What is UL 790A ?

The Underwriters Laboratories (UL) Standard 790, also known as UL 790, is a crucial industry benchmark for testing the fire resistance of roofing materials. It helps to ensure the safety and protection of buildings and their occupants. This article will provide a comprehensive understanding of UL 790, including its purpose, testing procedures, and key requirements.

Purpose of UL 790

UL 790 is designed to evaluate the fire resistance of roof coverings under specified test conditions. The standard evaluates two primary aspects: flame spread resistance and external fire resistance.

Flame spread resistance measures the ability of a material to resist the spread of flame along its surface. It is essential for a roof material to have a low flame spread rating to minimize the risk of fire spread and fire damage.

External fire resistance evaluates the material's capability to withstand a fire originating from sources outside the building, such as neighboring structures or vegetation. It is important for a roof material to have a high external fire resistance rating to minimize the risk of fire damage from external sources.

Testing Procedures

UL 790 testing procedures are designed to ensure that roofing materials meet the standard's requirements. The testing procedures involve several steps, including:

Sample preparation: The roofing material is cut into specified test specimens, which are then conditioned to a standard temperature and humidity.

Vertical Burn Test (V-Burn): The roofing material is set on a fire-resistant support and a flame source, and the time required for the material to burn through the fire resistance rating is recorded.

Horizontal Burn Test (H-Burn): The roofing material is set on a fire-resistant support and a flame source, and the time required for the material to burn through the fire resistance rating is recorded.

Flame Spread Test (FST): The roofing material is spread with a flame, and the time required for the material to spread and ignite is recorded.

External Fire Test: The roofing material is exposed to a flame from an external source, such as a neighboring building or vegetation, and the time required for the material to ignite and burn is recorded.

Key Requirements

UL 790 has several key requirements that manufacturers must meet in order to ensure that their roofing materials are fire resistant. These requirements include:

Flame Spread Rating (FSR): The material must have a low FSR to minimize the risk of fire spread.

External Fire Resistance Rating (ESR): The material must have a high ESR to minimize the risk of fire damage from external sources.

Thermal Burn Characteristics: The material must have a high thermal burn rate, low thermal ignition temperature, and low thermal conductivity to minimize the risk of fire spread and damage.

Fire-Resistance Material (FRM) Test: The material must undergo a fire-resistance material test to ensure that it meets the material's fire resistance requirements.

Conclusion

UL 790 is an essential industry standard for evaluating the fire resistance of roofing materials. It provides valuable information for manufacturers, contractors, and building owners to ensure the safety and compliance of roofing materials. By understanding the purpose of UL 790 testing procedures and key requirements, manufacturers can ensure that their products meet the necessary criteria for fire resistance, while building owners can be confident in the safety and protection provided by their roofing materials