptions about FR clothing can be dangerous. For example, Margolin cites the erroneous belief that cotton is an upgrade from synthetic blend materials. While cotton doesn't melt, wearing cotton garments in the event of arc flash or a flash fire could be deadly.

“Cotton ignites just as readily as poly cotton, and it burns hotter, meaning it will do more damage to your skin more quickly,” Margolin says. “It's harder to extinguish and it's typically heavier, which means more fuel for a longer fire. Cotton is not an upgrade. It does ignite, and it's equally hazardous.”

Another troubling misconception is that workers need an FR shirt or jacket but not FR pants. Not wearing full protection, Margolin warns, is a dangerous move.

“You wouldn't do that any more than you would wear half a hard hat or one lens of a safety glass, or just the right glove for shock protection but not the left one,” he says. “A shirt-only program is not a program at all. You're not compliant, [and] you're not going to save yourself the fatalities or medical costs.”