ASTM D7570-17

5.1 The determination of dimensional change of pile yarn floor covering is useful in quality and cost control during manufacture of pile yarn floor covering. The appearance and performance may be affected by the changes in the dimensions of pile yarn floor covering. This test method is considered satisfactory for acceptance testing of commercial shipment because current estimates of between laboratory precision are acceptable, and this method is commonly used in the trade for acceptance testing.

5.2 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them using competent statistical assistance. As a minimum use the samples for such comparative tests that are as homogenous as possible, drawn from the same lot of material as the samples that resulted in disparate results during initial testing and randomly assigned in equal numbers to each laboratory. The test results from the laboratories involved should be compared using a statistical test for unpaired data, a probability level chosen prior to the testing series. If a bias is found either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.

1.1 This test method covers the determination of dimensional changes in the lengthwise and width-wise direction and distortion likely to occur when pile floor coverings are exposed to various conditions of moisture and heat. This method is applicable to all pile floor coverings including carpet module form.

1.2 This method is applicable to machine made pile yarn floor covering.

1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversion to SI units that are provided for information only and are not considered standard.

1.4 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.