ASTM D7486-14

Standard Test Method for Measurement of Fines and Dust Particles on Plastic Pellets by Wet Analysis

SIGNIFICANCE AND USE
5.1 Molding and extruding plastic pellets require dust free, dry pellets to prevent processing problems. Plastic producers try to remove the dust and streamers with dust removal systems prior to packaging and loading. How to accurately measure dust and streamer content in plastic pellets is an important quality control issue.  
5.2 Particle size analysis is used to determine a percentage of particle size distribution from a representative sample of the whole. In terms of size analysis concerning plastic pellets, sieving is used to determine the dust content in the range of 500 to 2000 micron. Test Method D1921, Test Method B, is used to determine this type of particle sizing.  
5.3 After dry sieve analysis, particles smaller than 500 microns need to be analyzed by wet method. A fresh sample shall be used for wet analysis. This test method allows washing down the fines attached to the pellets by electrostatic forces.  
5.4 The wet analysis provides accurate quantification of small to large amounts of fines, negating static effects, and eliminating detrimental effects of mechanical agitation. A wet analysis must be employed to accurately quantify lower PPM dust levels in plastic pellets.
SCOPE
1.1 This test method measures the amount of fine particles adhered on plastic pellets or granules in which they are commonly produced and supplied. The lower limit of this test method is restricted only by the porosity of the filter disc used to capture the particle size being quantified.  
1.2 The wet analysis technique allows for separation and collection of statically charged particles by liquid wash and filtration methods. This must be performed under standard laboratory conditions.  
1.3 The values stated in SI units are to be regarded as standard.  
1.4 This test method describes an essential practice to check the quality of plastics once the production cycle is terminated and to evaluate the performance of pellet cleaning systems or of the special pneumatic conveying systems for the distinct size fractions below 500 micron only.  
1.5 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.
Note 1: There is no known ISO equivalent to this standard.

General Information

• Status: Historical
• Publication Date: 31-Jul-2014
• ICS: 83.140.99 - Other rubber and plastics products
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.70 - Analytical Methods

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: D7486 − 14
Standard Test Method for
Measurement of Fines and Dust Particles on Plastic Pellets
1
by Wet Analysis
This standard is issued under the fixed designation D7486; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
3
1. Scope* 2.2 FEM Standards:
FEM2482Test Method to Determine Content of Fines and
1.1 This test method measures the amount of fine particles
Streamers in Plastic Pellets.
adhered on plastic pellets or granules in which they are
commonly produced and supplied. The lower limit of this test
3. Terminology
method is restricted only by the porosity of the filter disc used
3.1 Definitions—For definitions of terms associated with
to capture the particle size being quantified.
plastic materials, see Terminology D883.
1.2 The wet analysis technique allows for separation and
3.2 Definitions of Terms Specific to This Standard:
collection of statically charged particles by liquid wash and
3.2.1 fines—fines (Dust) are small particles of plastic which
filtration methods. This must be performed under standard
have been torn away from the original pellet by contact with a
laboratory conditions.
rough surface and friction at high conveying velocities. They
1.3 The values stated in SI units are to be regarded as
are defined as the particle fraction with a particle size up to
standard.
2000 µm.
1.4 Thistestmethoddescribesanessentialpracticetocheck
3.2.2 streamers—strings of plastics of various lengths that
the quality of plastics once the production cycle is terminated
are created when the resin travels through pneumatic convey-
and to evaluate the performance of pellet cleaning systems or
ing lines at high velocity. Streamers are also known as angel
ofthespecialpneumaticconveyingsystemsforthedistinctsize
hair, foil, floss, film or snake skin.
fractions below 500 micron only.
4. Summary of Test Method
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 Fines or streamers, or both, are generated in polymer
responsibility of the user of this standard to establish appro-
resins during pneumatic conveying. Fines and streamers are
priate safety and health practices and determine the applica-
known to cause problems in plastic producing and processing
bility of regulatory limitations prior to use.
plants by clogging the transporting and procession lines. On
finished products, fines cause the formation of gel,
NOTE 1—There is no known ISO equivalent to this standard.
contamination, surface imperfection and weak spots.
2. Referenced Documents
4.2 The streamer content for a particle size considerably
2
largerthanthepelletdiameteraredeterminedbydryscreening
2.1 ASTM Standards:
D883Terminology Relating to Plastics according to Test Method D1921.
D1921Test Methods for Particle Size (Sieve Analysis) of
4.3 The fundamental principle used in this document is
Plastic Materials
based upon the condition that statically charged fines normally
E11Specification forWovenWireTest Sieve Cloth andTest
adhering to plastic pellets be removed by rinsing the test
Sieves
sample with a washing liquid, causing fines in the sample to
wash away into a container. These particles are then poured
intoafilterfunneltoseparatethefinesfromthewashingliquid.
1
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics The weight of the filter paper is accurately measured before
and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
and after the collection process, and used to calculate the PPM
Current edition approved Aug. 1, 2014. Published September 2014. Originally
level for that sample.
ϵ1
approved in 2008. Last previous edition approved in 2013 as D7486 - 08(2013) .
DOI:10.1520/D7486-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM AvailablefromEuropeanFederationofMaterialsHandling,DiamantBuilding,
Standards volume information, refer to the standard’s Document Summary page on 80BoulevardAugusteReyersB,1030Brussels,Belgium,http://www.fem-eur.com.
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 ----------------------
D7486 − 14
TABLE 1 Comparison of Typical Particle Sizes Measured
7. Apparatus
Type Lower Limit Upper Limit Test Method
7.1 The function of the apparatus (see Fig. 1) is to separate
D1921 500 µm 2000 µm dry
A
all fines below 500 micron from the pellet
...

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: D7486 − 08 (Reapproved 2013) D7486 − 14
Standard Test Method for
Measurement of Fines and Dust Particles on Plastic Pellets
1
by Wet Analysis
This standard is issued under the fixed designation D7486; 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
ε NOTE—Reapproved with editorial changes to Section 3 in November 2013.
1. Scope Scope*
1.1 This test method measures the amount of fine particles adhered on plastic pellets or granules in which they are commonly
produced and supplied. The lower limit of this test method is restricted only by the porosity of the filter disc used to capture the
particle size being quantified.
1.2 The wet analysis technique allows for separation and collection of statically charged particles by liquid wash and filtration
methods. This must be performed under standard laboratory conditions.
1.3 The values stated in SI units are to be regarded as standard.
1.4 This test method describes an essential practice to check the quality of plastics once the production cycle is terminated and
to evaluate the performance of pellet cleaning systems or of the special pneumatic conveying systems for the distinct size fractions
below 500 micron only.
1.5 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.
NOTE 1—There is no known ISO equivalent to this standard.
2. Referenced Documents
2
2.1 ASTM Standards:
D883 Terminology Relating to Plastics
D1921 Test Methods for Particle Size (Sieve Analysis) of Plastic Materials
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
3
2.2 FEM Standards:
FEM 2482 Test Method to Determine Content of Fines and Streamers in Plastic Pellets.
3. Terminology
3.1 Definitions—For definitions of terms associated with plastic materials, see Terminology D883.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 fines—fines (Dust) are small particles of plastic which have been torn away from the original pellet by contact with a rough
1
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.70 on Analytical Methods.
Current edition approved Nov. 1, 2013Aug. 1, 2014. Published December 2013September 2014. Originally approved in 2008. Last previous edition approved in 20082013
ϵ1
as D7486 - 08.08(2013) DOI:10.1520/D7486-08R13. DOI:10.1520/D7486-14.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Available from European Federation of Materials Handling, Diamant Building, 80 Boulevard Auguste Reyers B, 1030 Brussels, Belgium, http://www.fem-eur.com.
TABLE 1 Comparison of Typical Particle Sizes Measured
Type Lower Limit Upper Limit Test Method
D1921 500 μm 2000 μm dry
A
D7486 1.6 μm 500 μm wet
A
The lower limit is set by the porosity of the filter disk.
*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 ----------------------
D7486 − 14
surface and friction at high conveying velocities. They are defined as the particle fraction with a particle size up to 2000 μm.
3.2.2 streamers—strings of plastics of various lengths that are created when the resin travels through pneumatic conveying lines
at high velocity. Streamers are also known as angel hair, foil, floss, film or snake skin.
4. Summary of Test Method
4.1 Fines or streamers, or both, are generated in polymer resins during pneumatic conveying. Fines and streamers are known
to cause problems in plastic producing and processing plants by clogging the transporting and procession lines. On finished
products, fines cause the formation of gel, contamination, surface imperfection and weak spots.
4.2 The streamer content for a particle size considerably larger than the pellet diameter are determined by dry screening
according to Test Method D1921.
4.3 The fundamental prin
...