1、Designation: C 1121 04e1Standard Test Method forTurner and Newall (T and N) Wet-Length Classification ofAsbestos1This standard is issued under the fixed designation C 1121; 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.e1NOTEAsbestos warning was moved from 7.1 to 1.6 in September 2004.1. Scope1.1 This test method covers the operation of the Tur
3、ner andNewall (T and N) wet sieving classifier for asbestos,2and aprocedure for the determination of fiber length distribution andfines (defined in Terminology D 2946) content of milledasbestos fiber (74 m (200 mesh) sieve described in Speci-fication E11.1.2 For purposes of estimating length distrib
4、ution, the test islimited to samples free from excessive quantities of non-fibrous particles or contaminants. Quantities exceeding 0.05 gretained in any given length fractions are considered excessive.1.3 For comparisons between different fiber grades, onlythose specimens which have approximately th
5、e same degree offiberization as determined by Test Methods D 2752 will givecompletely meaningful results.1.4 This test method is not applicable to ultrafine grades ofasbestos powders which contain little or no fibers retained ona 74-m (200 mesh) sieve. This method is restricted to QuebecStandard3gra
6、des 4A to 7D inclusive as determined by TestMethod D 3639.NOTE 1This is an alternative procedure to Test Method D 2589.1.5 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.6 WarningBreathing of asbestos dust is hazardous.Asbes
7、tos and 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 chrysoltile asbestos, refer to “Safe U
8、seof Chrysotile Asbestos: A Manual on Preventive and ControlMeasures.”41.7 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 th
9、e applica-bility of regulatory limitations prior to use. For a specifichazard statement, see 1.6.2. Referenced Documents2.1 ASTM Standards:5D 2589 Test Method for McNett Wet Classification ofAsbestos FiberD 2590 Test Method for Sampling Chrysotile AsbestosD 2752 Test Methods for Air Permeability of
10、AsbestosFibersD 2946 Terminology Relating to AsbestosD 3639 Test Method for Classification of Asbestos Fibersby the Quebec Standard TestD 3879 Test Method for Sampling Amphibole AsbestosE11 Specification for Wire-Cloth Sieves for Testing Pur-posesE 177 Practice for Use of the Terms Precision and Bia
11、s inASTM Test Methods2.2 Other Standard:Quebec Asbestos Mining Association (QAMA) StandardDesignation of Chrysotile Asbestos Grades33. Terminology3.1 DefinitionsRefer to Terminology D 2946.1This test method is under the jurisdiction of ASTM Committee C17 onFiber-Reinforced Cement Products and is the
12、 direct responsibility of SubcommitteeC17.03 on Asbestos - Cement Sheet Products and Accessories.Current edition approved June 1, 2004. Published July 2004. Originally approvedin 1989. Last previous edition approved in 1999 as C 1121 90 (1999).2The apparatus is supplied, on a non-profit basis, as a
13、service to the asbestosindustry by TAF International, Bowdon House, Ashburton Rd. W, Trafford Park,Manchester M170RQ, England.3Available from the Asbestos Institute, 1300 Sherbrooke St. West, Suite 412,Montreal QC, Canada H3A 2M8.4Available from The Asbestos Institute, http:/ referenced ASTM standar
14、ds, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
15、19428-2959, United States.4. Summary of Test Method4.1 A weighed specimen of asbestos fiber is dispersed inwater and the dispersion is allowed to flow by gravity througha series of superposed screens which rotate in a horizontalplane. The suspension flows through successively finer screenswhich reta
16、in the oversized fibers. The rotation of the screensdistributes the incoming fiber suspension throughout the ves-sel, and the swirling motion created by the incoming jet ofwater maintains the fibers in suspension and ensures that theyall encounter the screen apertures.4.2 At the end of the test peri
17、od, the screens bearing theclassified fiber fractions are removed from the vessels, dried,and weighed. The 74 m fines content is estimated bydifference.5. Significance and Use5.1 This test method provides a simple procedure forobtaining information on the fiber length distribution of suit-able asbes
18、tos fiber. The use of relatively low cost apparatus,small test specimens, and a short test period, enhance theusefulness of this test method.5.2 Normally, results obtained by this test method arereproducible under comparable laboratory conditions. How-ever, close agreement cannot be expected unless
19、all deviationsfrom the procedure, however minor, are avoided. Moreover,results for longer fiber grades are influenced to a greater extentby differences in fiber length distribution, and characteristics,than are those for shorter grades.5.3 This test is suitable for specification acceptance andmanufa
20、cturing control.5.4 It is assumed that all undersized fibers, and only those,will pass through any given sieve aperture. However, thisidealized condition is not normally achieved. Thus, resultsshould not be misconstrued as true length distribution data.6. Apparatus6.1 Wet Sieving Classifier, consist
21、ing of four 127-mm (5-in.)diameter rotating circular vessels, the bottom of which arefitted with 98-mm (3.86-in.) diameter screens, stacked verti-cally and concentrically in order of diminishing screen aper-tures. The apparatus is fitted with stirrers to prevent screenblinding, and with spouts for c
22、onducting the drainage fromeach vessel to the following vessel. The lowest vessel dis-charges onto a 74-m (200 mesh) sieve 203.2 mm (8 in.) indiameter, in the base of the apparatus as shown in Fig. 1.6.1.1 The rotational speed for the sieves must be 190 + 5rpm.6.1.2 The stroke frequency for the agit
23、ators must be 192 +5 strokes/min.6.2 Sieve Disks fitted with screen cloth equivalent to 2.36mm, 1.18 mm, 600 m, 300 m, 74 m, and 63 m (US No. 8,16, 30, 50, and 200), are required. British Standard, Tyler, andUS Standard equivalent sieves are listed in Table 1.6.3 Test Sieve (74-m (200 mesh), 203.2-m
24、m (8-in.) diam-eter, as described in Specification E11, or equivalent Tyler orBritish Standard for country of use.6.4 Sieve Disk (63 m (U.S. No. 230), of finer mesh fordrying 74-m (200 mesh) fractions.6.5 Fraction Collector, supplied with the apparatus, oroptional suction arrangement, such as a Bchn
25、er funnel.6.6 Drying Apparatus Drying Oven (Convection Type, orMechanical Draft) or Infrared Drying Device.6.7 Pressure Regulator and Filterif required, to ensure aconstant flow of clean water to the classifier.7. Hazards7.1 Warningsee 1.6.8. Sampling, Test Specimens, and Test Units8.1 Sampling:8.1.
26、1 Select samples in accordance with Test MethodsD 2590, in the case of chrysotile asbestos, and D 3879 foramphibole asbestos.FIG. 1 Turner and Newall ClassifierTABLE 1 Sieve EquivalentsStandard Designations Alternative Designations Aperture SizesAUSABandBritishTylerMeshper in.USA No.BritishMesh(appr
27、ox.)per in.mmin. (ap-prox.)2.36 mm 8 8 7 2.36 0.09291.18 mm 14 16 14 1.18 0.0465600 m 28 30 25 0.60 0.0236300 m 48 50 52 0.30 0.011875 m 200 200 200 0.075 0.0029553 m 250 230 240 0.063 0.00248ASpecified apertures are now identical for the three series.BIdentical with ASTM Standard sieves and ISO Sta
28、ndard apertures.C112104e128.2 Test Specimen:8.2.1 From the bulk laboratory sample, draw two specimensweighing approximately 15 g (0.5 oz). Reduce each specimenby coning and quartering to 2 6 0.005 g.9. Procedure9.1 Disperse a test specimen in 400 cm3of water in a500-cm3beaker and allow it to soak 4
29、min. After this period,stir intermittently by hand for a further period of 1 min. Stirgently and diametrically across the beaker to disperse theasbestos without excessive fiberizing action.9.2 While the test specimen is soaking, thoroughly wet allthe disks of the sieve series and fit to the classifi
30、er. Thoroughlywet the screen cloth of a clean 74-m (200 mesh), 203.2-mm(8-in.) diameter standard test sieve and place it in the recess inthe top of the classifier base, and center the small plastic disksupplied with the apparatus atop the screen surface beneath thefourth vessel outlet.NOTE 2Verify t
31、he tare weight of each sieve disk daily.9.3 Open the water control valve, start the drive motor,adjusting the flow of water through the classifier to 0.0808cm3/s (1.28 U.S. gal/min) or the 64 graduation on the flowme-ter tube when reading the top of the float, and ensure that thereare no leaks cause
32、d by inadequate clamping of the sieve disks.Rectify any such leaks by unclamping the plastic vessel,readjusting the sieve disk, and reclamping the plastic vessel.Ensure that the side of the water jet impinges on the top screenabout 3 mm from the inner edge of the lower bevelled part ofthe plastic ve
33、ssel. Adjust the water spout if necessary.NOTE 3Check the operating water level in the top three vessels daily.The level should be to the top surface of the clamping lugs within 63.2mm (0.125 in.). If the water level is high or low in any vessel, adjust thecopper outlet tube of that vessel to obtain
34、 the desired level. Only veryslight adjustments are necessary.9.4 Slowly pour the water dispersion containing the testspecimen from the beaker into the first (top) vessel, ensuringno overflow.Accomplish this operation within 20 to 25 s. Startthe timing period at this point. Wash out any residue from
35、 thebeaker with a small volume of clean water into the first vessel.NOTE 4A plastic wash bottle is useful for this purpose.9.5 During the test, manually rotate the 74-m (200 mesh)screen slightly at 30 s intervals, recentering the plastic disk oneach occasion, for improved operation and to prevent bl
36、inding.If the water level in either of the two lowest rotating sieve unitsrises continuously, as may happen with short or talcy grades,lower the stirrer on the appropriate sieve by pressing down onthe control knob on the left-hand side of the classifier body.Immediately clear any fiber which lodges
37、in the orifices of anyof the sieving units, by means of a wire hook. A clue to thismalfunction is given if the water level in any of the units risesunduly.9.6 At the end of the 300-s (5 min) test period, stop the flowof water and when each unit has drained, wash down any fiberremaining on the walls
38、of the vessel, using a plastic wash-bottle and directing the water jet in a direction opposite to themotion of the vessel. Then, stop the motor.9.7 Unclamp the plastic vessels and remove each sieve diskin turn from its sieving unit, after ensuring that any fiberremaining in the conical depression in
39、 the sieve holder abovehas been washed down.9.8 Carefully wash the fiber retained by the 203.2-mm (8in.) diameter, 74-m (200 mesh) sieve onto a 63-m (230mesh) sieve disk held in the fraction collector (or Bchnerfunnel) and apply a vacuum to speed the filtration. A venturitype water-jet suction pump
40、may be used for this purpose.Connect the suction tube to the outlet of the fraction collector.9.9 Dry the fiber fractions retained on their respective sievedisks to a constant weight of 105 to 110C (220 to 230F) bymeans of the drying apparatus.9.10 After drying, cool the sieve disks and their fiberf
41、ractions for a minimum period of 0.9 ks (15 min) in apartly-closed container and immediately determine the mass to0.005 g. Subtract the tare weight (previously determined) ofeach sieve disk from the gross weight of the correspondingfiber fraction and sieve disk.10. Calculation or Interpretation of R
42、esults10.1 A typical classification of a Grade 4 fiber, with calcu-lation, is provided in the following example:Screen2.36mm1.18mm600m300m74m74mMassretained, g0.080 0.460 0.500 0.180 0.270 .74 m (200mesh) = 2.0 (0.80 + 0.460 + 0.500 + 0.180 + 0.270) = 0.510 gFractionmass, %4.0 23.0 25.0 9.0 13.5 25.
43、5Cumulativemass, %4.0 27.0 52.0 61.0 74.5 100.011. Report11.1 Fully identify the sample stating the origin and thegrade designation.11.2 Report the average values of two acceptable tests andstate the series of screens used.11.3 If cumulative values have been calculated, report thosealso.12. Precisio
44、n and Bias12.1 General Considerations:12.1.1 If the corresponding individual percentages obtainedfor each screen fraction of the duplicate specimens differ bymore than three units of percentage, test a third specimen.Average the results of two acceptable tests.12.2 PrecisionTo obtain the desired pre
45、cision observe theprecautions in Annex A1.12.3 Repeatability:12.3.1 The intralaboratory multiple-operator, single-apparatus repeatability is 60.1 g (2 s) obtained on any fraction,with Grade 4 fibers, as defined in Practice E 177.12.3.2 The equivalent repeatability for Grade 7D fibers is60.1 g.12.4 R
46、eproducibility Reproducibility has not yet beenestablished in accordance with the requirements of ASTM.12.5 BiasIn comparison with the results obtained by TestMethod D 2589 for results expressed as cumulative fractionsC112104e13retained as a function of screen aperture on log-probabilitygraph paper,
47、 no statistically significant bias has been obtained.NOTE 5At some laboratory locations, the use of stainless steel screencloth has been found to give reproducible results over a longer period oftime.NOTE 6In the case of crudy fibers, the classified fractions may beretained for examination and the p
48、ercentage of crudy bundles and rockparticles determined by an approved method.13. Keywords13.1 asbestos; classification; length; length classification;T and N; Turner and Newall; wet length; wet length classifi-cationANNEXES(Mandatory Information)A1. PRECAUTIONS TO PROMOTE PRECISION AND PREVENT BIAS
49、A1.1 To obtain required precision and bias, the followinggeneral precautions should be observed.A1.1.1 Determine that all the retained material has beenwashed from the walls of the vessels onto the correspondingscreens and, having removed a given screen, wash any materialin the cone beneath it into the vessel below.A1.1.2 A water temperature of 21 6 10C (706 20F) isrecommended.A1.1.3 Run-in new screens by making at least ten trials, andpreferably more, before they are put into regular
