Understanding NFPA 2112: The Basic

Relationship Between ASTM D6413 and NFPA 2112

• NFPA 2112 (Standard on Flame-Resistant Clothing for Industrial Personnel) references ASTM D6413 as the primary test method for evaluating flame resistance.

• Key Requirements in NFPA 2112 (Section 5.1.1.1):

  • Fabrics must be tested per ASTM D6413 (Vertical Flame Test).

  • Maximum allowable limits:

    • Afterflame ≤ 2 seconds

    • Afterglow ≤ 2 seconds

    • Char length ≤ 100 mm (4 in.)

• Purpose: Ensures fabrics self-extinguish quickly and resist flame propagation in short-duration thermal exposures (e.g., flash fires).

Parameter	Measures	NFPA 2112 Limit
Char Length	Fabric destruction distance	≤ 100 mm (4 in.)
Afterflame	Flame persistence after ignition	≤ 2 sec
Afterglow	Smoldering after flame stops	≤ 2 sec

Difference Between Afterflame/s and Afterglow/s

• Afterflame indicates flammability resistance (does the fabric sustain flames?).

• Afterglow indicates residual combustion risk (does it smolder dangerously after flames stop?).

• A true FR material must minimize both to ensure full protection (e.g., NFPA 2112 requires ≤ 2 sec for each).

Parameter	Definition	NFPA 2112 Limit	Significance
Afterflame (s)	Time (seconds) a material keeps burning with visible flames after ignition stops.	≤ 2 sec	Measures immediate flame spread risk.
Afterglow (s)	Time (seconds) a material smolders (glows without flame) after flames extinguish.	≤ 2 sec	Assesses hidden combustion risk (e.g., reignition or toxic smoke).

What Does "Char Length ≤ 100 mm (4 in.)" Mean?

• It quantifies how far the flame damages the fabric when exposed to a controlled flame for 12 seconds (as per ASTM D6413).

• The test measures the length of the tear or hole created by burning, indicating the material's ability to resist flame propagation.

• How is Char Length Measured?

  
  

  1. Test Setup:

  • A fabric specimen (300 mm × 75 mm) is suspended vertically.

  • A flame is applied to the bottom edge for 12 seconds.

  
  

  2. After Burning:

  • After the flame extinguishes (afterflame & afterglow stop), the specimen is examined.

  
  

  3.Measurement:

  • The specimen is folded gently, and the maximum length of the damaged (charred) area is recorded.

  • If the fabric tears, the total length of the tear is included in the measurement.

  
  

  4. Why is the Limit ≤ 100 mm (4 in.) in NFPA 2112?

  • Safety Threshold: A shorter char length means the fabric self-extinguishes quickly, reducing burn injury risk.

  • Performance Benchmark:

    • ≤ 100 mm ensures the fabric does not burn excessively, maintaining protective integrity.

    • If char length exceeds 100 mm, the material fails NFPA 2112 compliance.

    
    

Key takeaway:

• ASTM D6413 is the key test method for NFPA 2112 compliance.

• Char length ≤ 100 mm ensures limited fabric damage.

• Afterflame & afterglow together assess both flaming and smoldering risks.

• All three criteria (char length, afterflame, afterglow) must pass for effective flame-resistant clothing.