1、Designation: D 2589 88 (Reapproved 2006)1Standard Test Method forMcNett Wet Classification of Dual Asbestos Fiber1This standard is issued under the fixed designation D 2589; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、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.1NOTESection 2 was corrected editorially in August 2009.1. Scope1.1 This test method covers the determination of the lengthdist
3、ribution and fines content of milled asbestos fiber by wetclassification employing the McNett fiber classifier.1.2 The values stated in SI units are the standard. Theinch-pound units shown in parentheses are provided for infor-mation only.1.3 WarningBreathing of asbestos dust is hazardous.Asbestos a
4、nd asbestos products present demonstrated healthrisks for users and for those with whom they 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 ofC
5、hrysotile: A Manual on Preventive and Control Measures.”21.4 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-bili
6、ty of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 2590 Test Method for Sampling Chrysotile AsbestosD 2946 Terminology for Asbestos and AsbestosCementProductsD 3639 Test Method for Classification of Asbestos byQuebec Standard TestD 3879 Test Method for Sampling Am
7、phibole AsbestosE11 Specification for Woven Wire Test Sieve Cloth andTest SievesE 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods2.2 ASTM Adjunct:Screen Clearing Device Drawings43. Terminology3.1 DefinitionsTerms relating to asbestos are defined inTerminology D 2946.4. Signi
8、ficance and Use4.1 Normally, results obtained by this test method arereproducible under comparable 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 c
9、hange.Moreover, results for longer fiber grades are influenced to agreater extent by differences in fiber length distribution andcharacteristics than those of shorter grades.5. Apparatus5.1 McNett Fiber Classifier (such as 203-A or 203-CA),5preferably equipped with vacuum suction cups for drainage,s
10、imilar in design to that shown in Fig. 1, or on page 7 of theService Manual 203-CA(see service manuals 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 c
11、ups on classifier. This shallbe thin, rapid filtering, ashless paper hardened to provideadequate 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 cleani
12、ng screens,made from a 10-cm (4-in.) length of automobile windshieldwiper, or equivalent, 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.1This test method is under the jurisdiction
13、 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 June 1, 2006. Published June 2006. Originallyapproved in 1967. Last previous edition approved in 2002 as D 258
14、9 88 (2002)1.2Available 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 information, refer to the standards Document Summary page onthe ASTM website.4Avail
15、able from ASTM International Headquarters. Order Adjunct No.ADJD2589. Original adjunct produced in 1967.5Currently supplied classifier 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,
16、 Canada, or Springfield, OH.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2.4 Drying Oven, (convection type, or mechanical draft),or infrared drying unit.5.2.5 Automatic Overflow Alarm, as shown inAppendix X1.5.2.6 Optional Acces
17、sory, 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 samples in accordance with Test Me
18、thod D 2590for chrysotile or Test Method D 3879 for amphibole fibers asdefined in Terminology D 2946. Duplicate specimens shall betested. (WarningSee 1.3.)7. Test Specimen, Screen Sizes, and Test Duration7.1 Relationships between the type of specimen, screensizes, masses, and duration of test may be
19、 found in Table 1.7.2 For reference, Tyler, U.S. Standard and British Standardequivalent 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 f
20、or the fiber grade being testedand set in place, making certain that the baffle plates are in theirslots behind the screens. If the fiber grade is unknown, refer toTest Method D 3639.8.2 Insert the rubber stoppers, and fill the tanks with water.8.3 Start the agitators to rotate at 540 6 40 r/min and
21、 adjustthe water valve to give a flow slightly in excess of 0.19 L/s (3.0U.S. gal/min). This 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.FIG. 1
22、 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 20(4, 14, 35, 200)Other Group 7 fibers 119, 420 m, 199 m, 74 m 20 6
23、0.05 20(14, 35, 100, 200)“Floats” 177 m, 44 m 20 6 0.05 30(80, 325)AQuebec Asbestos Mining Association (QAMA) standard designation of chrysotile asbestos grades.D 2589 88 (2006)128.5 Pour the slurry into the first tank (tank with coarsestscreen mesh) and wash out any fiber residue in the beaker with
24、clean, 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 screen. Mark theweight of
25、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 into position.8.7 Close th
26、e 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 screen surface with a soft rub
27、berscraper.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 desired. Failure to pe
28、rform 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, carefully wash the scree
29、n 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 cup valve. Failureto c
30、lose 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 dry toconstant mass at 10
31、5 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 mass of the filter paper
32、 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. Interpretation of Results9.
33、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 m(200 mesh/in.)10.0 (0.5 + 1.3 + 1.9 + 1.4) = 4.9 gResults, % 5
34、.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, single apparatusr
35、epeatability is 60.9 g (0.03 oz) (2S) obtained on any fraction,with Grade 4 fibers, as defined in Practice E 177.11.1.2 The equivalent repeatability for Grade 7D fibers is60.6g(60.02 oz).11.2 ReproducibilityReproducibility has not yet been es-tablished in accordance with the requirements of ASTM.11.
36、3 Bias:11.3.1 Bias cannot be established on asbestos fibers for lackof 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 deg
37、ree to which the screencloth is worn.11.4 If the corresponding individual 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 desir
38、ed accuracy, the following generalprecautions should be observed:TABLE 2 Sieve EquivalentsISO OpeningSITyler Series U.S. Standard British StandardMesh Opening Mesh Opening Mesh Opening(in.) 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
39、 (0.0469) 14 1.20 (0.0474)420 m 35 0.417 (0.0164) 40 0.42 (0.0165) 36 0.42 (0.0166)177 m 80 0.175 (0.0069) 80 0.177 (0.0070) 85 0.177 (0.0070)149 m 100 0.147 (0.0058) 100 0.149 (0.0059) 100 0.152 (0.0060)74 m 200 0.074 (0.0029) 200 0.074 (0.0029) 200 0.076 (0.0030)44 m 325 0.043 (0.0017) 325 0.044 (
40、0.0017) . . .D 2589 88 (2006)1311.5.1 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 b
41、e run in at least8htoconditionthem 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 te
42、nd tooverflow. Test results may not 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 wit
43、h the micro switch of the overflow 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
44、very fine products, use filter papers 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 on
45、ly:11.6.1 Screens should be checked 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 ti
46、ghtenough to hold the screen plates 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 t
47、o preventslippage. The use of positive 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 oncep
48、er operating shift) for damage, holes, 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. AUTOM
49、ATIC OVERFLOW ALARM AND CLEARING DEVICE FOR SCREENSX1.1 Fig. X1.1 illustrates a suitable method of mountingfloat switches to activate an automatic overflow alarm, and aclearing device for installation on the fourth tank of theclassifier.6The support must be fabricated to fit individualclassifiers due to slight differences in pertinent dimensions.Fig. X1.1 also gives appropriate dimensions for locating theaxis of the clearing device with respect to the classifier tank.6Detail drawings for a
