1、Designation: D 1481 02An American National StandardStandard Test Method forDensity and Relative Density (Specific Gravity) of ViscousMaterials by Lipkin Bicapillary Pycnometer1This standard is issued under the fixed designation D 1481; the number immediately following the designation indicates the y
2、ear oforiginal adoption or, in the case of revision, the 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.1. Scope1.1 This test method covers the determination of the den
3、sityof oils more viscous than 15 cSt at 20C (mm2/s), and ofviscous oils and melted waxes at elevated temperatures, but notat temperatures at which the sample would have a vaporpressure of 100 mm Hg (13 kPa) or above.NOTE 1To determine the densities of less viscous liquids at 20 or25C use Test Method
4、 D 1217.1.2 This test method provides a calculation procedure forconverting density to relative density (specific gravity).1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It
5、is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1217 Test Method for Density and Relative Density(Specific Gravity) of Liquids b
6、y Bingham Pycnometer2D 1250 Guide for Petroleum Measurement Tables23. Terminology3.1 Definitions:3.1.1 densitythe weight in a vacuum (that is, the mass) ofa unit volume of the material at any given temperature.3.1.2 relative density (specific gravity)the ratio of themass (weight in a vacuum) of a gi
7、ven volume of material at atemperature, t1, to the mass of an equal volume of water at areference temperature, t2; or the ratio of the density of thematerial at t1to the density of water at t2.4. Summary of Test Method34.1 The liquid is drawn into the bicapillary pycnometerthrough the removable siph
8、on arm and adjusted to volume atthe temperature of test, in such a manner that there ispractically no drainage in the unfilled tubing. After equilibra-tion at the test temperature, liquid levels are read, and thepycnometer is removed from the thermostated bath, cooled toroom temperature, and weighed
9、.4.2 Density or relative density (specific gravity), as desired,is then calculated from the volume at the test temperature andthe weight of the sample. The effect of air buoyancy is includedin the calculations.5. Significance and Use5.1 Density is a fundamental physical property that can beused in c
10、onjunction with other properties to characterize boththe light and heavy fractions of petroleum and to access thequality of crude oils.5.2 Determination of the density or relative density ofpetroleum and its products is necessary for the conversion ofmeasured volumes to volumes at the standard tempe
11、ratures of15C.5.3 The determination of densities at the elevated tempera-tures of 40 and 100C is particularly useful in providing thedata needed for the conversion of kinematic viscosities incentistokes (mm2/s) to the corresponding dynamic viscositiesin centipoises (mPas).6. Apparatus6.1 Pycnometer4
12、A side-arm type of pycnometer conform-ing to the dimensions given in Fig. 1 and made of borosilicateglass. The weight shall not exceed 35 g without the side arm.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of S
13、ubcommitteeD02.04.0D on Physical and Chemical Methods.Current edition approved Nov. 10, 2002. Published January 2003. Originallyapproved in 1957. Last previous edition approved in 1997 as D 148193(1997).2Annual book of ASTM Standards, Vol 05.01.3For a more complete discussion of this procedure, see
14、Lipkin, M. R., Mills, I.W., Martin, C. C., and Harvey, W. T., Analytical Chemistry, ANCHA, Vol 21, 1949,p. 504.4The sole source of supply of the pycnometers known to the committee at thistime is Reliance Glass Co., 220 Gateway Rd., Bensenville, IL 60106-0825 havebeen found satisfactory. If you are a
15、ware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc
16、ken, PA 19428-2959, United States.6.2 RackA rack to use in filling the pycnometer (see Fig.2).6.3 Constant-Temperature OvenAn oven for use in fillingthe pycnometer. Any oven capable of holding the filling rack,and of maintaining a temperature of approximately 100C, canbe used.6.4 Constant-Temperatur
17、e BathA mixture of water andglycerin, or oil bath having a depth of at least 305 mm (12 in.)and provided with heating, stirring, and thermostating devicesadequate to maintain desired temperatures in the range from 20to 100C with an accuracy of 60.01C.6.5 Bath ThermometersThermometers graduated in 0.
18、1Csubdivisions and standardized for the range of use to thenearest 0.01C (ASTM Saybolt Viscosity Thermometers 17Cto 22C are recommended). For most hydrocarbons, the densitycoefficient is about 0.0008 units/C, and therefore a tempera-ture error of 60.013C would cause an error of 60.000 01 indensity.6
19、.6 Pycnometer HolderA holder, as shown in Fig. 3, isrecommended for supporting the pycnometer in the bath. Asingle clamp device may be used.6.7 BalanceA balance able to reproduce weighings within0.1 mg when carrying a load of 35 g or less on each pan. Thebalance shall be located in a room shielded f
20、rom drafts andfumes and in which the temperature changes between relatedweighings (empty and filled pycnometer) do not cause asignificant change in the ratio of the balance arms. Otherwise,weighings shall be made by the substitution method in whichthe calibrated weights and pycnometer are alternativ
21、elyweighed on the same balance pan. The same balance shall beused for all related weighings.6.8 WeightsWeights shall be used whose relative valuesare known to the nearest 0.05 mg or better. The same set ofweights shall be used for the calibration of the pycnometer andthe determination of the densiti
22、es, or the sets of weights shallbe calibrated relative to each other.7. Reagents and Materials7.1 Acetone(WarningExtremely flammable. Use ad-equate ventilation.)7.2 Isopentane(WarningExtremely flammable. Avoidbuildup of vapors and remove all sources of ignition, especiallynonexplosion-proof electric
23、al apparatus.)7.3 Chromic Acid (Potassium Dichromate/Conc. SulfuricAcid)(WarningCauses severe burns. A recognized car-cinogen. Do not get in eyes, on skin or clothing.)7.4 Xylenes(WarningFlammable liquid. Aspirationhazard. May irritate skin, eyes, respiratory tract or digestivetract, or both. May ca
24、use central nervous system depression,liver and kidney damage, or exhibit reproductive and fetaleffects, or both.)8. Preparation of Apparatus8.1 Thoroughly clean the pycnometer and side arm with hotchromic acid cleaning solution (WarningSee 7.4). Chromicacid solution is the most effective cleaning a
25、gent. However,surfactant cleaning fluids have also been used successfully.Rinse well with distilled water; and dry at 105 to 110C for atleast 1 h, preferably with a slow current of filtered air passingthrough the pycnometer. Cleaning shall be done in this mannerwhenever the pycnometer is to be calib
26、rated or whenever liquidfails to drain cleanly from the walls of the pycnometer or itscapillary. Ordinarily, the pycnometer may be cleaned betweendeterminations by washing with a suitable solvent, such asisopentane or xylenes, and vacuum drying. If acetone is used asthe wash liquid, the pycnometer s
27、hould then be rinsed withisopentane or xylenes.FIG. 1 PycnometerFIG. 2 Rack for Filling PycnometerD14810229. Calibration of Pycnometer9.1 Weigh the clean, dry pycnometer (without the side arm)to the nearest 0.1 mg, and record the weight.9.2 Fill the pycnometer with freshly boiled distilled water.Thi
28、s may be conveniently done by placing the pycnometer inthe holder with the side arm dipping into a sample cupcontaining water. Allow the pycnometer to fill by siphoning.Break the siphon by removing the side arm when the liquidlevel in the bulb arm of the pycnometer reaches 6 on the scale.9.3 Remove
29、the side arm which was used to fill thepycnometer and remove excess liquid from the capillary tip bywiping with a small piece of absorbent paper.9.4 Place the pycnometer in the holder in the constant-temperature bath at temperature t with the liquid level in thecapillaries below the liquid level in
30、the bath. When the liquidlevel has reached equilibrium (not less than 15 min), read thescale to the nearest 0.2 small division at the liquid level in eacharm. After 5 min, read the liquid level again. If the sum of thescale readings in each reading differs by more than 60.04,repeat readings at 5-min
31、 intervals. When readings are constant,record.9.5 Remove the pycnometer from the bath and allow it tocome to room temperature. Rinse the outer surface withdistilled water, with acetone, then with redistilled xylenes, anddry thoroughly with a chemically clean lint-free cloth, slightlydamp with water.
32、 Allow to stand a few minutes, and then weighto nearest 0.1 mg.NOTE 2In atmospheres of low humidity (60 % or lower), drying thepycnometer by rubbing with dry cotton cloth will induce static chargesequivalent to a loss of about 1 mg or more in the weight of thepycnometer. This charge may not be compl
33、etely dissipated in less than12h and can be detected by touching the pycnometer to the wire hook on thebalance and then drawing it away slowly. If the pycnometer exhibits anattraction for the wire hook, it may be considered to have a static charge.9.6 Repeat the above, but break the siphon when wate
34、r hasreached the 3 mark in the bulb arm, and in the next experiment,at the 0 mark in the bulb arm. Obtain the apparent volume foreach filling by dividing the weight of water held by thepycnometer in each experiment by the density of water at thecalibration temperature t. Calibration shall be made at
35、 20, 40,and 50C. Prepare a calibration curve for 20C by plotting thesum of the two scale readings versus the apparent volume at20C. If the curve is not a straight line, and future checks donot correct it, discard the pycnometer. The line shall not bemore than 0.0002 mL/unit from any one determined p
36、oint.9.7 Corresponding calibration curves shall be made for 40and 50C. These calibration curves are checked using thefollowing equation:V25 V11 1 ct! (1)where:V2= apparent volume at test temperature,V1= apparent volume at 20C, andc = cubical coefficient of expansion of borosilicate glass(9.9 3 106/C
37、).The calculated and determined curves at 40 and 50C shouldcheck to within 60.0002 mL/unit at all points. The calibrationcurves for higher temperatures shall be obtained by calculation.10. Procedure10.1 Weigh the clean, dry pycnometer, without the side arm,to 0.1 mg and record the weight.10.2 Place
38、a 10-mL sample beaker in the wooden rack (Fig.2). Before attaching the side arm to the pycnometer, drain afew drops of sample through the side arm to wet the insidesurface and reduce the chance of trapping air bubbles in thecapillary during the filling operation. Place the side arm on thepycnometer,
39、 and place the assembly on the rack with the sidearm dipping into the sample beaker as shown in Fig. 4.10.3 In filling the pycnometer with very viscous oils orhigh-melting waxes, place the whole filling assembly in ahot-air oven to facilitate filling. An oven at approximately100C is usually hot enou
40、gh for this purpose.10.4 Apply gentle suction to the bulb arm of the pycnometerto start the siphoning action. The suction must be gentle toavoid the formation of bubbles. After siphoning is started,allow filling by siphoning to continue until the liquid level inMetric Equivalentsin. mm in. mm in. mm
41、12 3.212 12.7 158 41.314 6.4916 14.3 2316 55.7516 7.934 19.1 712 19138 9.5 112 38.1FIG. 3 Pycnometer HolderD1481023the bulb arm ceases to rise. Then remove the pycnometer fromthe rack and place in the thermostated bath, in the same tiltedposition, until the oil ceases to contract. At this point, pla
42、ce thepycnometer in an upright position, and allow the liquid level inthe bulb arm to reach the upper portion of the calibratedcapillary, but not above 6.4. Stop siphoning by removing theside arm.NOTE 3With viscous oils, it will reduce drainage errors to fill to the6.0 to 6.4 mark, and it may be nec
43、essary to apply a little suction to the longarm during cooling to prevent the meniscus in the bulb arm from falling.Maintain the meniscus at about the same level in the long arm throughoutthe whole determination.10.5 After removing the side-arm cap from the short arm ofthe pycnometer, wipe the tip a
44、nd ground joint of the pycnom-eter, and adjust it to an upright position in the thermostatedbath. The bath liquid level shall be above the 6 mark on thepycnometer and below the ground glass tip of the pycnometer.10.6 Allow 15 min for equilibrium to be obtained. After thestated 15-min time for coming
45、 to equilibrium, read the menis-cus levels in both arms of the pycnometer to the nearest 0.2 ofthe smallest scale division. Wait 5 min and check readings. Ifthe sum of the readings at the two different times do not agreeto within 60.04, repeat at 5-min intervals until checks areobtained. Record the
46、sum of these readings and also record thecorresponding apparent volume from the calibration curve forthe same temperature.NOTE 4The final level of oil in the pycnometer should not be morethan 5 mm below the tip of the ground glass end of the pycnometer, andthe level in the long (bulb) side of the py
47、cnometer should be no lower thanit has been at any time during the procedure. With these precautions,drainage error (which is important with very viscous samples) is entirelyeliminated.10.7 Remove the pycnometer from the bath and tilt it so thatthe liquid moves down in the short arm and up in the bu
48、lb arm.Clean and dry the outside of the pycnometer as described in thecalibration procedure (Section 9). Allow to come to balanceroom temperature. Weigh to the nearest 0.1 mg. Subtract theweight of empty pycnometer, without the side arm, to get theweight of sample.11. Calculation11.1 Calculate the d
49、ensity of the sample, corrected tovacuum, by the following equation:Density in vacuum, dt, g/mL 5 W/V! 1 C (2)where:W = weight of sample in air, g,V = apparent volume, mL, andFIG. 4 Pycnometer Filling AssemblyD1481024C = vacuum correction, obtained from Table 1.11.2 Calculate the relative density (specific gravity) of thesample at t1/t2by dividing the density, as calculated in 10.1, bythe density of water at the reference temperature, t2,asobtained from Table 2. Relative density (specific gravity) att1/15.56C (t/60F where t i
