1、Designation: D7642 12Standard Practice forEstablishment of Calibration Cottons for CottonClassification Instruments1This standard is issued under the fixed designation D7642; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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 provides instructions for the developmentof calibration cotton standards by establishing cotton fibe
3、rvalues for micronaire, length, uniformity index, and strength.The purpose of calibration cotton standards is for calibration ofcotton classification instruments to the level of the internation-ally recognized United States Department of Agriculture(USDA) Benchmark Reference Cotton Standards. The US
4、DAhas established calibration cotton standards for domestic up-land and Extra Long Staple (ELS) cottons and this practiceprovides an instruction for other geographical regions toestablish their own calibration cotton standards for cottonclassification instruments.1.2 This practice shall be used for
5、the establishment ofcalibration cottons for the testing of Upland and ELS cottons.1.3 Only saw ginned cottons shall be used in this practice.Roller gin cottons are not valid for use due to higher measure-ment variability.1.4 The calibration cotton established by this practice is notvalid for use as
6、a micronaire calibration standard. The mi-cronaire standard value is not for the instrument calibration ofthe micronaire module; it is utilized by the instrument for thecorrection of the strength measurement during the calibrationroutine.1.5 The values stated in inch-pound are to be regarded as thes
7、tandard. The values given in parentheses are mathematicalconversions to SI units that are provided for information only.1.6 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-pr
8、iate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD7139 Terminology for Cotton FibersD7410 Practice for Qualification of Cotton ClassificationInstruments for Cotton
9、Marketing3. Terminology3.1 For all the terminology related to D13.11, refer toTerminology D7139.3.1.1 The following terms are relevant to this standard:calibration cotton standards, candidate bale, Extra Long StapleCotton, fanhead, fanheading, length, ringer cotton, rollerginned cotton, saw ginned c
10、otton, strength, Universal mi-cronaire calibration cotton standards, USDA benchmark refer-ence cotton standard, value setting, value setting group, valuesetting subgroup.3.2 For definitions of all other textile terms see TerminologyD123.4. Summary of Practice4.1 In order to establish calibration cot
11、ton standards for usein calibration of cotton classification instruments, testing shallbe performed on samples from each candidate bale while beingtested in conjunction with benchmark cottons and ringercottons. The samples shall be tested in a minimum of fourlaboratories and on a minimum of six cott
12、on classificationinstruments. Established values are calculated based on thelevel of the benchmark cottons.5. Significance and Use5.1 The purpose of this practice is to provide standardiza-tion in the value setting of calibration cotton standards to beused for cotton classification instrument calibr
13、ation.1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.11 on Cotton Fibers.Current edition approved July 1, 2012. Published September 2012. DOI:10.1520/D7642122For referenced ASTM standards, visit the ASTM website, www.
14、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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 The
15、 practice provides procedures for the value settingfor calibration cotton standards. These procedures are for useby cotton fiber testing organizations that establish standardvalues on candidate bales that will be utilized as calibrationcotton standards for cotton classification instruments on thelev
16、el of the benchmark cottons.NOTE 1Benchmark cottons are of high value and of limited supply.Long term accuracy and stability of the internationally recognized USDAcotton standards are dependent on long term maintenance of the bench-mark cottons. Therefore, distribution of the benchmark cottons will
17、betightly controlled by the USDA.6. Apparatus and Materials6.1 Cotton classification instruments with a fully automatedcomb sampling device.6.1.1 A minimum of six (6) total cotton classificationinstruments from a minimum of four (4) total laboratories shallbe utilized in value setting. One (1) USDAc
18、otton classificationinstrument from one (1) USDA laboratory shall be included aspart of the total instruments and laboratories.6.1.2 The cotton classification instruments shall adhere tothe requirements of Practice D7410 for the qualification ofcotton classification instruments. Each instrument to b
19、e in-cluded in value setting shall successfully complete the quali-fication process within one month prior to testing. If multiplevalue settings will be performed, the instrument qualificationprocess shall be successfully completed on a six-month basisduring value settings.6.2 Benchmark cotton (shor
20、t/weak), with established valuesfor length, uniformity index, strength and micronaire.6.3 Benchmark cotton (long/strong), with established valuesfor length, uniformity index, strength and micronaire.6.4 Ringer cotton (short/weak), with established values forlength, uniformity index, strength and mic
21、ronaire.6.5 Ringer cotton (long/strong), with established values forlength, uniformity index, strength and micronaire.6.6 Candidate bales (up to 18), saw-ginned cotton withtargeted measurement ranges for micronaire, length, unifor-mity index and strength as given in 7.1.2.7. Sampling7.1 Value settin
22、g begins by obtaining test samples from amaximum of twenty-two (22) bales. Samples from one bench-mark cotton (short/weak), one benchmark cotton (long/strong),one ringer cotton (short/weak), one ringer cotton (long/strong)and a maximum of eighteen (18) candidate bales are includedin each value setti
23、ng group.7.1.1 Candidate bales shall be saw-ginned. Ginning shalltake place a minimum of one calendar year prior to beingincluded in a value setting group.7.1.2 Candidate bales for short/weak and long/strong cali-bration cottons are selected according to Table 1.7.1.3 A total of ten (10) samples sha
24、ll be removed from ten(10) equally spaced positions across the fanheaded candidatebale (see Fig. 1). Ensure each sample is no less than 4 lb (2000g) or 1 lb (450 g) times the number of laboratories.7.2 A value setting group also includes a total of ten (10)samples of cotton for each designated bench
25、mark and ringercotton.7.2.1 Benchmark and ringer samples shall be obtained fromUSDA, AMS, Cotton Division.7.2.2 Ten (10) samples of cotton for each designated bench-mark and ringer cotton shall be subdivided into the number ofvalue setting subgroups to be prepared (minimum of 4). Ensurethat each sub
26、divided sample is a minimum of 1 lb (450 g).7.3 Assign the sample identification numbers such that thesample identification is associated with the bale number andthe location within the fanheaded bale. See Attachment 1 as anexample.7.3.1 Subdivide the ten samples taken from each bale intothe number
27、of value setting subgroups to be prepared (mini-mum of 4). Ensure that each subdivided sample is a minimumof 1 lb (450 g).7.4 Distribute the value setting subgroups to the laborato-ries. An additional 1 lb (450 g) of each benchmark cotton shallbe included in each subgroup for calibration of the cott
28、onclassification instruments.8. Conditioning8.1 Standard atmospheric conditions shall be maintained ineach laboratory at 21 6 1C(706 2 F) and 65 6 2 % relativehumidity.8.1.1 Condition each value setting subgroup for a minimumof 72 h prior to testing according to 8.1.9. Procedure9.1 Arrange the indiv
29、idual samples of the value settingsubgroup in numerical order.9.2 Calibrate each participating cotton classification instru-ment for length, uniformity index and strength with thebenchmark cottons included for instrument calibration pur-poses.TABLE 1 Measurement Value Ranges for Calibration CottonsB
30、ale Micronaire Length Uniformity Index StrengthUpland Short/Weak 3.5 to 4.5 Below 1.01 in.(25.64 mm)77 to 82 Lower than 26Upland Long/Strong 3.5 to 4.5 1.17 to 1.24 in.(29.72 to 31.50 mm)83 to 87 33 to 38ELS Long/Strong 3.5 to 4.5 1.35 to 1.50 in.(34.29 to 38.10 mm)84 to 88 40 to 48D7642 1229.3 Cali
31、brate each of the cotton classification instrumentsfor micronaire according to instrument manufacturers recom-mended methods to achieve a testing level verifiable to 60.1with the Au and Gu Universal micronaire calibration cottonstandards.9.4 Perform and record the calibration verification using theb
32、enchmark cottons prior to value setting tests. (SeeAttachment2: Calibration Verification)9.4.1 The calibration verification requires the benchmarkshort and benchmark long cottons used for instrument calibra-tion to be tested ten times each. If the average of the ten (10)readings exceeds 60.10 for mi
33、cronaire, 60.010 in. (0.25 mm)for length, 61.0 for uniformity index or 61.0 for strength, theinstrument must be re-calibrated. The instrument must pass thecalibration verification process before sample testing canbegin.9.5 Test the value setting subgroup across the designatedcotton classification in
34、struments without interruption. Recali-bration of cotton classification instruments is not permittedduring sample testing. Upon completion of sample testing,perform and record the calibration verification again.9.5.1 For value setting on Upland cottons, set up theinstrument to perform a two specimen
35、 test for length, unifor-mity index and strength from each sample of the value settingsubgroup.9.5.2 For value setting on Extra Long Staple cottons, set upthe instrument to perform a four specimen test for length,uniformity index and strength from each sample of the valuesetting subgroup.9.5.3 The i
36、nstrument data precision shall be reported formicronaire to the nearest one hundredth of a unit, length to thenearest one hundredth of a millimeter (one thousandth of aninch), uniformity index to the nearest one tenth of a unit,strength to the nearest one tenth of a unit.9.6 Two separate test replic
37、ations per instrument shall beperformed on the value setting subgroup.NOTE 2Completion of steps 9.2 through 9.5 constitutes one testreplication.10. Calculation10.1 Collect the data from the cotton classification instru-ments utilized in the value setting.Measurement Outliers10.2 Calculate averages f
38、or the measurements ofmicronaire, length, uniformity index, and strength of all datapoints by measurement for each bale.10.3 Subtract each individual data point from the averagescalculated in 10.2.10.4 Compare the differences from 10.3 to the tolerances inTable 2. Remove all measurement data by test
39、 replication, byinstrument for any sample where a single measurement fallsoutside of the tolerances.10.4.1 No more than ten (10) data points shall be removedfor any one measurement for any instrument for any replicationbased on comparison to the average.10.4.2 If the number of data points removed in
40、 10.4.1 isexceeded, the value setting shall be repeated for the instru-ment(s) in question until the requirements of 10.4.1 are met.Benchmark Outliers10.5 Calculate the average of the benchmark short andbenchmark long cottons for each instrument for each testreplication.10.6 Compare the observed ave
41、rages of the benchmarkshort and benchmark long cottons from each instrument oneach test replication to the standard values for the benchmarkcottons.10.6.1 The difference between the observed benchmarkaverages for any instrument by test replication and the standardvalues cannot exceed the tolerances
42、as shown in Table 3.10.6.2 If the tolerance for any instrument by test replicationon any one measurement is exceeded, the value setting shall berepeated for the instrument(s) in question until the require-ments are met.NOTE 3Benchmark cottons are not the reference basis for themicronaire measurement
43、.Standard Deviation Outliers10.7 Identify outliers based on standard deviations for eachbale in the value setting.10.7.1 For each bale, calculate the standard deviations of alldata points for the measurements of micronaire, length, uni-formity index and strength.10.7.2 For each bale, calculate the s
44、tandard deviations bytest replication by instrument for the measurements ofmicronaire, length, uniformity index and strength.10.7.3 Calculate the difference between 10.7.1 and 10.7.2.Ifthe differences exceed the values listed in Table 4, identify asstandard deviation outliers any measurement data by
45、 testreplication, by instrument for any bale.10.7.4 No more than eight standard deviation outliers forany measurement for any instrument can be included in thevalue setting.FIG. 1 Fanheaded BaleTABLE 2 Single Measurement Removal TolerancesMicronaire LengthUniformityIndexStrength 0.35 0.05 in.(1.27 m
46、m)4.0 4.0D7642 12310.7.5 If the number of standard deviation outliers in 10.7.4is exceeded, the value setting shall be repeated for theinstrument(s) in question until the requirements of 10.7.4 aremet.Correction of Data10.8 Calculate the slopes and offsets by instrument and testreplication based upo
47、n the standard values of the benchmarkcottons for the measurements of length, uniformity index andstrength.10.8.1 Calculate the slope using the following formula:Slope = (Standard Value of Benchmark Long Standard Value of Benchmark Short)/ (Observed Average of Benchmark Long Observed Average of Benc
48、hmark Short)10.8.2 Calculate the appropriate offset using the followingformula:Offset = Standard Value of Benchmark Long (Slope * Observed Value of Benchmark Long)orOffset = Standard Value of Benchmark Short (Slope * Observed Value of Benchmark Short)10.9 Calculate the corrected values for each data
49、 point forlength, uniformity index and strength.10.9.1 Multiply each single test data point by the appropri-ate slope and add the appropriate offset calculated for eachinstrument for each test replication.NOTE 4As a result of benchmark cottons not being the reference basisfor the micronaire measurement, a correction is not applied to themicronaire data.11. Bale Value Establishment11.1 Using the corrected data calculate an average value anda standard deviation for each bale for the measurements oflength, uniformity index and strength.11.2 Using the uncorrected micron
