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    ASTM D4821 - 20

    Standard Guide for Carbon Black—Validation of Test Method Precision and Bias

    Active Standard ASTM D4821 | Developed by Subcommittee: D24.61

    Book of Standards Volume: 09.01

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    Significance and Use

    4.1 This guide provides insight into the environmental conditions required for operation of laboratories or to aid in the design of new laboratories that perform carbon black testing activities using those test methods that are under D24’s jurisdiction. This guide does not supersede any specific requirements a laboratory may choose to establish.

    4.2 This guide recommends the use of statistical x-charts to graphically monitor test data determined for the ASTM reference blacks for those test methods given in Section 2. All laboratories are encouraged to utilize statistical x-charts and ASTM reference blacks because this enables a comparison of testing precision within and between laboratories. The guide describes practices for the use of repeatability and reproducibility limits and x-charts.

    4.3 In addition to the calibration of a test method by physicochemical means, a statistical method for achieving calibration of a test method is presented (that is, normalization).

    4.4 Poor test precision can be the result of poor repeatability or poor reproducibility or both. Causes may include inadequate operator training, improperly maintained equipment or laboratory environment, variation in sample preparation or analysis techniques, the lack of calibration or standardization of instrumentation, worn-out apparatus, reagents that do not meet specifications, different sources of instrumentation or equipment, and material heterogeneity. The sum of all sources of testing error is unique for an individual laboratory.

    4.5 Precision data for ASTM Reference Blacks are found in Tables 1-3. These include standard reference blacks (SRB’s) Series 8, HT and INR Iodine Standards. The HT or INR Iodine standards are recommended for monitoring iodine testing.

    (A) The iodine adsorption number of carbon black has been shown to decrease in value as the carbon black ages. Generally, the higher the surface area the faster the rate of change. Therefore, the target or mean values given in Table 1A may not be obtained due to this aging effect. Iodine Number testing should be monitored using HT or INR iodine standards and their reference values found in Table 2 and Table 3. See Section 10 for additional information.

    Note 1: Preferred precision values are bolded in Tables 1-3.

    1. Scope

    1.1 This guide covers procedures for using the ASTM Standard Reference Blacks2 (SRBs) and the HT and INR Iodine Number Standards to continuously monitor the precision of those carbon black test methods for which reference values have been established. It also offers guidelines for troubleshooting various test methods.

    1.2 This guide defines the environmental conditions that are required for laboratories that perform carbon black testing activities for those test methods under D24’s jurisdiction.

    1.3 This guide establishes procedures for the use of x-charts to continuously monitor those tests listed in Section 2 for within-lab precision (repeatability) and between-lab accuracy (reproducibility).

    1.4 This guide provides a statistical procedure for improving test reproducibility when a laboratory cannot physically calibrate its apparatus to obtain the reference values of the ASTM reference blacks, within the ranges given in this guide.

    1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D1510 Test Method for Carbon BlackIodine Adsorption Number

    D1513 Test Method for Carbon Black, PelletedPour Density

    D1765 Classification System for Carbon Blacks Used in Rubber Products

    D2414 Test Method for Carbon BlackOil Absorption Number (OAN)

    D3265 Test Method for Carbon BlackTint Strength

    D3324 Practice for Carbon Black--Improving Test Reproducibility Using ASTM Standard Reference Blacks

    D3493 Test Method for Carbon BlackOil Absorption Number of Compressed Sample (COAN)

    D6556 Test Method for Carbon BlackTotal and External Surface Area by Nitrogen Adsorption

    D7854 Test Method for Carbon Black-Void Volume at Mean Pressure

    E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods

    E2282 Guide for Defining the Test Result of a Test Method

    E2586 Practice for Calculating and Using Basic Statistics

    ICS Code

    ICS Number Code 83.040.20 (Rubber compounding ingredients)

    Referencing This Standard
    Link Here
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    DOI: 10.1520/D4821-20

    Citation Format

    ASTM D4821-20, Standard Guide for Carbon Black—Validation of Test Method Precision and Bias, ASTM International, West Conshohocken, PA, 2020, www.astm.org

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