ASTM D1481-93(1997)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn
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Designation:D1481–93 (Reapproved 1997) An American National Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Density and Relative Density (Specific Gravity) of Viscous
Materials by Lipkin Bicapillary Pycnometer
This standard is issued under the fixed designation D1481; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Summary of Test Method
1.1 Thistestmethodcoversthedeterminationofthedensity 4.1 The liquid is drawn into the bicapillary pycnometer
of oils more viscous than 15 cSt at 20°C (mm /s), and of through the removable siphon arm and adjusted to volume at
viscousoilsandmeltedwaxesatelevatedtemperatures,butnot the temperature of test, in such a manner that there is
at temperatures at which the sample would have a vapor practically no drainage in the unfilled tubing. After equilibra-
pressure of 100 mm Hg (13 kPa) or above. tion at the test temperature, liquid levels are read, and the
pycnometer is removed from the thermostated bath, cooled to
NOTE 1—To determine the densities of less viscous liquids at 20 or
room temperature, and weighed.
25°C use Test Method D941 or Test Method D1217.
4.2 Density or relative density (specific gravity), as desired,
1.2 This test method provides a calculation procedure for
is then calculated from the volume at the test temperature and
converting density to relative density (specific gravity).
theweightofthesample.Theeffectofairbuoyancyisincluded
1.3 The values stated in acceptable SI units are to be
in the calculations.
regarded as the standard.
1.4 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 Density is a fundamental physical property that can be
responsibility of the user of this standard to establish appro-
used in conjunction with other properties to characterize both
priate safety and health practices and determine the applica-
the light and heavy fractions of petroleum and to access the
bility of regulatory limitations prior to use.
quality of crude oils.
5.2 Determination of the density or relative density of
2. Referenced Documents
petroleum and its products is necessary for the conversion of
2.1 ASTM Standards:
measured volumes to volumes at the standard temperatures of
D941 Test Method for Density and Relative Density (Spe-
15°C.
cific Gravity) of Liquids by Lipkin Bicapillary Pycnom-
5.3 The determination of densities at the elevated tempera-
eter
tures of 40 and 100°C is particularly useful in providing the
D1217 Test Method for Density and Relative Density
data needed for the conversion of kinematic viscosities in
(Specific Gravity) of Liquids by Bingham Pycnometer 2
centistokes (mm /s) to the corresponding dynamic viscosities
D1250 Guide for Petroleum Measurement Tables
in centipoises (mPa·s).
3. Terminology
6. Apparatus
3.1 Definitions:
6.1 Pycnometer —Aside-armtypeofpycnometerconform-
3.1.1 density—the weight in a vacuum (that is, the mass) of
ing to the dimensions given in Fig. 1 and made of borosilicate
a unit volume of the material at any given temperature.
glass. The weight shall not exceed 35 g without the side arm.
3.1.2 relative density (specific gravity)—the ratio of the
6.2 Rack—Arack to use in filling the pycnometer (see Fig.
mass (weight in a vacuum) of a given volume of material at a
2 ).
temperature, t , to the mass of an equal volume of water at a
6.3 Constant-Temperature Oven—An oven for use in filling
reference temperature, t ; or the ratio of the density of the
the pycnometer. Any oven capable of holding the filling rack,
material at t to the density of water at t .
1 2
and of maintaining a temperature of approximately 100°C, can
be used.
6.4 Constant-Temperature Bath—A mixture of water and
This test method is under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
For a more complete discussion of this procedure see Lipkin, M. R., Mills, I.
D02.04on Hydrocarbon Analysis.
W., Martin, C. C., and Harvey,W.T., Analytical Chemistry,ANCHA,Vol 21, 1949,
Current edition approved Feb. 15, 1993. Published June 1993. Originally
p. 504.
published as D1481–57T. Last previous edition D1481–91.
Pycnometers available from Reliance Glass Co., 220 Gateway Rd., Bensen-
Annual book of ASTM Standards, Vol 05.01.
ville, IL 60106-0825 have been found satisfactory.
D1481
ture error of60.013°C would cause an error of60.00001 in
density.
6.6 Pycnometer Holder—A holder, as shown in Fig. 3 , is
recommended for supporting the pycnometer in the bath. A
single clamp device may be used.
6.7 Balance—Abalanceabletoreproduceweighingswithin
0.1 mg when carrying a load of 35 g or less on each pan. The
balance shall be located in a room shielded from drafts and
fumes and in which the temperature changes between related
weighings (empty and filled pycnometer) do not cause a
significant change in the ratio of the balance arms. Otherwise,
weighings shall be made by the substitution method in which
the calibrated weights and pycnometer are alternatively
weighed on the same balance pan. The same balance shall be
used for all related weighings.
6.8 Weights—Weights shall be used whose relative values
are known to the nearest 0.05 mg or better. The same set of
weightsshallbeusedforthecalibrationofthepycnometerand
the determination of the densities, or the sets of weights shall
be calibrated relative to each other.
FIG. 1 Pycnometer
FIG. 2 Rack for Filling Pycnometer
glycerin, or oil bath having a depth of at least 305 mm (12 in.)
and provided with heating, stirring, and thermostating devices
adequatetomaintaindesiredtemperaturesintherangefrom20
Metric Equivalents
to 100°C with an accuracy of 60.01°C.
in. mm in. mm in. mm
6.5 BathThermometers—Thermometersgraduatedin0.1°C
1 1 5
⁄2 3.2 ⁄2 12.7 1 ⁄8 41.3
subdivisions and standardized for the range of use to the
1 9 3
⁄4 6.4 ⁄16 14.3 2 ⁄16 55.7
5 3 1
nearest 0.01°C (ASTM Saybolt Viscosity Thermometers 17C ⁄16 7.9 ⁄4 19.1 7 ⁄2 191
3 1
⁄8 9.5 1 ⁄2 38.1
to 22C are recommended). For most hydrocarbons, the density
coefficient is about 0.0008 units/°C, and therefore a tempera- FIG. 3 Pycnometer Holder
--``,`````,,,,`,`,`````,,```,`-`-`,,`,,`,`,,`---
D1481
h and can be detected by touching the pycnometer to the wirehookonthe
7. Reagents and Materials
balance and then drawing it away slowly. If the pycnometer exhibits an
7.1 Acetone—Warning—Extremely flammable. Use ad-
attraction for the wire hook, it may be considered to have a static charge.
equate ventilation.
9.6 Repeat the above, but break the siphon when water has
7.2 Isopentane—Warning—Extremely flammable. Avoid
reachedthe3markinthebulbarm,andinthenextexperiment,
buildupofvaporsandremoveallsourcesofignition,especially
at the 0 mark in the bulb arm. Obtain the apparent volume for
nonexplosion-proof electrical apparatus.
each filling by dividing the weight of water held by the
7.3 Chromic Acid (Potassium Dichromate/Conc. Sulfuric
pycnometer in each experiment by the density of water at the
Acid)—Warning—Causessevereburns.Arecognizedcarcino-
calibration temperature t. Calibration shall be made at 20, 40,
gen. Do not get in eyes, on skin or clothing.
and 50°C. Prepare a calibration curve for 20°C by plotting the
7.4 Benzene—Warning—Poison. Known carcinogen. Ex-
sum of the two scale readings versus the apparent volume at
tremely flammable. Avoid contact with skin and eyes.
20°C. If the curve is not a straight line, and future checks do
8. Preparation ofApparatus
not correct it, discard the pycnometer. The line shall not be
more than 0.0002 mL/unit from any one determined point.
8.1 Thoroughlycleanthepycnometerandsidearmwithhot
9.7 Corresponding calibration curves shall be made for 40
chromic acid cleaning solution (Warning—See 7.4.) Chromic
and 50°C. These calibration curves are checked using the
acid solution is the most effective cleaning agent. However,
surfactant cleaning fluids have also been used successfully. following equation:
Rinse well with distilled water; and dry at 105 to 110°C for at
V 5 V ~11 ct! (1)
2 1
least 1 h, preferably with a slow current of filtered air passing
where:
through the pycnometer. Cleaning shall be done in this manner
V 5 apparent volume at test temperature,
wheneverthepycnometeristobecalibratedorwheneverliquid 2
V 5 apparent volume at 20°C, and
fails to drain cleanly from the walls of the pycnometer or its
c 5 cubical coefficient of expansion of borosilicate glass
capillary. Ordinarily, the pycnometer may be cleaned between
−6
(9.9310 /°C).
determinations by washing with a suitable solvent, such as
Thecalculatedanddeterminedcurvesat40and50°Cshould
isopentane or benzene, and vacuum drying. If acetone is used
check to within60.0002 mL/unit at all points. The calibration
as the wash liquid, the pycnometer should then be rinsed with
curvesforhighertemperaturesshallbeobtainedbycalculation.
isopentane or benzene.
10. Procedure
9. Calibration of Pycnometer
10.1 Weightheclean,drypycnometer,withoutthesidearm,
9.1 Weigh the clean, dry pycnometer (without the side arm)
to 0.1 mg and record the weight.
to the nearest 0.1 mg, and record the weight.
10.2 Pla
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