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Safety ARC Ratings ///

 

 

Flame Resistant Safety Information

The ATPV value represents the amount of incident energy that would cause the onset of second-degree burns. It also signifies the amount of protection the clothing affords when an electrical arc comes in contact with the fabric.

ATPV (ARC) RATINGS FOR ANS PRODUCTS
FR FABRIC GARMENT Fabric Weight ARC rating Hazard/ Risk
SHIRTS      
Nomex IIIA 6 oz. 5.7 1
Ultra Soft 7 oz. 8.2 2
Ultra Soft 9.5 oz. 11.1 2
PANTS      
Nomex IIIA 6 oz. 5.7 1
Ultra Soft 9.5 oz. 11.1 2
Ultra Soft 14.7 oz. 18 2
COVERALLS      
Nomex IIIA 6 oz. 5.7 1
Ultra Soft 9.5 oz. 11.1 2
OUTERWEAR      
Nomex IIIA Polar Fleece 13 oz. 24.4 2
Carhartt Ultra Soft 14.75 oz. 50.4 4
ARCTIC OUTERWEAR      
Ultra Soft 13 oz. 32 4
Nomex IIIA 9.5 oz 39 4
 

Layering of Garments
Workers may require multiple garments to maintain safety while performing multiple tasks within a day's work. There may be many pieces of clothing, but only one philosophy: adequate protection at all times for changing risk. Layering is the sensible answer that combines comfort, convenience and safety.

The protection level providing through layering is not simply a matter of adding up each garments' ATPV. Air, in ever-present layers amid multiple garments and as the ultimate buffer between garments and skin, adds positively to the safety equation. Loose fit, not snug fit, is the goal as it creates a vital air "envelope" for additional insulation.

The layering of FR garments is an alternative to using specialized garments when developing clothing systems to meet higher ATPV levels, for example for HRC 3 and 4. Picking the right FR uniform combination can help you achieve the required protection level.

FR and natural fiber undergarments shall be permitted to be used as a layered system in order to meet the required HRC level for a specific task. A typical layering system may include a 100% cotton undershirt, a FR shirt and FR pant and FR coverall. Combined, this system can be mixed and matched in order to take you to the appropriate ATPV rating. In addition to garments, other PPE may be required to meet the hazard risk category like head, eye and hand protection.

It is important to note that any garment worn as an outer layer over FR clothing, such as jackets or rainwear, needs to be made of flame-resistant material.

Examples of various garment layering combinations and ATPV ratings are listed below:

ULTRA SOFT ATPV LAYERING COMBINATIONS
Description ATPV rating HRC rating
7 oz. Ultra Soft Shirt    
9.5 oz. Ultra Soft Pant    
7 oz. Ultra Soft Coverall 27.2 3
     
7 oz. Ultra Soft Shirt    
9.5 oz. Ultra Soft Pant    
9.5 oz. Ultra Soft Coverall 36.2 3
 
NOMEX IIIA ATPV LAYERING COMBINATIONS
Description ATPV rating HRC rating
4.5 oz. Nomex Shirt    
7.5 oz. Nomex Pant    
4.5 oz. Nomex Coverall 14.4 2
     
4.5 oz. Nomex Shirt    
7.5 oz. Nomex Pant    
6 oz. Nomex Coverall 16.2 2
     
4.5 oz. Nomex Blend Shirt    
6 oz. Nomex Work Pant    
6 oz. outershell,
9 oz Nomex Batt Insulation Coverall
61.5 4
 

Nomex

Fabric Descriptions:
Fabric Content: DuPont NOMEX® IIIA aramid (93% NOMEX - 5% KEVLAR - 2%Carbon).
Characteristics: Inherently flame resistant anti-static fabric engineered to reduce "nuisance" static. Self-extinguishing, will not ignite, melt, drip or burn. These characteristics make NOMEX® an exceptional all around fabric for applications such as petroleum refining, petro-chemical, fire service, and gas and electric utilities.
Nomex® is a registered trademark of DuPont.DuPont

Indura

Fabric Content: INDURA® (100% Flame Resistant Cotton).
Characteristics: 100% cotton treated with a permanent flame resistant finish. INDURA® offers protection with the comfort and affordability of cotton. INDURA® is most popular in industrial applications and is effective protection against potential risks associated with welding and similar activities. INDURA® retains the beneficial properties of natural cotton for wearer comfort and absorbency.
INDURA® is a registered trademark of Westex, Inc.

Standards and Regulations (Courtesy of Carhartt inc.)

The National Fire Protection Agency (NFPA) has served as an authority in the U.S. on fire, electricity and building safety since 1896. In 1979, the NFPA published NFPA 70E, a Standard for Electrical Safety in the Workplace. NFPA 70E is a comprehensive national consensus standard for electrical safety issues covering work practices, installation, maintenance and special equipment.

Over the years several editions of NFPA 70E have been published. The 2000 edition was the first to include electric arc flash hazard and required flame resistant clothing (FRC) to protect workers against it. The most recent edition approved on February 11, 2004, added sections on personal protective equipment (PPE). OSHA recognizes NFPA 70E as an industry practice and has referenced it in citations.

Flame resistant clothing is addressed in Chapter 1 of the standard, Safety-Related Work Practices. It states that all equipment must be de-energized before being worked on unless the employer can demonstrate that de-energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations. If de-energizing the equipment is not feasible, the employer must establish a "flash protection boundary" which is the minimum distance from an arc source where a person could receive a "curable" or second degree burn if an arc flash occurred. An employer must determine the appropriate PPE including FRC required for all employees who cross the flash protection boundary. A hazard risk assessment to determine arc hazard level must be completed. NFPA 70E provides several options for determining arc hazard level and it is defined by "calories per square centimeter" or cal/cm2.

After arc hazard levels have been assigned for job tasks, required protective clothing may be determined. The table above, adapted from NFPA 70E-2004 (Table 130.7(C)(11)) gives the five hazard risk categories, corresponding required minimum arc rating of PPE and the Carhartt HRC color codes. Layering FRC increases thermal protection and should be considered when evaluating required PPE.

For more information or to purchase a copy of the NFPA 70E standard visit: www.nfpa.org.

FR staff

FR Department staff