Stunnier Tunnel

The Steiner Tunnel is a large-scale fire testing apparatus used to evaluate the surface burning characteristics of building materials, particularly wall and ceiling finishes. The test is conducted in accordance with ASTM E84, developed by ASTM International. In this method, a test specimen is mounted on the ceiling of a long horizontal tunnel furnace and exposed to a controlled flame produced by gas burners at one end. Airflow is maintained through the tunnel to simulate real fire conditions, allowing the flame to travel along the surface of the material. During the test, key parameters such as the Flame Spread Index (FSI) and Smoke Developed Index (SDI) are measured. These results help determine how quickly flames propagate and how much smoke is generated, providing essential data for assessing the fire performance and safety classification of building materials used in construction.