Test Method D 1294 for the determination of tensile strength may be used for the acceptance testing of commercial shipments of wool, but caution is advised since technicians may fail to get good agreement between results. Comparative tests as directed in 5.1.1 may be advisable.

5.1.1 If there are differences of practical significance between reported test results for two laboratories (or more), comparative test 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 a comparative test 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 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.

This test method is useful in studying the relationship between fiber strength and product quality; results should be considered comparative rather than fundamental since the strength found will be lower than the sum of the strengths of the individual fibers present due to slight differences in tensioning.

Elongation may be obtained also but the accuracy of elongation measurements is limited and their determination is, therefore, not included as a formal part of this test method.

The basic differences between the procedures employed in this test method and those of Test Method D 2524 are in the gage lengths employed and the methods of clamping. In Test Method D 2524, specific clamps are required whereas in Test Method D 1294, any conventional clamps may be used. Results for breaking load determined by Test Method D 2524 average 30 % higher than those obtained by Test Method D 1294.

1.1 This test method covers the determination of the breaking force (or load) and estimation of the tensile strength and tenacity of wool fiber bundles with a 1-in. (25.4-mm) gage length. A procedure for preparation of the fiber bundle is included.

1.2 The values stated in inch-pound units are to be regarded as standard; the values in SI units are provided for information only. Because the instrument is calibrated in inch-pound units, inch-pound units are shown first, contrary to Committee D13 policy.

Note 1--For other methods of measuring breaking tenacity of fiber bundles, refer to Test Methods D1445 and D2524.

Note 2--This test method can be used for other fibers that lend themselves to the same kind of preparation but the difference in density must be taken into account when calculating the tensile strength. It is not necessary to know or correct for the density of a fiber when calculating breaking tenacity.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibiltiy of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.