Testing burn characteristics via ASTM E84

ASTM E84 is used to assess the surface burning characteristics of building products. The results help fire protection engineers better understand how various materials will react during a fire.

By Karl Houser, PE, LEED AP, Intertek, York, Pa. August 12, 2016

Learning objectives:

  • Demonstrate the tests required to assess surface burning characteristics of building products.
  • Examine how the test is run and how to use the results.

ASTM E84: Standard Test Method for Surface Burning Characteristics of Building Materials (often referred to as "E84") is one of the most frequently specified standard test methods for assessing the surface burning characteristics of building products. The purpose of this test is to observe the flame spread along a sample in order to determine the relative burning behavior of the material.

Through the E84 test, both flame spread index (FSI) and smoke developed index (SDI) are reported for a given sample. FSI is the measurement for the speed at which flames progress across the interior surface of a building, while SDI provides some measure of the amount of smoke a sample emits as it burns.

When is the E84 test required?

The 2015 International Building Code (IBC) specifies that "interior wall and ceiling finishes shall be classified in accordance with ASTM E84 or UL 723." Additionally, NFPA 101: Life Safety Code requires that "interior wall or ceiling finish that is required elsewhere in this Code to be Class A, Class B, or Class C shall be classified based on test results from ASTM E84, or UL 723."

How is the test run?

An E84 test is conducted by placing a 24-in. wide x 24-in. long sample into a Steiner Tunnel (see description of a Steiner Tunnel below), wherein the test is administered through the use of two burners which provide 89 kW of energy. During the test, the sample is mounted on the ceiling under a removable lid, and a forced draft is provided in order for the movement of air and products of combustion within the tunnel, and to the exhaust/scrubber system.

The progress of the flame is then monitored through viewports on one side of the apparatus and recorded, with software computing the various data points to derive the FSI and SDI. Smoke developed is also measured through the optical density of a light obscuration meter. It should be noted that the "fuel contributed" measurement is no longer in use.

What is a Steiner Tunnel?

Developed by Albert Steiner in the 1940s, the Steiner Tunnel (see Figure 1) is a steel box lined on its sides and floor with fire brick, and featuring a removable lid. The tunnel contains a 12-in.-high fire chamber with two burners at one end providing 89 kW of energy. The Steiner Tunnel was adopted as an ASTM standard in 1950 and given the designation of E84. Equivalent standards are maintained by NFPA and UL as NFPA 255, UL 723, and with certain modifications as CAN/ULC-S102. Under the Canadian standard, additional fire bricks are installed on the floor of the tunnel and the view glass is removed. UL 1256 also references a modified version of the Steiner Tunnel for use on certain roofing systems.

Is certification required?

No, certification is not required for E84 tests. However, because certification is a quality-control process that helps to ensure that the product being tested is the product being manufactured, certification can be used as a way to differentiate a product from similar market products. If product certification is involved, the product sampled and tested after certification must not vary wildly from that used for original certification.

What if a product fails? Passes?

ASTM E84 is a comparative test, and as such there is no real "pass" or "fail." The test generates numbers expressed as FSI and SDI, and while there are no pass-fail criteria in the standard, certain codes and regulations define required FSI value and/or SDI value for applications and installations. If a sample’s values do not meet code directives, the product may be limited or prohibited. In such cases, it may be advisable to run additional tests (perhaps with modified materials) to legitimately improve the product’s FSI or SDI.

What are the differences in the U.S. and Canadian versions of the test?

The major difference that distinguishes the U.S. from the Canadian version of the Steiner Tunnel test is the way in which the sample is mounted in the testing chamber. For U.S. testing, the sample is mounted on the roof of the testing chamber, while the Canadian version requires that certain samples be mounted on the floor, depending upon the composition of the sample, or its intended use. This is not allowed for U.S. testing because any products mounted on the floor of the tunnel are no longer qualified. Given these variations in the testing, results for a sample will differ between the U.S. and Canada, though both will provide important test data.

Karl Houser is the senior fire protection engineer, building and construction, at Intertek, a testing, inspection, and certification organization. As the leader of Intertek project consulting services, Houser is responsible for outreach to architects, code officials, general contractor, building owners, and others in the construction community.