ASTM D6413 Standard Test Method for Flame Resistance of Textiles (Vertical Test)

ASTM D6413 Introduction

Fire resistance of textiles is found to be one of the more critical properties in a fire-prone area. This method provides a standardized procedure to evaluate the fire retardancy performance of fabric materials. This vertical test measures after-flame time, afterglow time, and char length when a conditioned fabric sample is exposed to an open flame under controlled conditions. Results that can assist manufacturers and regulators in ascertaining that the materials possess relevant performance qualities in terms of fire safety based on occupational health and safety, protective clothing, and interior environments.

ASTM D6413 Test Method

ASTM D6413 Equipment and Sample Preparation

ASTM D6413 Results and Interpretation

Three laboratory test variables are measured in quantifiable ways: afterflame time, afterglow time, and char length. Short afterflame and afterglow times, together with small car lengths, indicate good flame resistance. Thus, good flame-resistant protective fabrics used for firefighters’ suits are commonly stated to yield an afterflame time of about 2 seconds and char lengths below 100 mm. Conditioning and exposure to the flame should be performed under reproducible conditions to assure reproducibility; the results provide no insight into how the materials would behave in real-life fire scenarios, but do lend themselves to comparison of how those materials behave under standardized conditions. 

Related Test Methods

ASTM D6413 is often combined with other flammability testing methods so that a broader view of a material fire resistance behavior may be established. For instance, ASTM F1506 gives performance requirements for flame-resistant clothing intended for electrical workers and protection against arc flash hazards.

ASTM D6413 Applications and Industry Use

This test method is very important for industries where flame resistance is the most important safety requirement. It is most widely adopted in occupational safety to classify flame resistance in fabrics with which firefighter turnout gear, industrial uniforms, and electrical PPE are made. In military and defense, it validates protective clothing and equipment assessment regarding protection from battlefield fire hazards. The same test is also performed in the automotive and aerospace industries to ensure that upholstery, insulation, and cabin interior materials conform to fire resistance standards.

ASTM D6413 Common Challenges and Troubleshooting

Many factors could influence the consistency and accuracy of test outcomes. Periodic calibration and maintenance of the burner system are obligatory. Another obstacle to the variability of specimens is dissimilarities in the thickness of fabric, in the weave, or in the surface treatment, which can cause variance in patterns of charring or burning. One way of lessening the impact of this variability is by using representative samples taken from the same production lot. Also, inappropriate environmental conditioning may give erroneous results in moisture content, which has a very significant effect on the reaction of the fabric with flame. Valid and repeatable results are likely to be achieved by controlling the humidity and temperature before the test.

ASTM D6413 Safety and Best Practices

Testing for flame resistance implies exposure to open flames; therefore, strict laboratory safety practices must be followed. Tests should be carried out in Flameproof chambers or fume hoods having fire extinguishing systems. The operators should wear flame-resistant gloves, laboratory coats, and face shields while setting up and running tests against possible unforeseen developments of flame and/or contact with hot components.

Importance of ASTM D6413

This testing methodology forms an integral part of one of the most essential inspections relating to flame resistance in textiles. Its simplicity, repeatability, and straightforward metrics render it easy to employ in quality control and regulatory compliance. While it does not simulate the conditions during a real fire, baseline data is valuable regarding flame spread and material behavior in the very initial stages of ignition. Industries concerned about safety and fire protection use this test to ensure that any product meets relevant fire resistance requirements, thereby ensuring the safety of people and property from an accidental flame exposure.