1、Designation: D2589/D2589M 88 (Reapproved 2011)1Standard Test Method forMcNett Wet Classification of Dual Asbestos Fiber1This standard is issued under the fixed designation D2589/D2589M; the number immediately following the designation indicates theyear of original adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEUnits information was editorially corrected in February 2012.1. Scope1.1 This test method covers the determina
3、tion of the lengthdistribution and fines content of milled asbestos fiber by wetclassification employing the McNett fiber classifier.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; th
4、erefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.3 WarningBreathing of asbestos dust is hazardous.Asbestos and asbestos products present demonstrated healthrisks for users and for those with whom they
5、come into contact.In addition to other precautions, when working with asbestos-cement products, minimize the dust that results. For informa-tion on the safe use of chrysotile asbestos, refer to “Safe Use ofChrysotile: A Manual on Preventive and Control Measures.”21.4 This standard does not purport t
6、o 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:3D2590 Te
7、st Method for Sampling Chrysotile AsbestosD2946 Terminology for Asbestos and AsbestosCementProductsD3639 Test Method for Classification of Asbestos by Que-bec Standard TestD3879 Test Method for Sampling Amphibole Asbestos4E11 Specification for Woven Wire Test Sieve Cloth and TestSievesE177 Practice
8、for Use of the Terms Precision and Bias inASTM Test Methods2.2 ASTM Adjunct:Screen Clearing Device Drawings53. Terminology3.1 DefinitionsTerms relating to asbestos are defined inTerminology D2946.4. Significance and Use4.1 Normally, results obtained by this test method arereproducible under comparab
9、le laboratory conditions. How-ever, it must not be expected that results obtained by differentoperators at various laboratories and times will be in exactagreement due to some seemingly minor procedural change.Moreover, results for longer fiber grades are influenced to agreater extent by differences
10、 in fiber length distribution andcharacteristics than those of shorter grades.5. Apparatus5.1 McNett Fiber Classifier (such as 203-A or 203-CA),6preferably equipped with vacuum suction cups for drainage,similar in design to that shown in Fig. 1, or on page 7 of theService Manual 203-CA(see service m
11、anuals for identificationof classifiers parts).NOTE 1Drainage through muslin filter cloths or 200-mesh sieve(325-mesh for float products) is acceptable.5.2 Accessories:5.2.1 Filter paper, to fit suction cups on classifier. This shallbe thin, rapid filtering, ashless paper hardened to provide1This te
12、st method is under the jurisdiction of ASTM Committee C17 onFiber-Reinforced Cement Products and is the direct responsibility of SubcommitteeC17.03 on Asbestos - Cement Sheet Products and Accessories.Current edition approved Nov. 1, 2011. Published February 2012. Originallyapproved in 1967. Last pre
13、vious edition approved in 2006 as D2589 88 (2006)1.DOI: 10.1520/D2589_D2589M-88R11E01.2Available from The Asbestos Institute, http:/ referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume informatio
14、n, refer to the standards Document Summary page onthe ASTM website.4Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.5Available from ASTM International Headquarters. Order Adjunct No.ADJD2589. Original adjunct produced in 1967.6Currently supplied classifi
15、er Model 203-CA and service manuals for theinstallation, operation and maintenance of Models 203-A and 203-CA are availablefrom the Bauer Bros. Co. Ltd., Brantford, ON, Canada, or Springfield, OH.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Uni
16、ted States.adequate wet strength and resistance to washing. Alternatively,325-mesh screen cloths mounted in suitable metal rings mayreplace filter papers (see Note 5 in 11.5.4).5.2.2 T-Shaped Soft Rubber Scraper, for cleaning screens,made from a 10-cm 4-in. length of automobile windshieldwiper, or e
17、quivalent, held in a suitable handle, similar to a hoe.5.2.3 Rubber Hose, 6-mm 14-in. bore with control valvenozzle for rinsing classifier screens and tanks with filteredwater.5.2.4 Drying Oven, (convection type, or mechanical draft),or infrared drying unit.5.2.5 Automatic Overflow Alarm, as shown i
18、nAppendix X1.5.2.6 Optional Accessory, Automatic clearing device on thefourth tank, as shown in Appendix X1 (see Note 3 in 11.5.4).5.3 Water SupplyProvide a suitable filtering device on thewater supply to ensure a constant flow of clean water to theclassifier and rinsing hose.6. Sampling6.1 Select s
19、amples in accordance with Test Method D2590for chrysotile or Test Method D3879 for amphibole fibers asdefined in Terminology D2946. Duplicate specimens shall betested. (WarningSee 1.3.)7. Test Specimen, Screen Sizes, and Test Duration7.1 Relationships between the type of specimen, screensizes, masse
20、s, and duration of test may be found in Table 1.FIG. 1 Suction CupTABLE 1 Screen Size, Test Specimen and Duration RelationshipsTest Specimen, QAMAAFiber GroupScreen Sizes,SI openings Tyler mesh/in.Specimen Mass, g Duration ofTest, min3, 4, 5, 6 and 7D 476, 119, 420 m, 74 m 10 6 0.05 204, 14, 35, 200
21、Other Group 7 fibers 119, 420 m, 199 m, 74 m 20 6 0.05 2014, 35, 100, 200“Floats” 177 m, 44 m 20 6 0.05 3080, 325AQuebec Asbestos Mining Association (QAMA) standard designation of chrysotile asbestos grades.D2589/D2589M 88 (2011)127.2 For reference, Tyler, U.S. Standard and British Standardequivalen
22、t sieves are listed in Table 2.7.3 Screen cloth must be double-lock, double-crimp style,with the warp in the horizontal direction, and it must conformto Specification E11.8. Procedure8.1 Select screens specified for the fiber grade being testedand set in place, making certain that the baffle plates
23、are in theirslots behind the screens. If the fiber grade is unknown, refer toTest Method D3639.8.2 Insert the rubber stoppers, and fill the tanks with water.8.3 Start the agitators to rotate at 540 6 40 r/min and adjustthe water valve to give a flow slightly in excess of 0.19 L/s 3.0U.S. gal/min. Th
24、is rate of flow is achieved when the overflowfrom the constant head tank is pencil-size.8.4 Add the test specimen to 800 cm3of water in a 1000-mLbeaker and stir until the asbestos is thoroughly dispersed.8.5 Pour the slurry into the first tank (tank with coarsestscreen mesh) and wash out any fiber r
25、esidue in the beaker withclean, filtered water. Set the timer for 20 or 30 min, dependingupon the sample under test, as given in Table 1.8.6 During the operation, center the filter papers, previouslyweighed to the nearest 0.01 g at equilibrium with roomconditions, in suction cups on the supporting s
26、creen. Mark theweight of the filter paper, sample designation, classifier screenmesh, and other pertinent data around the outside edge of eachfilter paper with a soft black pencil before inserting into thesuction cup, placing the writing against the supporting screen.Wet the filter paper and clamp i
27、nto position.8.7 Close the main vacuum valve and open each suction cupvalve.NOTE 2It is advantageous to perform the above two steps during thetime in which the classifier tanks are initially being filled.8.8 Watch screens carefully during the test, and if any tankappears to overflow, clean the scree
28、n surface with a soft rubberscraper.8.9 At the end of the test period, stop the impellers, shut offthe water, and open the main vacuum valve until a vacuum ofapproximately 1 kPa 4 in. of water gage is attained. Removethe drain plugs from each tank, and progressively increase thevacuum to the maximum
29、 desired. Failure to perform thisoperation slowly, or to remove all the drain plugs before anyone tank is completely drained, may cause rupture of the filterpapers.8.10 During draining, remove the screens and place them intheir respective tanks. Immediately after a tank has beencompletely drained, c
30、arefully wash the screen and tank usingthe rinsing hose to ensure that all remaining fiber, includingentrapped fiber and particles deposited behind the screen, arewashed into the suction cup.8.11 When all the fiber in a tank is deposited into the suctioncup, and the cup itself has drained, close the
31、 cup valve. Failureto close the cup valve after washing down and emptying thetank causes atmospheric air to enter the vacuum system andsubstantially lowers the vacuum of the system.8.12 After closing the cup valve, open the cup and removethe filter paper with its classified specimen fraction, and dr
32、y toconstant mass at 105 to 110C 220 to 230F under an infraredunit, or in a drying oven.8.13 After all the fractions are dried and allowed to return toequilibrium with room conditions, weigh each paper andfraction together. Obtain the net weight of the specimenfraction by subtracting the initial mas
33、s of the filter paper andrecord as a percentage. The amount of minus 200 mesh orminus 325 mesh in the original specimen is calculated bysubtracting the cumulative weight of the fractions retained onthe filter papers from the original mass of the specimen (seeNote 6 concerning crudy fibers).9. Interp
34、retation of Results9.1 A typical example of a Group 5 fiber wet classificationtest (10-g specimen, 20-min test duration) with calculationsfollows:Screen SI opening(Tyler mesh)4.76 mm(4)1.19 mm(14)420 m(35)74 m(200)74 m(200)Mass retained, g 0.5 1.3 1.9 1.414 m200 mesh/in.10.0 0.5 + 1.3 + 1.9 + 1.4 =
35、4.9 gResults, % 5.0 13.0 19.0 14.0 49.010. Report10.1 Report the percentage of fiber retained on each screenand the percentage passing through the last screen. Fullyidentify the origin and description of the sample.11. Precision and Bias11.1 Repeatability:11.1.1 The intralaboratory single-operator,
36、single apparatusrepeatability is 60.9 g 0.03 oz (2S) obtained on any fraction,with Grade 4 fibers, as defined in Practice E177.11.1.2 The equivalent repeatability for Grade 7D fibers is60.6g60.02 oz.11.2 ReproducibilityReproducibility has not yet been es-tablished in accordance with the requirements
37、 of ASTM.TABLE 2 Sieve EquivalentsISO OpeningSITyler Series U.S. Standard British StandardMesh Opening Mesh Opening Mesh Openingin. mm in. in.1 mm in. in.1 mm in.4.76 4 4.699 0.185 4 4.76 0.187 . . .1.19 14 1.168 0.046 16 1.19 0.0469 14 1.20 0.0474420 m 35 0.417 0.0164 40 0.42 0.0165 36 0.42 0.01661
38、77 m 80 0.175 0.0069 80 0.177 0.0070 85 0.177 0.0070149 m 100 0.147 0.0058 100 0.149 0.0059 100 0.152 0.006074 m 200 0.074 0.0029 200 0.074 0.0029 200 0.076 0.003044 m 325 0.043 0.0017 325 0.044 0.0017 . . .D2589/D2589M 88 (2011)1311.3 Bias:11.3.1 Bias cannot be established on asbestos fibers for la
39、ckof a referee method. Bias associated with each of the sievesused may be determined as described in the appendixes toSpecification E11.11.3.2 It has been observed that the retention of fibers oneach sieve may be a function of the degree to which the screencloth is worn.11.4 If the corresponding ind
40、ividual percentages obtainedfor each screen fraction of the duplicate specimens differ bymore than five units of percentage, make a third test. Averagethe results of two acceptable tests and report the average.11.5 To obtain the desired accuracy, the following generalprecautions should be observed:1
41、1.5.1 It is important that all material be washed from thetanks into the suction cups; and that the filter papers arehandled with care.11.5.2 For better accuracy and reproducibility a water tem-perature of 21 6 10C 70 6 20F is recommended.11.5.3 New screens should be run in at least8htoconditionthem
42、 before they are put into regular use. When the classifieris not in use, the tanks should be kept full of water to preventdeposits from forming on screens.11.5.4 To obtain prescribed accuracy, screens should not becleaned during a classification, unless the tanks tend tooverflow. Test results may no
43、t be reproducible when screensare cleaned frequently and at irregular intervals during the test.NOTE 3At many laboratory locations, the use of an automatic clearingdevice on the fourth tank, similar to that shown in the appendix with themotor connected in series with the micro switch of the overflow
44、 alarm oron a separate switch, has been found to eliminate the necessity forcleaning the screen.NOTE 4At some laboratory locations, the use of stainless steel screencloth has been found to give reproducible results over a longer period oftime.NOTE 5When classifying very fine products, use filter pap
45、ers forbetter accuracy.NOTE 6In the case of crudy fibers, the classified fractions may beretained for examination and the percentage of crudy bundles and rockparticles determined by an approved method.11.6 The following precautions apply to Model 203-Aclassifiers only:11.6.1 Screens should be checke
46、d regularly (at least onceevery operating shift) for damage, holes, warped frames, etc.Likewise, the rubber gaskets should be examined and replacedif defective as this is frequently the cause of abnormal minus200 mesh results. The clamping screws should be turned tightenough to hold the screen plate
47、s firmly against the tank; but ifturned too tight, or not uniformly, the screen frames may bepermanently warped out of shape causing leakage past thegaskets.11.6.2 The normal agitator speed (540 6 40 r/min) shouldbe checked daily, and the belts should be inspected to preventslippage. The use of posi
48、tive traction belts and sprockets isrecommended.11.6.3 The equipment must be lubricated and maintained asdescribed in Service Manual 203-A.11.7 The following precautions apply to Model 203-CAclassifiers only:11.7.1 Screens should be checked regularly (at least onceper operating shift) for damage, ho
49、les, warped frames, etc.11.7.2 The equipment must be lubricated and maintained asdescribed in Service Manual 203-CA.12. Keywords12.1 asbestos; classification; fiber; fiber length distribution;McNett; wet; wet classificationAPPENDIX(Nonmandatory Information)X1. AUTOMATIC OVERFLOW ALARM AND CLEARING DEVICE FOR SCREENSX1.1 Fig. X1.1 illustrates a suitable method of mountingfloat switches to activate an automatic over
