ASTM D6940/D6940M-20

Standard Practice for Measuring Sifting Segregation Tendencies of Bulk Solids

SIGNIFICANCE AND USE
5.1 Sifting segregation can cause horizontal segregation (for example, center-to-periphery) within bins used to hold and transport bulk solids. This can affect final product quality or subsequent processes in industrial applications.  
5.2 By measuring a bulk solid's segregation tendency, one can compare results to other bulk solids with known history, or determine if the given bulk solid may have a tendency to segregate in a given process.  
5.3 Sifting, which is a process by which smaller particles move through a matrix of larger ones, is a common method of segregation. Four conditions must exist for sifting to occur:  
5.3.1 A Difference in Particle Size between the Individual Components—This ratio can be as low as 1.3 to 1. In general, the larger the ratio of particle sizes, the greater the tendency for particles to segregate by sifting.  
5.3.2 A Sufficiently Large Mean Particle Size—Sifting segregation can occur with a mean particle size in the 50 μm range and can become a dominant segregation mechanism if the mean particle size is above 100 μm.  
5.3.3 Sufficiently Free Flowing Material—This allows the smaller particles to sift through the matrix of larger particles. With cohesive materials, the fine particles are bound to one another and do not enter the voids among the coarse particles.  
5.3.4 Interparticle Motion—This can be caused during formation of a pile, by vibration, or by a velocity gradient across the flowing material.  
5.4 All four of these conditions must exist for sifting segregation to occur. If any one of these conditions does not exist, the material will not segregate by this mechanism.
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 ...
SCOPE
1.1 This practice covers an apparatus and procedure for simulating the segregation tendencies of bulk solids by means of the sifting mechanism.  
1.2 Temperature- and humidity-sensitive bulk solids may need to be tested at different temperatures and moisture contents, as would happen in an industrial environment.  
1.3 The maximum particle size should be limited to 3 mm [1/8 in.], to reduce the likelihood of binding the slide gate.  
1.4 This standard is not applicable to all bulk solids and segregation mechanisms: while sifting is a common segregation mechanism experienced by many bulk solids, other segregation mechanisms not evaluated by this standard might induce segregation in practice. Practice D6941 covers another common mechanism: fluidization.  
1.5 The extent to which segregation will occur in an industrial situation is not only a function of the bulk solid and its tendency to segregate, but also the handling equipment (for example, bin design), process (for example, transfer rates), and environment.  
1.6 Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.  
1.7 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.  
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 docum...

General Information

• Status: Published
• Publication Date: 31-Dec-2019
• ICS: 19.120 - Particle size analysis. Sieving
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.24 - Characterization and Handling of Powders and Bulk Solids

Relations

• Replaces: ASTM D6940-18 - Standard Practice for Measuring Sifting Segregation Tendencies of Bulk Solids
• Effective Date: 01-Jan-2020
• Refers: ASTM D3740-23 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Nov-2023
• Refers: ASTM D3740-19 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Oct-2019
• Refers: ASTM D6941-19 - Standard Practice for Measuring Fluidization Segregation Tendencies of Powders
• Effective Date: 01-May-2019
• Refers: ASTM D2216-19 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Mar-2019
• Refers: ASTM D653-14 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Aug-2014
• Refers: ASTM D6941-12 - Standard Practice for Measuring Fluidization Segregation Tendencies of Powders
• Effective Date: 01-Nov-2012
• Refers: ASTM D3740-12a - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-May-2012
• Refers: ASTM D3740-12 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2012
• Refers: ASTM D653-11 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Sep-2011
• Refers: ASTM D3740-11 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Sep-2011
• Refers: ASTM D2216-10 - Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by Mass
• Effective Date: 01-Jul-2010
• Refers: ASTM D3740-10 - Standard Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used in Engineering Design and Construction
• Effective Date: 01-Mar-2010
• Refers: ASTM D653-09 - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Jan-2009
• Refers: ASTM D653-08a - Standard Terminology Relating to Soil, Rock, and Contained Fluids
• Effective Date: 01-Dec-2008

Overview

ASTM D6940/D6940M-20: Standard Practice for Measuring Sifting Segregation Tendencies of Bulk Solids establishes a standardized method to evaluate the tendency of bulk solids to undergo sifting segregation. Sifting segregation, a primary cause for product heterogeneity or process inefficiency, occurs when smaller particles migrate through the voids of larger particles, leading to horizontal segregation within bins and containers. This standard simulates these tendencies using a prescribed apparatus and procedure, enabling practitioners in industries handling powders and granular materials to compare segregation properties and optimize handling processes for higher quality and uniformity.

Key Topics

• Definition and Mechanism of Sifting Segregation: The standard details sifting as a process where smaller, free-flowing particles filter down through a matrix of larger ones, typically driven by differences in particle size, particle size mean, material flowability, and interparticle motion.
• Critical Conditions for Sifting Segregation:
  • Sufficient difference in particle sizes (even as low as a 1.3:1 ratio)
  • Mean particle size typically above 50 μm, with significant effect above 100 μm
  • Material must be sufficiently free flowing and non-cohesive
  • Presence of interparticle motion caused by pile formation, vibration, or velocity gradients
• Apparatus and Procedure: The document describes specialized hoppers, slide gates, and specimen collection methods to simulate and assess segregation under controlled conditions.
• Analysis of Segregation: Examination of collected specimens for changes in parameters such as particle size, chemical composition, or density to quantify the degree of segregation.
• Reporting Requirements: Includes guidelines for documenting materials, testing conditions, observations, and analytical data.

Applications

Implementing ASTM D6940/D6940M-20 is valuable in various sectors where bulk solids are handled, stored, or processed. Practical uses include:

• Quality Assurance in Manufacturing: Ensuring uniform product composition by measuring and mitigating segregation in raw materials, additives, or powder blends.
• Bin and Silo Design: Informing equipment design to minimize segregation zones and improve discharge consistency.
• Process Optimization: Assessing bulk solid formulations before scaling up industrial processes, aiding in the selection of materials less prone to sifting.
• Research and Development: Comparing the segregation tendencies of new powder blends or raw materials against standards or known products.

Industries benefiting from this standard include pharmaceuticals, food processing, chemicals, building materials (such as cement or aggregates), and any operation dealing with bin-stored powders or granular solids.

Related Standards

To provide a comprehensive framework for understanding and controlling bulk solid segregation, ASTM D6940/D6940M-20 frequently references other important standards, such as:

• ASTM D6941 - Practice for Measuring Fluidization Segregation Tendencies of Powders (addresses fluidization-driven segregation, complementing the sifting focus of D6940/D6940M)
• ASTM D653 - Terminology Relating to Soil, Rock, and Contained Fluids (provides relevant definitions)
• ASTM D2216 - Test Methods for Laboratory Determination of Water Content of Soil and Rock
• ASTM D3740 - Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection for soil and rock, cited for ensuring testing competence
• ASTM D6026 - Practice for Using Significant Digits in Geotechnical Data

Keywords: sifting segregation, bulk solids, ASTM D6940, particle segregation, powder testing, bulk material handling, industrial quality control, hopper flow, material uniformity, particle size distribution, process optimization

By adhering to ASTM D6940/D6940M-20, organizations can systematically assess and reduce the risks related to segregation in bulk solids, leading to improved product consistency and process efficiency.

Standards Content (Sample)

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: D6940/D6940M − 20
Standard Practice for
Measuring Sifting Segregation Tendencies of Bulk Solids
This standard is issued under the fixed designation D6940/D6940M; 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
simulating the segregation tendencies of bulk solids by means
title of this document means only that the document has been
of the sifting mechanism.
approved through the ASTM consensus process.
1.2 Temperature- and humidity-sensitive bulk solids may
1.9 This standard does not purport to address all of the
need to be tested at different temperatures and moisture
safety concerns, if any, associated with its use. It is the
contents, as would happen in an industrial environment.
responsibility of the user of this standard to establish appro-
1.3 The maximum particle size should be limited to 3 mm
priate safety, health, and environmental practices and deter-
[ ⁄8 in.], to reduce the likelihood of binding the slide gate.
mine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accor-
1.4 This standard is not applicable to all bulk solids and
dance with internationally recognized principles on standard-
segregation mechanisms: while sifting is a common segrega-
ization established in the Decision on Principles for the
tion mechanism experienced by many bulk solids, other
Development of International Standards, Guides and Recom-
segregation mechanisms not evaluated by this standard might
mendations issued by the World Trade Organization Technical
induce segregation in practice. Practice D6941 covers another
Barriers to Trade (TBT) Committee.
common mechanism: fluidization.
1.5 The extent to which segregation will occur in an
2. Referenced Documents
industrial situation is not only a function of the bulk solid and
2.1 ASTM Standards:
its tendency to segregate, but also the handling equipment (for
D653 Terminology Relating to Soil, Rock, and Contained
example, bin design), process (for example, transfer rates), and
Fluids
environment.
D2216 Test Methods for Laboratory Determination of Water
1.6 Units—The values stated in either SI units or inch-
(Moisture) Content of Soil and Rock by Mass
pound units are to be regarded separately as standard. The
D3740 Practice for Minimum Requirements for Agencies
values stated in each system may not be exact equivalents;
Engaged in Testing and/or Inspection of Soil and Rock as
therefore, each system shall be used independently of the other.
Used in Engineering Design and Construction
Combining values from the two systems may result in noncon-
D6026 Practice for Using Significant Digits in Geotechnical
formance with the standard.
Data
D6941 Practice for Measuring Fluidization SegregationTen-
1.7 All observed and calculated values shall conform to the
dencies of Powders
guidelines for significant digits and rounding established in
Practice D6026.
3. Terminology
1.8 This practice offers a set of instructions for performing
3.1 Definitions:
one or more specific operations. This document cannot replace
3.1.1 Forcommondefinitionsoftermsinthisstandard,refer
educationorexperienceandshouldbeusedinconjunctionwith
to Terminology D653.
professional judgment. Not all aspects of this practice may be
3.1.2 funnel flow pattern, n—in storing, handling and pro-
applicable in all circumstances. This ASTM standard is not
cessing bulk solids using industrial equipment,aflowsequence
intended to represent or replace the standard of care by which
in a bin or hopper characterized by having some particles
moving while other particles are stagnant during discharge.
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2020. Published January 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 2003. Last previous edition approved in 2018 as D6940–18. DOI: Standardsvolume information, refer to the standard’s Document Summary page on
10.1520/D6940_D6940M-20. 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
D6940/D6940M − 20
cautioned that compliance with Practice D3740 does not in itself assure
3.1.3 mass flow pattern, n—in storing, handling and pro-
reliable results. Reliable results depend on many factors; Practice D3740
cessing bulk solids using industrial equipment,aflowsequence
provides a means of evaluating some of those factors.
in a bin or hopper characterized by having all particles moving
Practice D3740 was developed for agencies engaged in the testing
when discharge occurs.
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
3.1.4 sifting segregation, n—in storing, handling and pro-
recognize that the framework of Practice D3740 is appropriate for
cessing bulk solids using industrial equipment, a mechanism in
evaluating the quality of an agency performing this practice. Currently
which finer particles preferentially percolate into a zone within
there is no known qualifying national authority that inspects agencies that
the bulk solid.
perform this practice.
4. Summary of Practice 6. Apparatus
6.1 The apparatus is shown in Fig. 1, and all critical
4.1 A representative sample of a bulk solid is placed in the
upper hopper of the apparatus. dimensions are specified in Fig. 2. The apparatus consists of
the following:
4.2 The bulk solid is discharged to form a pile within the
lower hopper, allowing segregation to take place. 6.2 Anupperhopperassemblyconsistingofaninnerhopper
seated within an outer hopper. This outer hopper, which
4.3 The segregated material is discharged in a funnel flow
provides support for the inner hopper has an attached slide gate
pattern intended to recover zones of segregated material in a
to start/stop material flow and a guide cylinder to direct
known sequence. Specimens are collected from the discharge
discharging particles to the lower hopper. The outer hopper
stream.
also has support legs, which mate to the lower hopper
4.4 The specimens are then available to be tested for
assembly.
differences relevant to the application, for example, particle
6.2.1 The inner hopper has a steep conical section made of
size or chemical assay.
metal or plastic and is designed to sit within the upper outer
hopper and to provide mass flow for most bulk solids.
5. Significance and Use
6.2.2 The outer hopper has a conical section made of metal
5.1 Sifting segregation can cause horizontal segregation (for
or plastic and is designed to provide funnel flow for most bulk
example, center-to-periphery) within bins used to hold and
solids.
transport bulk solids. This can affect final product quality or
6.2.2.1 Transparent plastic should be used to construct the
subsequent processes in industrial applications.
inner and outer hoppers when observations of particle flow are
desirable.
5.2 By measuring a bulk solid’s segregation tendency, one
6.2.2.2 The slide gate, when open, shall have an opening
can compare results to other bulk solids with known history, or
size matching the opening size of the bottom of the outer
determine if the given bulk solid may have a tendency to
hopper.
segregate in a given process.
NOTE 2—Although only the inner hopper is used to contain the bulk
5.3 Sifting, which is a process by which smaller particles
solid being tested, placing this hopper inside the outer hopper provides a
move through a matrix of larger ones, is a common method of means to locate and support it, as well as a means to fill and empty the
hopper (by using the slide gate). In addition, this outer hopper can be used
segregation. Four conditions must exist for sifting to occur:
for alternate test procedures that involve recycling material to and from a
5.3.1 A Difference in Particle Size between the Individual
hopper of similar type. In this case a second inner hopper is also required.
Components—This ratio can be as low as 1.3 to 1. In general,
6.3 A lower hopper assembly consisting of a second outer
the larger the ratio of particle sizes, the greater the tendency for
hopper. This outer hopper provides support for the upper
particles to segregate by sifting.
hopper assembly, has an attached slide gate to start/stop
5.3.2 A Suffıciently Large Mean Particle Size—Sifting seg-
material flow, and a guide cylinder for dispensing material into
regation can occur with a mean particle size in the 50 µm range
collecting cups. The outer hopper also h
...

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.
Designation: D6940 − 18 D6940/D6940M − 20
Standard Practice for
Measuring Sifting Segregation Tendencies of Bulk Solids
This standard is issued under the fixed designation D6940;D6940/D6940M; 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 practice covers an apparatus and procedure for simulating the segregation tendencies of bulk solids by means of the
sifting mechanism.
1.2 Temperature- and humidity-sensitive bulk solids may need to be tested at different temperatures and moisture contents, as
would happen in an industrial environment.
1.3 The maximum particle size should be limited to 3 mm, mm [ ⁄8 in.], to reduce the likelihood of binding the slide gate.
1.4 This standard is not applicable to all bulk solids and segregation mechanisms: while sifting is a common segregation
mechanism experienced by many bulk solids, other segregation mechanisms not evaluated by this standard might induce
segregation in practice. Practice D6941 covers another common mechanism: fluidization.
1.5 The extent to which segregation will occur in an industrial situation is not only a function of the bulk solid and its tendency
to segregate, but also the handling equipment (for example, bin design), process (for example, transfer rates), and environment.
1.6 Units—The values stated in either SI units or inch-pound units are to be regarded as standard. No other units of measurement
are included in this separately as standard. The values stated in each system may not be exact equivalents; therefore, each system
shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
1.7 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice
D6026.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.10 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:
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
D6026 Practice for Using Significant Digits in Geotechnical Data
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 June 1, 2018Jan. 1, 2020. Published July 2018January 2020. Originally approved in 2003. Last previous edition approved in 20102018 as
D6940–10.–18. DOI: 10.1520/D6940-18.10.1520/D6940_D6940M-20.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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
D6940/D6940M − 20
D6941 Practice for Measuring Fluidization Segregation Tendencies of Powders
3. Terminology
3.1 Definitions:
3.1.1 For common definitions of terms in this standard, refer to Terminology D653.
3.1 Definitions:
3.1.1 For common definitions of terms in this standard, refer to Terminology D653.
3.1.2 funnel flow pattern, n—in storing, handling and processing bulk solids using industrial equipment, a flow sequence in a
bin or hopper characterized by having some particles moving while other particles are stagnant during discharge.
3.1.3 mass flow pattern, n—in storing, handling and processing bulk solids using industrial equipment, a flow sequence in a bin
or hopper characterized by having all particles moving when discharge occurs.
3.1.4 sifting segregation, n—in storing, handling and processing bulk solids using industrial equipment, a mechanism in which
finer particles preferentially percolate into a zone within the bulk solid.
4. Summary of Practice
4.1 A representative sample of a bulk solid is placed in the upper hopper of the apparatus.
4.2 The bulk solid is discharged to form a pile within the lower hopper, allowing segregation to take place.
4.3 The segregated material is discharged in a funnel flow pattern intended to recover zones of segregated material in a known
sequence. Specimens are collected from the discharge stream.
4.4 The specimens are then available to be tested for differences relevant to the application, for example, particle size or
chemical assay.
5. Significance and Use
5.1 Sifting segregation can cause horizontal segregation (for example, center-to-periphery) within bins used to hold and
transport bulk solids. This can affect final product quality or subsequent processes in industrial applications.
5.2 By measuring a bulk solid’s segregation tendency, one can compare results to other bulk solids with known history, or
determine if the given bulk solid may have a tendency to segregate in a given process.
5.3 Sifting, which is a process by which smaller particles move through a matrix of larger ones, is a common method of
segregation. Four conditions must exist for sifting to occur:
5.3.1 A Difference in Particle Size between the Individual Components—This ratio can be as low as 1.3 to 1. In general, the
larger the ratio of particle sizes, the greater the tendency for particles to segregate by sifting.
5.3.2 A Suffıciently Large Mean Particle Size—Sifting segregation can occur with a mean particle size in the 50 μm range and
can become a dominant segregation mechanism if the mean particle size is above 100 μm.
5.3.3 Suffıciently Free Flowing Material—This allows the smaller particles to sift through the matrix of larger particles. With
cohesive materials, the fine particles are bound to one another and do not enter the voids among the coarse particles.
5.3.4 Interparticle Motion—This can be caused during formation of a pile, by vibration, or by a velocity gradient across the
flowing material.
5.4 All four of these conditions must exist for sifting segregation to occur. If any one of these conditions does not exist, the
material will not segregate by this mechanism.
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.
6. Apparatus
6.1 The apparatus is shown in Fig. 1, and all critical dimensions are specified in Fig. 2. The apparatus consists of the following:
6.2 An upper hopper assembly consisting of an inner hopper seated within an outer hopper. This outer hopper hopper, which
provides support for the inner hopper, and has a hopper has an attached slide gate to start/stop material flow. flow and a guide
cylinder to direct discharging particles to the lower hopper. The outer hopper also has support legs, which mate to the lower hopper
assembly.
6.2.1 The inner hopper has a steep conical section made of metal or plastic and is designed to sit within the upper outer hopper
and to provide mass flow for most bulk solids.
6.2.2 The outer hopper has a conical section made of metal or plastic
...