ASTM D1298-99(2005)
(Test Method)Standard Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
Standard Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method
SIGNIFICANCE AND USE
Accurate determination of the density, relative density (specific gravity), or API gravity of petroleum and its products is necessary for the conversion of measured volumes to volumes or masses, or both, at the standard reference temperatures during custody transfer.
This test method is most suitable for determining the density, relative density (specific gravity), or API gravity of low viscosity transparent liquids. This test method can also be used for viscous liquids by allowing sufficient time for the hydrometer to reach equilibrium, and for opaque liquids by employing a suitable meniscus correction.
When used in connection with bulk oil measurements, volume correction errors are minimized by observing the hydrometer reading at a temperature close to that of the bulk oil temperature.
Density, relative density (specific gravity), or API gravity is a factor governing the quality and pricing of crude petroleum. However, this property of petroleum is an uncertain indication of its quality unless correlated with other properties.
Density is an important quality indicator for automotive, aviation and marine fuels, where it affects storage, handling and combustion.
SCOPE
1.1 This test method covers the laboratory determination using a glass hydrometer, of the density, relative density (specific gravity), or API gravity of crude petroleum, petroleum products, or mixtures of petroleum and nonpetroleum products normally handled as liquids, and having a Reid vapor pressure of 101.325 kPa (14.696 psi) or less.
1.2 Values are measured on a hydrometer at either the reference temperature or at another convenient temperature, and readings corrected to the reference temperature by means of the Petroleum Measurement Tables; values obtained at other than the reference temperature being hydrometer readings and not density measurements.
1.3 Values determined as density, relative density, or API gravity can be converted to equivalent values in the other units at alternate reference temperatures by means of the Petroleum Measurement Tables.
1.4 Annex A1 contains a procedure for verifying or certifying the equipment for this test method.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D1298 – 99 (Reapproved 2005)
Designation: Manual of Petroleum Measurement Standards (MPMS), Chapter 9.1
Designation: 160/99
Standard Test Method for
Density, Relative Density (Specific Gravity), or API Gravity
of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method
This standard is issued under the fixed designation D1298; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (ϵ) 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 2. Referenced Documents
1.1 This test method covers the laboratory determination 2.1 ASTM Standards:
using a glass hydrometer, of the density, relative density D97 Test Method for Pour Point of Petroleum Products
(specificgravity),orAPIgravityofcrudepetroleum,petroleum D323 Test Method for Vapor Pressure of Petroleum Prod-
products, or mixtures of petroleum and nonpetroleum products ucts (Reid Method)
normally handled as liquids, and having a Reid vapor pressure D1250 GuideforUseofthePetroleumMeasurementTables
of 101.325 kPa (14.696 psi) or less. D2500 Test Method for Cloud Point of Petroleum Products
1.2 Values are measured on a hydrometer at either the D3117 Test Method for WaxAppearance Point of Distillate
reference temperature or at another convenient temperature, Fuels
and readings corrected to the reference temperature by means D4057 Practice for Manual Sampling of Petroleum and
of the Petroleum MeasurementTables; values obtained at other Petroleum Products (API MPMS Chapter 8.1)
than the reference temperature being hydrometer readings and D4177 Practice for Automatic Sampling of Petroleum and
not density measurements. Petroleum Products (API MPMS Chapter 8.2)
1.3 Values determined as density, relative density, or API D5854 PracticeforMixingandHandlingofLiquidSamples
gravity can be converted to equivalent values in the other units ofPetroleumandPetroleumProducts(API MPMSChapter
at alternate reference temperatures by means of the Petroleum 8.3)
Measurement Tables. E1 Specification for ASTM Liquid-in-Glass Thermometers
1.4 AnnexA1 contains a procedure for verifying or certify- E100 Specification for ASTM Hydrometers
ing the equipment for this test method. 2.2 API Standards:
1.5 This standard does not purport to address all of the MPMS Chapter 8.1 Manual Sampling of Petroleum and
safety concerns, if any, associated with its use. It is the Petroleum Products (ASTM Practice D4057)
responsibility of the user of this standard to establish appro- MPMS Chapter 8.2 Automatic Sampling of Petroleum and
priate safety and health practices and determine the applica- Petroleum Products (ASTM Practice D4177)
bility of regulatory limitations prior to use.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This test method is under the jurisdiction of ASTM Committee D02 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Petroleum Products and Lubricants and theAPI Committee on Petroleum Measure- Standards volume information, refer to the standard’s Document Summary page on
ment, and is the direct responsibility of D02.02 /COMQ on Hydrocarbon Measure- the ASTM website.
ment for Custody Transfer (Joint ASTM-API). Withdrawn. The last approved version of this historical standard is referenced
Current edition approved Nov. 1, 2005. Published December 2005. Originally on www.astm.org.
´2 4
approved in 1953. Last previous edition approved in 1999 as D1298–99 . DOI: Published as Manual of Petroleum Measurement Standards.Available from the
10.1520/D1298-99R05. American Petroleum Institute (API), 1220 L St., NW, Washington, DC 20005.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D1298 – 99 (2005)
MPMSChapter8.3 MixingandHandlingofLiquidSamples appropriate hydrometer, also at a similar temperature, is
of Petroleum and Petroleum Products (ASTM Practice lowered into the test portion and allowed to settle. After
D5854) temperature equilibrium has been reached, the hydrometer
2.3 Institute of Petroleum Standards: scale is read, and the temperature of the test portion is taken.
IP 389 Determination of wax appearance temperature The observed hydrometer reading is reduced to the reference
(WAT) of middle distillate fuels by differential thermal temperaturebymeansofthePetroleumMeasurementTables.If
analysis (DTA) or differential scanning calorimetry (DSC) necessary, the hydrometer cylinder and its contents are placed
IPStandardMethodsBook, AppendixA,Specifications–IP in a constant temperature bath to avoid excessive temperature
Standard Thermometers variation during the test.
2.4 ISO Standards:
5. Significance and Use
ISO 649-1 Laboratory glassware – Density hydrometers for
general purpose – Part 1: Specification
5.1 Accurate determination of the density, relative density
(specific gravity), orAPI gravity of petroleum and its products
3. Terminology
is necessary for the conversion of measured volumes to
3.1 Definitions of Terms Specific to This Standard: volumes or masses, or both, at the standard reference tempera-
3.1.1 API gravity, n—a special function of relative density
tures during custody transfer.
(specific gravity) 60/60°F, represented by: 5.2 This test method is most suitable for determining the
density, relative density (specific gravity), or API gravity of
° API 5 141.5/~sp gr 60/60°F!2 131.5 (1)
low viscosity transparent liquids. This test method can also be
3.1.1.1 Discussion—No statement of reference temperature
used for viscous liquids by allowing sufficient time for the
is required, as 60°F is included in the definition.
hydrometer to reach equilibrium, and for opaque liquids by
3.1.2 cloud point, n—temperature at which a cloud of wax
employing a suitable meniscus correction.
crystalsfirstappearsinaliquidwhenitiscooledunderspecific
5.3 When used in connection with bulk oil measurements,
conditions.
volume correction errors are minimized by observing the
3.1.3 density, n—the mass of liquid per unit volume at 15°C
hydrometerreadingatatemperatureclosetothatofthebulkoil
and 101.325 kPa with the standard unit of measurement being
temperature.
kilograms per cubic metre.
5.4 Density, relative density (specific gravity), orAPI grav-
3.1.3.1 Discussion—Other reference temperatures, such as
ity is a factor governing the quality and pricing of crude
20°C, may be used for some products or in some locations.
petroleum. However, this property of petroleum is an uncertain
Less preferred units of measurement (for example, kg/L or
indication of its quality unless correlated with other properties.
g/mL) are still in use.
5.5 Densityisanimportantqualityindicatorforautomotive,
3.1.4 observed values, n—values observed at temperatures
aviation and marine fuels, where it affects storage, handling
otherthanthespecifiedreferencetemperature.Thesevaluesare
and combustion.
only hydrometer readings and not density, relative density
(specific gravity), or API gravity at that other temperature.
6. Apparatus
3.1.5 pour point, n—lowest temperature at which a test
6.1 Hydrometers, of glass, graduated in units of density,
portion of crude petroleum or petroleum product will continue
relative density, or API gravity as required, conforming to
to flow when it is cooled under specified conditions.
Specification E100 or ISO 649-1, and the requirements given
3.1.6 relative density (specific gravity), n—the ratio of the
in Table 1.
mass of a given volume of liquid at a specific temperature to
6.1.1 The user should ascertain that the instruments used for
the mass of an equal volume of pure water at the same or
thistestconformtotherequirementssetoutabovewithrespect
different temperature. Both reference temperatures shall be
to materials, dimensions, and scale errors. In cases where the
explicitly stated.
instrument is provided with a calibration certificate issued by a
3.1.6.1 Discussion—Common reference temperatures in-
recognized standardizing body, the instrument is classed as
clude 60/60°F, 20/20°C, 20/4°C. The historic deprecated term
certified and the appropriate corrections listed shall be applied
specific gravity may still be found.
3.1.7 wax appearance temperature (WAT), n—temperature
at which waxy solids form when a crude petroleum or
TABLE 1 Recommended Hydrometers
A
petroleum product is cooled under specified conditions.
Units Range Scale Meniscus
Each
A A
Total Interval Error Correction
4. Summary of Test Method
Unit
4.1 The sample is brought to a specified temperature and a
Density, kg/m at 15°C 600 - 1100 20 0.2 6 0.2 +0.3
600 - 1100 50 0.5 6 0.3 +0.7
test portion is transferred to a hydrometer cylinder that has
600 - 1100 50 1.0 6 0.6 +1.4
been brought to approximately the same temperature. The
Relative density (specific 0.600 - 1.100 0.020 0.0002 6 0.0002 +0.0003
gravity) 60/60°F 0.600 - 1.100 0.050 0.0005 6 0.0003 +0.0007
0.600 - 1.100 0.050 0.001 6 0.0006 +0.0014
5 Relative density (specific
Available from Energy Institute, 61 New Cavendish St., London, W1M 8AR,
gravity), 60/60°F 0.650 - 1.100 0.050 0.0005 60.0005
UK.
API −1 - +101 12 0.1 6 0.1
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
A
4th Floor, New York, NY 10036. Interval and Error relate to Scale.
D1298 – 99 (2005)
to the observed readings. Instruments that satisfy the require- 7.3.1 Volatile Crude Petroleum and Petroleum Products
ments of this test method, but are not provided with a Having an RVP Greater than 50 kPa—Mix the sample in its
recognized calibration certificate, are classed as uncertified. original closed container in order to minimize the loss of light
components.
6.2 Thermometers, having range, graduation intervals and
maximumpermittedscaleerrorshowninTable2andconform-
NOTE 1—Mixingvolatilesamplesinopencontainerswillleadtolossof
ing to Specification E1 or IP Appendix A.
light components and consequently affect the value of the density
obtained.
6.2.1 Alternate measuring devices or systems may be used,
providedthatthetotaluncertaintyofthecalibratedsystemisno
7.3.2 Waxy Crude Petroleum—If the petroleum has a pour
greater than when using liquid-in-glass thermometers.
point above 10°C, or a cloud point or WAT above 15°C, warm
6.3 Hydrometer Cylinder, clear glass, plastic (see 6.3.1), or
thesampleto9°Cabovethepourpoint,or3°Cabovethecloud
metal. The inside diameter of the cylinder shall be at least
point or WAT, prior to mixing. Whenever possible, mix the
25 mm greater than the outside diameter of the hydrometer and
sample in its original closed container in order to minimize the
the height shall be such that the appropriate hydrometer floats
loss of light components.
in the test portion with at least 25 mm clearance between the
7.3.3 Waxy Distillate—Warm the sample to 3°C above its
bottom of the hydrometer and the bottom of the cylinder.
cloud point or WAT prior to mixing.
6.3.1 Hydrometer cylinders constructed of plastic materials
7.3.4 Residual Fuel Oils—Heat the sample to the test
shall be resistant to discoloration or attack by oil samples and temperature prior to mixing (see 8.1.1 and Note 4).
shallnotaffectthematerialbeingtested.Theyshallnotbecome
7.4 Additional information on the mixing and handling of
opaque under prolonged exposure to sunlight. liquid samples will be found in Practice D5854 (API MPMS
6.4 Constant-Temperature Bath, if required, of dimensions Chapter 8.3).
such that it can accommodate the hydrometer cylinder with the
8. Procedure
test portion fully immersed below the test portion liquid
8.1 Temperature of Test:
surface, and a temperature control system capable of maintain-
8.1.1 Bringthesampletothetesttemperaturewhichshallbe
ing the bath temperature within 0.25°C of the test temperature
such that the sample is sufficiently fluid but not so high as to
throughout the duration of the test.
causethelossoflightcomponents,norsolowastoresultinthe
6.5 Stirring Rod, optional, of glass or plastic, approximately
appearance of wax in the test portion.
400 mm in length.
NOTE 2—The density, relative density orAPI gravity determined by the
hydrometer is most accurate at or near the reference temperature.
7. Sampling
NOTE 3—The volume and density, the relative density, and the API
7.1 Unless otherwise specified, samples of non-volatile
correctionsinthePetroleumMeasurementTablesarebasedontheaverage
petroleum and petroleum products shall be taken by the
expansions of a number of typical materials. Since the same coefficients
procedures described in Practices D4057 (API MPMS Chapter were used in compiling each set of tables, corrections made over the same
temperature interval minimize errors arising from possible differences
8.1) and D4177 (API MPMS Chapter 8.2).
between the coefficient of the material under test and the standard
7.2 Samples of volatile crude petroleum or petroleum prod-
coefficients. This effect becomes more important as temperatures diverge
ucts are preferably taken by Practice D4177 (API MPMS
from the reference temperature.
Chapter 8.2), using a variable volume (floating piston) sample
NOTE 4—The hydrometer reading is obtained at a temperature appro-
receiver to minimize any loss of light components which may
priate to the physico-chemical characteristics of the material under test.
affect the accuracy of the density measurement. In the absence This temperature is preferably close to the reference temperature, or when
the value is used in conjunction with bulk oil measurements, within 3°C
of this facility, extreme care shall be taken to minimize these
of the bulk temperature (see 5.3).
losses, including the transfer of the sample to a chilled
container immediately after sampling. 8.1.2 For crude petroleum, bring the sample close to the
reference temperature or, if wax is present, to 9°C above its
7.3 Sample Mixing—May be necessary to obtain a test
pour point or 3°C above its cloud point or WAT, whichever is
portion representative of the bulk sample to be tested, but
higher.
precautions shall be taken to maintain the integrity of the
sample during this operation. Mixing of volatile crude petro-
NOTE 5—For crude petroleum an indication of the WAT can be found
leum or petroleum products containing water or sediments, or
using IP 389, with the modification of using 50 µL 6 5 µLof sample. The
both, or the heating of waxy volatile crude petroleum or precision of WAT for crude petroleum using this technique has not been
determined.
petroleum products may result in the loss of light components.
Thefollowingsections(7.3.1to7.3
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.