Meaning and Purpose
3.1 A number of laboratory procedures are used to evaluate the effectiveness of flame retardant and refractory treatments and coatings. In general, these methods measure three stages of fire development: (1) ignition; (2) Flame spread (the growth rate of the fire); (3) Fire extent. While all three are extremely important, flame spread has been recognized as a major factor relevant for testing flame retardant coatings.

3.2 Flame spread rating based on test method E84 has gained general acceptance from regulatory authorities, but such large-scale testing is rarely practical during the development or modification of flame retardant-based coatings.

3.3 The test method provides the relative flame spread of the experimental coating using small specimens under conditions established in a 2-foot tunnel. By experimentally calibrating 2-foot tunnels with a similar test method E84 grade flame retardant paint, the results obtained from this test method can be used to screen the suitability of the coating for testing in test method E84 tunnels.

3.3.1 The test method is intended as an experimental tool for evaluating experimental coatings for further development. The results of this test method are not directly related to, or implied by, the results of the test method E84 tunnel.

3.3.2 The results obtained by this test method cannot by itself be used as an accurate predictor of the performance in test method E84 and shall not be used to certify any class of flame spread performance.

ASTM D 3806-98-2019 “Small-scale Evaluation of Flame Retardant Coatings (2-Foot Tunnel Method)”

Scope of
1.1 This test method determines the protection provided by the coating to its substrate and the comparative combustion characteristics of the coating by assessing the flame spread over the surface during ignition under controlled conditions in a small tunnel. This sets the stage for comparing the surface combustion characteristics of different coatings without specifically considering all end-use parameters that may affect the surface combustion characteristics under real fire conditions.

1.2 In addition to the experimental flame spread rate, panel weight consumed, time of combustion and afterglow, coke size and index, and expansion height can also be measured in this test. However, a relationship between these measures should not be assumed.

1.3 This standard is used to determine certain fire test responses of materials, products or components to heat and flame under controlled conditions by using results obtained from fire test response standards. The results obtained using this standard do not in themselves constitute a measure of fire hazard or fire risk.

1.4 Values expressed in SI units should be considered standard. The values given in parentheses are for reference only.

1.5 This standard is used to measure and describe the reaction of materials, products or components to heat and flame under controlled conditions, but does not in itself contain all the factors required for fire hazard or fire risk assessment of materials, products or components under actual fire conditions.

ASTM D 3806-98-2019 “Small-scale Evaluation of Flame Retardant Coatings (2-Foot Tunnel Method)”

1.6 Fire testing is inherently dangerous. Appropriate personnel and property protection measures should be taken when these tests are carried out.

1.7 This standard is not intended to address all safety issues, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health and environmental practices and to determine the applicability of regulatory restrictions prior to use.

1.8 This international Standard has been developed in accordance with the internationally recognized standardization principles established in the Decision on Principles for the Development of International Standards, Guidelines and Recommendations issued by the Committee on Technical Barriers to Trade of the World Trade Organization.