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Steiner Tunnel

ASTM E84 (Steiner Tunnel) 
Building codes and regulations continue to stress lower flame spread and low smoke generation for many materials. The Steiner Tunnel (ASTM E-84) is frequently referenced as a method to assess flame spread and smoke density and is a mandated test for many commercial building materials. The test consists of a 25' vented tunnel, lined with firebrick, with the test material mounted to the top of the chamber. At one end of the chamber, the sample is subjected to a high-energy flame for ten minutes. Flame spread is determined visually through windows built into the tunnel. An optical cell mounted at the tunnel exhaust measures smoke density.

A similar test used to qualify plenum grade communication cable is UL 910. In this case, the test specimens are multiple cable constructions. Requirements for plenum cable are considered the most restrictive in the industry. Qualification of flame retarded materials by either E-84 or UL 910 is a major hurdle involving considerable time and expense. 

Significance and Use

This test method is intended to provide only comparative measurements of surface flame spread and smoke density measurements with that of select grade red oak and fiber-cement board surfaces under the specific fire exposure conditions described herein.

This test method exposes a nominal 24-ft (7.32-m) long by 20-in. (508-mm) wide specimen to a controlled air flow and flaming fire exposure adjusted to spread the flame along the entire length of the select grade red oak specimen in 5 ½min.

This test method does not provide for the following:

Measurement of 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.

1. Scope

1.1 This fire-test-response standard for the comparative surface burning behavior of building materials is applicable to exposed surfaces such as walls and ceilings. The test is conducted with the specimen in the ceiling position with the surface to be evaluated exposed face down to the ignition source. The material, product, or assembly shall be capable of being mounted in the test position during the test. Thus, the specimen shall either be self-supporting by its own structural quality, held in place by added supports along the test surface, or secured from the back side.

1.2 The purpose of this test method is to determine the relative burning behavior of the material by observing the flame spread along the specimen. Flame spread and smoke developed index are reported. However, there is not necessarily a relationship between these two measurements.

1.3 The use of supporting materials on the underside of the test specimen has the ability to lower the flame spread index from those which might be obtained if the specimen could be tested without such support. These test results do not necessarily relate to indices obtained by testing materials without such support.

1.4 Testing of materials that melt, drip, or delaminate to such a degree that the continuity of the flame front is destroyed, results in low flame spread indices that do not relate directly to indices obtained by testing materials that remain in place.

1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.6 The text of this standard references notes and footnotes that provide explanatory information. These notes and footnotes, excluding those in tables and figures, shall not be considered as requirements of the standard.

1.7 This standard is used to measure and describe the response of materials, products, or assemblies to heat and flame under controlled conditions, but does not by itself incorporate all factors required for fire-hazard or fire-risk assessment of the materials, products, or assemblies under actual fire conditions..

1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Subpages (1): ASTM E84