ASTM_D_7486_-_14.pdf

Designation:D748614Standard Test Method forMeasurement of Fines and Dust Particles on Plastic Pelletsby Wet Analysis1This standard is issued under the fixed designation D7486;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 test method measures the amount of fine particlesadhered on plastic pellets or granules in which they arecommonly produced and supplied.The lower limit of this testmethod is restricted only by the porosity of the filter disc usedto capture the particle size being quantified.1.2 The wet analysis technique allows for separation andcollection of statically charged particles by liquid wash andfiltration methods.This must be performed under standardlaboratory conditions.1.3 The values stated in SI units are to be regarded asstandard.1.4 This test method describes an essential practice to checkthe quality of plastics once the production cycle is terminatedand to evaluate the performance of pellet cleaning systems orof the special pneumatic conveying systems for the distinct sizefractions below 500 micron only.1.5 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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1921 Test Methods for Particle Size(Sieve Analysis)ofPlastic MaterialsE11 Specification for Woven Wire Test Sieve Cloth and TestSieves2.2 FEM Standards:3FEM 2482 Test Method to Determine Content of Fines andStreamers in Plastic Pellets.3.Terminology3.1 DefinitionsFor definitions of terms associated withplastic materials,see Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 finesfines(Dust)are small particles of plastic whichhave been torn away from the original pellet by contact with arough surface and friction at high conveying velocities.Theyare defined as the particle fraction with a particle size up to2000 m.3.2.2 streamersstrings of plastics of various lengths thatare created when the resin travels through pneumatic convey-ing lines at high velocity.Streamers are also known as angelhair,foil,floss,film or snake skin.4.Summary of Test Method4.1 Fines or streamers,or both,are generated in polymerresins during pneumatic conveying.Fines and streamers areknown to cause problems in plastic producing and processingplants by clogging the transporting and procession lines.Onfinishedproducts,finescausetheformationofgel,contamination,surface imperfection and weak spots.4.2 The streamer content for a particle size considerablylarger than the pellet diameter are determined by dry screeningaccording to Test Method D1921.4.3 The fundamental principle used in this document isbased upon the condition that statically charged fines normallyadhering to plastic pellets be removed by rinsing the testsample with a washing liquid,causing fines in the sample towash away into a container.These particles are then pouredinto a filter funnel to separate the fines from the washing liquid.The weight of the filter paper is accurately measured beforeand after the collection process,and used to calculate the PPMlevel for that sample.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Aug.1,2014.Published September 2014.Originallyapproved in 2008.Last previous edition approved in 2013 as D7486-08(2013)1.DOI:10.1520/D7486-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from European Federation of Materials Handling,Diamant Building,80 Boulevard Auguste Reyers B,1030 Brussels,Belgium,http:/www.fem-.*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 4.4 Wet analysis quantifies the amounts of dust with particlesizes typically from 1.6 to 500 microns.5.Significance and Use5.1 Molding and extruding plastic pellets require dust free,dry pellets to prevent processing problems.Plastic producerstry to remove the dust and streamers with dust removal systemsprior to packaging and loading.How to accurately measuredust and streamer content in plastic pellets is an importantquality control issue.5.2 Particle size analysis is used to determine a percentageof particle size distribution from a representa