ASTM D6941-12
(Practice)Standard Practice for Measuring Fluidization Segregation Tendencies of Powders
Standard Practice for Measuring Fluidization Segregation Tendencies of Powders
SIGNIFICANCE AND USE
5.1 Fluidization segregation can cause vertical segregation within bins used to hold and transport powders. This can affect product quality in industrial applications.
5.2 By measuring a powder's segregation tendency, one can compare results to other powders with known history, or determine if the given powder may have a tendency to segregate in a given process.
5.3 Fine powders generally have a lower permeability than coarse bulk solids and therefore tend to retain air longer. Thus, when a bin is filled with a fluidizable powder, the coarser particles settle or are driven into the bed while the finer particles remain fluidized near the surface.
5.4 Fluidization, which serves as a driving force for this mechanism of segregation, is likely to occur when fine powders are pneumatically conveyed into a bin, the bin is filled or discharged at high rates, or if sufficient air flow counter to the flow of powder is present within the bin.Note 1—The quality of the result produced by this practice 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 practice are cautioned that compliance with Practice D3740 does not in itself assure 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 and/or inspection of soil and rock. As such it is not totally applicable to agencies performing this practice. However, users of this practice should recognize that the framework of Practice D3740 is appropriate for evaluating the quality of an agency performing this practice. Currently there is no known qualifying national authority that inspects agencies that perform this practice.
SCOPE
1.1 This practice covers an apparatus and procedure for creating several specimens of a powder sample that, if the powder is one that segregates by the fluidization mechanism, should be different from one another.
1.2 A powder sample is fluidized then, after the fluidizing gas is turned off, it is separated into three or more specimens that can be analyzed for parameters of interest. The difference in these parameters between the specimens is an indication of the segregation potential of the powder.
1.3 Powders must be capable of being fluidized in order to be tested by this practice.
1.4 Temperature- and moisture-sensitive powders may need to be tested at different temperatures and moisture contents, as would happen in an industrial environment.
1.5 This standard is not applicable to all bulk solids and segregation mechanisms: while fluidization is a common segregation mechanism experienced by many fine powders, other segregation mechanisms not evaluated by this standard might induce segregation in practice. Practice D6940 covers another common mechanism: sifting.
1.6 The extent to which segregation will occur in an industrial situation is not only a function of the powder and its tendency to segregate, but also the handling equipment (for example, bin design), process (for example, transfer rates), and environment.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many ...
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Designation: D6941 − 12
Standard Practice for
1
Measuring Fluidization Segregation Tendencies of Powders
This standard is issued under the fixed designation D6941; 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* the adequacy of a given professional service must be judged,
nor should this document be applied without consideration of
1.1 This practice covers an apparatus and procedure for
a project’s many unique aspects.The word Standard in the title
creating several specimens of a powder sample that, if the
of this document means only that the document has been
powder is one that segregates by the fluidization mechanism,
approved through the ASTM consensus process.
should be different from one another.
1.9 This standard does not purport to address all of the
1.2 A powder sample is fluidized then, after the fluidizing
safety concerns, if any, associated with its use. It is the
gas is turned off, it is separated into three or more specimens
responsibility of the user of this standard to establish appro-
that can be analyzed for parameters of interest. The difference
priate safety and health practices and determine the applica-
in these parameters between the specimens is an indication of
bility of regulatory limitations prior to use.
the segregation potential of the powder.
1.3 Powders must be capable of being fluidized in order to 2. Referenced Documents
be tested by this practice. 2
2.1 ASTM Standards:
1.4 Temperature- and moisture-sensitive powders may need D653 Terminology Relating to Soil, Rock, and Contained
to be tested at different temperatures and moisture contents, as Fluids
would happen in an industrial environment. D2216 Test Methods for Laboratory Determination of Water
(Moisture) Content of Soil and Rock by Mass
1.5 This standard is not applicable to all bulk solids and
D3740 Practice for Minimum Requirements for Agencies
segregation mechanisms: while fluidization is a common
Engaged in Testing and/or Inspection of Soil and Rock as
segregation mechanism experienced by many fine powders,
Used in Engineering Design and Construction
other segregation mechanisms not evaluated by this standard
D6940 Practice for Measuring Sifting Segregation Tenden-
might induce segregation in practice. Practice D6940 covers
cies of Bulk Solids
another common mechanism: sifting.
1.6 The extent to which segregation will occur in an
3. Terminology
industrial situation is not only a function of the powder and its
3.1 Definitions:
tendency to segregate, but also the handling equipment (for
3.1.1 For common definitions of technical terms in this
example, bin design), process (for example, transfer rates), and
standard, refer to Terminology D653.
environment.
3.1.2 fluidization, n—in powders, the state in which a
1.7 The values stated in SI units are to be regarded as
powder exhibits fluid-like properties.
standard. No other units of measurement are included in this
3.1.3 fluidization segregation, n—in powders, a mechanism
standard.
that causes vertical segregation, that is, horizontal layering of
1.8 This practice offers a set of instructions for performing fine and coarse particles, as resulting from fluidization of the
one or more specific operations. This document cannot replace bulk solid.
educationorexperienceandshouldbeusedinconjunctionwith
3.1.4 segregation, n—in powders, a process through which
professional judgment. Not all aspects of this practice may be
blended or uniform powders or bulk solids become non-
applicable in all circumstances. This ASTM standard is not
uniform, with regions of varying composition, for example,
intended to represent or replace the standard of care by which
particle size.
3.2 Definitions of Terms Specific to This Standard:
1
This practice is under the jurisdiction of ASTM Committee D18 on Soil and
Rock and is the direct responsibility of Subcommittee D18.24 on Characterization
2
and Handling of Powders and Bulk Solids. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2012. Published December 2012. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ε1
approved in 2003. Last previous edition approved in 2005 as D6941–05 . DOI: Standardsvolume information, refer to the standard’s Document Summary page on
10.1520/D6941-12. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6941 − 12
3.2.1 hi
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This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: D6941 − 05 D6941 − 12
Standard Practice for
1
Measuring Fluidization Segregation Tendencies of Powders
This standard is issued under the fixed designation D6941; 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
εNOTE—Section 7.10 and Figure 2 were corrected editorially in July 2007.
1. Scope Scope*
1.1 This practice covers an apparatus and procedure for simulating the segregation tendencies of powders by means of the
fluidization mechanism.creating several specimens of a powder sample that, if the powder is one that segregates by the fluidization
mechanism, should be different from one another.
1.2 A powder sample is fluidized then, after the fluidizing gas is turned off, it is separated into three or more specimens that
can be analyzed for parameters of interest. The difference in these parameters between the specimens is an indication of the
segregation potential of the powder.
1.3 Powders must be capable of being fluidized in order to be tested by this practice.
1.4 Temperature- and humidity-sensitivemoisture-sensitive powders may need to be tested at different temperatures and
moisture contents, as would happen in an industrial environment. Further, the gas supply (type, temperature, and humidity) should
also match the industrial conditions.
1.5 This standard is not applicable to all bulk solids and segregation mechanisms: while fluidization is a common segregation
mechanism experienced by many fine powders, other segregation mechanisms not evaluated by this standard might induce
segregation in practice. Practice D6940 covers another common mechanism: sifting.
1.6 The extent to which segregation will occur in an industrial situation is not only a function of the powder and its tendency
to segregate, but also the handling equipment (for example, bin design), process (for example, transfer rates), and environment.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.8 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace
education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be
applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the
adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s
many unique aspects. The word Standard in the title of this document means only that the document has been approved through
the ASTM consensus process.
1.9 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D653 Terminology Relating to Soil, Rock, and Contained Fluids
D2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
D3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in
Engineering Design and Construction
D6940 Practice for Measuring Sifting Segregation Tendencies of Bulk Solids
1
This practice is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.24 on Characterization and
Handling of Powders and Bulk Solids.
Current edition approved Nov. 1, 2005Nov. 1, 2012. Published November 2005December 2012. Originally approved in 2003. Last previous edition approved in 20042005
ε1
as D6941–04.–05 . DOI: 10.1520/D6941-05E01.10.1520/D6941-12.
2
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
Standardsvolume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D6941 − 12
3. Terminology
3.
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