1、Designation:D252513Standard Practice forSampling Wool for Moisture1This standard is issued under the fixed designation D2525;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates
2、the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the design of a sampling plan to beused to obtain samples for the determination of the moisturecontent of grease wool,scoured wool,carded wool,garnett
3、edwool,wool top and intermediate products,and rovings.1.2 Directions are given for the designation of samplingunits,calculation of the number of sampling units required toachieve a preselected precision and confidence level or,alternatively,for calculating the confidence limits for the meanbased on
4、the variability of the sample tested.NOTE1This practice for devising a sampling plan is intended for usein connection with Test Method D1576 or Test Method D2462.Thesampling of raw wool for the determination of clean wool fiber present iscovered in Practice D1060.1.3 This standard does not purport t
5、o address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D123 Termino
6、logy Relating to TextilesD1060 Practice for Core Sampling of Raw Wool in Packagesfor Determination of Percentage of Clean Wool FiberPresentD1576 Test Method for Moisture in Wool by Oven-DryingD2462 Test Method for Moisture in Wool by DistillationWith TolueneD4845 Terminology Relating to WoolE122 Pra
7、ctice for Calculating Sample Size to Estimate,WithSpecified Precision,the Average for a Characteristic of aLot or Process3.Terminology3.1 For all terminology related to D13.13,Wool and Felt,see Terminology D4845.3.1.1 The following terms are relevant to this standard:laboratory sample,lot lot sample
8、,sample,sampling unit,specimen.3.2 For definitions of all other textile terms see TerminologyD123.4.Summary of Practice4.1 Directions are given for subdividing a lot of materialinto potential sampling units and for providing each potentialsampling unit with its own unique identification.4.2 Directio
9、ns are given for calculating the number of suchsampling units required to give a preselected allowable varia-tion at a stated probability level,or for calculating confidencelimits for the sample mean obtained for a given size of sample.4.3 Directions are given for deciding which particular sam-pling
10、 units should be chosen to constitute the required lotsample.These directions ensure that all potential samplingunits have approximately the same chance of being selected forthe lot sample.5.Significance and Use5.1 This recommended practice furnishes directions for thesampling of wool of the various
11、 forms indicated in Section 1,in order that correct probability statements may be made aboutthe relationship between the sample mean and the populationmean.If these statements are to be correct,certain conditions,which are stated,must hold.5.2 This recommended practice requires that a deliberate act
12、of randomization be performed so that all potential samplingunits have approximately the same chance of being taken andno sampling unit is deprived of its chance of being taken.5.3 In any case where insufficient information about thevariability of the sampling units within the lot is available,direc
13、tions are given for calculating confidence limits for thesample mean so that a correct probability statement can still bemade.1This practice is under the jurisdiction of the ASTM Committee D13 onTextilesand is the direct responsibility of Subcommittee D13.13 on Wool and Felt.Current edition approved
14、 July 1,2013.Published August 2013.Originallyapproved in 1966.Last previous edition approved in 2008 as D2525 90(2008).DOI:10.1520/D2525-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume in
15、formation,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Preliminary Conditions6.1 If it is desired to calculate a sample size to achieve apreselected precision at a prese
16、lected level of confidence,knowledge of the variation of the moisture content is neces-sary.6.1.1 The test method to be used must be the same methodthat was used to derive any prior information with respect tothe variability of the moisture content.6.1.2 The sampling unit must be the fundamental unit interms of which the variance is expressed.In other words,if thesampling unit is chosen to be a 25-g handful of bulk materialor a 4-yd(3.65-m)length of sliver,then the variance used mustbe the numbe
