ASTM_D_1485_-_07_2015.pdf

Designation:D148507(Reapproved 2015)Standard Practice forRubber from Natural SourcesSampling and SamplePreparation1This standard is issued under the fixed designation D1485;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 the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice,intended for referee purposes,covers auniform procedure for sampling lots of solid natural rubber.Natural rubber generally is marketed in bales or packages ofvarious sizes.1.2 A procedure for determining the acceptability of lots ofnatural rubber is given.This procedure is based on a variablesampling plan.1.3 The sample size is based on the assumption of a visuallyhomogeneous material.If obvious heterogeneity exists,thenumber of samples shall be increased.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 This standard does not purport to 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:2D1278 Test Methods for Rubber from Natural SourcesChemical AnalysisD3182 Practice for RubberMaterials,Equipment,and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsD3184 Practice for RubberEvaluation of NR(NaturalRubber)2.2 ANSI Standard:Z1.9 Sampling Procedures and Tables for Inspection byVariables for Percent Defective33.Significance and Use3.1 This practice outlines a procedure for sampling andsample preparation of natural rubber.A statistical method fordetermining a quality index and lot acceptability is given.Thesampling plan is optional for quality control or production,butmay be used when needed for referee purposes.4.Sampling4.1 Sample SizeThe number of samples to be selected torepresent the lot shall be determined by the size of the lot asindicated in Table 1.A sample bale is selected randomly fromthe lot for each sample required.NOTE1The sampling plan is more efficient for large lots.The risk forthe producer and consumer decreases as the sample size increases.4.2 Removal of Test Portion:4.2.1 From each sample bale selected,cut one 600 to 1500-gtest portion of rubber,depending on the tests to be made.Eachtest portion is tested separately.Cut the test portion through theentire bale,normal to the bale surfaces of the largest area,without the use of lubricant.Remove outer wrapping sheets,polyethylene film,bale coating,or other extraneous surfacematerial from the test portion.Unless the test portion is to betested immediately,place it in an airtight container of not morethan twice the volume of the test portion,or wrap it tightly intwo layers of aluminum foil until tested.NOTE2In testing for volatile matter only,a sample weighingapproximately 150 g may be taken as a continuous piece from any part ofthe bale.5.Lot Acceptability5.1 Each property of the lot is evaluated separately.Therequirements of these tests are of two types:(1)those having asingle limit such as a minimum or maximum and(2)thosehaving double limits,that is,a minimum and a maximum.Aquality index is calculated for each property tested,and from1This practice is under the jurisdiction ofASTM Committee D11 on Rubber andis the direct responsibility of Subcommittee D11.22 on Natural Rubber.Current edition approved Aug.1,2015.Published October 2015.Originallyapproved in 1957.Last previous edition approved in 2011 as D1485 07(2011).DOI:10.1520/D1485-07R15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute,25 W.43rd St.,4thFloor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 this index,an estimate is made of the percent of the lot that isdefective.If this percentage does not exceed the allowablevalues shown in Table 1,the lot is considered acceptable.5.2 Quality Index Calculations:5.2.1 For a requirement having a maximum limit,calculatethe quality index as follows:Q 5U 2 X!/S(1)where:Q=quality index,U=maximum value permitted by the specification,X=mean of all sample values obtained,andS=standard deviation of the sample values.5.2.2 For a requirement having a minimum limit,calculatethe quality index as follows:Q 5X2 L!/S(2)where:Q,X,and S=same as those for maximum value andL=minimumvaluepermittedbythespecification.5.3 Acceptability:5.3.1 For a quality characteristic having a single specifica-tion limit,a lot is acceptable if the qua