What are the different UL94 and ASTM E84 ratings?

UL94 and ASTM E84 are two common flame retardancy testing standards used to evaluate the flame propagation performance and burning characteristics of materials. The following are the main differences between them.

Here's a brief overview of each standard:

UL94 Ratings

UL94 is a standard published by Underwriters Laboratories that specifically focuses on the flammability of plastic materials. The standard outlines different tests that are used to assess the burning characteristics of plastics. The tests are designed to evaluate how a material behaves under specific fire conditions.

UL94 ratings are classified into several categories, including V-0, V-1, V-2, HB, and others. Each category represents a different level of flammability. Here's a brief description of each rating:

• V-0: Materials that have received a V-0 rating have demonstrated the highest level of resistance to ignition and the lowest burning rate during all specified testing conditions.
• V-1: V-1 rated materials have a lower level of resistance to ignition and burning compared to V-0, but still offer good flame retardant properties.
• V-2: V-2 rated materials have a higher burning rate than V-1 and V-0 rated materials and may not self-extinguish when the ignition source is removed.
• HB: Materials that receive an HB rating do not self-extinguish, and burning continues after the ignition source is removed. However, the burning rate is slower than lower classifications.

These ratings are determined through a series of tests such as the horizontal and vertical burning tests, as well as the 5VA and 5VB tests for thicker materials.

ASTM E84 Ratings

ASTM E84 is a standard test method for surface burning characteristics of building materials. This standard is used to evaluate the surface burning characteristics of materials such as wall and ceiling finishes. The test measures the flame spread and smoke developed index of a material when exposed to specific fire conditions.

The results of the ASTM E84 test are expressed in terms of a flame spread index and a smoke developed index. The flame spread index is a relative measurement of how quickly the flame spreads across the surface of the material, while the smoke developed index measures the amount of smoke a material emits as it burns.

Materials that receive low flame spread and smoke developed index values are considered to have better fire performance. These ratings are used by building code officials and designers to assess the suitability of materials for use in various building applications.

It should be noted that UL94 and ASTM E84 are only two common standards for flame retardancy testing, and other countries and regions may use different standards to evaluate the flame retardancy of materials. Selection of the appropriate standard is based on specific applications and needs. In practice, it is recommended to follow the applicable standards and consult professional organizations or laboratories to ensure that the flame retardant properties of the materials meet the safety requirements.