1、Designation: D 2589 88 (Reapproved 2006)Standard 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 o
2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the lengthdistribution and fines content of milled asbestos fiber by w
3、etclassification 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 and asbestos products present demonstrated healthrisks fo
4、r 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 ofChrysotile: A Manual on Preventive and Control Measures.”
5、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-bility of regulatory limitations prior to use.2. Referenced
6、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 Amphibole AsbestosE11 Specification for Wire Cloth and Sie
7、ves for TestingPurposesE 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods3. Terminology3.1 DefinitionsTerms relating to asbestos are defined inTerminology D 2946.4. Significance and Use4.1 Normally, results obtained by this test method arereproducible under comparable laborat
8、ory 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 in fiber
9、length distribution andcharacteristics than those of shorter grades.5. Apparatus5.1 McNett Fiber Classifier (such as 203-A or 203-CA),4preferably 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 manuals for
10、 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 provideadequate wet stren
11、gth 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 equivalent, held in a suitab
12、le 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 inAppendix X1.1This test m
13、ethod is under the jurisdiction of ASTM Committee C17 onFiber-Reinforced Cement Products and is the direct responsibility of SubcommitteeC17.03 on AsbestosCement Sheet Products and Accessories.Current edition approved June 1, 2006. Published June 2006. Originallyapproved in 1967. Last previous editi
14、on approved in 2002 as D 2589 88 (2002)e1.2Available 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 p
15、age onthe ASTM website.4Currently 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, Canada, or Springfield, OH.1Copyright ASTM International, 100 Barr Harbor Drive,
16、 PO Box C700, West Conshohocken, PA 19428-2959, United States.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 thecl
17、assifier and rinsing hose.6. Sampling6.1 Select samples in accordance with Test Method 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 Relationsh
18、ips between the type of specimen, screensizes, masses, and duration of test may be 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,
19、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 are in theirslots behind the screens. If the fiber grade is unknown, refer toTest Method D 3639.8.2 Insert the rubber stoppers, and
20、 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). 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 w
21、ater in a 1000-mLbeaker and stir until the asbestos is thoroughly dispersed.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, 7
22、4 m 10 6 0.05 20(4, 14, 35, 200)Other Group 7 fibers 119, 420 m, 199 m, 74 m 20 6 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)28.5 Pour the slurry into the first tank
23、(tank with coarsestscreen mesh) and wash out any fiber residue 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
24、with roomconditions, in suction cups on the supporting screen. 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 agains
25、t the supporting screen.Wet the filter paper and clamp into 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 t
26、est, and if any tankappears to overflow, clean the screen 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
27、 tank, and progressively increase thevacuum to the maximum 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 tan
28、ks. Immediately after a tank has beencompletely drained, carefully 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
29、 the suctioncup, and the cup itself has drained, close the 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
30、filter paper with its classified specimen fraction, and dry 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 w
31、eight of the specimenfraction by subtracting the initial mass 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 o
32、f the specimen (seeNote 6 concerning crudy fibers).9. Interpretation 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
33、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, % 5.0 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 Bia
34、s11.1 Repeatability:11.1.1 The intralaboratory single-operator, single apparatusrepeatability 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 ReproducibilityReproducibil
35、ity has not yet been es-tablished in accordance with the requirements of ASTM.11.3 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 bee
36、n 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 individual percentages obtainedfor each screen fraction of the duplicate specimens differ bymore than five units of percentage, make a third test. Averageth
37、e results of two acceptable tests and report the average.11.5 To obtain the desired 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.
38、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 (0.0474)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
39、(0.0029) 200 0.074 (0.0029) 200 0.076 (0.0030)44 m 325 0.043 (0.0017) 325 0.044 (0.0017) . . .D 2589 88 (2006)311.5.1 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 wate
40、r tem-perature of 21 6 10C (70 6 20F) is recommended.11.5.3 New screens should be 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 acc
41、uracy, screens should not becleaned during a classification, unless the tanks tend 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 t
42、ank, similar to that shown in the appendix with themotor connected in series with 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
43、to give reproducible results over a longer period oftime.NOTE 5When classifying 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 a
44、pproved method.11.6 The following precautions apply to Model 203-Aclassifiers only: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
45、cause of abnormal minus200 mesh results. The clamping screws should be turned tightenough 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 sp
46、eed (540 6 40 r/min) shouldbe checked daily, and the belts should be inspected to 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 2
47、03-CAclassifiers only:11.7.1 Screens should be checked regularly (at least onceper 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 distrib
48、ution;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 overflow alarm, and aclearing device for installation on the fourth tank
49、of theclassifier.5The 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.5Detail drawings for a suitable screen-clearing device are available from ASTMHeadquarters, 100 Barr Harbor Drive, W. Conshohocken, PA 19428, at a nominalprice. Request Adjunct ADJD2589.D 2589 88 (2006)4ASTM International takes no position respect
