Steiner Tunnel test methods, such as ASTM E84, UL 723, CAN/ULC-S102, and CAN/ULC-S102.2, measure the surface burning characteristics of building materials. The results of these tests provide comparative measurements of surface flame spread and smoke density. There are several ways these results are used, and the three most common are product development, customer and market acceptance, and evidence for code compliance.
Who and Why?
Many building products are tested using the Steiner Tunnel. Products tested include interior finish materials (such as gypsum wallboard, fiber cement, wall coverings, and wood structural panels), plastics, foam plastics (such as composite siding, expanded polystyrene, and spray polyurethane) paints, coatings, and fire-retarded materials.
These product manufacturers may be using the test data for several different reasons. The data may feed into their research and development process, helping them refine an innovative solution to market needs. The product may already be developed, but a customer may have a unique application that now requires test data to satisfy regulations or project specifications. The manufacturer may be developing a certification report (such as an Evaluation Service Report or a Listing Report) with an accredited third-party certification agency that needs the test data to verify compliance with building codes or standards.
Procedure of Test
There are two different ways for the Steiner Tunnel to be used in testing (Ceiling-mounted or Floor-mounted). Both these tests will provide measurements of surface flame spread and smoke-developed measurements of the product. The product itself will determine what position the specimen will be placed. In most cases, the ceiling-mounted tests are performed (ASTM E84, UL 723, CAN/ULC-S102), whereas materials that tend to be installed on the floor are floor-mounted using the CAN/ULC-S102.2 test method.
In both the ceiling-mounted and floor-mounted scenarios, these test methods expose a nominal 24-foot-long by a 20-inch-wide specimen to a controlled airflow and fire exposure to the face of the specimen via two burners. These tests will measure how far and how fast flames spread across the test specimen’s surface. During this 10-minute test, the specimen is monitored for flame spread through the windows on the side of the tunnel, and smoke development is measured through a light obscuration meter. Data is recorded while computers compute the various data received to calculate the Flame-Spread Index (FSI) and Smoke Developed Index (SDI).
Results of Tests
After performing the Steiner Tunnel test on a specimen, the Flame-Spread Index (FSI) and Smoke Developed Index (SDI) will be determined. Flame Spread Index is a unitless value that provides a comparative measure of how fast the flame/fire spreads along the surface and how far it travels down the tunnel in comparison to calibration materials (red oak and cement board). Building Codes such as the International Building Code provide classifications, for material used in buildings, based on the results of this test as shown in the chart below.
Note: The Steiner Tunnel tests will not provide the following:
- Heat transmission through the tested surface
- The effect of aggravated flame spread behavior of an assembly resulting from the proximity of combustible walls and ceilings
- Classifying or defining a material as noncombustible by means of a flame spread index by itself.