ASTM D720/D720M-23

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.
Designation: D720/D720M − 23
Standard Test Method for
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Free-Swelling Index of Coal
This standard is issued under the fixed designation D720/D720M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
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2.1 ASTM Standards:
1.1 This test method is a small-scale, empirical test for
D2013/D2013M Practice for Preparing Coal Samples for
obtaining information regarding the free-swelling properties of
Analysis
a coal. The results may be used as an indication of the caking
E691 Practice for Conducting an Interlaboratory Study to
characteristic of the coal when burned as a fuel. This test is not
Determine the Precision of a Test Method
recommended as a method for the determination of expansion
of coals in coke ovens.
3. Significance and Use
1.2 Units—The values stated in either SI units or non-SI
3.1 This test method, in addition to indicating the caking
units are to be regarded separately as standard. The values
properties of a coal when burned as a fuel, can be used to give
stated in each system are not necessarily exact equivalents;
a broad indication of the degree of oxidation of a coal.
therefore, to ensure conformance with the standard, each
system shall be used independently of the other, and values
4. Apparatus
from the two systems shall not be combined.
4.1 This test method can be performed using either electric
1.3 This standard does not purport to address all of the
or gas heating. When using electric heating, the results ob-
safety concerns, if any, associated with its use. It is the
tained must be the same as those obtained when using the gas
responsibility of the user of this standard to establish appro-
heating method. The apparatus common to both electric and
priate safety, health, and environmental practices and deter-
gas methods shall consist of the following:
mine the applicability of regulatory limitations prior to use.
4.1.1 Crucible, translucent silica, low-form, with a flat,
1.4 This international standard was developed in accor- close-fitting silica ring-handle lid and an extra pierced lid for
use in determining the crucible temperature, conforming to the
dance with internationally recognized principles on standard-
following requirements:
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
Mass, g 11.0 to 12.75
External height, mm 26 ± 0.5
mendations issued by the World Trade Organization Technical
External diameter at top, mm 41 ± 0.75
Barriers to Trade (TBT) Committee.
Internal diameter at base, min, mm 11
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Capacity (approximate), cm 17
4.1.2 Sight Tube, as shown in Fig. 1, for viewing the coke
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buttons so that the effect of parallax will be eliminated. Make
This test method is under the jurisdiction of ASTM Committee D05 on Coal
and Coke and is the direct responsibility of Subcommittee D05.15 on Metallurgical
the tube of any rigid and preferably opaque material and
Properties of Coal and Coke.
support vertically on a ring stand. The sight tube shall be
Current edition approved Nov. 1, 2023. Published December 2023. Originally
38 mm [1.5 in.] in diameter and 250 mm [10 in.] in length and
approved in 1943. Last previous edition approved in 2022 as D720/D720M – 22.
supported on the ring stand at a height of 76 mm [3.0 in.] above
DOI: 10.1520/D0720_D0720M-23.
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This test method is an adaptation of the Crucible Swelling Test for Coal of the
the base of the stand.
British Standards Institution. For information concerning the experimental work on
which this adaptation is based, see paper by Ostborg, H. N., Limbacker, H. R., and
Sherman, R. A., “An Experimental Investigation of the British Standard Method for
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the Crucible Swelling Test for Coal,” Proceedings, Am. Soc. Testing Mats., Vol 42, For referenced ASTM standards, visit the ASTM website, www.astm.org, or
1042, p. 851. See also a paper by Selvig, W. A., and Ode, W. H., “An Investigation contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
of a Laboratory Test for Determination of the Free-Swelling Index of Coal,” U.S. Standards volume information, refer to the standard’s Document Summary page on
Bureau of Mines Report of Investigation 4238, Revision of R. I. 3989, 1948. the ASTM website.
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