What is the standard for flammability test?

Flammability Testing Standards refer to a series of specifications and methods for evaluating the behavior of materials, products, or components when exposed to flames, heat sources, or fire environments under controlled conditions. These standards play a crucial role in safety assessment, regulatory compliance, product design, and quality control. Flammability testing, through standardized procedures, helps manufacturers and testing organizations determine how a product performs under actual use or accidental fire conditions, thereby reducing fire risks, protecting life and property, and meeting relevant regulatory requirements.

Different industries, products, and material types have distinct flammability standards. For example, building materials, textiles, plastics, furniture, and aerospace components all require evaluation according to specific standards. These testing standards are issued by various organizations, including the International Organization for Standardization (ISO), ASTM International, the National Fire Protection Association (NFPA), and government regulatory bodies.

Significance and Basic Concepts of Flammability Testing

The core purpose of flammability testing is to evaluate, under the influence of a fire source (such as an open flame, small flame, heat radiation, or cigarette), whether a material or product:

Ignites easily;

Exhibits rapid burning or fire spread;

Produces harmful smoke or molten droplets;

Contributes to fire propagation;

Can self-extinguish or extinguish quickly.

Test results are generally used for:

Product safety certification;

Regulatory compliance (for consumer goods, building materials, vehicle components, etc.);

Material selection or improvement;

Product classification and labeling.

Testing is typically conducted under controlled laboratory conditions, following prescribed equipment, flame sources, specimen dimensions, and data recording procedures.

Common International and Domestic Flammability Standards

ISO Standards

The International Organization for Standardization (ISO) has published multiple standards for flammability testing or combustion behavior, covering methods to quantify the burning characteristics of materials. Common ISO standards include:

ISO 6940 and ISO 6941 — Flammability of Textiles

ISO 6940 specifies testing methods for vertically oriented textile samples exposed to a prescribed flame source, measuring ignition time and burning performance.

ISO 6941 measures flame spread of vertically placed fabric samples under small flame exposure, recording the burning behavior along timing lines.

These standards are mainly used to evaluate textiles, clothing fabrics, and curtains under small flame conditions.

ISO 12136 — Quantitative Testing of Combustion Behavior

This standard evaluates material burning characteristics, fire propagation tendencies, and related quantitative parameters, typically for research purposes rather than building code compliance.

ISO also includes flammability or fire safety tests for specific products and conditions, such as wheelchair cushions.

U.S. Standards and Regulations

UL 94 — Flammability of Plastic Materials

UL 94 is a key standard for assessing the burning behavior of plastics, determining whether materials self-extinguish or continue to burn after ignition. Materials are classified into grades such as HB (horizontal burning), V‑0. V‑1. V‑2 (vertical burning), and stricter 5VA and 5VB grades. Classification is based on burning speed, duration, and whether dripping material continues to burn. UL 94 mainly applies to plastics used in devices and equipment but can also serve as a reference for other non-metallic materials.

CFR Series — U.S. Federal Flammability Regulations

The U.S. Consumer Product Safety Commission (CPSC) has established several CFR standards for specific product categories:

16 CFR 1610/1611: Flammability of polyethylene films and similar thin materials.

16 CFR 1630/1631: Flammability standards for large- and small-area carpets.

16 CFR 1615/1616: Flammability requirements for children's sleepwear and textile clothing.

16 CFR 1633: Flammability testing of mattress assemblies under open flame.

These regulations are legally binding in the U.S., and products must pass corresponding tests to be sold legally.

ASTM International Standards

ASTM provides a wide range of flammability testing methods for various materials and applications, including:

ASTM D1230: Flammability of apparel fabrics, measuring flame spread time and assigning grades.

ASTM E162: Surface flammability evaluation under radiant heat.

ASTM D3675: Surface flammability of flexible materials such as foams.

ASTM E2058: Material burning characteristics in fire propagation devices, including ignition time, heat release rate, and other key parameters.

Other ASTM methods assess plastic burning speed, heat release, smoke generation, and are used in both product design and fire risk assessment.

Other International and National Standards

European EN standards often reference ISO 6940/6941 for fabric flammability evaluation and provide classification schemes for curtains, furniture, etc.

International railway standards like UIC 564‑2 define flammability grades for vehicle materials.

Chinese national standards (e.g., GB/T 8626) specify methods for building material flammability testing using direct small flame exposure.

These standards serve regulatory compliance, industry certification, and quality system requirements within their respective regions.

Major Flammability Testing Methods

Different standard systems use unique principles and evaluation criteria. Common methods include:

Horizontal/Vertical Burning Tests

Used for textiles, plastics, and films. Samples are fixed horizontally or vertically, a flame is applied, and parameters like burning duration, distance, and self-extinguishing behavior are recorded. Examples:

ASTM D1230: Sample placed at a 45° angle, fire applied, and flame spread time recorded.

UL 94 HB/V0/V1/V2: Material classified based on burning performance in horizontal or vertical conditions.

These tests reflect flame-induced burning speed and spread behavior.

Heat Release and Fire Propagation Tests

Standards like ASTM E2058 measure heat release rate, mass loss, and other fire propagation metrics in controlled devices. These data are critical for assessing material performance during fire development and are important for engineering design and fire safety evaluation.

Thermal Stability and Oxygen Index Tests

Methods such as the Limiting Oxygen Index (LOI) determine the minimum oxygen concentration required to sustain material burning, assessing flammability. These tests are often used in material development and flame-retardant evaluation.

Applications and Significance of Flammability Testing Results*

Product Safety Certification and Regulatory Compliance: Passing flammability tests is often a prerequisite for market entry and demonstrates compliance with safety requirements.

Material Design and Development: Comparing flammability across materials allows manufacturers to choose safer, more flame-retardant options.

Building and Engineering Design: Flammability testing of construction materials is critical for fire-safe building design, such as fire-resistant panels and wall coverings.

Challenges and Future Trends in Flammability Testing

While current standards cover many materials and products, emerging materials, composites, and smart manufacturing present challenges:

Complex burning behavior of new composites;

Evaluation of toxic smoke generation during combustion;

Better simulation of real fire scenarios without oversimplified lab conditions.

Future flammability standards may emphasize:

More realistic fire simulations;

Comprehensive quantitative metrics;

Harmonization across standards systems;

Integration of numerical simulation and experimental testing for fire risk assessment.

Flammability testing standards are essential for evaluating material and product performance under flame or high-temperature conditions. Common standards include:

UL 94: Plastic material burning classification;

ISO series (e.g., ISO 6940/6941): Textile flammability evaluation;

ASTM methods: Testing for plastics, textiles, and surface burning;

U.S. CFR regulations (e.g., 1610/1630): Legally mandated flammability tests;

National standards (e.g., GB/T in China): Specified burning test methods.

These standards play a core role in material definition, fire-safe design, and quality control, providing a unified framework for global product safety and ensuring basic fire safety requirements to protect users.