1、Designation: D 4821 07Standard Guide forCarbon BlackValidation of Test Method Precision andBias1This standard is issued under the fixed designation D 4821; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers a procedure for usingASTM StandardReference Blacks2(SRBs) to continuously monitor the preci-sion of those carbon b
3、lack test methods for which standardvalues have been established. It also offers guidelines fortroubleshooting various test methods.1.2 This guide establishes the x-chart control limits to beused when continuously monitoring those tests listed in Section2. Alternatively, these control limits may be
4、used as a basis forcomparison to testing precision computed within a laboratory.1.3 This guide uses statistical control chart methodology asdiscussed in STP-15-D3to determine if a laboratorys testresults differ significantly from the accepted values of theSRBs.1.4 This guide provides a statistical p
5、rocedure for improv-ing test reproducibility when a laboratory cannot physicallycalibrate its apparatus to obtain the standard values of theASTM SRBs, within the ranges given in the precision state-ment of the test method.1.5 The values stated in SI units are to be regarded as thestandard. The value
6、s given in parentheses are for informationonly.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-priate safety and health practices and determine the applica-bility of regu
7、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D 1510 Test Method for Carbon BlackIodine AdsorptionNumberD 1513 Test Method for Carbon Black, PelletedPourDensityD 1765 Classification System for Carbon Blacks Used inRubber ProductsD 2414 Test Method for Carbon BlackOil Abs
8、orptionNumber (OAN)D 3037 Test Methods for Carbon Black-Surface Area byNitrogen Adsorption5D 3191 Test Methods for Carbon Black in SBR (Styrene-Butadiene Rubber)Recipe and Evaluation ProceduresD 3192 Test Methods for Carbon Black Evaluation in NR(Natural Rubber)D 3265 Test Method for Carbon BlackTin
9、t StrengthD 3493 Test Method for Carbon BlackOil AbsorptionNumber of Compressed Sample (COAN)D 3765 Test Method for Carbon BlackCTAB (Cetyltrim-ethylammonium Bromide) Surface Area5D 4820 Test Methods for Carbon BlackSurface Area byMultipoint B.E.T. Nitrogen Adsorption (Discontinued2000) Replaced by
10、D 65565D 5816 Test Methods for Carbon BlackExternal SurfaceArea by Multipoint Nitrogen Adsorption (Discontinued2000) Replaced by D 65565D 6556 Test Method for Carbon BlackTotal and ExternalSurface Area by Nitrogen Adsorption3. Significance and Use3.1 One of the major causes of poor test precision is
11、 the lackof calibration or standardization of instruments, apparatus,reagents, and technique among laboratories. The sum of allsources of testing error is unique for an individual laboratory.A least-squares regression of a laboratorys actual test valuesfor reference materials to the established mean
12、 values willresult in a unique least-squares regression line (and equation)for that laboratory. Generally, there are two reasons for usingthe SRBs in testing: (1) to monitor testing performance (seeSection 4) to ensure that no systematic error or bias is affecting1This guide is under the jurisdictio
13、n ofASTM Committee D24 on Carbon Blackand is the direct responsibility of Subcommittee D24.61 on Carbon Black Samplingand Statistical Analysis.Current edition approved Oct. 1, 2007. Published November 2007. Originallyapproved in 1988. Last previous edition approved in 2006 as D 4821 06.2Standard Ref
14、erence Blacks are available from Laboratory Standards notto all the tests in Table 1 or Table 2.5.10 When it becomes necessary to use a statistical correc-tion factor, all the SRBs for the range of interest (A-F or A-G)must be used to develop the linear regression equation, even ifsome of the SRBs f
15、all outside the range of interest. At leastfour values (six preferred) should be used for each SRB. Anequal number of results must be used for each SRB. If theseinstructions are not followed, the correction equation will notbe comparable to the corrections made for other instrumentsand other laborat
16、ories. For the oil absorption test (Test MethodD 2414), it is acceptable to develop a separate linear regressionequation for the tread (A-C) and carcass (D-F) SRBs.5.11 Continuously monitor the selected SRBs and use themost current data to construct the correction equation.5.12 Use the correction eq
17、uation to obtain corrected valuesfor the SRBs and plot the corrected values until the controllimit is exceeded. When a test value exceeds the control limit,perform a retest immediately, and if the average of the tworemains outside the control limit, then recalculate the statisticalcorrection equatio
18、n using the most recent test data, excludingthe value that was outside the control limit, for each selectedSRB.5.13 If the corrected data using the new correction equationstill fall outside the control limits, then no further use should bemade of the test method until corrective action (see Section
19、6)brings the SRBs back inside the three standard deviationcontrol chart limits.5.14 Apply this procedure only to the interpretation of SRBtest data. If problems exist, correct them before making furtheruse of the test method. “Local reference” materials do not haveestablished “industry average” valu
20、es to be used in a linearregression equation.5.15 This procedure prescribes only the minimum actionneeded to continuously monitor test precision.Additional SRBtesting may be done and correction equations regularly recal-culated at individual discretion.5.16 Discontinue using a statistical correction
21、 equationwhen new or repaired test equipment is put into service, a newlot of SRBs are purchased and put into use, or other correctiveactions yield uncorrected test results that fall within the controllimits. Resume using a statistical correction equation onlywhen the conditions of Section 4 and 5.1
22、 have again beensatisfied.6. Assignable Causes6.1 The following lists suggest several assignable causes aspossible reasons for a test to be out of statistical control.6.1.1 Test Method D 1510 Iodine Adsorption Number:6.1.1.1 Incorrect normality of iodine and sodium thiosulfatesolutions,6.1.1.2 Volum
23、etric glassware not calibrated correctly,6.1.1.3 Purity of water insufficient,6.1.1.4 Incorrect pipet size,6.1.1.5 Incorrect cleaning and rinsing of glassware withdirty water,6.1.1.6 Incorrect potassium iodide (KI) concentration. Thisis especially suspect if using commercial iodine solutions,6.1.1.7
24、 The known decline in iodine number as the carbonblack ages, and6.1.1.8 Sample not dried.6.1.2 Test Method D 2414 Oil Absorption Number:6.1.2.1 Incorrect cooling time between samples,6.1.2.2 Incorrect setting of torque spring and collar,6.1.2.3 Incorrect setting of torque limit switch,6.1.2.4 Excess
25、ive blade and bowl clearance,6.1.2.5 Incorrect finish roughness,6.1.2.6 Incorrect dashpot oil level,6.1.2.7 Incorrect rate and volume of oil delivery,6.1.2.8 Air bubbles in the oil delivery tube,6.1.2.9 Improper cleaning and lubrication of the area be-tween the blades and the backplate,6.1.2.10 Samp
26、le not dried, and6.1.2.11 SRB calibration curves need updating.6.1.3 Test Method D 3493 Oil Absorption Number, Com-pressed Sample:6.1.3.1 Same as in 6.1.2,6.1.3.2 Hydraulic press system pressure not properly cor-rected for diameter of piston, and6.1.3.3 Incorrect number of compressions.6.1.4 Test Me
27、thod D 3265 Tint Strength:6.1.4.1 Incorrect or contaminated ITRB,6.1.4.2 Incorrect number of mullings,6.1.4.3 Muller glass plates excessively scratched or scored,6.1.4.4 Reflectance meter not properly calibrated, and6.1.4.5 Sample not dried.6.1.5 Test Methods D 3037 Nitrogen Surface Area:6.1.5.1 Lea
28、ks in apparatus, and6.1.5.2 Faulty O-rings.6.1.6 Test Method D 3765 CTAB Surface Area:6.1.6.1 Incorrect ITRB for scaling,6.1.6.2 Incorrect manifold pressure,6.1.6.3 Incorrect filters,6.1.6.4 Failure to check standardization curve daily, and6.1.6.5 Insufficient light intensity on automatic titrator.6
29、.1.7 Test Method D 6556 Total and External Surface Area:6.1.7.1 Leaks in apparatus,6.1.7.2 Faulty O-rings,6.1.7.3 Incorrect sample size,6.1.7.4 P/Ponot in the linear range of the B.E.T. equation,and6.1.7.5 STSA greater than NSA.NOTE 3All Test Methods: If contamination or unusual aging degra-dation o
30、f an SRB is suspected, try using a different SRB sample.7. Guide to Accepted Normalization Practices for CarbonBlack Test Methods7.1 Accepted normalization practices for test methods foundin Classification D 1765 are described below:D48210767.1.1 Test Method D 1510, Iodine NumberShould notrequire no
31、rmalization. A statistical correction factor per Sec-tion 5 using the values in Table 1 or Table 2 shall not be useddue to the known phenomenon that the iodine number candecrease due to aging. See Fig. 3 for an example of sampleaging. The SRB HT materials are specially prepared carbonblacks that hav
32、e been shown to have stable iodine numbervalues over a period of many years. If normalization isrequired, it shall be done using only the SRB HT materials.7.1.2 Test Method D 1513, Pour DensityNo normaliza-tion required.7.1.3 Test Method D 2414, Oil AbsorptionThe only nor-malization that is required
33、 is using the tread or carcass SRBs asdiscussed in the test method.7.1.4 Test Method D 3265, Tint StrengthThe only normal-ization that is required is using the ITRB as discussed in thetest method. Normalization to the SRBs is not recommended.7.1.5 Test Method D 3493, Oil Absorption of CompressedSamp
34、leThe only normalization that is required is using thetread or carcass SRBs as discussed in the test method.7.1.6 Test Methods D 3192, Stress-Strain in NaturalRubber(Also applies to Test Methods D 3191, Stress-Strainin SBR.). Normalization not recommended.7.1.7 Test Method D 6556, NSA and STSAShould
35、 notrequire normalization.8. Report8.1 Report the following information on statistical controlcharts:8.1.1 Proper identification of the test method standard,8.1.2 Proper identification of the reference material,8.1.3 Indicate whether the mean and control limits are fromTable 1, Table 2,orTable 3, or
36、 calculated from test data, and8.1.4 If the mean and control limits are calculated from testdata, identify the number of data points used for the calcula-tions.9. Precision and Bias9.1 The bias of testing an SRB for certain tests may bedetermined by taking an average, x, of the most recent 20 to 30t
37、est results for a test (corrected, uncorrected, or both) andcalculating the bias or difference from the ASTM acceptedvalue ( x xASTM). To reduce the uncertainty associated withthe mean value, at least 20 data points should be used toestimate the mean value. Using more than 30 data points doesnot sig
38、nificantly reduce the uncertainty.9.2 The precision of testing an SRB for a certain test may bedetermined by calculating the standard deviation, s, of the datapoints used in 9.1.s 5x12 x!21 . 1 xn2 x!2n 2 1(2)10. Keywords10.1 carbon black; continuously monitoring testing; SRBs;standard reference bla
39、cks; statistical control chartsFIG. 3 Iodine Number of SRB B-5 Decreases with Time (Data Represents Three Years)D4821077ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are express
40、ly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised,
41、either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may att
42、end. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D4821078
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