ASTM D287-12b(2019)
(Test Method)Standard Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)
Standard Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)
SIGNIFICANCE AND USE
5.1 Accurate determination of the gravity of petroleum and its products is necessary for the conversion of measured volumes to volumes at the standard temperature of 60 °F (15.56 °C).
5.2 This procedure is most suitable for determining the 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 temperature equilibrium, and for opaque liquids by employing a suitable meniscus correction. Additionally for both transparent and opaque fluids the readings shall be corrected for the thermal glass expansion effect before correcting to the reference temperature.
5.3 When used in connection with bulk oil measurements, volume correction errors are minimized by observing the hydrometer reading at a temperature as close to reference temperature as feasible.
5.4 Gravity is a factor governing the quality of crude oils. However, the gravity of a petroleum product is an uncertain indication of its quality. Correlated with other properties, gravity can be used to give approximate hydrocarbon composition and heat of combustion.
5.5 Gravity 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 determination by means of a glass hydrometer in conjunction with a series of calculations of the API gravity of crude petroleum and petroleum products normally handled as liquids and having a Reid vapor pressure (Test Method D323) of 101.325 kPa (14.696 psi) or less. Gravities are determined at 60 °F (15.56 °C), or converted to values at 60 °F, by means of Adjunct to D1250 Guide for Petroleum Measurement Tables (API MPMS Chapter 11.1). These tables are not applicable to nonhydrocarbons or essentially pure hydrocarbons such as the aromatics.
1.2 The initial values obtained are uncorrected hydrometer readings and not density measurements. Values are measured on a hydrometer at either the reference temperature or at another convenient temperature, and readings corrected for the meniscus effect, the thermal glass expansion effect, alternate calibration temperature effects and to the reference temperature by means of volume correction tables.
1.3 The hydrometer readings determined shall be recorded before performing any calculations. Then the calculations required in Section 9 shall be performed and documented before using the final result in a subsequent calculation procedure (measurement ticket calculation, meter factor calculation, or base prover volume determination).
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific warning statement, see 8.3.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Designation: D287 − 12b (Reapproved 2019)
Standard Test Method for
API Gravity of Crude Petroleum and Petroleum Products
(Hydrometer Method)
This standard is issued under the fixed designation D287; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope mine the applicability of regulatory limitations prior to use.
For specific warning statement, see 8.3.
1.1 This test method covers the determination by means of
1.6 This international standard was developed in accor-
a glass hydrometer in conjunction with a series of calculations
dance with internationally recognized principles on standard-
of theAPI gravity of crude petroleum and petroleum products
ization established in the Decision on Principles for the
normally handled as liquids and having a Reid vapor pressure
Development of International Standards, Guides and Recom-
(Test Method D323) of 101.325kPa (14.696psi) or less.
mendations issued by the World Trade Organization Technical
Gravities are determined at 60°F (15.56°C), or converted to
Barriers to Trade (TBT) Committee.
values at 60°F, by means of Adjunct to D1250 Guide for
Petroleum Measurement Tables (API MPMS Chapter 11.1).
2. Referenced Documents
These tables are not applicable to nonhydrocarbons or essen-
2.1 ASTM Standards:
tially pure hydrocarbons such as the aromatics.
D323TestMethodforVaporPressureofPetroleumProducts
1.2 The initial values obtained are uncorrected hydrometer
(Reid Method)
readings and not density measurements. Values are measured
D1250Guide for the Use of the Joint API and ASTM
on a hydrometer at either the reference temperature or at
Adjunct for Temperature and Pressure Volume Correction
another convenient temperature, and readings corrected for the
FactorsforGeneralizedCrudeOils,RefinedProducts,and
meniscus effect, the thermal glass expansion effect, alternate
Lubricating Oils: API MPMS Chapter 11.1
calibrationtemperatureeffectsandtothereferencetemperature
D1298Test Method for Density, Relative Density, or API
by means of volume correction tables.
Gravity of Crude Petroleum and Liquid Petroleum Prod-
1.3 The hydrometer readings determined shall be recorded
ucts by Hydrometer Method
before performing any calculations. Then the calculations
D6822Test Method for Density, Relative Density, and API
required in Section 9 shall be performed and documented
Gravity of Crude Petroleum and Liquid Petroleum Prod-
before using the final result in a subsequent calculation
ucts by Thermohydrometer Method
procedure (measurement ticket calculation, meter factor
E1Specification for ASTM Liquid-in-Glass Thermometers
calculation, or base prover volume determination).
E100Specification for ASTM Hydrometers
2.2 EI Standards:
1.4 Thevaluesstatedininch-poundunitsaretoberegarded
Specifications for IP Standard Thermometers
as standard. The values given in parentheses are mathematical
IP Specifications for Petroleum Hydrometers
conversions to SI units that are provided for information only
and are not considered standard. 2.3 API Standards:
MPMS Chapter 9.1Test Method for Density, Relative
1.5 This standard does not purport to address all of the
Density, or API Gravity of Crude Petroleum and Liquid
safety concerns, if any, associated with its use. It is the
Petroleum Products by Hydrometer Method (ASTM Test
responsibility of the user of this standard to establish appro-
Method D1298)
priate safety, health, and environmental practices and deter-
1 2
This test method is under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Petroleum Products, Liquid Fuels, and Lubricants and the API Committee on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Petroleum Measurement, and is the direct responsibility of Subcommittee D02.02 Standards volume information, refer to the standard’s Document Summary page on
/COMQ, the joint ASTM-API Committee on Hydrocarbon Measurement for the ASTM website.
Custody Transfer (Joint ASTM-API). Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
Current edition approved Dec. 1, 2019. Published December 2019. Originally U.K., http://www.energyinst.org.
approved in 1928. Last previous edition approved in 2012 as D287–12b. DOI: Available from American Petroleum Institute (API), 1220 L. St., NW,
10.1520/D0287-12BR19. Washington, DC 20005-4070, http://www.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D287 − 12b (2019)
MPMS Chapter 9.3Test Method for Density, Relative 4.3 The observed hydrometer reading is corrected for the
Density, andAPI Gravity of Crude Petroleum and Liquid meniscus effect, the thermal glass expansion effect, alternate
Petroleum Products by Thermohydrometer Method calibration temperature effects and reduced to the reference
(ASTM Test Method D6822) temperature by means of the volume correction tables. If
MPMS Chapter 11.1Temperature and PressureVolume Cor- necessary, the hydrometer cylinder and its contents are placed
rection Factors for Generalized Crude Oils, Refined in a constant temperature bath to avoid excessive temperature
Products,andLubricatingOils(AdjuncttoASTMD1250) variation during the test.
2.4 ASTM Adjuncts:
5. Significance and Use
AdjuncttoD1250GuideforPetroleumMeasurementTables
5.1 Accurate determination of the gravity of petroleum and
(API MPMS Chapter 11.1)
its products is necessary for the conversion of measured
volumes to volumes at the standard temperature of 60°F
3. Terminology
(15.56°C).
3.1 Definitions:
5.2 This procedure is most suitable for determining theAPI
3.1.1 API gravity, n—a special function of relative density
gravity of low viscosity transparent liquids. This test method
60/60°F (15.56/15.56°C), represented by:
can also be used for viscous liquids by allowing sufficient time
°API 5 @141.5/ relativedensity60/60°F # 2131.5 (1)
~ !
for the hydrometer to reach temperature equilibrium, and for
No statement of reference temperature is required, since
opaque liquids by employing a suitable meniscus correction.
60°F is included in the definition. Additionally for both transparent and opaque fluids the read-
ings shall be corrected for the thermal glass expansion effect
3.1.2 hydrometer reading, n—the point on the hydrometer
before correcting to the reference temperature.
scale at which the surface of the liquid cuts the scale.
3.1.2.1 Discussion—In practice for transparent fluids this
5.3 When used in connection with bulk oil measurements,
can be readily determined by aligning the surface of the liquid
volume correction errors are minimized by observing the
on both sides of the hydrometer and reading the Hydrometer
hydrometer reading at a temperature as close to reference
scale where these surface readings cut the scale (Hydrometer
temperature as feasible.
Reading – Observed). For nontransparent fluids the point at
5.4 Gravity is a factor governing the quality of crude oils.
which the liquid surface cuts the Hydrometer scale cannot be
However, the gravity of a petroleum product is an uncertain
determined directly and requires a correction (Meniscus Cor-
indication of its quality. Correlated with other properties,
rection). The value represented by the point (Meniscus Read-
gravity can be used to give approximate hydrocarbon compo-
ing) at which the liquid sample rises above the main surface of
sition and heat of combustion.
the liquid subtracted from the value represented by where the
5.5 Gravityisanimportantqualityindicatorforautomotive,
main surface of the liquid cuts the Hydrometer scale is the
aviation and marine fuels, where it affects storage, handling
amount of the correction or Meniscus correction. This menis-
and combustion.
cus correction is documented and then subtracted from the
value represented by the Meniscus Reading to yield the
6. Apparatus
Hydrometer Reading corrected for the Meniscus (Hydrometer
Reading – Observed, Meniscus Corrected).
6.1 Hydrometers, of glass, graduated in degrees API as
listed in Table 1 and conforming to Specification E100.
3.1.3 specific gravity, n—historical term, no longer used,
6.1.1 Theusershouldascertainthattheinstrumentsusedfor
which has been replaced by relative density.
this method conform to the requirements set out above with
respect to materials, dimensions, and scale errors. In cases
4. Summary of Test Method
where the instrument is provided with a calibration certificate
4.1 This test method is based on the principle that the
issued by a recognized standardizing body, the instrument is
gravity of a liquid varies directly with the depth of immersion
classed as certified and the appropriate corrections for the
of a body floating in it. The floating body, which is graduated
meniscus effect, the thermal glass expansion effect, and alter-
by API gravity units in this test method, is called an API
native calibration temperature effects shall be applied to the
hydrometer.
observed readings prior to corrections. Instruments that satisfy
4.2 TheAPI gravity is read by observing the freely floating
API hydrometer and noting the graduation nearest to the
apparent intersection of the horizontal plane surface of the
TABLE 1 Available Hydrometers Scaled, Degrees API
liquid with the vertical scale of the hydrometer, after tempera-
API Range, deg Scale
Designation Type
ture equilibrium has been reached. The temperature of the
Series Total Each Unit Division Error
sample is read from a separate accurateASTM thermometer in
1H to 10H long plain −1 to 101 12 0.1 0.1
the sample. 21H to 40H short plain 0 to 101 6 0.1 0.2
51H to 60H thermo −1 to 101 12 0.1 0.1
71H to 74H thermo −1 to 41 12 0.1 0.1
A
thermo 15 to 51 8
A
Available from ASTM International Headquarters. Order Adjunct No.
Eight-degree range thermohydrometers are available.
ADJD1250. Original adjunct produced in 1983.
D287 − 12b (2019)
the requirements of this test method, but are not provided with boiling constituents of the more volatile samples. (Warning—
a recognized calibration certificate, are classed as uncertified. Extremely flammable. Vapors may cause flash fire.) For the
more volatile samples, transfer to the hydrometer cylinder by
6.2 Thermometers, having a range from −5°F to +215°F
siphoning. (Do not start the siphon by mouth.) Use a rubber
and conforming to the requirements for Thermometer 12F as
aspiratorbulb.Removeanyairbubblesformed,aftertheyhave
prescribed in Specification E1 or Thermometer 64F of the
collected on the surface of the sample, by touching them with
Specification for IP Standard Thermometers.
a piece of clean filter paper or other suitable means before
6.2.1 Alternate measuring devices or systems may be used,
inserting the hydrometer. For field testing, make the gravity
providedthatthetotaluncertaintyofthecalibratedsystemisno
measurement directly in the sampling thief. Place the cylinder
greater than when using liquid-in-glass thermometers. The
containing the sample in a vertical position in a location free
stated repeatability and reproducibility values are not appli-
cableifalternatefluidsareusedintheliquid-in-glassthermom- from air currents. Take precautions to prevent the temperature
eters. of the sample from changing appreciably during the time
necessarytocompletethetest.Duringthisperiod,thetempera-
NOTE1—TheASTMGravityThermometer12Fhas0.5°Fsubdivisions
ture of the surrounding medium should not change more than
and allowable 60.25°F scale error.
5°F (2°C).
6.3 Hydrometer Cylinder, clear glass, plastic, or metal (see
6.3.1). The inside diameter of the cylinder shall be at least
8.4 Lower the hydrometer gently into the sample and, when
25mmgreaterthantheoutsidediameterofthehydrometerand
ithassettled,depressitabouttwoscaledivisionsintotheliquid
the height shall be such that the appropriate hydrometer floats
andthenreleaseit;keeptherestofthestemdry,asunnecessary
in the test portion with at least 25mm clearance between the
liquid on the stem changes the effective weight of the
bottom of the hydrometer and the bottom of the cylinder.
instrument, and so affects the reading obtained. With samples
6.3.1 Hydrometer cylinders constructed of plastic materials
of low viscosity, a slight spin imparted to the instrument on
shall be resistant to discoloration or attack by oil samples and
releasingassistsinbringingittorest,floatingfreelyawayfrom
shallnotaffectthematerialbeingtested.Theyshallnotbecome
the walls of the hydrometer cylinder.Allow sufficient time for
opaque under prolonged exposure to sunlight.
the hydrometer to become completely stationary and for all air
bubblestocometothesurface.Thisisparticularlynecessaryin
7. Temperature of Test
the case of the more viscous samples.
7.1 The gravity determined by the hydrometer method is
8.5 When the hydrometer has come to rest, floating freely,
most accurate at or near the standard temperature of 60°F
(15.56°C).Usethisoranyothertemperaturebetween0°Fand and the temperature of the sample is constant to 0.2°F
(0.1°C),readthehydrometertothenearestscaledivision.The
195°F (–18°C and + 90°C) for the test, so far as it is
consistent with the type of sample and necessary limiting correct reading is that point on the hydrometer scale at which
conditions shown in Table 2. the surface of the liquid cuts the scale. Determine this point by
placingtheeyeslightlybelowtheleveloftheliquidandslowly
8. Procedure
raising it until the surface, first seen as a distorted ellipse,
appears to become a straight line cutting the hydrometer scale.
8.1 For referee testing, use the long plain form of hydrom-
eter (1H to 10H). For field testing, use the thermohydrometer
8.6 To make a reading with nontransparent liquids, observe
method in Test Method D6822 (API MPMS Chapter 9.3).
the point on the hydrometer scale to which the sample rises
8.2 Adjustthetemperatureofthesampleinaccordancewith
aboveitsmainsurface,placingtheeyeslightlyabovetheplane
Table 2. For field testing, test temperatures other than those
surface of the liquid. This reading requires a correction.
listedinTable2maybeused.Thehydrometercylindershallbe
Determine this correction for the particular hydrometer in use
approximatelythesametemperatureasthesampletobetested.
by observing the height above the main surface of the liquid to
8.3 Transfer the sample into the clean hydrometer cylinder which the sample rises on the hydrometer scale when the
hydrometer in question is immersed
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D287 − 12b D287 − 12b (Reapproved 2019)
Standard Test Method for
API Gravity of Crude Petroleum and Petroleum Products
(Hydrometer Method)
This standard is issued under the fixed designation D287; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*Scope
1.1 This test method covers the determination by means of a glass hydrometer in conjunction with a series of calculations of
the API gravity of crude petroleum and petroleum products normally handled as liquids and having a Reid vapor pressure (Test
Method D323) of 101.325 kPa (14.696 psi) 101.325 kPa (14.696 psi) or less. Gravities are determined at 60°F (15.56°C),60 °F
(15.56 °C), or converted to values at 60°F,60 °F, by means of Adjunct to D1250 Guide for Petroleum Measurement Tables (API
MPMS Chapter 11.1). These tables are not applicable to nonhydrocarbons or essentially pure hydrocarbons such as the aromatics.
1.2 The initial values obtained are uncorrected hydrometer readings and not density measurements. Values are measured on a
hydrometer at either the reference temperature or at another convenient temperature, and readings corrected for the meniscus effect,
the thermal glass expansion effect, alternate calibration temperature effects and to the reference temperature by means of volume
correction tables.
1.3 The hydrometer readings determined shall be recorded before performing any calculations. Then the calculations required
in Section 9 shall be performed and documented before using the final result in a subsequent calculation procedure (measurement
ticket calculation, meter factor calculation, or base prover volume determination).
1.4 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For specific warning statement, see 8.3.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D323 Test Method for Vapor Pressure of Petroleum Products (Reid Method)
D1250 Guide for the Use of the Joint API and ASTM Adjunct for Temperature and Pressure Volume Correction Factors for
Generalized Crude Oils, Refined Products, and Lubricating Oils: API MPMS Chapter 11.1
D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method
D6822 Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Products by
Thermohydrometer Method
E1 Specification for ASTM Liquid-in-Glass Thermometers
E100 Specification for ASTM Hydrometers
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and the API Committee on Petroleum
Measurement, and is the direct responsibility of Subcommittee D02.02 /COMQ, the joint ASTM-API Committee on Hydrocarbon Measurement for Custody Transfer (Joint
ASTM-API).
Current edition approved June 1, 2012Dec. 1, 2019. Published October 2012December 2019. Originally approved in 1928. Last previous edition approved in 2012 as
D287–12a.–12b. DOI: 10.1520/D0287-12B.10.1520/D0287-12BR19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D287 − 12b (2019)
2.2 EI Standards:
Specifications for IP Standard Thermometers
IP Specifications for Petroleum Hydrometers
2.3 API Standards:
MPMS Chapter 9.1 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum
Products by Hydrometer Method (ASTM Test Method D1298)
MPMS Chapter 9.3 Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum
Products by Thermohydrometer Method (ASTM Test Method D6822)
MPMS Chapter 11.1 Temperature and Pressure Volume Correction Factors for Generalized Crude Oils, Refined Products, and
Lubricating Oils (Adjunct to ASTM D1250)
2.4 ASTM Adjuncts:
Adjunct to D1250 Guide for Petroleum Measurement Tables (API MPMS Chapter 11.1)
3. Terminology
3.1 Definitions:
3.1.1 API gravity, n—a special function of relative density 60/60°F (15.56/15.56°C),60/60 °F (15.56/15.56 °C), represented by:
°API 5 141.5/ relative density 60/60°F 2 131.5 (1)
@ ~ !#
No statement of reference temperature is required, since 60°F60 °F is included in the definition.
3.1.2 hydrometer reading, n—the point on the hydrometer scale at which the surface of the liquid cuts the scale.
3.1.2.1 Discussion—
In practice for transparent fluids this can be readily determined by aligning the surface of the liquid on both sides of the hydrometer
and reading the Hydrometer scale where these surface readings cut the scale (Hydrometer Reading – Observed). For nontransparent
fluids the point at which the liquid surface cuts the Hydrometer scale cannot be determined directly and requires a correction
(Meniscus Correction). The value represented by the point (Meniscus Reading) at which the liquid sample rises above the main
surface of the liquid subtracted from the value represented by where the main surface of the liquid cuts the Hydrometer scale is
the amount of the correction or Meniscus correction. This meniscus correction is documented and then subtracted from the value
represented by the Meniscus Reading to yield the Hydrometer Reading corrected for the Meniscus (Hydrometer Reading –
Observed, Meniscus Corrected).
3.1.3 specific gravity, n—historical term, no longer used, which has been replaced by relative density.
4. Summary of Test Method
4.1 This test method is based on the principle that the gravity of a liquid varies directly with the depth of immersion of a body
floating in it. The floating body, which is graduated by API gravity units in this test method, is called an API hydrometer.
4.2 The API gravity is read by observing the freely floating API hydrometer and noting the graduation nearest to the apparent
intersection of the horizontal plane surface of the liquid with the vertical scale of the hydrometer, after temperature equilibrium
has been reached. The temperature of the sample is read from a separate accurate ASTM thermometer in the sample.
4.3 The observed hydrometer reading is corrected for the meniscus effect, the thermal glass expansion effect, alternate
calibration temperature effects and reduced to the reference temperature by means of the volume correction tables. If necessary,
the hydrometer cylinder and its contents are placed in a constant temperature bath to avoid excessive temperature variation during
the test.
5. Significance and Use
5.1 Accurate determination of the gravity of petroleum and its products is necessary for the conversion of measured volumes
to volumes at the standard temperature of 60°F (15.56°C).60 °F (15.56 °C).
5.2 This procedure is most suitable for determining the 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 temperature equilibrium, and for opaque
liquids by employing a suitable meniscus correction. Additionally for both transparent and opaque fluids the readings shall be
corrected for the thermal glass expansion effect before correcting to the reference temperature.
5.3 When used in connection with bulk oil measurements, volume correction errors are minimized by observing the hydrometer
reading at a temperature as close to reference temperature as feasible.
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.
Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, http://www.api.org.
Available from ASTM International Headquarters. Order Adjunct No. ADJD1250. Original adjunct produced in 1983.
D287 − 12b (2019)
5.4 Gravity is a factor governing the quality of crude oils. However, the gravity of a petroleum product is an uncertain indication
of its quality. Correlated with other properties, gravity can be used to give approximate hydrocarbon composition and heat of
combustion.
5.5 Gravity is an important quality indicator for automotive, aviation and marine fuels, where it affects storage, handling and
combustion.
6. Apparatus
6.1 Hydrometers, of glass, graduated in degrees API as listed in Table 1 and conforming to Specification E100.
6.1.1 The user should ascertain that the instruments used for this method conform to the requirements set out above with respect
to materials, dimensions, and scale errors. In cases where the instrument is provided with a calibration certificate issued by a
recognized standardizing body, the instrument is classed as certified and the appropriate corrections for the meniscus effect, the
thermal glass expansion effect, and alternative calibration temperature effects shall be applied to the observed readings prior to
corrections. Instruments that satisfy the requirements of this test method, but are not provided with a recognized calibration
certificate, are classed as uncertified.
6.2 Thermometers, having a range from −5−5 °F to +215°F+215 °F and conforming to the requirements for Thermometer 12F
as prescribed in Specification E1 or Thermometer 64F of the Specification for IP Standard Thermometers.
6.2.1 Alternate measuring devices or systems may be used, provided that the total uncertainty of the calibrated system is no
greater than when using liquid-in-glass thermometers. The stated repeatability and reproducibility values are not applicable if
alternate fluids are used in the liquid-in-glass thermometers.
NOTE 1—The ASTM Gravity Thermometer 12F has 0.5°F0.5 °F subdivisions and allowable 60.25°F60.25 °F scale error.
6.3 Hydrometer Cylinder, clear glass, plastic, or metal (see 6.3.1). The inside diameter of the cylinder shall be at least 25 mm
25 mm greater than the outside diameter of the hydrometer and the height shall be such that the appropriate hydrometer floats in
the test portion with at least 25 mm 25 mm clearance between the bottom of the hydrometer and the bottom of the cylinder.
6.3.1 Hydrometer cylinders constructed of plastic materials shall be resistant to discoloration or attack by oil samples and shall
not affect the material being tested. They shall not become opaque under prolonged exposure to sunlight.
7. Temperature of Test
7.1 The gravity determined by the hydrometer method is most accurate at or near the standard temperature of 60°F
(15.56°C).60 °F (15.56 °C). Use this or any other temperature between 00 °F and 195°F (–18195 °F (–18 °C and + 90°C)90 °C)
for the test, so far as it is consistent with the type of sample and necessary limiting conditions shown in Table 2.
8. Procedure
8.1 For referee testing, use the long plain form of hydrometer (1H to 10H). For field testing, use the thermohydrometer method
in Test Method D6822 (API MPMS Chapter 9.3).
8.2 Adjust the temperature of the sample in accordance with Table 2. For field testing, test temperatures other than those listed
in Table 2 may be used. The hydrometer cylinder shall be approximately the same temperature as the sample to be tested.
8.3 Transfer the sample into the clean hydrometer cylinder without splashing, so as to avoid the formation of air bubbles and
to reduce to a minimum the evaporation of the lower boiling constituents of the more volatile samples. (Warning—Extremely
flammable. Vapors may cause flash fire.) For the more volatile samples, transfer to the hydrometer cylinder by siphoning. (Do not
start the siphon by mouth.) Use a rubber aspirator bulb. Remove any air bubbles formed, after they have collected on the surface
of the sample, by touching them with a piece of clean filter paper or other suitable means before inserting the hydrometer. For field
testing, make the gravity measurement directly in the sampling thief. Place the cylinder containing the sample in a vertical position
in a location free from air currents. Take precautions to prevent the temperature of the sample from changing appreciably during
the time necessary to complete the test. During this period, the temperature of the surrounding medium should not change more
than 5°F (2°C).5 °F (2 °C).
TABLE 1 Available Hydrometers Scaled, Degrees API
API Range, deg Scale
Designation Type
Series Total Each Unit Division Error
1H to 10H long plain −1 to 101 12 0.1 0.1
21H to 40H short plain 0 to 101 6 0.1 0.2
51H to 60H thermo −1 to 101 12 0.1 0.1
71H to 74H thermo −1 to 41 12 0.1 0.1
A
thermo 15 to 51 8
A
Eight-degree range thermohydrometers are available.
D287 − 12b (2019)
TABLE 2 Limiting Conditions and Testing Temperatures
Initial Boiling Point
Sample Type Gravity Limits Other Limits Test Temperature
Limits
Highly volatile lighter than 70° API Cool to 35°F (2°C) or lower in original closed
container.
Moderately volatile heavier than 70° API below 250°F (120°C) Cool to 65°F (18°C) or lower in original closed
container.
Moderately volatile and viscous heavier than 70° API below 250°F (120°C) Viscosity too high at Heat to minimum temperature for sufficient
65°F (18°C) fluidity.
Nonvolatile heavier than 70° API above 250°F (120°C) Any temperature between 0 and 195°F (−18 and
...
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