1、Designation: D 2495 07Standard Test Method forMoisture in Cotton by Oven-Drying1This standard is issued under the fixed designation D 2495; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pare
2、ntheses 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 amountof moisture in cotton by oven-drying and is applicable to rawcotton, cotton stock in process,
3、 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 desiccator (9.4).NOT
4、E 1For other methods of determination of moisture in textilematerials refer to Test Method D 2654, which includes two options basedon drying in an oven, and one option based on distillation with animmiscible solvent: Methods D 885, Test Method D 1576, Test MethodD 2462.1.4 The values stated in SI un
5、its 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 practices and
6、 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 123 Terminology Relating to TextilesD 885 Test Methods for Tire Cords, Tire Cord Fabrics, andIndustrial Filament Yarns Made from ManufacturedOrganic-Base FibersD 1441 Practice for Sampli
7、ng Cotton Fibers for TestingD 1576 Test Method for Moisture in Wool by Oven-DryingD 2462 Test Method for Moisture in Wool by DistillationWith TolueneD 2654 Test Methods for Moisture in Textiles3D 7139 Terminology for Cotton Fibers3. Terminology3.1 For all terminology relating to D13.11, Cotton Fiber
8、s,refer to Terminology D 7139.3.1.1 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 textil
9、es, refer toTerminology D 123.4. 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 tes
10、ting 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 pe
11、rformed 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. Other
12、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 re
13、sults 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 strengt
14、h.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 increasesthe brittleness of the fiber and results in fiber breakage during1This test method is under the jurisdiction
15、of ASTM Committee D13 on Textilesand is the direct responsibility of Subcommittee D13.11 on Cotton Fibers.Current edition approved Jan. 1, 2007. Published January 2007. Originallyapproved in 1961 T. Last previous edition approved in 2001 as D 249501.2For referenced ASTM standards, visit the ASTM web
16、site, 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.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
17、 United States.ginning, cleaning, and mill processing. Low moisture alsoincreases fly waste and may cause manufacturing difficultiesdue to static electricity.5.3 Variations in the amount of moisture present affect themass and hence the market value of a lot of material sold at adefinite price per un
18、it 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 in turn controls yarn number variation.5.5 The mass of the oven-dry specimen used in this methodis the mass
19、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, are believed to be without significance incommercial transactions.6. Apparatus6.1 Oven, thermostatically cont
20、rolled 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 the ovenmust come from the standard atmosphere for testing textiles.6.2 Balance(s), of sufficient capacity to
21、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 can be completed more quickly if aseparate balance is available for weighing the specimens before drying.Other
22、wise, 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 and 9.2).6.3.1 The weighing containers may be perforated metalbaskets or shallow pans, of a size to fit the
23、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 trash, orline the lower part of the basket with metal foil, but thistechnique may prolong the drying period r
24、equired.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 begreater than its height.6.4 Desiccator, large enough to hold as many weighingcontainers as will be dried at one
25、 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 other effective, noncaustic desiccant may be used.(For the desiccator procedure only, see 9.1.2 and 9.4.)6.6
26、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 3For very dry material, that must be weighed in the containers,lightweight containers are desirable. For damp
27、 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 UnitConsider bales or other ship-ping containers to be the primary sampling unit.7.2 Laboratory Sample UnitAs a labora
28、tory sample unitfor acceptance testing, take at random from the primarysampling units as directed in Practice D 1441.7.3 Since the purpose of this test method is to determine themoisture content of the cotton in the shipping containers in thelot sample, the laboratory sampling units are taken direct
29、lyfrom the shipping container and placed directly into the samplecontainer. Therefore, for this test method, laboratory samplingunits will be used as specimens and the terms “laboratorysampling unit,” “sample,” and “specimen” can be used inter-changeably.7.4 Sample Size:7.4.1 The recommended minimum
30、 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.7.4.3 It is anticipated that only one specimen will be testedfrom each sample container. However, a 1-L (1-q
31、t) 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 byconfined ambient air.7.4.4 In identifying containers or specimens, do not use anymaterial of variable moisture c
32、ontent. 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. Identifycontainers by etching, stamping, or by scratching numbers onthem, or by marking with crayon, ink, or pai
33、nt.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 pneumatic convey-ors between machines, take the specimen as the material flowspast the sampling location. P
34、lace 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 air in the mill. Take short sections from anumber of strands as directed in 7.5.1 and place enough ofthem in t
35、he 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. Immediately after the sample hasbeen placed in the container, close the latter with a tightlyfitting cover.7
36、.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 specimen (1) by taking the surface cotton from thebottom of the cavity, or (2) by pulling cotton from the face ofth
37、e section that was nearest the inside of the bale.7.5.4 When the material is far from moisture equilibriumwith the surrounding air, seal the containers as quickly asD2495072possible and do not take time to adjust the specimen to an exactmass. If specimens are taken while the material is very dry(les
38、s 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 arenot conducted under controlled atmospheric conditions), takeat least three specimens from each lot: one near the
39、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 not exceed 1h. If atmospheric conditions are changing rapidly, it may benecessary to sample as often as every 15 min.7
40、.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 rovingall sampled at one time, take one or more specimens from eachsuch unit if the number of units is not greater than t
41、he 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 thespecimens.7.5.7 When sampling stock in process from a group ofmachines, take one or more specimens from each machine i
42、fthe 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. If the machines, such as drawing frames,combers, or roving frames, have two to six points at whichstock is delivere
43、d, 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 delivery points.7.6 Number of Specimens:7.6.1 Unless otherwise agreed upon, as when specified in anapplicable material spec
44、ification, 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 average (that is, a theoretical average obtainedfrom an infinite number of observations). Determine thenumber of specime
45、ns 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 thismethod, calculate the number of specimens using Eq 1:n 5 t23 s2!/E25 15.4 3 s2(1)where:n = number of specimens (ro
46、unded 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-operator precision,t = 1.960, the value of Students t for infinite degreesof freedom, for two-sided limits, and a 95 %prob
47、ability 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 sWhen there is no reliableestimate of s for the users laboratory, Eq 1 should not be useddirectly. Instead, specify the
48、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 usually found in practice.When a reliable estimate of s for the users laboratory becomesavailable, Eq 1 will usually req
49、uire 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 is adequate for most test purposes,the error in weighing being less than the usual sampling error.When the equipment is
