# ASTM F660-83 (Reapproved 2013)

Designation: F660 − 83 (Reapproved 2013)Standard Practice forComparing Particle Size in the Use of Alternative Types ofParticle Counters1This standard is issued under the fixed designation F660; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon (´) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice provides a procedure for comparing thesizes of nonspherical particles in a test sample determined withdifferent types of automatic particle counters, which operate ondifferent measuring principles.1.2 A scale factor is obtained by which, in the examinationof a given powder, the size scale of one instrument may bemultiplied to agree with the size scale of another.1.3 The practice considers rigid particles, free of fibers, ofthe kind used in studies of filtration, such as: commerciallyavailable test standards of quartz or alumina, or fly ash, orsome powdered chemical reagent, such as iron oxide orcalcium sulfate.1.4 Three kinds of automatic particle counters are consid-ered:1.4.1 Image analyzers, which view stationary particles un-der the microscope and, in this practice, measure the longestend-to-end distance of an individual particle.1.4.2 Optical counters, which measure the area of a shadowcast by a particle as it passes by a window; and1.4.3 Electrical resistance counters, which measure the vol-ume of a particle as it passes through an orifice in anelectrically conductive liquid.1.5 This practice also considers the use of instruments thatprovide sedimentation analyses, which is to say providemeasures of the particle mass distribution as a function ofStokes diameter. The practice provides a way to convert massdistribution into number distribution so that the meaning ofStokes diameter can be related to the diameter measured by theinstruments in 1.4.1.6 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:2F661 Practice for Particle Count and Size Distribution Mea-surement in Batch Samples for Filter Evaluation Using anOptical Particle Counter (Discontinued 2000) (Withdrawn2000)3F662 Test Method for Measurement of Particle Count andSize Distribution in Batch Samples for Filter EvaluationUsing an Electrical Resistance Particle Counter (Discon-tinued 2002) (Withdrawn 2002)3F796 Practice for Determining The Performance of a FilterMedium Employing a Single-Pass, Constant-Pressure,Liquid Test (Withdrawn 2002)33. Summary of Practice3.1 After calibrating an automatic particle counter withstandard spherical particles, such as latex beads, the instrumentis presented with a known weight of filtration-test particlesfrom which is obtained the data: cumulative number ofparticles, ∑ N, as a function of particle diameter, d; and a plotof these data is made on log-log paper.3.2 The plot from the results of one kind of instrument isplaced over the plot from another and one plot is moved alongthe particle-diameter axis until the two separate curves coin-cide. (If the two separate curves cannot be made to coincide,then this practice cannot be used.)3.3 The magnitude of the shift from one diameter scale tothe other provides the scale-conversion factor.3.4 Any of the three particle counters in 1.4 can provide theframe-of-reference measurement of particle diameter.3.5 An alternative reference is the Stokes diameter, asmentioned in 1.5.4. Significance and Use4.1 This practice supports test methods designed to evaluatethe performance of fluid-filter media, for example, Practice1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,and Open-Channel Flow.Current edition approved Jan. 1, 2013. Published January 2013. Originallyapproved in 1983. Last previous edition approved in 2007 as F660 – 83 (2007).DOI: 10.1520/F0660-83R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at service@astm.org. For Annual Book of ASTMStandards volume information, refer to the standard’s Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1F796 wherein particle size distributions are addressed and atthe same time this practice provides a means to compare sizemeasurements obtained from several different types of instru-ments.4.2 The factor for converting one kind of diameter scale toanother is only valid for the specific test particles studied.5. Apparatus5.1 Automatic Particle Counters :5.1.1 Any, or all, of the three types are employed:5.1.1.1 The Image Analyzer—This instrument counts par-ticles by size as those particles lie on a microscope slide. In thispractice, size means the longest end-to-end distance. Thisdiameter, in the examples to follow, is designated de.5.1.1.2 The Optical Counter—This instrument measures thearea of a shadow cast by a particle as it passes a window. Fromthat area the instrument reports the diameter of a circle of equalarea. This diameter is designated do. See Practice F661.5.1.1.3 The Electrical Resistance Counter— This instru-ment measures the volume of an individual particle. From thatvolume the instrument reports the diameter of a sphere of equalvolume. This diameter is designated dv. See Method F662.5.2 Sedimentation Instruments—These instruments providea measure of the mass distribution of particles (as opposed tothe number distributions determined in 5.1). This diameter, theStokes diameter, is designated ds.6. Procedure6.1 Calibrate each particle counter with standard, sphericalparticles, following the instructions of the manufacturer of thecounter.6.2 Present a known mass of particles to the counter. That is,with the image analyzer present a known mass of particles toa field of view; and, with the other counters present a liquidsuspension with a known mass concentration of particles.6.3 In counting particles at the small-diameter end of thespectrum, present at least three different, relatively small,masses of particles. In counting particles at the large-diameterend, present at least three different, relatively large, masses.6.4 After obtaining the counts (6.3) correct them all toreflect the count of a common mass. For example, correct allcounts to show particle distribution for each milligram ofsolids. Plot the counts in the manner of Fig. 1.6.5 From these plots select the true number distribution;show it as a solid line as shown in Fig. 1.NOTE 1—It is important to deduce the optimum raw count to look forduring the examination of a liquid where the mass concentration ofparticles is not known. The manufacturers of each counter specify themaximum count per unit volume of liquid that is meaningful. If the countexceeds this maximum limit, dilute the sample with clean liquid. (Cleanliquid means that where the particle count is less than 10 %, or preferablyless than 1 %, of the sample count.) Alternatively, if the sample shows acount so low that a meaningful count of large particles is not obtained,examine a larger sample.6.6 Compare the Fig. 1 type plot obtained with one particlecounter to the plot(s) made from another counter (or othercounters). Follow the example of Fig. 2.6.7 Now, choose one counter to provide the frame-of-reference measure of diameter. Relate other diameter scales to^N = cumulative number of particles per unit mass of powderd = particle diameter (see 5.1)The solid line represents the “real” count. The broken lines represent failuresto obtain correct counts because of either presenting too many particles to thecounter, a, or of presenting too few, b.FIG. 1 Example of Particle Counts^N = cumulative number of particles per unit mass of powderd = particle diameter, µm (see 5.1)FIG. 2 Example of a Blend of Particle Counts Obtained with Dif-ferent CountersF660 − 83 (2013)2that “standard.” For example, if from the present example ofFig. 2, the descale is the standard, then,de5 1.30 do(1)andde5 1.72 dv(2)ordo5 0.769 de(3)anddv5 0.581 de(4)6.8 In those cases where measurements of particle-sizedistribution are based on mass (rather than number), in Fig. 3,convert the Fig. 3 type data to Fig. 1 type data by the followingtechnique:6.8.1 Divide the diameter scale of Fig. 3 into portions sothat there are ten equally wide portions per decade. That is, oneportion will be in the diameter scale of 1.00 to 1.26 µm, thenext will be in the range 1.26 to 1.59 µm, etc. That is to say,follow the example in Method F662, where the factor of 1.26is, in fact, the cube root of 2, that is, 1.25992.6.8.2 Replot the Fig. 3 data to obtain the ∑W curve and the∆W bar chart of Fig. 4.6.8.3 Now, since the diameter scale has been divided intoportions where for an equal weight of particles in two adjacentdiameter ranges the smaller range will contain twice as manyparticles, employ this 2.0 factor to convert the ∆W bar chartinto the ∆N bar chart; then subsequently draw the ∑N curve.6.9 Superimpose the ∑N curve of Fig. 4 over the curves ofFig. 2, to obtain, in the present example, Fig. 5. See, from Fig.5, thatde5 1.60 ds(5)ords5 0.625 de(6)7. Precision7.1 The examples presented here to explain this practice areresults of actual work where different investigators, usingdifferent instruments, examined a common lot of quartz testdust.47.2 Fig. 6 shows the agreement achieved among threeinvestigators, each of whom employed an electrical resistancecounter; Fig. 7 shows the agreement among three investigatorswho employed optical counters.7.3 While the factors reported in 6.7 and 6.9 (for convertingone diameter scale to another) are shown as three significantfigures, such implied precision is not justified by the presentdata.7.4 From the blend of data in Fig. 5 it is obvious that suchconversion factors are valid only over a finite range of particlediameters, depending on which instruments are involved.8. Keywords8.1 particle counters; Strokes diameter4Johnston, P. R., and Swanson, R. R., “A Correlation Between the Results ofDifferent Instruments Used to Determine the Particle-Size Distribution in AC FineTest Dust,” Powder Technology, Vol 32, No. 1, pp. 119–124.^W = cumulative mass of particles per unit mass of powderds= Stokes diameter of a particle, µmFIG. 3 Example of a Particle-Size Distribution Obtained by Sedi-mentation Analysis^W = cumulative mass of particles per unit mass of powder, from Fig. 3∆W = mass fraction of particles in each diameter range (deduced from ^W)∆N = relative number of particles in each diameter range (deduced from ∆W)^N = cumulative number of particlesds= Stokes diameter of particles, µmFIG. 4 Example of Converting a Weight Distribution into a Num-ber DistributionF660 − 83 (2013)3^N = cumulative number of particles per unit mass of test powderds= Stokes diameter, µmdv= diameter of sphere of equal volumede= longest end-to-end distancedo= diameter of circle of equal areaFIG. 5 Blend of Fig. 2 and the ^ N Curve of Fig. 4^N = cumulative number of particles per millilitre in a slurry containing 5 mg/Ldv= particle diameter, µm, when instrument is calibrated with standard latex beadsFIG. 6 Particle-Size Distribution in Lot 121 of AC Fine Test Dustas Determined by Three Separate Investigators, in DifferentLaboratories, Each Employing an Electrical Resistance CounterF660 − 83 (2013)4ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or service@astm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/^N = cumulative number of particles per millilitre in a slurry containing 5 mg/Ldo= particle diameter, µm, when instrument is calibrated with standard latex beadsFIG. 7 Particle-Size Distribution in Lot 121 of AC Fine Test Dustas Determined by Three Separate Investigators, in DifferentLaboratories, Each Employing an Optical Particle CounterF660 − 83 (2013)5