This method determines the breaking strength of single strands of yarns, including monofilaments, single yarns, plied or folded yarns, cabled yarns, cords, threads and twines. It is designed primarily for testing yarn in package form but can be used for single strands removed from a fabric.

The method is applicable to testing yarns either in the conditioned state or when wet.

The method may be used with constant-rate-of-extension type (e.g., strain gauge), constant-rate-of-traverse type (e.g., pendulum), or constant-rate-of-loading type (e.g., inclined plan) testing machines. (The three types of testing machines do not necessarily give the same breaking strength of a given sample of yarn when tested at a constant-time-of-break. Good experimental agreement (differences of 5% or less) has been reported in the literature between the results obtained on CRE and CRT testers when the times-to-break were the same, but the agreement with the results obtained on CRL testers was not as good (averages differes from those on CRE or CRT testers by as much as 15%).)

Automatic yarn-testing machines may be used provided they can be operated under the conditions specified.

The testing and evaluation of a product against this method may require the use of materials and/or equipment that could be hazardous. This document does not purport to address all the safety aspects associated with its use. Anyone using this method has the responsibility to consult the appropriate authorities and to establish appropriate health and safety practices in conjunction with any existing applicable regulatory requirements prior to its use.