The determination of the mass per unit area of pile yarn floor covering is useful in quality and cost control during the manufacture of pile floor covering. Both appearance and performance may be affected by changes in mass per unit area.

In case of a dispute arising from differences in reported test results when using this test method for acceptance testing of commercial shipments, the purchaser and supplier should conduct comparison testing to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum the two parties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the type in question. The test specimens should then be randomly assigned to each laboratory for testing. The average results from the two laboratories should be compared using Student's t-test for unpaired data and an acceptable probability level chosen by the two parties prior to testing. If a bias is found, either its cause must be found and corrected or the purchaser and supplier must agree to interpret future test results with consideration to the known bias.

1.1 This test method covers the measurement of mass per unit area of machine-made woven, knitted, and tufted pile yarn floor covering both before and after an adhesive-back coating application.

1.2 This test method encompasses three techniques for determination of mass per unit area as applicable:

1.2.1 Section 1.3, for determining total mass per unit area, applies to both coated and uncoated (unfinished) pile floor coverings.

1.2.2 Section 1.4, for determining component mass per unit area, applies only to uncoated (unfinished) pile yarn floor coverings.

1.2.3 Section 1.5, for determining pile yarn mass per unit area, applies only to back-coated, or finished, pile yarn floor coverings.

1.3 Determination of mass per unit area of pile yarn floor coverings was previously contained within Test Methods D 418. For user convenience, Subcommittee D 13.21 subdivided Test Methods D 418 into separate standards, of which this test method is one.

1.4 The values stated in SI units are to be regarded as standard for all measurements. The inch-pound units given in parentheses are provided for information only.

1.5 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. Specific precautionary statements are given in 9.5.