Significance and Use

This test method provides a description of the behavior of material specimens under a specified fire exposure in terms of the release rate of heat and visible smoke. It is possible to determine the change in behavior of materials and products with change in heat-flux exposure by testing specimens in a series of exposures that cover a range of heat fluxes.

The data obtained for a specific test describe the rate of heat and smoke release of the specimen when exposed to the specific environmental conditions and procedures used in performing that test.

The entire exposed surface of the specimen will not be burning during the progressive involvement phase when piloted, point ignition (impingement) procedures are used. During the period of progressive surface involvement, release rates of heat and smoke are per square metre of original exposed surface area not per square metre of flame involved surface.

The rates of both heat and smoke release are calculated per square metre of original surface area exposed. If a specimen swells, sags, delaminates, or otherwise deforms so that the exposed surface area changes, calculated release rates correspond to the original area, not to the new surface area.

Heat-release values depend on mode of ignition. Gas phase ignition gives a more dimensionally consistent measure of release rate when very rapid or immediate flame involvement of the specimen surface occurs. However, piloted, point ignition allows release-rate information to be obtained at external heat flux from zero up to that required for satisfactory gas-phase ignition, usually over 20 kW/m ² external exposure. No correlation between the two modes of piloted ignition has been established.

Release rates depend on many factors, some of which cannot be controlled. It is possible that samples that produce a surface char, a layer of adherent ash, or those that are composites or laminates do not attain a steady-state release rate. Thermally thin specimens, that is, specimens whose unexposed surface changes temperature during period of test, will not attain a steady-state release rate. Therefore, release rates for a given material will depend, for example, on how the material is used, its thickness, and the method of mounting.

Heat-release values are for the specific specimen size (exposed area) tested. Results are not directly scalable to different exposed surface areas for some products.

The method is limited to specimen sizes of materials in accordance with 7.1 and to products from which it is possible to obtain a test specimen representative of the product in actual use. The test is limited to exposure of one surface; there are two options for exposure orientation: either vertical or horizontal. If a heat release rate of 8 kW, which is equivalent to 355 kW/m ² for 150-mm [6-in.] by 150-mm [6 in.] vertical specimens, or 533 kW/m ² for 100-mm [4-in.] by 150-mm [6-in.] horizontal specimens is exceeded, there is danger of combustion occurring above the stack.

No general relationship between release rate values obtained from horizontally and vertically oriented specimens has been established. Conduct tests on specimens in the form in which the material is oriented in end use conditions. To provide additional information, conduct tests in the horizontal orientation for those specimens that melt and drip in the vertical orientation.

Release rate measurements provide useful information for product development by giving a quantitative measure of specific changes in fire test performance caused by product modifications.

This test method differs in both the method of exposure and the calculation procedure from the techniques used in Test Method E1354 , the cone calorimeter, which assesses heat release by oxygen consumption calorimetry, using a truncated cone as a radiant source.

1. Scope

1.1 This test method provides for determining the release rates of heat and visible smoke (Note 1) from materials, products, or assemblies when exposed to different levels of radiant heat.

Note 1Visible smoke is described in terms of the obscuration of transmitted light caused by combustion products released during the tests (see 14.2.1).

1.2 This fire-test-response method assesses heat release by a thermal method, thermopile, using a radiant heat source composed of an array of four electrical resistance elements.

1.3 This test method provides for radiant thermal exposure of a specimen both with and without a pilot. Piloted ignition results from direct flame impingement on the specimen (piloted, point ignition) or from use of the pilot to ignite gases evolved by pyrolysis of the specimen.

1.4 Heat and smoke release are measured from the moment the specimen is injected into a controlled exposure chamber. The measurements are continued during the period of ignition (and progressive flame involvement of the surface in the case of point ignition), and to such a time that the test is terminated.

1.5 The apparatus described in this test method is often referred to as the Ohio State University (OSU) rate of heat release apparatus. Configurations A and B are variations on the original design.

1.6 This test method is suitable for exposing essentially planar materials, products or assemblies to a constant, imposed external heat flux that ranges from 0 to 80 kW/m ² .

1.7 This test method is intended for use in research and development and not as a basis for rating, regulatory, or code purposes.

1.8 The apparatus described in this test method has been used in two configurations. Configuration A is that which is used by the Federal Aviation Administration for assessing materials for aircraft use, at an external heat flux of 35 kW/m ² (DOT/FAA/AR-00/12), while configuration B is suitable, at various incident heat fluxes, for research and development purposes.

1.9 This test method does not provide information on the fire performance of the test specimens under fire conditions other than those conditions specified in this test method. Known limitations of this test method are described in 1.9.1-1.9.5.

1.9.1 Heat and smoke release rates depend on a number of factors, including the formation of surface char, the formation of an adherent ash, sample thickness, and the method of mounting.

1.9.2 Heat release values are a function of the specific specimen size (exposed area) tested. Results are not directly scaleable to different exposed surface areas for some products.

1.9.3 The test method is limited to the specified specimen sizes of materials, products, or assemblies. If products are to be tested, the test specimen shall be representative of the product in actual use. The test is limited to exposure of one surface; the options for exposed surface are vertical and horizontal facing up.

1.9.4 At very high specimen heat release rates, it is possible that flaming is observed above the stack, which makes the test invalid.

1.9.5 No general relationship has been established between heat release rate values obtained from horizontally and vertically oriented specimens. Specimens that melt and drip in the vertical orientation shall be tested horizontally.

1.10 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.11 Fire testing of products and materials is inherently hazardous, and adequate safeguards for personnel and property shall be employed in conducting these tests. Fire testing involves hazardous materials, operations, and equipment. See Section 6.

1.12 This standard is used to measure and describe the response or 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.

1.13 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.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

D618 Practice for Conditioning Plastics for Testing

E176 Terminology of Fire Standards

E1354 Test Method for Heat and Visible Smoke Release Rates for Materials and Products Using an Oxygen Consumption Calorimeter

Federal Aviation Administration Standard

Keywords

calorimetry; ignitability; heat release; smoke obscuration; smoke release; Burning characteristics--building materials; Combustion; Fire-resistant materials/testing; Heating tests--building products; Heat release; Ignition--building materials; Radiant heat fill; Radiation exposure; Release rates; Roofing materials/applications; Smoke analysis ;

ICS Code

ICS Number Code 13.220.50 (Fire-resistance of building materials and elements)

DOI: 10.1520/E0906_E0906M-10

ASTM International is a member of CrossRef.

ASTM E906 / E906M