BS ISO 2648:2020 pdf free.Wool — Determination of fibre length distributionparameters — Capacitance method.
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 themeasurement) 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 directlyapplicable to slivers made up of a blend of wool/synthetic fibres.
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references,only the edition cited applies.Forundated references, the latest edition of the referenced document (including any amendments) applies.ISo 139,Textiles —Standard atmospheres for conditioning and testing.
For the purposes of this document, the following terms and definitions apply.
In the analogue system, the record is a galvanometric recorder,which automatically traces thecumulative 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 toeither 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 bycross-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 thesampling conditions.
Generally, regardless of the origin of the sample of sliver, the preliminary conditioning period is 24 h inthe standard atmosphere for testing as defined in IS0 139.In order to standardize the procedure, this period of 24 h may be adopted for all cases where nourgency exists.
For slivers coming from a process involving soaking, drying or oiling, a conditioning period of24 h in standard atmosphere is to be observed.For tops sampled in the normal way at a passage following combing, and drawing slivers androvings sampled from a machine where fibre lubricant is not applied, the period of conditioning instandard atmosphere can be reduced to a minimum of 4 h.BS ISO 2648 pdf download.