How to Decide Which Flammability Test to Use: UL 94 or ASTM E84?

Choosing Between UL 94 and ASTM E84 Flammability Tests: A Comprehensive Guide

Selecting the appropriate flammability test is crucial for assessing the fire performance of materials. Two widely used standards for evaluating flammability are UL 94 and ASTM E84. In this guide, we will explore the key differences between these standards, their applications, and factors to consider when deciding which test is suitable for your specific needs.

Understanding UL 94:

Overview:

UL 94 is a standard developed by Underwriters Laboratories (UL) to assess the flammability of plastic materials. This test is particularly relevant for industries where plastic materials are commonly used, such as electronics, automotive, and consumer goods.

Testing Procedure:

The UL 94 test involves assessing the burning characteristics of a vertically oriented test specimen. The material is subjected to a controlled flame ignition source, and its burning behavior is observed. The test provides a classification based on specific criteria, including the material's burning rate, afterglow, and dripping.

Classification Ratings:

UL 94 classifies materials into different ratings:

• V-0 (V-Zero): The highest rating, indicating that the material self-extinguishes within 10 seconds and does not have any flaming drips.
• V-1: The material self-extinguishes within 60 seconds, with limited flaming drips allowed.
• V-2: The material self-extinguishes within 60 seconds, with no restrictions on flaming drips.

Applications:

UL 94 is commonly used for assessing the flammability of plastic components, such as enclosures, connectors, and housing materials in electrical and electronic devices.

Understanding ASTM E84:

Overview:

ASTM E84, also known as the Steiner tunnel test, is a standard developed by ASTM International to measure the surface burning characteristics of building materials. This test is widely used in the construction and building materials industry.

Testing Procedure:

In the ASTM E84 test, a specimen is mounted horizontally, and a controlled flame is applied to its surface. The flame spread along the specimen is measured, and the results are used to calculate the Flame Spread Index (FSI) and Smoke Developed Index (SDI).

Classification Ratings:

• Class A: Flame Spread Index 0-25, Smoke Developed Index 0-450.
• Class B: Flame Spread Index 26-75, Smoke Developed Index 0-450.
• Class C: Flame Spread Index 76-200, Smoke Developed Index 0-450.

Applications:

ASTM E84 is widely used for assessing the fire performance of interior finish materials, including wall and ceiling coverings, as well as insulation materials in buildings.

Key Differences:

Material Types:

• UL 94: Primarily designed for plastics and plastic components.
• ASTM E84: Applicable to a broader range of building materials, including but not limited to plastics.

Test Configuration:

• UL 94: Vertical orientation of the specimen.
• ASTM E84: Horizontal orientation of the specimen.

Test Objectives:

• UL 94: Focuses on the burning characteristics of plastics, including factors like dripping and afterglow.
• ASTM E84: Measures flame spread and smoke development in building materials.

Classifications:

• UL 94: V-0, V-1, V-2.
• ASTM E84: Class A, Class B, Class C.

Industries and Applications:

• UL 94: Commonly used in electronics, automotive, and consumer goods industries for plastic components.
• ASTM E84: Widely applied in the construction industry for assessing the fire performance of building materials.

Factors to Consider When Choosing:

Material Composition:

• Plastics: If your material is primarily plastic or contains plastic components, UL 94 may be more suitable.
• Building Materials: For a broader range of building materials, including plastics, ASTM E84 is appropriate.

Industry Requirements:

• Electronics and Plastics Industry: UL 94 is often specified in industry standards and regulations for electrical and electronic devices.
• Construction Industry: ASTM E84 is commonly referenced in building codes and regulations for interior finish materials.

Regulatory Compliance:

• Check Industry Standards: Verify whether your industry or application has specific standards or regulations that dictate the use of a particular flammability test.

Material Application:

• Consider the End Use: Determine the intended application of the material. For example, if it will be used in a building or construction setting, ASTM E84 may be more relevant.

Testing Cost and Resources:

• UL 94 Testing Facilities: Ensure access to testing facilities that can conduct UL 94 tests if this standard is chosen.
• ASTM E84 Testing Facilities: Similarly, check for facilities capable of performing ASTM E84 tests if that standard is preferred.

Global Recognition:

• UL 94: May have more global recognition in industries where Underwriters Laboratories is prevalent.
• ASTM E84: ASTM standards are widely recognized globally and may be more applicable in international markets.

Conclusion:

In conclusion, the choice between UL 94 and ASTM E84 depends on various factors, including the material type, industry requirements, regulatory compliance, end-use application, testing cost, and global recognition. Both standards are valuable tools for assessing the flammability of materials, but they are designed for different purposes and industries.

When in doubt, consulting relevant industry standards, regulations, and local building codes can provide guidance on which test method is most appropriate for your specific needs. Ultimately, the decision should align with the intended application and industry requirements to ensure the material meets the necessary safety and performance standards.