ASTM C729-75(2000)
(Test Method)Standard Test Method for Density of Glass by the Sink-Float Comparator
Standard Test Method for Density of Glass by the Sink-Float Comparator
SCOPE
1.1 This test method covers the determination of the density of glass or nonporous solids of density from 1.1 to 3.3 g/cm. It can be used to determine the apparent density of ceramics or solids, preferably of known porosity.
1.2 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:C729–75(Reapproved 2000)
Standard Test Method for
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Density of Glass by the Sink-Float Comparator
This standard is issued under the fixed designation C729; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope tiallythesolutions,specimen,andstandardareatatemperature
near 25°C, and both the standard and the specimen float in the
1.1 Thistestmethodcoversthedeterminationofthedensity
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solution. The temperature of the system is raised at a uniform
of glass or nonporous solids of density from 1.1 to 3.3 g/cm .
rate.Becausetheexpansioncoefficientofthesolutionishigher
It can be used to determine the apparent density of ceramics or
than that of the glass standard and specimen, both the standard
solids, preferably of known porosity.
and the specimen will sink (settle) in the solution. The
1.2 This standard does not purport to address all of the
temperatures at which the specimen and standard reach the
safety concerns, if any, associated with its use. It is the
mid-pointofthetesttubearenotedandbyuseofspecialtables,
responsibility of the user of this standard to establish appro-
the density of the specimen is obtained.
priate safety and health practices and determine the applica-
3.2 Range of a Given Density Solution— A given density
bility of regulatory limitations prior to use.
solution can be used to measure specimens whose density is
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2. Referenced Documents within60.0200g/cm ofthedensityofthesolutionat35°C,by
operating the comparator bath in the range 25 to 45°C.
2.1 ASTM Standards:
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C693 Test Method for Density of Glass by Buoyancy
4. Significance and Use
D1217 Test Method for Density and Relative Density
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4.1 The sink-float comparator method of test for glass
(Specific Gravity) of Liquids by Bingham Pycnometer
densityprovidesthemostaccurate(yetconvenientforpractical
E12 Terminology Relating to Density and Specific Gravity
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applications) method of evaluating the density of small pieces
of Solids, Liquids, and Gases
or specimens of glass. The data obtained are useful for daily
E29 Practice for Using Significant Digits in Test Data to
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quality control of production, acceptance or rejection under
Determine Conformance with Specification
specifications, and for special purposes in research and devel-
E77 Test Method for Inspection and Verification of Ther-
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opment.
mometers
4.2 Although this test scope is limited to a density range
F77 Test Method for Apparent Density of Ceramics for
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2 from 1.1 to 3.3 g/cm , it may be extended (in principle) to
Electron Device and Semiconductor Application
higher densities by the use of other miscible liquids (Test
3. Summary of Method Method F77) such as water and thallium malonate-formate
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(approximately 5.0 g/cm ). The stability of the liquid and the
3.1 The specimen of unknown density is compared with a
precision of the test may be reduced somewhat, however, at
reference standard of known density. The specimen to be
higher densities.
measured is placed in a test tube containing a solution whose
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density at 35°C is within 0.0200 g/cm of the density of the
5. Apparatus
specimen at 25°C. The solution is prepared using miscible
5.1 Single Tube and Multiple-Tube Comparators (Method
liquids of known densities bracketing the desired range. The
E77)— A single-tube comparator can be constructed from
tube also contains a glass density reference standard whose
materials readily available in a typical laboratory, and useful if
densityat35°Cisclosetothatofthesolutionat35°C;thetube
one wishes to measure the density of materials within a fairly
is immersed in a variable-temperature comparator bath. Ini-
narrow range, or if only a few tests need to be run each day.
The multiple-tube comparator can be purchased commer-
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This test method is under the jurisdiction ofASTM Committee C-14 on Glass
cially. It is useful if materials with a wide range of density
and Glass Products and is the direct responsibility of Subcommittee C14.04 on
must be tested or if many specimens must be tested each day.
Physical and Mechanical Properties.
The comparators shall consist of the following:
Current edition approved Aug. 29, 1975. Published November 1975. Originally
5.1.1 Single-Tube Comparator (Fig. 1):
published as C729–72T. Last previous edition C729–72T.
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Annual Book of ASTM Standards, Vol 15.02.
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Annual Book of ASTM Standards, Vol 05.01.
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Annual Book of ASTM Standards, Vol 15.05.
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Annual Book of ASTM Standards, Vol 14.02. A multiple-tube comparator is available from American Glass Research, Inc.,
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Annual Book of ASTM Standards, Vol 14.03. Box 149, Butler, PA 16001.
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