1、Designation: D 1217 93 (Reapproved 2007)An American National StandardStandard Test Method forDensity and Relative Density (Specific Gravity) of Liquids byBingham Pycnometer1This standard is issued under the fixed designation D 1217; the number immediately following the designation indicates the year
2、 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.This standard has been approved for use by agencies of the Departme
3、nt of Defense.1. Scope1.1 This test method covers the measurement of the densityof pure hydrocarbons or petroleum distillates boiling between90 and 110C that can be handled in a normal fashion as aliquid at the specified test temperatures of 20 and 25C.1.2 This test method provides a calculation pro
4、cedure forthe conversion of density to relative density (specific gravity).1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its
5、 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 limitations prior to use. Specific warningstatements are given in Section 7.2. Referenced Documents2.1 ASTM Standards:2E1 Specification for
6、ASTM Liquid-in-Glass Thermometers3. Terminology3.1 Definitions:3.1.1 densitythe weight in vacuo, (that is, the mass) of aunit volume of the material at any given temperature.3.1.2 relative density (specific gravity)the ratio of themass (weight in vacuo) of a given volume of material at atemperature,
7、 t1, to the mass of an equal volume of water at areference temperature, t2; or it is the ratio of the density of thematerial at t1to the density of water at t2. When the referencetemperature is 4.00C, the temperature at which the relativedensity of water is unity, relative density (specific gravity)
8、 anddensity are numerically equal.4. Summary of Test Method4.1 The liquid sample is introduced into a pycnometer,equilibrated to the desired temperature, and weighed. Therelative density (specific gravity) or density is then calculatedfrom this weight and the previously determined weight ofwater tha
9、t is required to fill the pycnometer at the sametemperature, both weights being corrected for the buoyancy ofair.5. Significance and Use5.1 Density is a fundamental physical property which can beused in conjunction with other properties to characterize purehydrocarbons and their mixtures.5.2 This te
10、st method was originally developed for thedetermination of the density of the ASTM Knock Test Refer-ence Fuels n-heptane and isooctane, with an accuracy of0.00003 g/mL. Although it is no longer employed extensivelyfor this purpose, this test method is useful whenever accuratedensities of pure hydroc
11、arbons or petroleum fractions withboiling points between 90 and 110C are required.6. Apparatus6.1 Pycnometer, Bingham-type,3conforming to the dimen-sions given in Fig. 1, constructed of borosilicate glass, andhaving a total weight not exceeding 30 g.6.2 Constant-Temperature Bath, provided with suita
12、ble py-cnometer holders or clips and means for maintaining tempera-tures constant to 60.01C in the desired range.6.3 Bath Thermometer, graduated in 0.1C subdivisions andstandardized for the ice point and the range of use to the nearest0.01C. ASTM Saybolt Viscosity Thermometer 17C as pre-scribed in S
13、pecification E1, designed for tests at 21.1C and1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.04.0D on Physical and Chemical Methods.Current edition approved Dec. 1, 2007. Published January 20
14、08. Originallyapproved in 1952. Last previous edition approved in 2003 as D 121793(2003)e1.2For referenced ASTM standards, 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 Su
15、mmary page onthe ASTM website.3The sole source of supply of the pycnometer known to the committee at thistime is Reliance Glass Co., 220 Gateway Rd., Bensenville, IL 60106-0825. If youare aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments
16、 will receive careful consideration at ameeting of the responsible technical committee,2which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.25C, is recommended. A standardized platinum resistancethermometer may also
17、be used, and offers the best means forobserving minute temperature changes in the bath. Whichevermeans are available, it must be realized that for most hydro-carbons the density coefficient is about 0.0008 units/C, andtherefore an error of 60.013C would cause an error of60.00001 in density.6.4 Hypod
18、ermic Syringe, 30-mL capacity, of chemicallyresistant glass, equipped with a 152-mm (6-in.) needle made ofstainless steel tubing as shown in Fig. 2.6.5 Draw-Off Needle, made of stainless steel tubing asshown in Fig. 2.6.6 Solvent-Cleaning Assembly, as shown in Fig. 3.6.7 Chromic Acid Cleaning Appara
19、tus, similar to thatshown in Fig. 4.6.8 Balance, capable of reproducing weighings within 0.1mg. Mechanical balances should have sensitivity which causesthe pointer to be deflected 2 or 3 scale divisions per 1 mg whencarrying a load of 30 g or less on each pan. The balance shouldbe located in a room
20、shielded from drafts and fumes and inwhich the temperature changes between related weighings(empty and filled pycnometer) do not cause a significantchange in the ratio of the balance arms. Otherwise weighingsshall be made by the method of substitution, in which thecalibrated weights and pycnometer a
21、re alternately weighed onthe same balance pan. The same balance shall be used for allrelated weighings.6.9 Weights, whose relative values are known to the nearest0.05 mg or better. The same set of weights shall be used for thecalibration of the pycnometer and the determination of densi-ties.7. Reage
22、nts and Materials7.1 Acetone(WarningExtremely flammable. Use ad-equate ventilation.)7.2 Isopentane(WarningExtremely flammable. Avoidbuildup of vapors and remove all sources of ignition, especiallynon-explosion proof electrical apparatus.)7.3 Chromic Acid (Potassium Dichromate/Conc. SulfuricAcid)(War
23、ningCauses severe burns. A recognized car-cinogen. Do not get in eyes, or on skin or clothing.)8. Preparation of Apparatus8.1 Thoroughly clean the pycnometer with hot chromic acidcleaning solution by means of the assembly shown in Fig. 4.Chromic acid solution (WarningSee 7.3) is the most effec-tive
24、cleaning agent. However, surfactant cleaning fluids havealso been used successfully. Mount the apparatus firmly andconnect the trap to the vacuum. Warm the necessary amount ofcleaning acid in the beaker, place the pycnometer on theground joint, and evacuate by opening the stopcock to vacuum.Fill the
25、 pycnometer with acid by turning the stopcock, repeatseveral times or remove the filled pycnometer, and allow it tostand for several hours at 50 to 60C. Remove the acid from thepycnometer by evacuation, empty the acid from the trap, andflush the pycnometer with water. Cleaning should be made inthis
26、manner whenever the pycnometer is to be calibrated orwhenever liquid fails to drain cleanly from the walls of thepycnometer or its capillary. Ordinarily, the pycnometer may becleaned between determinations by washing with a suitablesolvent, rinsing with pure, dry acetone, followed by isopentane,and
27、vacuum drying.8.2 Transfer the pycnometer to the cleaner assembly shownin Fig. 3, with vacuum line and trap attached to the side tubeas indicated. Place the pycnometer on the cleaner with theupper hypodermic needle extending upward into the pycnom-eter, and press the edge of the ground joint on the
28、rubberstopper until the vacuum holds it in place. Draw out all theliquid or sample. Immerse the lower end of the hypodermictube in a suitable solvent and draw 20 to 25 mL through thepycnometer. Leaving the pycnometer in place, draw air throughit until it is dry. Clean the hypodermic syringe with the
29、 sameapparatus.9. Calibration of Pycnometer9.1 Proceeding as directed in Section 10, determine theweight of freshly-boiled and cooled distilled water (distilledfrom alkaline permanganate through a tin condenser) held bythe pycnometer when equilibrated to volume at the bathtemperature to be used in t
30、he determination. Repeat until atleast three values agree to 60.2 mg.10. Procedure10.1 Using another 25-mL pycnometer as a tare (Note 1),weigh the clean, dry pycnometer to 0.1 mg and record theweight.FIG. 1 Bingham-Type Pycnometer, 25 mLD 1217 93 (2007)2NOTE 1It is convenient to use the lightest of
31、a set of pycnometers asa tare. For best results the treatment and environment of both pycnometerand tare should be identical for some time prior to weighing.10.2 Cool the sample to 5 to 10C below the test tempera-ture, and fill the clean 30-mL hypodermic syringe. Transfer thesample to the pycnometer
32、 through the filling needle; avoidtrapping air bubbles (WarningExtremely flammable. Avoidbuildup of vapors and remove all sources of ignition, especiallynon-explosion proof electrical apparatus) in the bulb or capil-lary of the pycnometer. If any are present, draw them into thesyringe where possible
33、. Also remove with the syringe ordraw-off needle any liquid above the calibration mark in thecapillary or overflow reservoir. Dry the remainder with a cottonfiber pipe cleaner or cotton swab which has been dampenedslightly with acetone.FIG. 2 Accessories for Bingham-Type PycnometerFIG. 3 Cleaner Ass
34、embly for Bingham-Type PycnometerD 1217 93 (2007)3NOTE 2For work of highest accuracy on pure compounds, dissolvedair may be removed from the sample by repeated freezing and remeltingof the sample under vacuum in the pycnometer.10.3 Close the pycnometer with the glass stopper andimmerse it to a point
35、 above the calibration mark in theconstant-temperature bath adjusted to a constancy of 60.01Cat the desired temperature. Periodically, or before the liquidexpands into the overflow chamber, remove the stopper, raisethe pycnometer sufficiently to expose the calibration mark toview, and readjust the l
36、iquid level to the mark by withdrawingliquid through the steel draw-off needle until expansion hasstopped, indicating that the liquid has reached the temperatureof the thermostat. Do not allow the liquid to expand more than10 mm above the calibration mark at any time, to minimizeerrors caused by fau
37、lty drainage. Allow the contents to equili-brate an additional 10 min and draw the level down exactly tothe calibration line, avoiding parallax and using a magnifier, ifnecessary, to obtain good visibility. Remove any liquid adher-ing to the walls above the calibration mark, with the draw-offneedle
38、or pipe cleaner, depending upon the volatility of thesample. Portions in the overflow bulb may be removed with acotton swab moistened with acetone.10.4 Replace the glass stopper, remove the pycnometerfrom the bath, wash the outside surface with acetone, and drythoroughly with a chemically clean, lin
39、t-free, slightly dampcloth. Place the pycnometer in or near the balance case for 20min and weigh to the nearest 0.1 mg. In atmospheres of lowhumidity (60 % or lower), drying the pycnometer by rubbingwith a dry cotton cloth will induce static charges equivalent toa loss of about 1 mg in the weight of
40、 the pycnometer. Thischarge need not be completely dissipated in less than 30 min.The use of about 0.1-mg radium bromide- or polonium-coatedfoil in the balance case, or maintaining the relative humidity at60 % or higher, aids in reducing weighing difficulties due tostatic charges.10.5 Record tempera
41、ture of the balance, barometric pres-sure, and relative humidity.11. Calculation11.1 Calculate the true density of the sample as follows:Density, g/mL at C 5 Ws1 1 da/ds! 2 da/dwt!dw/Ww1 1 da/dw!2 da/dwt! (1)where:Ws= weight in air of sample contained in the pycnometerat the test temperature, g,Ww=
42、weight in air of the water contained in the pycnom-eter at the calibration temperature, g,dw= density of water at the calibration temperature, asobtained from Table 1,da= density of air in balance case at the time of weigh-ing, as calculated from 10.3,dwt= density of weights used in weighing the sam
43、ple andwater (brass = 10.4 g/mL, stainless steel = 7.75g/mL), andds= approximate density of sample orWs3 d!/Ww(2)11.2 The equation assumes that the weighings of the pyc-nometer empty and filled are made in such a short time intervalthat the air density has not changed. If significant changeshould oc
44、cur, the calculated apparent weight of the sample, Ws,in this equation, must be corrected for the difference in airbuoyancy exerted on the pycnometer as follows:Ws5 W2PS2 W8p1 1 d8a/2.2!2 d8a/dwt!/1 1 da2/2.2! 2 da2/dwt! (3)where:W2PS= weight of pycnometer and contained sample undersecond or final a
45、ir density,W8P= weight of pycnometer in air of first density,d8a= density of air when weighing empty pycnometer,da2= density of air when weighing filled pycnometer,dwt= density of weights, and2.2 = borosilicate glass.Likewise, if the pycnometer, empty and filled with water forcalibration, is weighed
46、 under different air densities a similarcorrection for different air buoyancies shall be applied.11.3 Calculate the relative density (specific gravity) of thesample by dividing the density as obtained in 11.1 by therelative density of water at the reference temperature obtainedfrom Table 1.11.4 Calc
47、ulate the density of air in the balance room asfollows:FIG. 4 All-Glass Pycnometer Cleaner Assembly for Use with Hot Chromic Acid Cleaning SolutionD 1217 93 (2007)4Air density da!, g/mL5 B 0.3783 Hp!0.000465!#/273 1 t!(4)where:B = barometric pressure, mm Hg, corrected to 0C,H = relative humidity, de
48、cimal fraction,p = vapor pressure of water at temperature t, mm Hg, andt = room temperature, C.NOTE 3If this test method is to be used frequently, a considerableamount of calculation can be avoided by use of a gas density balance todetermine the air density. Weigh a sealed 250-mL glass bulb at sever
49、aldifferent air densities and plot the weight against the air density. Todetermine the air density at some later time, weigh the bulb and read theair density from the point on the curve corresponding to the weight.11.5 To calculate the density or relative density (specificgravity) at any test temperature, t, other than the calibrationtemperature, tc(to correct for the cubical coefficient of thermalexpansion of borosilicate glass), divide the value obtained in10.1 or 10.2 by the following expression:1 1 9.6 3 1026t 2 tc! (5)12.
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