ASTM D4821-03

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 4821 – 03
Standard Guide for
Carbon Black—Validation of Test Method Precision and
1
Bias
This standard is issued under the fixed designation D 4821; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 1765 Classification System for Carbon Blacks Used in
4
Rubber Products
1.1 This guide covers a procedure for using ASTM Standard
2
D 2414 Test Method for Carbon Black—Oil Absorption
Reference Blacks (SRBs) to continuously monitor the preci-
4
Number
sion of those carbon black test methods for which standard
4
D 3265 Test Method for Carbon Black—Tint Strength
values have been established. It also offers guidelines for
D 3493 Test Method for Carbon Black—Oil Absorption
troubleshooting various test methods.
4
Number of Compressed Sample
1.2 This guide establishes the x-chart control limits to be
D 6556 Test Methods for Carbon Black—Total and Exter-
used when continuously monitoring those tests listed in Section
4
nal Surface Area by Nitrogen Adsorption
2. Alternatively, these control limits may be used as a basis for
comparison to testing precision computed within a laboratory.
3. Significance and Use
1.3 This guide uses statistical control chart methodology as
3 3.1 One of the major causes of poor test precision is the lack
discussed in STP-15-D to determine if a laboratory’s test
of calibration or standardization of instruments, apparatus,
results differ significantly from the accepted values of the
reagents, and technique among laboratories. The sum of all
SRBs.
sources of testing error is unique for an individual laboratory.
1.4 This guide provides a statistical procedure for improv-
A least-squares regression of a laboratory’s actual test values
ing test reproducibility when a laboratory cannot physically
for reference materials to the established mean values will
calibrate its apparatus to obtain the standard values of the
result in a unique least-squares regression line (and equation)
ASTM SRBs, within the ranges given in the precision state-
for that laboratory. Generally, there are two reasons for using
ment of the test method.
the SRBs in testing: (1) to monitor testing performance (see
1.5 The values stated in SI units are to be regarded as the
Section 4) to ensure that no systematic error or bias is affecting
standard. The values given in parentheses are for information
the test results, or (2) to establish a statistical calibration (see
only.
Section 5) when the correction of assignable causes (see
1.6 This standard does not purport to address all of the
Section 6) does not yield in-control test results.
safety concerns, if any, associated with its use. It is the
3.2 In addition to the calibration of a test method by
responsibility of the user of this standard to establish appro-
physicochemical means, a statistical method for achieving
priate safety and health practices and determine the applica-
calibration of a test method is presented.
bility of regulatory limitations prior to use.
3.3 This guide outlines the use of control charts to graphi-
2. Referenced Documents cally present calibration test data determined for the ASTM
SRBs for those test methods given in Section 2. All laborato-
2.1 ASTM Standards:
ries are encouraged to utilize statistical control charts and the
D 1510 Test Method for Carbon Black—Iodine Adsorption
4
SRBs because this allows a comparison of testing precision
Number
within a laboratory to the “industry average” values found in
Table 1.
1
This guide is under the jurisdiction of ASTM Committee D24 on Carbon Black 3.4 The techniques of this guide can be used to continuously
and is the direct responsibility of Subcommittee D24.61 on Carbon Black Sampling
monitor testing execution and precision for other tests that are
and Statistical Analysis.
not listed in Section 2 or for materials that fall outside the range
Current edition approved Jan. 10, 2003. Published February 2003. Originally
of the SRBs for those tests listed in Section 2. In these cases,
approved in 1988. Last previous edition approved in 2001 D 4821 – 01a.
2
Standard Reference Blacks are available from Laboratory Standards & Tech-
each laboratory will have to establish the applicable mean and
nologies, Inc., 227 Somerset St., Borger, TX 79007. Phone/fax: (806) 273-3006.
control limit values for the “local reference.” The monitoring
E-mail: jwbal@infinitytx.net.
3 will then consist of a comparison of present test results for the
Symposium on Manual on Presentation of Data and Control Chart Analysis,
ASTM STP 15D, ASTM, 1976.
4
Annual Book of ASTM Standards, Vol 09.01.
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