Low-level chemical, arc flash, and flame protection is possible at a reasonable cost
Any petrochemical worker or electrician exposed to electric arc has something in common with a meth lab cleanup team. When they arrive on the job site, they may not know exactly what hazards they'll be exposed to, but they do know the potential for fire and chemical exposure exists. Ethanol, acids, oils, ammonia, and other chemicals are the standard issue, but fire is always a possibility.
The hazmat team, the electrician in a petrochemical plant, and a meatpacking company electrician all have something else in common: hydrocarbon loading potential on their clothing. When flame-resistant (FR) clothing has substantial hydrocarbon loading, ignition sources, such as potential flash fires or electric arcs, can make an FR garment less effective. In this type of situation, the worker must be cognizant of his or her surroundings and use personal protective equipment (PPE) made for those types of exposures. Under these circumstances, disposable FR garments are often the best solution. Let's take a quick look at the evolution of these garments for background.
Quick history lesson
Disposables have improved significantly from the first polyester spun-laced throw-away garments that changed the chemical protection world just a decade ago. Those garments were resistant to many chemicals but were not adequate if a flash fire or electric arc ensued. They did — and still do — make many low-level chemical exposures less hazardous for workers at a very reasonable cost. Newer coated and sealed seam garments on the chemical protection side have made even higher-level exposures, including chemical warfare, a less likely scenario. However, the flame-resistant side of the equation is still fraught with misunderstanding, especially when it comes to disposable garments.
In 1994, the first arc- and flame-resistant raingear was developed. A difficult battle was fought to get folks out of “FR”-labeled garments that passed small-scale tests but would melt onto workers in a 2- to 3-second flash fire exposure or electric arc event. This campaign was very successful. Now, another industry has a similar need. There are chemical-resistant garments that are flame-resistant and have been flash fire and arc tested, but many garments on the market should not be used in a flame or arc exposure. How can you tell the difference?
Melting makes the difference
Any material that melts and drips in electric arc or flash fire should not be used, even in low-risk potentials. The NFPA 70E standard requires that no melting materials be worn by a worker in any arc potential. Shouldn't this same interpretation be used in potential flame exposures? The most effective way to remedy this misunderstanding is to educate the market.
Cleaning up potentially hazardous materials is often part of the job. In electrical work, it could be oil containing small amounts of PCBs. This oil could also add hydrocarbon loading to the FR clothing. Cleaning up these materials requires a system of safety PPE that can be difficult to balance. It begs the question, “Do I need FR, chemical protection, or both?”
Market confusion about FR disposables and the meaning of some test methods is also a problem. Table 1 (click here to see Table 1) includes a list of the primary standards with an explanation of their proper uses. The first standard to address FR disposable garments was NFPA 2112, which added the allowance for FR disposable materials as “non-woven” materials. Some materials have been tested against this standard, but most specification writers are unaware of it. In addition, the standard also has some disadvantage to the end-user who wants a disposable garment. The disposable must meet a minimum body burn percentage and other tests that make the non-woven “disposable” beneficial in some jobs but less disposable from a cost perspective.
With a garment to be worn over FR clothing and disposed of readily when soiled, this standard's requirements may create a garment with a lower value proposition. NFPA 2112 disposable garments make sense in some specific applications, particularly when the FR disposable can be worn longer or in lieu of FR clothing, such as an inexpensive coverall for a supervisor, engineer, or visitor, or as outerwear in a higher potential threat.
Most FR disposable garments in the past would have been tested with a vertical flame test to differentiate them from a non-FR garment. Researchers now know this is not sufficient. This and other small-scale tests alone are inadequate to predict flash fire or arc burn protection. Full-scale tests (such as ASTM F1959 Electric Arc or ASTM F1930 Flash Fire) are best for these evaluations (click here to see Table 2). Because these full-scale tests entered the scene in the mid-1990s, the small-scale tests have been seen as less predictive of performance and usually are used for quality control only. A garment that passes a vertical flame test may still be life-threatening even in medial level flash fires or electric arcs, especially if the material is a melting material.
There is no standard for low-cost FR disposable garments. While FR raingear manufacturers are changing their claims on flame resistance based on these full-scale tests and better knowledge, the FR disposable market has not kept up because there is no real specification using the available full-scale test methods. Melting materials such as polyethylene, olefin, polyester, nylon are not acceptable even if labeled FR. (Note: A small percentage of these types of materials may be in full-scale tested FR materials and can add value to their performance.)
How do you know you're purchasing the right product for the action at hand? Here are some factors to look for when selecting appropriate FR disposable garments.
Passes vertical flammability
Passes heat resistance
No melting and dripping in full-scale tests
Has some protective value from a full-scale test (ASTM F1930 or ASTM F1959)
Must not melt and drip in your exposure potential
Lighter weight materials may not meet 50% body burn or have a high arc rating, but they should be evaluated by a full-scale test method. Other FR clothing should be worn underneath the disposable unless its full-scale rating is adequate for the task.
A disposable that can be decontaminated or incinerated might be desirable in some applications (click here to see Table 3).
In upcoming years, the industry will likely demand a disposable FR standard either from ASTM F1506, ISEA, or NFPA (click here to see Table 4). Until that happens, examine the choices carefully. Look for full-scale data and evaluate the clothing system for the desired characteristics.
Hoagland does training on and testing of PPE in electric arc and flash fire, and is a member of IEEE, ASTM, NFPA, ASSE, and IEC. He is president of ArcWear.com in Louisville, Ky.