What is the ASTM E84
ASTM E84, also known as the Standard Test Method for Surface Burning Characteristics of Building Materials, is a widely used fire testing standard developed by ASTM International. It measures how building materials behave when exposed to fire, focusing on two critical metrics:
Flame Spread Index (FSI): This index measures how quickly flames spread across the material's surface. The lower the FSI, the slower the fire spreads, making the material safer. Class A materials, for example, have an FSI of 0-25, which indicates minimal flame spread.
Smoke Developed Index (SDI): This index assesses the smoke produced as the material burns. Materials with lower SDI values are preferred because they produce less smoke, which can reduce toxicity and improve visibility in fire situations.
The ASTM E84 test is conducted in a horizontal, 25-foot tunnel furnace, known as the Steiner Tunnel, where the material is exposed to flames under controlled conditions. The results help classify materials into fire ratings:
Class A (Class 1): FSI of 0-25, SDI of 0-450
Class B (Class 2): FSI of 26-75, SDI of 0-450
Class C (Class 3): FSI of 76-200, SDI of 0-450
A material with a Class A rating is considered to have superior fire resistance, making it suitable for high-risk applications such as wall assemblies, ceilings, and critical structural components.
How is ASTM E84 testing performed?
The ASTM E84 test, or Steiner Tunnel test, is a rigorous method for evaluating the surface burning characteristics of building materials. Here is a step-by-step outline of the test procedure:
Specimen Conditioning:
The test specimen is first conditioned at 73.4 ± 5°F and 50 ± 5% relative humidity until it reaches equilibrium moisture content, which is determined by weighing.
Tunnel Preparation:
The Steiner Tunnel is preheated to a brick temperature of 150°F* and then cooled to 105 ± 5°F. Once the temperature stabilizes, the tunnel lid is lifted, and the conditioned test specimen is placed horizontally, with the flame-exposed side facing down. A 1/4-inch fiber-cement board is placed behind the specimen to protect the tunnel lid.
Establishing Airflow:
After the test specimen is positioned, the lid is closed, and a 240 ft./min airflow is set up. This airflow helps simulate real-world conditions by drawing air through the tunnel.
Preheating:
The specimen is preheated for 2 minutes with airflow circulating through the tunnel, allowing for stable conditions before ignition.
Ignition:
An 88 kW burner with two upward ports is ignited, heating the specimen's face. The burner remains active for the entire 10-minute duration of the test.
Data Collection:
Flame Spread: An observer (referred to as the "Reader") tracks the progression of the flame front as it travels down the tunnel.
Smoke Density: A photometer system in the exhaust duct measures smoke density throughout the test.
Temperature: A thermocouple probe 23 feet from the burner centerline and 1 inch below the specimen records temperature data, providing additional insight into the material's reaction to fire.
The results, including the Flame Spread Index (FSI) and Smoke Developed Index (SDI), are then calculated based on the observed flame progression and smoke density measurements, determining the material's fire classification.
MagMatrix MgO Structural Sheathing Board With ASTM E84 for Class A Ratings
MagMatrix BMSC 517 new sulfate Magnesium Oxide (MgO) boards have been tested according to ASTM E84 and achieved a Class A (Class 1) fire rating, the highest possible rating for flame spread and smoke development. This rating means that these boards have excellent fire resistance properties, characterized by:
1. Flame Spread Index (FSI): we between 0 and 25, indicating very low flame spread across the board's surface.
2. Smoke Developed Index (SDI): We are in the range of 0 to 450, though MgO boards often produce very low smoke due to their mineral composition.
MagMatrix new sulfate MgO boards with ASTM E84 certification can be used in a variety of fire-rated applications, including:
- Fire-rated wall assemblies
- Partitions and ceilings in fire-prone areas
For compliance and safety assurance, verifying the specific ASTM E84 rating of any MgO board product is crucial, as ratings can vary based on board density, formulation, and other factors.
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