BS EN ISO 2061:2010 pdf download.Textiles一Determination of twist in yarns一Direct counting method.
10 Procedure 2 — Determination of the amount of twist
10.1 Preliminary procedure
10.1.1 Bring the laboratory sample packages. or the laboratory sample skeins reeled from the packages (see 5.4), to equilibrium in the standard atmosphere for testing as specified in ISO 139.
10.1.2 Unwind the yam over the end or from the side of the package, as in normal use of the package and at the lowest practicable tension, taking care, when unwinding and handling the samples, to avoid any change in the original twist. Unwind and discard approximately 5 m of yam before taking the first specimen.
10.1.3 Mount the specimen in the clamps of the twist counter (5.1) before cutting it free from the package. If additional specimens are to be taken from the package, hold the free end in a stationary clip or clamp, or under a weight, to prevent lass of twist.
10.2 SIngle, spun yarn
10.2.1 Set the movable clamp of the twist counter (5.1) at the distance specified for the nominal staple length of the fibres in the spun yarn being tested, ±0,5 mm (see 8.1.1). Remove any lateral play in the damps which might significantly affect the gauge length of the specimen. Verify the gauge length by measuring the clamp separation with an accurate gauge or caliper. Set the revolution counter to zero.
10.2.2 Taking care not to disturb the twist, mount the specimen in the clamps under a pretension equivalent to (0,5 ± 0,1) cNltex.
10.2.2.1 If yarns which extend 0,5 % or more under the specified pretension are to be tested, they shall be subjected to a pretension which produces an extension not greater than 0,1 %. The pretension used in these exceptional cases shall be reported and shall be agreed to by all persons interested in the test results.
10.2.3 Remove the twist by turning the rotatable clamp until it Is possible to pass a needle (5.2) from the face of the nonrotatable clamp to the face of the rotatable clamp between the untwisted fibres. Use a means of magnification (5.3), if necessary, to make sure that all the twist has been removed.
10.2.4 Note the direction of twist as indicated on the revolution counter. Be sure It agrees with the direction determined by inspection of the specimen. (See Clause 9.)
10.2.5 Record the initial length, the direction of twist and the number of turns (to the accuracy specified in 5.1) in the specimen.
10.2.6 Repeat the operation until the required number of specimens, n, has been tested (see 8.3).
10.3.1 Set the clamps of the twist counter at a distance of 250 mm (or, by agreement. 500 mm) ±0,5 mm. Remove any lateral play In the clamps that might significantly affect the gauge length of the specimen. Verify the gauge length of the specimen by measuring the clamp separation with an accurate gauge or caliper. Set the revolution counter to zero.
10.3.2 Proceed as directed for single, spun yams in 10.2.2 to 10.2.5.
10.3.3 When information on change in length on untwisting is desired, release the mechanism fixing the movable clamp and determine the length of the original specimen after untwisting and under the original tension. Note the change in length and specify increase or decrease in length.
10.3.4 Repeat the operation until the required number of specimens, ii, has been tested (see 8.3).
10.4 Plied yarns
10.4.1 Determine the plied twist by the procedures given for single. multAfilament yams in 10.3.1 to 10.3.3.
10.4.2 After removing the twist from the plied yarn, cut loose and remove all but one of the component yarns to obtain an individual end of the single yam. It is assumed that all components of the original yam have the same direction and amout of twist. If this is not known to be so, it shall be verified. If any difference in kind exists, each component yarn shall be tested and reported separately.
If the component yams are spun yams, additional specimens will be required, and it is desirable to save the cut-away strands without loss of twist to provide the specimens.
10.4.3 If the single yarn component has been spun from staple fibres, determine the twist in the single yarn in accordance with 10.2, but if the single yarn component is multifilament, determine the twist in accordance with 10.3.
10.4.4 When information on change in length on untwisting is desired, release the mechanism fixing the movable clamp and determine the length of the original components after untwisting and under the original tension. Note the change in length and specify increase or decrease in length.
10.4.5 Repeat the operation until the required number of specimens, n. has been tested (see 8.3).
10.5 Cabled yarns
10.5.1 Determine the cable twist as directed for single multifilament yams in 10.3.1 to 10.3,3 to obtain the total number of turns of hawser or cab4e twist in the test specimens.
10.5.2 After removing the cable twist, cut loose and discard all but one of the component yarns to obtain an individual strand of plied yam. Note the length under the original tension and determine the plied twist as directed for multifilament yams in 10.3.1 to 10.3.3 to obtain the total number of turns of the plied yarn component (see 10.4.2).
10.5.3 Cut loose and remove all but one of the component yams to obtain an individual single yam (see 10.4.2).
10.5.4 If the single yarn has been spun from staple fibres, determine the single yarn twist in accordance with
10.2. but if the single yam is multifilament, determine the single yam twist in accordance with 10.3.
10.5.5 When information on change in length on untwisting is desired, release the mechanism fixing the movable clamp and determine the length of the original specimen after untwisting and under the orgininal tension. Note the change in length and specify increase or decrease in length.
10.5.6 Repeat the operation until the required number of specimens, n, has been tested (see 8.3).BS EN ISO 2061 pdf download.