1、Designation: D 891 95 (Reapproved 2004)Standard Test Methods forSpecific Gravity, Apparent, of Liquid Industrial Chemicals1This standard is issued under the fixed designation D 891; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he year of 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.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods cover
3、the determination of thespecific gravity, apparent, of liquid industrial chemicals. Twotest methods are covered as follows:1.1.1 Test Method A, specific gravity, apparent, by means ofa hydrometer.1.1.2 Test Method B, specific gravity, apparent, by means ofa pycnometer.NOTE 1Test Method D 4052 descri
4、bes an instrumental procedure.1.2 In common usage the term specific gravity, apparent, isunderstood to mean specific gravity. Since this test method is tobe in conformity with Terminology E12, all terms readingspecific gravity were changed to specific gravity, apparent,without altering the meaning o
5、f specific gravity and, the termapparent could be dropped in everyday operations after estab-lishing the use term equivalency.1.3 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 ap
6、pro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 Review the current Materials Safety Data Sheets(MSDS) for detailed information concerning toxicity, first aidprocedures, handling, and safety precautions.2. Referenced Documents2.1 ASTM
7、 Standards:2D 1193 Specification for Reagent WaterD 4052 Test Method for Density and Relative Density ofLiquids by Digital Density MeterE 1 Specification for ASTM ThermometersE 12 Terminology Relating to Density and Specific Gravityof Solids, Liquids, and GasesE 100 Specification for ASTM Hydrometer
8、sE 202 Test Methods for Analysis of Ethylene Glycols andPropylene GlycolsE 302 Test Methods for Monobasic Organic AcidsE 346 Test Methods for Analysis of Methanol3. Terminology3.1 Definitions of Terms Specific to This Standard:33.1.1 specific gravity, apparentthe ratio of the weight inair of a unit
9、volume of a material at a stated temperature to theweight in air of equal density of an equal volume of gas-freedistilled water (see Note 2) at a stated temperature. It shall bestated as follows:Specific gravity, apparent, x/yC (1)where x is the temperature of the material and y is thetemperature of
10、 the water.NOTE 2Gas-free distilled water is distilled water that has been boiledto eliminate dissolved gases.4. Significance and Use4.1 Specific gravity, apparent, may be used as a qualitativetest in establishing the identity of a chemical. It may be used tocalculate the volume occupied by a produc
11、t whose weight isknown, or to calculate the weight of a product from its volume.It may be used to determine the composition of binary mixturesof pure chemicals. In the case of most refined industrialchemicals specific gravity, apparent, is of minimal value indefining quality, although it may detect
12、gross contamination.4.2 Of the two test methods described, the pycnometermethod (Test Method B, 1.1.2) is the most accurate andprecise. For this reason it is the preferred method in case ofdisputes. The hydrometer method (Test MethodA, 1.1.1)istheleast accurate and precise, but it is also the simple
13、st and fastestto perform and is often entirely satisfactory for many purposes.If the sample is too viscous to permit the hydrometer to floatfreely, the pycnometer test method should be used.1These test methods are under the jurisdiction of ASTM Committee E15 onIndustrial Chemicals and are the direct
14、 responsibility of Subcommittee E15.01 onGeneral Standards.Current edition approved Oct. 1, 2004. Published November 2004. Originallyapproved in 1946 as D 891 46 T. Last previous edition approved in 2000 asD 891 95 (2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
15、t ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3These definitions conform to those in Terminology E12with this explanationmodified as follows: specific gravity corresponds to apparent sp
16、ecific gravity asdefined in Terminology E12and absolute specific gravity corresponds to specificgravity as defined in Terminology E12.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Test Temperatures5.1 Specifications for industri
17、al chemicals often specifydifferent temperatures at which specific gravity, apparent, shallbe measured, for example:Specific gravity, apparent, at 15.56/15.56C,Specific gravity, apparent, at 20/20C,Specific gravity, apparent, at 25/25C, orSpecific gravity, apparent, at 60/60FWhere precision is desir
18、ed, it is necessary to determine thespecific gravity, apparent, at the temperature prescribed in thespecifications for the material to be tested and to use instru-ments that have been calibrated and standardized at thespecified temperature.5.2 The expression “specific gravity, apparent, at 25.0/15.5
19、6C,” for example, means the ratio of the weight in air ofa unit volume of a material at 25.0C to the weight in air ofequal density of an equal volume of gas-free distilled water at15.56C.5.3 It is possible to convert the specific gravity, apparent, atx/T1C to the corresponding value at x/T2C by mult
20、iplying thevalue at T1by the factor given in Table 1. For example, a liquidhas a specific gravity, apparent, of 0.9500 at 20/20C and thevalue at 20/4C is desired: 0.9500 3 0.9982336 = 0.9483, thevalue at 20/4C. The values in Table 1 are the ratios of thedensity of water at the appropriate temperatur
21、es.5.4 If the change in specific gravity, apparent, with tempera-ture of the liquid is known, the specific gravity, apparent, atT1/y may be converted to that at T2/y by the following equation:Specific gravity, apparent, at T2/y 5 T12 T2!k1 specific gravity, apparent, at T1/y(2)where:T1= original tem
22、perature, C,T2= the second temperature, C, andk = change in specific gravity, apparent, per C.Example: The specific gravity, apparent, of n-butanol at20/20C is 0.8108 and the change in specific gravity, apparent,is 0.00074/C. What is the specific gravity, apparent, at4/20C?Specific gravity, apparent
23、, at 4/20C 5 20 2 4!0.00074 1 0.81085 0.8226 (3)TEST METHOD ASPECIFIC GRAVITY,APPARENT, BY MEANS OF A HYDROMETER6. Summary of Test Method6.1 The specific gravity, apparent, of the sample is deter-mined by immersing a calibrated hydrometer in the sample atthe test temperature. The displacement of the
24、 hydrometer is afunction of the specific gravity, apparent, of the sample that isread on the hydrometer scale at the level of the meniscus of thesample.7. Apparatus7.1 HydrometerThe hydrometers to be used shall be thosespecified in Specification E 100, as follows:Nominal Apparent SpecificGravity Ran
25、geASTMHydrometer No.0.650 to 0.700 82H-620.700 to 0.750 83H-620.750 to 0.800 84H-620.800 to 0.850 85H-620.850 to 0.900 86H-620.900 to 0.950 87H-620.950 to 1.000 88H-621.000 to 1.050 89H-621.050 to 1.100 90H-621.100 to 1.150 113H-621.150 to 1.200 114H-621.200 to 1.250 115H-62NOTE 3TheASTM hydrometers
26、 prescribed in Test MethodA, 7.1, arecalibrated as if all weights are in vacuum. Equivalent values at the sametemperature for all weights in air may be approximated for ambientconditions as follows:apparent specific gravity = 1.00120 3 (sp gr) 0.00120where:sp gr = specific gravity determined by ASTM
27、 hydrometer.7.2 Hydrometer CylinderThe vessel in which the samplefor the gravity test is confirmed shall be made of clear glass andshall be cylindrical in shape. For convenience in pouring, itmay have a lip on the rim. The inside diameter shall be at least25.4 mm (1.0 in.) greater than the outside d
28、iameter of thehydrometer used in it. The height of the cylinder shall be suchthat after equilibrium has been reached, the lowest point on thehydrometer will be at least 25 mm (1 in.) off the bottom of thecylinder.7.3 ThermometerThe thermometers used shall be thosespecified in Specification E1. Therm
29、ometer 90C, a 76-mmimmersion thermometer, covering 0 to 30C with 0.1C gradu-ations, is recommended for most work. Thermometer 63C issimilar except it is a total immersion type and covers 8 to30C with 0.1C graduations.7.4 Water BathA water bath capable of maintaining theselected test temperature 60.0
30、5C. The depth of the bath mustbe sufficient to immerse the hydrometer cylinder so that thecontained liquid is completely below the surface of the liquidin the bath.8. Procedure8.1 Cool the sample in the original container to about 2Cbelow the temperature at which the specific gravity, apparent,is to
31、 be determined. Rinse each piece of equipment with aTABLE 1 Conversion of Specific Gravities, Apparent, from Basis x/T1to Basis x/T2CSpecific Gravities,Apparent, on Basis x/T1Multiplied by This Factor Gives Specific Gravities, Apparent, on Basis x/T2t/4 t/15 t/15.56 t/20 t/25t/4 1 1.0008722 1.000958
32、6 1.0017695 1.0029335t/15 0.9991286 1 1.0000864 1.0008966 1.0020595t/15.56 0.9990423 0.9999136 1 1.0008101 1.0019730t/20 0.9982336 0.9991042 0.9991905 1 1.0011619t/25 0.9970751 0.9979447 0.9980309 0.9988395 1D 891 95 (2004)2portion of the sample and discard the rinse liquid. Pour thesample into the
33、clean hydrometer cylinder without splashing,so as to avoid formation of air bubbles. Remove any airbubbles adhering to the surface by touching them with a pieceof clean filter paper. Select a location that is free from aircurrents. Place the cylinder vertically in the waterbath and letthe temperatur
34、e of the sample reach the temperature of the bath60.05C as follows: Stir the contents of the cylinder, beingcareful to avoid formation of air bubbles. When the tempera-ture of the sample is about 0.2C below that of the bath, slowlyand carefully lower the hydrometer into the sample to a leveltwo smal
35、lest scale divisions below that at which it will floatand then release the hydrometer. After it has come to rest andfloats freely away from the walls of the cylinder, read thegravity as the point at which the surface of the sampleapparently cuts the hydrometer scale. When the temperature ofthe sampl
36、e matches that of the bath, make this observation byplacing the eye slightly below the level of the liquid and slowlyraise the eye until the surface of the sample first seen as adistorted ellipse seems to become a straight line cutting thehydrometer scale. Determine the temperature of the sample jus
37、tbefore and also, for referee tests, just after reading thehydrometer.9. Report9.1 Report the reading obtained in 8.1 plus any calibrationcorrection as the specific gravity, apparent, of the sample to thenearest 0.0001 unit.10. Precision and Bias10.1 Precision:10.1.1 The precision of this test metho
38、d should be deter-mined for each chemical to provide criteria for judging theacceptability of results. The following precision data reportedin Test Method E 302 for monobasic organic acids are typical.10.1.2 Repeatability (Single Analyst)The standard devia-tion for a single determination has been es
39、timated to be0.00020 unit at 24 DF. The 95 % limit for the differencebetween two such runs is 0.0005 unit.10.1.3 Within-Laboratory, Between-Days Variability (for-merly called repeatability)The standard deviation of results(each the average of duplicates), obtained by the same analyston different day
40、s, has been estimated to be 0.00016 unit at 12DF. The 95 % limits for the difference between two suchaverages is 0.005 unit.10.1.4 Reproducibility (Multilaboratory)The standard de-viation of results (each the average of duplicates), obtained byanalysts in different laboratories, has been estimated t
41、o be0.00057 unit at 5 DF. The 95 % limit for the difference betweentwo such averages is 0.0015 unit.10.2 BiasThe bias of this test method has not beendetermined due to the unavailability of suitable referencematerials. However, the bias is dependent upon the calibrationof the hydrometer and the degr
42、ee of control of the temperatureof the hydrometer bath.TEST METHOD BSPECIFIC GRAVITY, APPARENT,BY MEANS OF A PYCNOMETER411. Summary of Test Method11.1 A tared pycnometer is filled with freshly boiled waterthat has been cooled to the specified test temperature andweighed to determine the weight of wa
43、ter in the filledpycnometer. The same pycnometer is filled with the sample atthe test temperature and weighed. The ratio of the weight ofsample to water in air is the specific gravity, apparent.12. Apparatus12.1 PycnometerA pycnometer of 25-mL capacity with aground-glass stopper having a capillary o
44、pening, a chamber toprovide for expansion up to room temperature, and a cap toprevent evaporation.12.2 Water BathA water bath capable of maintaining thetest temperature at 60.05C during the test.12.3 ThermometerAn ASTM thermometer conforming tothe requirements of Specification E1and covering the req
45、uiredtemperature shall be used. Thermometer 90C, a 76-mm immer-sion thermometer, covers from 0 to 30C in 0.1C graduations,is suitable for most purposes. Thermometer 63C is similar, butis a total immersion type covering 8 to 32C.12.4 Analytical BalanceA balance capable of weighing150 g with a precisi
46、on of 0.1 mg.12.5 Analytical WeightsClass S weights, as certified bythe National Institute of Standards and Technology, or equiva-lent weights, if required by the balance.13. Reagents13.1 WaterReferences to water shall be understood tomean Type II or Type III reagent water conforming to Speci-ficati
47、on D 1193.14. Procedure14.1 Clean the pycnometer by filling it with a saturatedsolution of chromic acid in sulfuric acid (H2SO4, sp gr 1.84),allowing it to stand for a few hours, emptying, and rinsing well4For a high degree of accuracy, the following paper discusses an apparatus andmethod of much me
48、rit: Lipkin and Associates, “Pycnometer for Volatile Liquids,”Industrial and Engineering Chemistry,Analytical Edition, Vol 36, Jan. 15, 1944, pp.5558.TABLE 2 Precision for Specific Gravity, Apparent, by Means of a PycnometerRepeatability Within-Laboratory, Between Days Variability ReproducibilitySta
49、ndardDeviation, ppmDegrees ofFreedom95 % Limit,ppmStandardDeviation, ppmDegrees ofFreedom95 % Limit,ppmStandardDeviation, ppmDegrees ofFreedom95 % Limit,ppmMethanol 0.000028 36 0.00008 0.000026 18 0.00007 0.00017 8 0.00048Ethylene andPropylene Glycols0.000071 96 0.0002 0.0001 48 0.0003 0.0002 5 0.0006D 891 95 (2004)3with water. Fill the pycnometer with freshly boiled water thathas been cooled to about 2C below the test temperature. Placeit in the water bath maintained at the test temperature 60.05Cuntil the pycnome
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