BS ISO 2648:2020 pdf free.Wool-Determination of fibre length distribution parameters-Capacitance method.
BS ISO 2648 1 Scope This document specifies a method for the determination of fibre length distribution parameters (principally mean length, expressed as Hauteur or Barbe, and the coefficient of variation of the measurement) on slivers and rovings made from combed wool or combed synthetic fibres. As the fibres of different chemical structure have different di-electric values, the method is not directly applicable to slivers made up of a blend of wool/synthetic fibres. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 139, Textiles一Standard atmospheres for conditioning and testing 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: 一ISO Online browsing platform: available at https://www.iso.org/obp .IEC Electropedia: available at http://www.electropedia.org/
In the analogue system, the record is a galvanometric recorder, which automatically traces the cumulative Hauteur diagram on squared paper during measurement. In the digital system, the data are captured by a computer which is capable of outputting the results to either the screen or to a printer. The diagram ordinate gives the percentage of fibres (biased by cross- section) of length greater than the length indicated on the corresponding abscissa. (The percentage by cross-section is very close to the percentage by number).The sample, kept in the form of a twisted hank, is exposed to the conditioning atmosphere for aminimum period as indicated below. This period can vary according to the type of the material and the sampling conditions. Generally, regardless of the origin of the sample of sliver, the preliminary conditioning period is 24 h in the standard atmosphere for testing as defined in ISO 139.
In order to standardize the procedure, this period of 24 h may be adopted for all cases where nourgency exists.BS ISO 2648 pdf download.