ASTM D7743-12
(Test Method)Standard Test Method for Measuring the Minimum Fluidization Velocities of Free Flowing Powders (Withdrawn 2021)
Standard Test Method for Measuring the Minimum Fluidization Velocities of Free Flowing Powders (Withdrawn 2021)
SIGNIFICANCE AND USE
5.1 The data from this test can be used to determine the superficial gas velocity required to suspend a bed of powder in the fluidized state and the resulting pressure drop.Note 4—The quality of the results produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors: Practice D3740 provides a means of evaluating some of those factors.
Practice D3740 was developed for agencies engaged in the testing or inspection or both of soil and rock. As such it is not totally applicable to agencies performing this standard. However, users of this standard should recognize that the framework of Practice D3740 is appropriate for evaluating the quality of an agency performing this standard. Currently there is no known qualifying national authority that inspects agencies that perform this standard.
SCOPE
1.1 This test method describes the apparatus and procedure needed for determining the minimum fluidization velocity of Geldart Group A powders and the minimum fluidization or complete fluidization velocity of Geldart Group B powders.
1.1.1 This test method is for powders that are readily or easily fluidizable and fall into the category of Group A and B of the “Geldart” classification. The fluidization of Geldart Group C powders will be addressed in another standard. This test method could apply to Geldart Group D particles but the focus of this document is towards Group and A and B materials.
1.1.2 Geldart classification of powders is often defined by comparing the Sauter mean particle size with the difference between the particle density and the density of the fluidizing gas, as illustrated in Fig. 1 (1).2FIG. 1 Geldart Classification of Particles
1.1.2.1 Group A powders are easily fluidized but there is a difference between the gas velocity where the bed is initially fluidized and the velocity where bubbles are first observed. For Group A powders, bed expansion can be considerable before any bubbles are observed. Group B powders are also easily fluidized; but there is no difference between the velocity where the bed is fluidized and the velocity at the onset of bubbling. The minimum gas velocity, where all of the particles are fully supported by the gas for Group B powders, is often referred to as the “complete fluidization velocity” instead of minimum fluidization velocity. Group C powders are cohesive and can be difficult to fluidize.
1.1.2.2 Group A powders can be distinguished from Group B powders by the response to deaeration. Group A powders deaerate relatively slowly whereas Group B powders deaerate almost instantaneously in fluidized beds.
1.1.2.3 Group A Powders that lie near or on the Group A/C boundary may be tested by this method. However, if the powders do not fluidize freely, test results should be considered invalid.
1.1.2.4 Temperature, moisture (water) content, particle size distribution, particle shape and sometimes other variables influence the Geldart classification of a powder. Deaeration testing specified in 1.1.2.2 is a more definitive test than simply using particle size and density differences as described in 1.1.2.Note 1—A Standard Practice for deaeration testing is under development.
1.2 This test method should be performed in a laboratory under controlled conditions of temperature and humidity.
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.
1.3.1 The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as the industry standard. In ...
General Information
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D7743 −12
Standard Test Method for
Measuring the Minimum Fluidization Velocities of Free
1
Flowing Powders
This standard is issued under the fixed designation D7743; 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 1.1.2.2 Group A powders can be distinguished from Group
B powders by the response to deaeration. Group A powders
1.1 This test method describes the apparatus and procedure
deaerate relatively slowly whereas Group B powders deaerate
needed for determining the minimum fluidization velocity of
almost instantaneously in fluidized beds.
Geldart Group A powders and the minimum fluidization or
1.1.2.3 Group A Powders that lie near or on the Group A/C
complete fluidization velocity of Geldart Group B powders.
boundary may be tested by this method. However, if the
1.1.1 This test method is for powders that are readily or
powdersdonotfluidizefreely,testresultsshouldbeconsidered
easily fluidizable and fall into the category of Group A and B
invalid.
of the “Geldart” classification. The fluidization of Geldart
1.1.2.4 Temperature, moisture (water) content, particle size
Group C powders will be addressed in another standard. This
distribution, particle shape and sometimes other variables
test method could apply to Geldart Group D particles but the
influence the Geldart classification of a powder. Deaeration
focus of this document is towards Group and A and B
testing specified in 1.1.2.2 is a more definitive test than simply
materials.
usingparticlesizeanddensitydifferencesasdescribedin1.1.2.
1.1.2 Geldart classification of powders is often defined by
comparing the Sauter mean particle size with the difference
NOTE 1—A Standard Practice for deaeration testing is under develop-
ment.
between the particle density and the density of the fluidizing
2
gas, as illustrated in Fig. 1(1).
1.2 This test method should be performed in a laboratory
1.1.2.1 Group A powders are easily fluidized but there is a
under controlled conditions of temperature and humidity.
difference between the gas velocity where the bed is initially
1.3 All observed and calculated values shall conform to the
fluidized and the velocity where bubbles are first observed. For
guidelines for significant digits and rounding established in
Group A powders, bed expansion can be considerable before
Practice D6026.
any bubbles are observed. Group B powders are also easily
1.3.1 Theproceduresusedtospecifyhowdataarecollected/
fluidized; but there is no difference between the velocity where
recorded or calculated, in this standard are regarded as the
the bed is fluidized and the velocity at the onset of bubbling.
industry standard. In addition they are representative of the
The minimum gas velocity, where all of the particles are fully
significant digits that generally should be retained. The proce-
supported by the gas for Group B powders, is often referred to
dures used do not consider material variations, the purpose for
as the “complete fluidization velocity” instead of minimum
obtaining the data, special purpose studies, or any consider-
fluidizationvelocity.GroupCpowdersarecohesiveandcanbe
ations for the user’s objectives; and it is common practice to
difficult to fluidize.
increase or reduce significant digits of reported data to be
commensuratewiththeseconsiderations.Itisbeyondthescope
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
of this standard to consider significant digits used in analysis
Rock and is the direct responsibility of Subcommittee D18.24 on Characterization
methods for engineering design.
and Handling of Powders and Bulk Solids.
Current edition approved June 1, 2012. Published August 2012. DOI: 10.1520/
1.4 The values stated in SI units are to be regarded as
D7743-12.
2 standard. No other units of measurement are included in this
The boldface numbers in parentheses refer to a list of references at the end of
this standard. standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D7743−12
FIG. 1Geldart Classification of Particles
NOTE 2—At minimum fluidization, the pressure drop or differential
1.5 This standard does not purport to address all of the
pressure across the bed becomes relatively constant with additional gas
safety concerns, if any, associated with its use. It is the
velocity. The pressure drop at minimum fluidization corresponds to the
responsibility of the user of this standard to establish appro-
mass of the bed times the gravitational constant divided by the bed cross
priate
...
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