Arc flash and flash fire: why ordinary disposables are a hazard, and when FR disposables go over FR clothing
29 CFR 1910.269(l)(8)(iii) requires that an employee exposed to flames or electric arcs not wear clothing that could melt onto the skin or that could ignite and continue to burn, and the note to that paragraph says it prohibits clothing made from acetate, nylon, polyester, rayon and polypropylene, alone or in blends, unless the employer demonstrates the fabric has been treated to withstand the conditions. Most disposable coveralls are polypropylene or polyethylene film laminates; International Enviroguard’s catalog lists the MicroGuard MP flammability result as “Melt-down” and warns that its cleanroom apparel should not be used around heat, flames, sparks or in flammable or explosive environments. 1910.269(l)(8)(iv) requires the outer layer of clothing to be flame resistant when incident energy exceeds 2.0 cal/cm², among other conditions, and (l)(8)(v) requires arc-rated protection equal to or greater than the estimated incident energy. PyroGuard FR and PyroGuard CRFR pass ASTM D6413 with char damage under 6 inches and after flame under 2 seconds, and the manufacturer states both are secondary garments designed to be worn over primary FR or arc-rated apparel to keep it clean; neither sheet publishes an arc rating. The employer’s assessment under (l)(8)(i) and (ii), or the NFPA 70E program, decides the arc-rated layer; an FR disposable is the sacrificial layer over it, never a substitute for it.
Enviroguard 9019 PyroGuard FR Disposable FR Coverall, Hood and BootPhosphate-based FR fabric, attached hood and boots. ASTM D6413 char damage under 6 inches, after flame under 2 seconds. Secondary garment worn over primary FR apparel, per the manufacturer.Why is a plain disposable coverall a problem near an arc or a fire? Because of what the fabric does when it gets hot. OSHA’s electric power standard puts it in one sentence: the employee must not wear clothing that could melt onto the skin or that could ignite and continue to burn. Polypropylene, the base of SMS, spunbond and most microporous film coveralls, is one of the fibers the note to that paragraph names as prohibited unless the employer demonstrates it has been treated to withstand the conditions. The manufacturer’s own catalog reports the MicroGuard MP flammability result as “Melt-down.” A coverall that melts onto an arc-rated shirt defeats the shirt.
29 CFR 1910.269(l)(8)(iii) and its note; International Enviroguard Industrial Catalog, MicroGuard MP physical properties table (Flammability, GB/T 4744-1997, Melt-down).What do the rules and the sheets say?
The operative words from each source.
Can you wear a Tyvek-type disposable coverall over arc-rated clothing?
Not where 1910.269(l)(8) applies, unless the employer can make the demonstration the note describes. Two paragraphs stand in the way. (l)(8)(iii) bars clothing that could melt onto the skin or ignite and keep burning, and the note names polypropylene among the prohibited fibers unless treated. (l)(8)(iv) requires the outer layer to be flame resistant under the four conditions it lists, including any estimated incident energy over 2.0 cal/cm². A non-FR disposable worn on top is the outer layer. The manufacturer’s cleanroom catalog says the same thing about its own non-FR garments: cleanroom apparel should not be used around heat, flames, sparks or in potentially flammable or explosive environments.
29 CFR 1910.269(l)(8)(iii), note to (l)(8)(iii), and (l)(8)(iv)(A) through (D); International Enviroguard Cleanroom Catalog warning (MicroGuard CE and GammaGuard CE pages).Outside the electric power standard, the same hazard is handled through the general PPE rule and the employer’s electrical safety program; NFPA describes 70E as developed at OSHA’s request to assist compliance with 1910 Subpart S and 1926 Subpart K. The employer decides the arc-rated ensemble; the question for any disposable layer is only whether it is flame resistant and whether it could melt.
29 CFR 1910.132(a) and (d); NFPA 70E document page, nfpa.org.What does an FR disposable actually do?
It keeps the expensive layer clean. The manufacturer’s wording for PyroGuard FR is that it is secondary FR protective clothing worn over primary FR apparel to extend its life and protect it from dirt, grease, non-toxic liquids, sparks and flames. For PyroGuard CRFR the wording adds chemicals: worn over primary FR and arc-rated apparel to prevent flammable substances from saturating the primary garment, for environments where both chemical splash and flash fire are a concern. The flame data on both sheets is ASTM D6413, a vertical flame test; ASTM’s scope for that method says it measures vertical flame resistance of textiles, including afterflame and afterglow, under controlled laboratory conditions, and shall not be used to describe or appraise the fire hazard of materials under actual fire conditions. A D6413 pass means the fabric chars rather than melts and stops burning when the flame is removed; it is not an arc rating.
PyroGuard FR and PyroGuard CRFR sell sheets (description and physical properties); ASTM D6413/D6413M scope, paragraphs 1.1 through 1.2.CRFR carries two more numbers. Thermal protective performance by NFPA 1971-97, spaced, is 6.8 TPP. Third-party ASTM F1930 instrumented-manikin testing at North Carolina State University gave 16.4 percent total body burn for PyroGuard CRFR over Stanco Nomex NXG581. Read the second one as the manufacturer prints it: a result for the two-layer system, with a named primary garment underneath, not for the disposable alone.
PyroGuard CRFR sell sheet, physical properties and “Helps Reduce Total Body Burn” table.Is there an arc rating on these coveralls?
No. Neither PyroGuard sheet prints an ATPV or an arc rating, and 1910.269(l)(8)(v) is written in arc rating: protective clothing with an arc rating greater than or equal to the estimated incident energy whenever the estimate exceeds 2.0 cal/cm². The arc-rated shirt, pants or coverall underneath is what satisfies that paragraph. The disposable over it adds a layer that chars and does not drip, per the manufacturer, and keeps grease and solvents off the arc-rated fabric, which is the manufacturer’s stated purpose. If a site rule calls for an arc rating on the outermost garment, these do not have one to show.
29 CFR 1910.269(l)(8)(v); PyroGuard FR and PyroGuard CRFR sell sheets (no arc rating published).When does the FR disposable go over the FR clothing?
The manufacturer lists refinery turnarounds, oil and gas, manufacturing, industrial settings and electrical work for PyroGuard FR, and petrochemical, manufacturing, industrial and oil and gas for PyroGuard CRFR, with tank cleaning and chemical mixing named for the CRFR apron. The common thread is primary FR clothing that would otherwise be soaked in oil, grease or a flammable liquid, which the manufacturer says the disposable layer is there to prevent. Both lines also publish BS EN 1149-5 electrostatic data; the manufacturer states PyroGuard FR meets the ESD requirements for static decay and surface resistivity, and lists CRFR under the same standard. CRFR is single use: the catalog says it should not be washed or re-used.
PyroGuard FR sell sheet (applications, BS EN 1149-5 statement); PyroGuard CRFR sell sheet and CRFR apron sheet (applications); Industrial Catalog (single use, not a primary FR garment).What about the hood, the zipper and the seams?
Style matters because the rule covers the entire body. 9015 and 9115T have an attached hood with elastic wrists and ankles; 9019 and 9119T add attached boots; 9012 is open ankle with no hood. CRFR styles have a sealable storm flap over the zipper and taped seams; FR styles have serged seams and the storm flap the manufacturer describes as keeping contaminants from entering through exposed seams. None of this changes the flame data, but a hood that goes under the arc-rated face shield and balaclava, and boots that cover the laces, are how the sacrificial layer covers the same area as the layer it protects.
PyroGuard FR and PyroGuard CRFR garment lists; 29 CFR 1910.269(l)(8)(v) (entire body, with the exceptions in (A) through (E)).Questions people ask
Can you wear a Tyvek suit over FR clothing?
Where 29 CFR 1910.269(l)(8) applies, the outer layer must be flame resistant under the conditions in (l)(8)(iv), and (l)(8)(iii) bars clothing that could melt onto the skin, with polypropylene and polyester named in the note unless shown to be treated. A non-FR disposable on top is that outer layer.
Are PyroGuard FR coveralls arc rated?
No arc rating is printed on the PyroGuard FR or CRFR sell sheets. The manufacturer states both are secondary garments worn over primary FR or arc-rated apparel; the arc rating 1910.269(l)(8)(v) requires comes from the layer underneath.
What does ASTM D6413 test?
Vertical flame resistance of textiles, including afterflame and afterglow, under laboratory conditions; ASTM’s scope says it is not to be used to appraise fire hazard under actual fire conditions. PyroGuard FR and CRFR report char damage under 6 inches and after flame under 2 seconds.
What is the difference between NFPA 70E and NFPA 2112?
NFPA describes 70E as the electrical safety work-practice standard covering shock, arc flash and arc blast, and 2112 as the performance and test standard for flame-resistant fabric and garments against short-duration thermal exposure from fire; 2113 covers selection, care and use of 2112 garments.
Why does the rule prohibit polypropylene?
The note to 1910.269(l)(8)(iii) names acetate, nylon, polyester, rayon and polypropylene because the paragraph bars clothing that could melt onto the skin or ignite and continue to burn, unless the employer demonstrates the fabric has been treated to withstand the conditions.
Can PyroGuard CRFR be washed and reused?
No. The manufacturer’s catalog states it is designed for single use and should not be washed or re-used, and that it is not designed to be worn as a primary FR garment.
What is the 2.0 cal/cm² threshold?
Under 1910.269(l)(8)(iv)(D) and (l)(8)(v), an estimated incident energy above 2.0 cal/cm² triggers the flame-resistant outer layer and arc-rated protection equal to or greater than the estimate.
The ratings, test results and standards shown here are the manufacturers' published values, reproduced as published. Nothing on this page is a recommendation by Bayshore Safety that any product is suitable for a particular task, hazard or workplace. Selecting safety products and protective equipment is the responsibility of the end user and the employer, based on their own hazard assessment and the regulations that apply to their work. Confirm every value on the manufacturer's own documentation before use.