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ASTM E84 Class Test for Flexible Duct Connectors:

When it comes to HVAC (Heating, Ventilation, and Air Conditioning) systems, one crucial component that often goes unnoticed is the flexible duct connector. These connectors play a vital role in maintaining the integrity of the ductwork system and ensuring efficient airflow. However, to ensure their safety and performance, it is essential to subject them to rigorous testing, such as the ASTM E84 Class Test.

Understanding ASTM E84 Class Test:

The ASTM E84, also known as the "Standard Test Method for Surface Burning Characteristics of Building Materials," is a widely recognised testing standard used to evaluate the fire performance of various materials, including flexible duct connectors. The test measures the surface burning characteristics of the material by observing its flame spread and smoke development when exposed to controlled fire conditions.

Why is the ASTM E84 Class Test Important for Flexible Duct Connectors?

Flexible duct connectors are typically made from materials such as neoprene-coated fabric, thermoplastic elastomers, or similar materials. These connectors are designed to be flexible, lightweight, and resistant to wear and tear. However, they are also exposed to airflow carrying potentially hot or flammable substances. In case of a fire incident, the performance of these connectors becomes critical to prevent the rapid spread of flames and smoke throughout the building.

By subjecting flexible duct connectors to the ASTM E84 Class Test, manufacturers and users can assess their fire safety characteristics. The test results provide valuable information about the materials' ability to resist flames and smoke, thereby helping to identify potential fire hazards and mitigate risks associated with HVAC systems.

What Does the ASTM E84 Test Involve?

During the ASTM E84 Class Test, a sample of the flexible duct connector is exposed to a controlled flame. The flame spread and smoke development are measured and compared against specific criteria. The test results determine the material's flame spread index and smoke developed index, which then assigns the material a Class rating ranging from Class A to Class F, or Class 1 to 6.

- Class A / 1: Flame Spread Index 0-25, Smoke Developed Index 0-450

- Class B / 2: Flame Spread Index 26-75, Smoke Developed Index 0-450

- Class C / 3: Flame Spread Index 76-200, Smoke Developed Index 0-450

The higher the Class rating, the better the material's fire-resistant properties.


In conclusion, the ASTM E84 Class Test is a critical procedure to assess the fire safety of flexible duct connectors used in HVAC systems. By ensuring that these connectors have undergone proper testing and received an appropriate Class rating, we can have greater confidence in their ability to prevent the rapid spread of flames and smoke in the event of a fire.

As consumers, HVAC professionals, and building owners, it is essential to prioritise safety by choosing flexible duct connectors that meet the ASTM E84 Class Test requirements. This ensures that our HVAC systems function efficiently while minimising potential fire hazards, ultimately contributing to the overall safety and well-being of occupants within the building.

Our flexible duct connector from Aeroduct has gone through all tests and are certified. To visit, click on link:


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