ASTM_D_6941_-_12.pdf

Designation:D694112Standard Practice forMeasuring Fluidization Segregation Tendencies of Powders1This standard is issued under the fixed designation D6941;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This practice covers an apparatus and procedure forcreating several specimens of a powder sample that,if thepowder is one that segregates by the fluidization mechanism,should be different from one another.1.2 A powder sample is fluidized then,after the fluidizinggas is turned off,it is separated into three or more specimensthat can be analyzed for parameters of interest.The differencein these parameters between the specimens is an indication ofthe segregation potential of the powder.1.3 Powders must be capable of being fluidized in order tobe tested by this practice.1.4 Temperature-and moisture-sensitive powders may needto be tested at different temperatures and moisture contents,aswould happen in an industrial environment.1.5 This standard is not applicable to all bulk solids andsegregation mechanisms:while fluidization is a commonsegregation mechanism experienced by many fine powders,other segregation mechanisms not evaluated by this standardmight induce segregation in practice.Practice D6940 coversanother common mechanism:sifting.1.6 The extent to which segregation will occur in anindustrial situation is not only a function of the powder and itstendency to segregate,but also the handling equipment(forexample,bin design),process(for example,transfer rates),andenvironment.1.7 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.8 This practice offers a set of instructions for performingone or more specific operations.This document cannot replaceeducation or experience and should be used in conjunction withprofessional judgment.Not all aspects of this practice may beapplicable in all circumstances.This ASTM standard is notintended to represent or replace the standard of care by whichthe adequacy of a given professional service must be judged,nor should this document be applied without consideration ofa projects many unique aspects.The word Standard in the titleof this document means only that the document has beenapproved through the ASTM consensus process.1.9 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture)Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD6940 Practice for Measuring Sifting Segregation Tenden-cies of Bulk Solids3.Terminology3.1 Definitions:3.1.1 For common definitions of technical terms in thisstandard,refer to Terminology D653.3.1.2 fluidization,nin powders,the state in which apowder exhibits fluid-like properties.3.1.3 fluidization segregation,nin powders,a mechanismthat causes vertical segregation,that is,horizontal layering offine and coarse particles,as resulting from fluidization of thebulk solid.3.1.4 segregation,nin powders,a process through whichblended or uniform powders or bulk solids become non-uniform,with regions of varying composition,for example,particle size.3.2 Definitions of Terms Specific to This Standard:1This practice is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.24 on Characterizationand Handling of Powders and Bulk Solids.Current edition approved Nov.1,2012.Published December 2012.Originallyapproved in 2003.Last previous edition approved in 2005 as D6941051.DOI:10.1520/D6941-12.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandardsvolume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.1 high flow-rate,nin powders,the first stage flow-rateused to initiate fluidization.3.2.2 low flow-rate,nin powders,the second stage flow-rate used to maintain fluidization.3.2.3 representative sample,nin powders,a quantity ofthe bulk solid to be tested that is representative of that solid inan industrial application being studied.Parameters of interestthat may affect whether or no