An evaluation of precision for the ASTM E648-91A standard test method for critical radiant flux of floor-covering systems

Abstract

The primary goal of this project was to develop data to be used in writing a precision statement for the newly revised ASTM E 648 test procedure. Revisions to the standard included the use of a new line pilot burner, improved control over air flow through the test chamber and an extended chamber equilibration time before the apparatus is calibrated. An interlaboratory test program was conducted to develop the precision data. In this study, seven laboratories performed tests on seven sets of flooring materials. Six carpets and one resilient flooring material were selected for the evaluation. The interlaboratory study was designed and carried out using procedures recommended in ASTM E 691 standard on interlaboratory studies. Results from the program show that precision for the revised ASTM E 648 method is generally well within the range expected for standard fire test procedures. Coefficients of variation for repeatability ranged from 2.2 to 19.7 percent, and coefficients of variation for reproducibility ranged from 3.6 to 25.2 percent. In addition to these findings, a carpet variability problem appears to have been identified. A large variation in test results for two carpet products appears to be associated with carpet non-uniformity. Recommendations are made for research to develop an understanding of the variations associated with the specific style of carpeting. Recommendations are also made for studies to further improve the test standard.