ASTM D2495-2007(2012) Standard Test Method for Moisture in Cotton by Oven-Drying《用烘干法测定棉花中水分的标准试验方法》.pdf

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1、Designation: D2495 07 (Reapproved 2012)Standard Test Method forMoisture in Cotton by Oven-Drying1This standard is issued under the fixed designation D2495; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.

2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the amountof moisture in cotton by oven-drying and is applicable to rawcotton, cotton st

3、ock in process, and cotton waste.1.2 This test method may also, by agreement, be used fordetermining moisture in blends of cotton with other fibers.1.3 This test method offers alternative procedures forweighing the dried specimens, one procedure using an ovenbalance (9.3) and the other using a desic

4、cator (9.4).NOTE 1For other methods of determination of moisture in textilematerials refer to Test Method D2654, which includes two options basedon drying in an oven, and one option based on distillation with animmiscible solvent: Methods D885, Test Method D1576, Test MethodD2462.1.4 The values stat

5、ed in SI units are to be regarded as thestandard. No other units are included in this standard.1.5 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 pr

6、actices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD885 Test Methods for Tire Cords, Tire Cord Fabrics, andIndustrial Filament Yarns Made from ManufacturedOrganic-Base FibersD1441 Practice fo

7、r Sampling Cotton Fibers for TestingD1576 Test Method for Moisture in Wool by Oven-DryingD2462 Test Method for Moisture in Wool by DistillationWith TolueneD2654 Test Methods for Moisture in Textiles3D7139 Terminology for Cotton Fibers3. Terminology3.1 For all terminology relating to D13.11, Cotton F

8、ibers,refer to Terminology D7139.3.1.1 The following terms are relevant to this standard:cotton waste, ginned lint (cotton), lint cotton, moisture content,moisture-free, moisture regain, oven-dry, percentage point, rawcotton, seed cotton, stock in process.3.2 For all other terminology related to tex

9、tiles, refer toTerminology D123.4. Summary of Test Method4.1 Specimens are weighed, dried in an oven, and re-weighed. The difference between the original mass and theoven-dry mass is calculated in percent, either as moisturecontent or moisture regain.5. Significance and Use5.1 This test method for t

10、esting the moisture content ofcotton can be used for acceptance testing of commercialshipments of lint cotton provided the between-laboratory biasis known.5.1.1 If there are differences or practical significance be-tween reported test results for two laboratories, or more,comparative test should be

11、performed to determine if there is astatistical bias, using competent statistical assistance. As aminimum, use test samples as homogeneous as possible, drawnfrom the material from which the disparate test results areobtained, and assigned randomly in equal numbers to eachlaboratory for testing. Othe

12、r materials with established testvalues may be used for this purpose. Compare the test resultsfrom the two laboratories using a statistical test for unpaireddata at a probability level chosen prior to the testing series. Ifa bias is found, either its cause must be found and corrected, orfuture test

13、results must be adjusted in consideration of theknown bias.5.2 Information on the moisture content of cotton is desir-able since the physical properties of cotton are significantlyaffected by its moisture content. High moisture content in-creases flexibility, toughness, elongation, and tensile stren

14、gth.Too high a moisture content causes difficulty in processing dueto the tendency of the stock to “lap-up” on drafting rolls. Lowmoisture, on the other hand, facilitates cleaning but increases1This test method is under the jurisdiction of ASTM Committee D13 on Textilesand is the direct responsibili

15、ty of Subcommittee D13.11 on Cotton Fibers.Current edition approved July 1, 2012. Published August 2012. Originallyapproved in 1961 T. Last previous edition approved in 2007 as D249507. DOI:10.1520/D2495-07R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custo

16、mer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO

17、 Box C700, West Conshohocken, PA 19428-2959, United States.the brittleness of the fiber and results in fiber breakage duringginning, cleaning, and mill processing. Low moisture alsoincreases fly waste and may cause manufacturing difficultiesdue to static electricity.5.3 Variations in the amount of m

18、oisture present affect themass and hence the market value of a lot of material sold at adefinite price per unit mass. Knowledge of the moisture contentor regain can be accordingly an important financial consider-ation.5.4 Moisture content variation affects lap, sliver, and rovinglinear density which

19、 in turn controls yarn number variation.5.5 The mass of the oven-dry specimen used in this methodis the mass observed after the specimen has been dried in anoven supplied with ambient air. The observed mass is accord-ingly subject to minor variations as discussed in 3.6.1. Thesevariations, however,

20、are believed to be without significance incommercial transactions.6. Apparatus6.1 Oven, thermostatically controlled at a temperature of105 6 2C (220 6 4F) with fan-forced ventilation andpreferably equipped with a balance that permits weighing thespecimens without opening the oven. The air entering t

21、he ovenmust come from the standard atmosphere for testing textiles.6.2 Balance(s), of sufficient capacity to weigh the speci-mens in the containers that will be used and having a sensitivityof 0.01 g.NOTE 2Although all the weighing can be done on the oven balance,it is more convenient and the work c

22、an be completed more quickly if aseparate balance is available for weighing the specimens before drying.Otherwise, the oven must be allowed to cool to room temperature beforea new set of specimens can be weighed.6.3 Weighing Containers, to be used when the specimensare weighed in the oven (see 9.1.1

23、 and 9.2).6.3.1 The weighing containers may be perforated metalbaskets or shallow pans, of a size to fit the particular oven inwhich they are used. For specimens containing particles offoreign matter that are easily shaken out, use baskets made ofor lined with wire screening fine enough to hold the

24、trash, orline the lower part of the basket with metal foil, but thistechnique may prolong the drying period required.6.3.2 Weighing Bottles or Weighing Cans, with tight-fittingcovers, for use with the desiccator procedure (9.1.2 and 9.4).To expedite drying, the diameter of each container should begr

25、eater than its height.6.4 Desiccator, large enough to hold as many weighingcontainers as will be dried at one time. (For the desiccatorprocedure only, see 9.1.2 and 9.4.)6.5 DesiccantCalcium chloride is satisfactory, providedthat it is redried or replaced as required for effective desicca-tion. Any

26、other effective, noncaustic desiccant may be used.(For the desiccator procedure only, see 9.1.2 and 9.4.)6.6 Sample ContainersMetal cans, glass jars, or plasticcontainers of approximately 1-L (1-qt) capacity with airtightcovers are recommended for use when sampling cotton outsidethe laboratory.NOTE

27、3For very dry material, that must be weighed in the containers,lightweight containers are desirable. For damp cotton, which would rusttin-plated cans, the containers should be made of rustproof material (suchas aluminum, glass, or plastic).7. Sampling and Test Specimens7.1 Primary Sampling UnitConsi

28、der bales or other ship-ping containers to be the primary sampling unit.7.2 Laboratory Sample UnitAs a laboratory sample unitfor acceptance testing, take at random from the primarysampling units as directed in Practice D1441.7.3 Since the purpose of this test method is to determine themoisture conte

29、nt of the cotton in the shipping containers in thelot sample, the laboratory sampling units are taken directlyfrom the shipping container and placed directly into the samplecontainer. Therefore, for this test method, laboratory samplingunits will be used as specimens and the terms “laboratorysamplin

30、g unit,” “sample,” and “specimen” can be used inter-changeably.7.4 Sample Size:7.4.1 The recommended minimum size for a specimen oflint cotton or waste containing at least 50 % lint cotton is 5 g.7.4.2 The recommended minimum size for a specimen ofwaste containing less than 50 % lint cotton is 10 g.

31、7.4.3 It is anticipated that only one specimen will be testedfrom each sample container. However, a 1-L (1-qt) containerwill hold ample material for testing more than one specimen.The container should be well filled with the material beingsampled to minimize changes in moisture content caused byconf

32、ined ambient air.7.4.4 In identifying containers or specimens, do not use anymaterial of variable moisture content. For example, do notplace identifying tags or slips of paper inside the samplecontainers and do not paste labels on the outside if thespecimens are to be weighed in the containers. Iden

33、tifycontainers by etching, stamping, or by scratching numbers onthem, or by marking with crayon, ink, or paint.7.5 Sample Collection:7.5.1 When sampling lint cotton as it passes through (1) lintcleaners or condensers in the ginnery, (2) opening and cleaningmachinery in the mill, or (3) mechanical or

34、 pneumatic convey-ors between machines, take the specimen as the material flowspast the sampling location. Place it in the sample containerwithout delay, and immediately close the container with atightly fitting cover.7.5.2 Sliver and roving are usually in approximate moistureequilibrium with the ai

35、r in the mill. Take short sections from anumber of strands as directed in 7.5.1 and place enough ofthem in the container so that the total mass is as specified in7.4. Extreme haste is not necessary, but avoid handling thematerial more than necessary to minimize adsorption ofmoisture from the hands.

36、Immediately after the sample hasbeen placed in the container, close the latter with a tightlyfitting cover.7.5.3 To sample raw cotton in bales, cut out a sectionapproximately 0.15 m (6 in.) wide across the bale and at least0.15 m deep from the space between two bale ties. Immediatelytake the specime

37、n (1) by taking the surface cotton from thebottom of the cavity, or (2) by pulling cotton from the face ofthe section that was nearest the inside of the bale.D2495 07 (2012)27.5.4 When the material is far from moisture equilibriumwith the surrounding air, seal the containers as quickly aspossible an

38、d do not take time to adjust the specimen to an exactmass. If specimens are taken while the material is very dry(less than 2 %), the containers must not be opened before thefirst weighing.7.5.5 When sampling material over a period of time (forexample, in ginning or other processing experiments that

39、arenot conducted under controlled atmospheric conditions), takeat least three specimens from each lot: one near the beginningof the test, one at about the middle, and one at the end. If theexperiment runs for more than 2 h, take additional specimensso that the time interval between specimens does no

40、t exceed 1h. If atmospheric conditions are changing rapidly, it may benecessary to sample as often as every 15 min.7.5.6 When the material to be tested comprises a number ofbales of raw cotton, or a number of finished units of stock inprocess, such as picker laps, cans of sliver, or bobbins of rovin

41、gall sampled at one time, take one or more specimens from eachsuch unit if the number of units is not greater than the numberof specimens required (see Section 9). Otherwise, take onespecimen from each of the required number of units drawn atrandom from the entire quantity to be represented by thesp

42、ecimens.7.5.7 When sampling stock in process from a group ofmachines, take one or more specimens from each machine ifthe number of machines is not greater than the number ofspecimens required (see Section 9). Otherwise, take onespecimen from each of the required number of machinesselected at random.

43、 If the machines, such as drawing frames,combers, or roving frames, have two to six points at whichstock is delivered, take approximately equal portions from eachdelivery point. If there are more than six delivery points permachine, take approximately equal portions from each of atleast five deliver

44、y points.7.6 Number of Specimens:7.6.1 Unless otherwise agreed upon, as when specified in anapplicable material specification, take a number of specimenssuch that the user may expect at the 95 % probability level thatthe test result is not more than 0.50 percentage points above orbelow the true aver

45、age (that is, a theoretical average obtainedfrom an infinite number of observations). Determine thenumber of specimens as follows.7.6.1.1 Reliable Estimate of sWhen there is a reliableestimate of s based upon extensive past records for similarmaterial tested in the users laboratory as directed in th

46、ismethod, calculate the number of specimens using Eq 1:n 5 t23 s2!/E25 15.4 3 s2(1)where:n = number of specimens (rounded upward to a wholenumber),s = reliable estimate of the standard deviation of indi-vidual observations on similar materials in theusers laboratory under conditions of single-operat

47、or precision,t = 1.960, the value of Students t for infinite degreesof freedom, for two-sided limits, and a 95 %probability level (t2= 3.842),E = 0.50 percentage points, the value of the allowablevariation of the test result, and15.4 = a value calculated from t2/E2.7.6.2 No Reliable Estimate of sWhe

48、n there is no reliableestimate of s for the users laboratory, Eq 1 should not be useddirectly. Instead, specify the fixed numbers of specimensshown in Table 1. These numbers of specimens are calculatedusing values of s that are listed in Table 1 and which aresomewhat larger values of s than are usua

49、lly found in practice.When a reliable estimate of s for the users laboratory becomesavailable, Eq 1 will usually require fewer specimens than arelisted in Table 1.8. Conditioning8.1 Since the purpose of this method is to determine themoisture content of the material at a specified time or underprevailing conditions, do not precondition or condition thespecimens after they are taken.9. Procedure9.1 Alternative Weighing Procedures:9.1.1 Oven-Balance ProcedureAn oven with a built-inbalance is usually preferred for speed and convenience. Theprecision of such equipment i