ASTM E 648 Critical Radiant Flux

FLOORING RADIANT PANEL TEST (CRITICAL RADIANT FLUX), ASTM E 648, NFPA 253, FED. STD. NO. 372, NBSIR 75-950: The Floor Radiant Panel apparatus involves a horizontally mounted floor covering test sample which receives radiant energy from a gas-air fueled radiant panel mounted above one end of the sample and inclined at an angle of 30o. The radiant panel generates a radiant flux profile along the length of the sample ranging from a maximum of 1.1 W/cm2 immediately under the panel to approximately 0.1 W/cm2 at the end of the test sample. A gas fired pilot burner is used to initiate the ignition in the sample. The distance the flooring system burns to extinguishment is converted to watts per square centimeter (W/cm2) and is reported as critical radiant flux (CRF). This is the minimum radiant energy a fire needs to sustain flame propagation in the flooring system. In this test, a higher number indicates a more flame-resistant system; i.e., 0.45 W/cm2 is better than 0.22 W/cm2.

Radiant Panel Test Apparatus

GENERAL COMMENTS ON RESILIENT FLOOR COVERING FLAMMABILITY

Resilient floor coverings are not usually included in floor covering flammability requirements. Traditional floor coverings, such as filled vinyl and resilient tile, are not considered to be an unusual fire hazard. Consequently, building codes, like the NFPA Life Safety Code 101, the BOCA Basic/National Building Code, and the Standard Building Code exempt traditional resilient floor coverings from their flammability requirements.

Many state governments and federal agencies rely on the model building codes to establish their own standards. For instance, the Guidelines for Construction and Equipment of Hospital and Medical Facilities, supported by the U.S. Department of Health and Human Services, references the NFPA code and excludes traditional floor coverings from its flammability requirements. Exemption statements have also traditionally appeared in HUD Minimum Property Standards and many state codes.

Despite widespread recognition that resilient floor coverings are exempt, we supply flammability data. We do this because code officials are advised to inquire about unfamiliar products. They also might be interested because a test is used to evaluate floor covering flammability.

The test is the Flooring Radiant Panel Test (ASTM E 648). Model building codes and federal government agencies reference this test when they regulate floor covering flammability. Generally, there are two ratings:

Watts per square centimeter (W/cm2) 

Class I 0.45 W/cm2 or greater
Class II 0.22 W/cm2 or greater

In the Flooring Radiant Panel Test, a Class I rating implies a more flame-resistant system than a Class II rating. (This is opposite of the Tunnel Test where a lower number implied a more flame-resistant system.) In addition, the Flooring Radiant Panel Test is designed to measure corridor floor coverings. Because of their fire safety reputation, resilient floor coverings typically are not regulated in rooms. Sometimes resilient floor coverings are required to have a Class I rating in corridors of hospitals, nursing homes, day-care centers and other institutional-type occupancies.

NOTES ON THE E 84 TUNNEL TEST

The Steiner Tunnel Test is retired as a floor covering flammability test. However, it continues to be the most widely used surface flame spread test for wall and ceiling finishes. It was never designed to be a floor covering test and was only adopted for floors as a stopgap measure.

THERE ARE NO CORRELATIONS BETWEEN E 84 DATA AND FLOORING RADIANT PANEL DATA; i.e., a “Class A” E 84 rating does not imply a “Class I” E 648 rating and vice versa.

NOTE: Numerical flammability ratings alone may not define the performance of a product under actual fire conditions. These ratings provided only for use in the selection of products to meet specified limits.

PLEASE REMEMBER THAT FLAMMABILITY REQUIREMENTS MAY GOVERN ACTUAL PRODUCT USE. SPECIFIERS SHOULD ALWAYS CHECK FLOOR FLAMMABILITY REQUIREMENTS IN ADDITION TO REFERENCE SPECIFICATIONS BEFORE MAKING A FLOOR COVERING SELECTION.

This is a summary. For a copy of the latest version of ASTM E 648 Standard Test Method for Critical Radiant Flux of Floor-Covering Systems Using a Radiant Heat Energy Source, contact ASTM International at: https://www.astm.org/Standards/E648.htm

Updated on August 3, 2022