ASTM D1937-23

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Designation: D1937 − 21 D1937 − 23
Standard Test Method for
Carbon Black, Pelleted—Mass Strength
This standard is issued under the fixed designation D1937; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of the mass strength of pelleted carbon black. It is designed to determine the force
required to pack a cylindrical column of pelleted carbon black. The results of this test are believed to relate to the ability of the
carbon black to flow in bulk handling systems.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 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
2.1 ASTM Standards:
D1799 Practice for Carbon Black—Sampling Packaged Shipments
D1900 Practice for Carbon Black—Sampling Bulk Shipments
D4483 Practice for Evaluating Precision for Test Method Standards in the Rubber and Carbon Black Manufacturing Industries
3. Summary of Test Method
3.1 A sample of carbon black is placed in a vertical cylinder and pressed with a plunger for 10 s after which the bottom of the
cylinder is opened, whereupon all of the carbon black either falls out the bottom or forms a ring or bridge in the cylinder. The
process is repeated with a new sample until the minimum force required for the carbon black to form a ring or bridge is found.
The resultant force is called mass strength and is reported in Newtons.
4. Significance and Use
4.1 Mass strength gives an indication of the flowability in bulk handling. It is affected by pellet properties such as hardness, size,
shape, and especially fines content. Due to the influence of other variables, the user and the producer must determine an acceptable
mass strength level.
This test method is under the jurisdiction of ASTM Committee D24 on Carbon Black and is the direct responsibility of Subcommittee D24.51 on Carbon Black Pellet
Properties.
Current edition approved Nov. 1, 2021May 1, 2023. Published December 2021May 2023. Originally approved in 1962. Last previous edition approved in 20182021 as
D1937 – 18.D1937 – 21. DOI: 10.1520/D1937-21.10.1520/D1937-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
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D1937 − 23
5. Apparatus
5.1 Mass Strength Tester, with a compression chamber comprising:
5.1.1 Hollow Compression Cylinder, of 95.25 mm (3.75 in.) depth and 52.4 mm (2.06 in.) diameter, made of stainless steel.
5.1.2 Plunger, of 50.8 mm (2 in.) diameter and a central bore of 12.7 mm (0.5 in.) diameter and 19 mm (0.75 in.) depth, made
of stainless steel.
5.1.3 Force Application Mechanism, allowing the application of a controllable force onto the plunger.
5.2 Powder Funnel, to completely fill the cylinder.
5.3 Spatula, with a straight edge of at least 55 mm (2.2 in.).
5.4 Brush, approximately 40 mm (1.5 in.), stiff bristle.
6. Sampling
6.1 Samples shall be taken in accordance with Practices D1799 or D1900.
7. Calibration
7.1 The manufacturer will typically calibrate the instrument’s measurement system before delivery. Load cells are typically
calibrated or verified using a reference load cell or calibrated masses, or both. Traceability is recommended for all calibration
devices. Follow the manufacturer’s recommendations for calibration frequency and procedure.
8. Procedure
8.1 Compress the sample using a mass strength tester per the manufacturer instructions. A general procedure for compressing
carbon black involves the following steps:
8.1.1 Clean the cylinder with a brush to remove any adhering carbon black. With the sliding door (cylinder trap door) closed and
the funnel in position, pour carbon black pellets into the cylinder until an excess of pellets forms a cone above the rim. Level the
surface with a single sweep of a straightedge or spatula held perpendicular to, and in firm contact with the top of the cylinder. The
top surface of the carbon black column shall be level to prevent unequal pressure on the column.
8.1.2 Select the force to be applied. The setting for the initial press is discretionary and is based usually on lab experience.
NOTE 1—Soft pellets with irregular shape and high fines tend to have low mass strength. For these materials an initial setting of 100 N is suggested. More
spherical pellets with higher pellet hardness and low fines tend to have high mass strength. For these materials an initial setting of 250 N is suggested.
8.1.3 Activate the plunger, to start the compression. The timer shall be set to allow a total plunger application time of 10 s on the
sample.
8.1.4 After the plunger returns to the rest position above the sample, open the sliding door carefully and observe the inside of the
cylinder. If no black remains in the cylinder, the end point has not been reached. The test is then repeated on untested portions of
the sample using successively higher pressures following the test sequence in 8.1.1 – 8.1.4.
NOTE 2—The increments of increased force are discretionary. Steps of 50 or 100 N are appropriate.
8.2 Once a bridge of pressed carbon black is formed, the end point has been reached or exceeded. An additional test should be
performed at lower pressure(s) in
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