1、Designation: D 891 09Standard 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, the year of last re
2、vision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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. Scope*1.1 These test methods cover the determination
3、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 describes an instrumenta
4、l 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 of specific gravity
5、 and, the termapparent could be dropped in everyday operations after estab-lishing the use term equivalency.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thesetest methods with the exception of Fahrenheit (F) in 5.1 as anexample of a p
6、ossible industrial specification unit.1.4 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 li
7、mitations prior to use.1.5 Review the current Materials Safety Data Sheets(MSDS) for detailed information concerning toxicity, first aidprocedures, handling, and safety precautions.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 4052 Test Method for Density and Rel
8、ative Density ofLiquids by Digital Density MeterE1 Specification for ASTM Liquid-in-Glass ThermometersE12 Terminology Relating to Density and Specific Gravityof Solids, Liquids, and Gases3E 100 Specification for ASTM HydrometersE 202 Test Methods for Analysis of Ethylene Glycols andPropylene Glycols
9、E 302 Test Methods for Monobasic Organic Acids3E 346 Test Methods for Analysis of Methanol3. Terminology3.1 Definitions of Terms Specific to This Standard:43.1.1 specific gravity, apparentthe ratio of the weight inair of a unit volume of a material at a stated temperature to theweight in air of equa
10、l 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 the water.NOTE 2Gas-free distilled water is distilled water that has be
11、en 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 product whose weight isknown, or to calculate the weight of a product from its
12、 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 gross contamination.4.2 Of the two test methods described, the pycnomete
13、rmethod (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 simplest and fastest1These test methods are under the jurisdiction of ASTM Com
14、mittee E15 onIndustrial and Specialty Chemicals and are the direct responsibility of Subcommit-tee E15.01 on General Standards.Current edition approved April 1, 2009. Published April 2009. Originallyapproved in 1946. Last previous edition approved in 2004 as D 891 - 95(2004).2For referenced ASTM sta
15、ndards, 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.3Withdrawn.4These definitions conform to those in Terminology E12with this explanatio
16、nmodified as follows: specific gravity corresponds to apparent specific gravity asdefined in Terminology E12and absolute specific gravity corresponds to specificgravity as defined in Terminology E12.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100
17、Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.to 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.5. Test Temperatures5.1 Specifications for i
18、ndustrial 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 i
19、s desired, 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
20、.0/15.56C,” 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
21、by multiplying 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 tem
22、peratures.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= origi
23、nal temperature, 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, a
24、pparent, 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
25、 of the 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 SpecificGrav
26、ity RangeASTMHydrometer 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 hydr
27、ometers 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
28、by ASTM 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 mm greater than the outside diamet
29、er of the hydrometerused in it. The height of the cylinder shall be such that afterequilibrium has been reached, the lowest point on the hydrom-eter will be at least 25 mm off the bottom of the cylinder.7.3 ThermometerThe thermometers used shall be thosespecified in Specification E1. Thermometer 90C
30、, 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 60.05C. The de
31、pth of the bath mustTABLE 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 1.0009586 1.0017695 1.0029335t/15 0.9991
32、286 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 1D891092be sufficient to immerse the hydrometer cylinder so that thecontained liquid is completely below the surface of the l
33、iquidin 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 be determined. Rinse each piece of equipment with aportion of the sample and discard the rinse liquid. Pour thesample into the clean hydrometer cy
34、linder 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 temperature of the sample rea
35、ch 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 smallest scale division
36、s 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 sample matches that of t
37、he 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 justbefore and also, f
38、or 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 method should be deter-m
39、ined 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 estimated to be0.0002
40、0 unit at 24 DF. The 95 % limit for the differencebetween two such runs is 0.0005 unit.10.1.3 Within-Laboratory, Between-Days VariabilityThestandard deviation of results (each the average of duplicates),obtained by the same analyst on different days, has beenestimated to be 0.00016 unit at 12 DF. Th
41、e 95 % limits for thedifference between two such averages 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 to be0.00057 unit at 5 DF. The 95 % limit for the dif
42、ference 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 degree of control of the temperatureof the hydrometer ba
43、th.TEST METHOD BSPECIFIC GRAVITY, APPARENT,BY MEANS OF A PYCNOMETER511. 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 water in the filledpycnometer. The same pycnometer is
44、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 opening, a chamber toprovide for expansion up to room
45、 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 requiredtemperature shall be used. Thermometer 90C, a 7
46、6-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 precision of 0.1 mg.12.5 Analytical WeightsClass S weights,
47、 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-fication D 1193.14. Procedure14.1 Clean the pycnometer by
48、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 wellwith water. Fill the pycnometer with freshly boiled water thathas been cooled to about 2C below the test temperature. Placeit in the water bath mai
49、ntained at the test temperature 60.05Cuntil the pycnometer and its contents are at a constant volumeat the test temperature. After immersion in the bath for at least30 min, adjust the level of liquid to the proper point on thepycnometer, put the stopper in place, remove from the bath,wipe dry, and weigh. Empty the pycnometer, rinse successivelywith alcohol and ether, remove the ether vapor, immerse in thebath, and bring to the test temperature as was done before.After immersion at the test temperature for at least 30 min
