1、Designation: D4821 071Standard Guide forCarbon BlackValidation of Test Method Precision andBias1This standard is issued under the fixed designation D4821; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorially corrected Footnote 3 and corresponding references in August 2011.1. Scope1.1 This guide covers a procedure for usingASTM Standard
3、Reference Blacks2(SRBs) to continuously monitor the preci-sion of those carbon black 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 monito
4、ring those tests listed in Section2. Alternatively, these control limits may be used as a basis forcomparison to testing precision computed within a laboratory.1.3 This guide uses statistical control chart methodology asdiscussed in MNL73to determine if a laboratorys test resultsdiffer significantly
5、 from the accepted values of the SRBs.1.4 This guide provides a statistical procedure 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
6、.5 The values stated in SI units are to be regarded as thestandard. The values 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 appr
7、o-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4D1510 Test Method for Carbon BlackIodine AdsorptionNumberD1513 Test Method for Carbon Black, PelletedPour Den-sityD1765 Classification System for Ca
8、rbon Blacks Used inRubber ProductsD2414 Test Method for Carbon BlackOil AbsorptionNumber (OAN)D3037 Test Methods for Carbon Black-Surface Area byNitrogen Adsorption5D3191 Test Methods for Carbon Black in SBR (Styrene-Butadiene Rubber)Recipe and Evaluation ProceduresD3192 Test Methods for Carbon Blac
9、k Evaluation in NR(Natural Rubber)D3265 Test Method for Carbon BlackTint StrengthD3493 Test Method for Carbon BlackOil AbsorptionNumber of Compressed Sample (COAN)D3765 Test Method for Carbon BlackCTAB (Cetyltrim-ethylammonium Bromide) Surface Area5D4820 Standard Test Methods for Carbon Black-Surfac
10、eArea by Multipoint B.E.T. Nitrogen Adsorption5D5816 Standard Test Methods for Carbon Black-ExternalSurface Area by Multipoint Nitrogen Adsorption5D6556 Test Method for Carbon BlackTotal and ExternalSurface Area by Nitrogen Adsorption3. Significance and Use3.1 One of the major causes of poor test pr
11、ecision is 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.1This guide is under the jurisdiction ofASTM Committee D24 on Carbon Blackand is the direct respons
12、ibility 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 D4821 06. DOI:10.1520/D4821-07E01.2Standard Reference Blacks are available from Labora
13、tory 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 fall outside the range of interest. At l
14、eastfour 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 laboratories. For the oil absorption test (Tes
15、t MethodD2414), 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 equation to obtain corrected valuesfor the
16、 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 equation using the most recent test data, exclu
17、dingthe 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 6)brings the SRBs back inside the three
18、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” values to be used in a linearregression equa
19、tion.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 equationwhen new or repaired test equip
20、ment 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 have again beensatisfied.6. Assignable
21、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 D1510 Iodine Adsorption Number:6.1.1.1 Incorrect normality of iodine and sodium thiosulfatesolutions,6.1.1.2 Volumetric glassware not calibrated correctly,
22、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 The known decline in iodine number as th
23、e carbonblack ages, and6.1.1.8 Sample not dried.6.1.2 Test Method D2414 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 Excessive blade and bowl clearance,6.1.2.5 Incor
24、rect 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 Sample not dried, and6.1.2.11 SRB calibration
25、curves need updating.6.1.3 Test Method D3493 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 Method D3265 Tint Strength:6.1.4.1 Incorrect
26、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 D3037 Nitrogen Surface Area:6.1.5.1 Leaks in apparatus, and6.1.5.2 Faulty O-rings.6.
27、1.6 Test Method D3765 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.6.1.7 Test Method D6556 Total and External Surf
28、ace 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 of an SRB is suspected, try using a different SR
29、B sample.7. Guide to Accepted Normalization Practices for CarbonBlack Test Methods7.1 Accepted normalization practices for test methods foundin Classification D1765 are described below:D4821 07167.1.1 Test Method D1510, Iodine NumberShould notrequire normalization. A statistical correction factor pe
30、r 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 have been shown to have stable iodine numbervalues
31、 over a period of many years. If normalization isrequired, it shall be done using only the SRB HT materials.7.1.2 Test Method D1513, Pour DensityNo normalizationrequired.7.1.3 Test Method D2414, Oil AbsorptionThe only nor-malization that is required is using the tread or carcass SRBs asdiscussed in
32、the test method.7.1.4 Test Method D3265, 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 D3493, Oil Absorption of CompressedSampleThe only normalization that is required is using th
33、etread or carcass SRBs as discussed in the test method.7.1.6 Test Methods D3192, Stress-Strain in NaturalRubber(Also applies to Test Methods D3191, Stress-Strainin SBR.). Normalization not recommended.7.1.7 Test Method D6556, NSA and STSAShould notrequire normalization.8. Report8.1 Report the follow
34、ing 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 calculated from test data, and8.1.4 If the mean and con
35、trol 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 30test results for a test (corrected, uncorrected, or both)
36、 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 significantly reduce the uncertainty.9.2 The precision of t
37、esting 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 blacks; statistical control chartsFIG. 3 Iodine Number of S
38、RB B-5 Decreases with Time (Data Represents Three Years)D4821 0717ASTM 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 expressly advised that determination of the validity of any s
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