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FLAME RESISTANT
Especially important to many occupations are FR standards, which were created to keep exposed workers safe from potentially life-threatening hazards due to fire or electricity.
WHAT IS AN ARC RATING?
With increased awareness of the dangers of arc flash, the materials are tested for their arc rating.
The arc rating is the maximum incident energy resistance demonstrated by a material prior to break open (a hole in the material) or necessary to pass through and cause with 50% probability of a second or third degree burn.
Arc rating is normally expressed in cal/cm² (or small calories of heat energy per square centimeter) also known as ATPV (Arc thermal protective value)
Per ASTM 1506, ASTM F1959 is the test method used to determine the arc rating (ATPV).
ASTM F1891, Arc Standard for Flame Resistant Rainwear
Under NFPA 70E, all PPE receives an incident energy level determined by the fabric or garment’s arc rating from the ASTM test method.
There are four PPE categories setting the minimum arc rating required to meet each level.
NFPA 70E HAZARD/RISK CATEGORIES (CAT RATING)
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HAZARD / RISK CATEGORY |
|
CLOTHING DESCRIPTION |
|
REQUIRED MINIMUM ARC RATING OF PPE (cal/cm²) |
 |
|
Arc-rated FR shirt and FR pants or FR coverall (1 layer) |
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4 |
 |
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Arc-rated FR shirt and FR pants or FR coverall (1 or 2 layers) |
|
8 |
 |
|
Arc-rated FR shirt and FR pants or FR coverall, and arc flash suit selected so that the system arc rating meets the required minimum (2 or 3 layers) |
|
25 |
 |
|
Arc-rated FR shirt and FR pants or FR coverall, and arc flash suit selected so that the system arc rating meets the required minimum (3 or more layers) |
|
40 |
NFPA 70E & ASTM F1506
WHAT IT IS
NFPA 70E is an internationally accepted American National Standard that defines electrically safety-related work practices to safeguard employees faced with the threat of electrical arcs.
This includes ASTM F1506, which is the standard NFPA 70E cites for fabrics and garment testing and certification.
ASTM F1506 - Standard Performance Specification for Flame Resistant and Electric Arc Rated Protective Clothing Worn by Workers Exposed to Flames and Electric Arcs
HAZARD
ARC FLASH
- A sudden electrical explosion that produces intense heat four times hotter than the sun’s surface (up to 35,000°F) and energy.
- Light and heat produced from an electrical arc supplied with sufficient electrical energy to cause substantial damage, harm, fire or injury.
APPLICABLE TESTS
ASTM D6413 - Standard Test Method for Flame Resistance of Textiles (vertical test), when exposed to flame for 12 seconds fabric must:
- Self-extinguish in 2 seconds or less
- Char length of 6 inches or less
- No melting or dripping
- Meets this standard after 25 washes
ASTM F1959 - Standard Test Method for Determining Arc Rating of Materials for Clothing. Determines how much heat a certain fabric will block before second degree burns (ATPV value in cal/cm²)
ASTM F1891 - Standard Specification for Arc and Flame Resistant Rainwear
APPLICATIONS
ASTM F1506 certification allows a first-party self-declaration
NFPA 2112
WHAT IT IS
- NFPA 2112 - Standard on Flame Resistant Clothing for Protection of Industrial Personnel Against Short-Duration Thermal Exposures from Fire
- NFPA 2112 standard protects workers from flash fire exposure and injury by specifying performance requirements and test methods for flame-resistant fabric and garments
- NFPA 2112 certification - In order to demonstrate conformance with NFPA 2112, products must undergo finished product evaluation, design and label review, and quality manual review
HAZARD
SHORT-DURATION THERMAL EXPOSURE FROM FIRE (Flash Fire)
- A sudden, intense fire caused by ignition of a mixture of air and a dispersed flammable substance such as a solid, flammable or combustible liquid or a flammable gas
- It is characterized by high temperature, short duration, and a rapidly moving flame front
APPLICABLE TESTS
ASTM D6413 - Standard Test Method for Flame Resistance of Textiles (vertical test), when exposed to flame for 12 seconds fabric must:
- Self-extinguish in 2 seconds or less
- Char length of 4 inches or less
- No melting or dripping
- Meets this standard after 100 washes
ASTM D7138 (thread melting resistance) - thread must be flame-resistant fiber and not melt at 500°F
ASTM F2894 (heat resistance) - when exposed to 500°F for 5 minutes, material must not ignite, melt, drip, or separate, and not shrink more than 10%
ASTM F2700 (heat transfer) - when exposed to both convective & radiant heat at 2 cal/cm²/sec, fabric must have a HTP rating of 3 cal/cm² or greater (contact) and 6 cal/cm² (spaced)
ASTM F1930 (manikin test), predicted 2nd or 3rd degree total body injury is no more than 50% of total body surface after simulated flash fire
APPLICATIONS
NFPA 2112 certification requires third-party certification.