ASTM D6822-02(2008)
(Test Method)Standard Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Products by Thermohydrometer Method
Standard Test Method for Density, Relative Density, and API Gravity of Crude Petroleum and Liquid Petroleum Products by Thermohydrometer Method
SIGNIFICANCE AND USE
Density and API gravity are used in custody transfer quantity calculations and to satisfy transportation, storage, and regulatory requirements. Accurate determination of density or API gravity of crude petroleum and liquid petroleum products is necessary for the conversion of measured volumes to volumes at the standard temperatures of 15°C or 60°F.
Density and API gravity are also factors that indicate the quality of crude petroleum. Crude petroleum prices are frequently posted against values in kg/m3 or in degrees API. However, this property of petroleum is an uncertain indication of its quality unless correlated with other properties.
Field of Application—Because the thermohydrometer incorporates both the hydrometer and thermometer in one device, it is more applicable in field operations for determining density or API gravity of crude petroleum and other liquid petroleum products. The procedure is convenient for gathering main trunk pipelines and other field applications where limited laboratory facilities are available. The thermohydrometer method may have limitations in some petroleum density determinations. When this is the case, other methods such as Test Method D 1298 (API MPMS Chapter 9.1) may be used.
This test method is suitable for determining the density, relative density, or API gravity of low viscosity transparent or opaque liquids, or both. This test method, when used for opaque liquids, requires the use of a meniscus correction (see 7.2).
SCOPE
1.1 This test method covers the determination, using a glass thermohydrometer, of the density, relative density (specific gravity), or API gravity of crude petroleum and liquid petroleum products with Reid vapor pressures of 101.325 kPa (14.696 psi) or less. Values are determined at existing temperatures and corrected to 15°C or 60°F by means of international standard tables.
1.2 The values stated in either SI units or inch pound-units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
1.3 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.
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Standards Content (Sample)
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Designation:D6822–02 (Reapproved 2008)
Designation: Manual of Petroleum Measurement Standards (MPMS), Chapter 9.3
Standard Test Method for
Density, Relative Density, and API Gravity of Crude
Petroleum and Liquid Petroleum Products by
Thermohydrometer Method
This standard is issued under the fixed designation D6822; 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.
1. Scope D6300 Practice for Determination of Precision and Bias
Data for Use in Test Methods for Petroleum Products and
1.1 This test method covers the determination, using a glass
Lubricants
thermohydrometer, of the density, relative density (specific
E100 Specification for ASTM Hydrometers
gravity), or API gravity of crude petroleum and liquid petro-
2.2 API Standards:
leum products with Reid vapor pressures of 101.325 kPa
MPMS Chapter 9.1 Hydrometer Test Method for Density,
(14.696 psi) or less.Values are determined at existing tempera-
Relative Density (Specific Gravity) or API Gravity of
tures and corrected to 15°C or 60°F by means of international
Crude Petroleum and Liquid Petroleum Products (ASTM
standard tables.
Test Method D1298)
1.2 The values stated in either SI units or inch pound-units
MPMS Chapter 11.1 Temperature and Pressure Volume
are to be regarded separately as standard. The values stated in
Correction Factors for Generalized Crude Oils, Refined
each system may not be exact equivalents; therefore, each
Products, and Lubricating Oils
system shall be used independently of the other. Combining
2.3 ASTM Adjuncts:
values from the two systems may result in nonconformance
Adjunct to D1250, Guide for Use of the Petroleum Measure-
with the standard.
ment Tables (API MPMS Chapter 11.1)
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions of Terms Specific to This Standard:
priate safety and health practices and determine the applica-
3.1.1 API gravity (°API), n—a special function of relative
bility of regulatory limitations prior to use.
density 60/60°F, represented by:
2. Referenced Documents
°API 5 [141.5 / ~relative density 60/60°F!# 2 131.5 (1)
2.1 ASTM Standards:
3.1.1.1 Discussion—No statement of reference temperature
D1298 Test Method for Density, Relative Density (Specific
is required, as 60°F is included in the definition.
Gravity), or API Gravity of Crude Petroleum and Liquid
3.1.2 density, n—the mass of liquid per unit volume at 15°C
Petroleum Products by Hydrometer Method
and 101.325 kPa with the standard unit of measurement being
kilograms per cubic metre (kg/m ).
3.1.2.1 Discussion—Other reference temperatures, such as
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and theAPI Committee on Petroleum Measure- 20°Cmaybeusedforsomeproductsorinsomelocations.Less
ment, and is the direct responsibility of Subcommittee D02.02.09 on Density
preferredunitsofmeasurement;forexample,kg/Lorg/mL,are
Determination (API MPMS Chapter 9.0).
still in use.
Current edition approved Feb. 1, 2008. Published April 2008. Originally
approved in 2002. Last previous edition approved in 2002 as D6822-02. DOI:
10.1520/D6822-02R08.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from American Petroleum Institute (API), 1220 L. St., NW, Wash-
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM ington, DC 20005-4070, www.api.org.
Standards volume information, refer to the standard’s Document Summary page on Available from ASTM International Headquarters. Order Adjunct No.
the ASTM website. ADJD1250CD. Original adjunct produced in 2004.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6822–02 (2008)
TABLE 1 Density Thermohydrometers
3.1.3 observed values, n—hydrometer readings observed at
a temperature other than the defined reference temperature. ASTM Hydrometer No. Density, Range, kg/m
3.1.3.1 Discussion—These values are only hydrometer
300H 600 to 650
301H 650 to 700
readings and not density, relative density, orAPI gravity at the
302H 700 to 750
temperature.
303H 750 to 800
3.1.4 relative density, n—the ratio of the mass of a given
304H 800 to 850
305H 850 to 900
volume of liquid at a specific temperature to the mass of an
306H 900 to 950
equal volume of pure water at the same or different tempera-
307H 950 to 1000
ture. Both reference temperatures shall be explicitly stated.
308H 1000 to 1050
309H 1050 to 1100
3.1.4.1 Discussion—Common reference temperatures in-
clude 15/15°C, 60/60°F, 20/20°C, and 20/4°C. The historic Hydrometer
term specific gravity may still be found.
Total length, mm 374 to 387
Body diameter, mm 18 to 25
3.1.5 thermohydrometer, n—a glass hydrometer with a
Stem diameter, mm, min 4.0
self-contained thermometer.
Hydrometer Scale
Standard temperature, °C 15
4. Summary of Test Method
Subdivisions, kg/m 0.5
4.1 The density or API gravity, after temperature equilib-
Short intermediate lines at, kg/m 1
Long intermediate lines at, kg/m 5
rium has been reached, is read by observing the freely floating
Main (numbered) lines at, kg/m 10
thermohydrometer and noting the graduation nearest to the
Scale error at any point not to exceed, kg/m 0.5
apparent intersection of the horizontal plane surface of the
Length of nominal scale, mm 125 to 145
Scale extension beyond nominal range limits, kg/m 2.5
liquid with the vertical scale of the hydrometer after tempera-
ture equilibrium has been reached. The observed thermohy- Thermometer Scale
drometer reading is reduced to the reference temperature value
Range, °C
Designation L −20 to +65
by means of the Petroleum Measurement Tables (the appropri-
Designation M 0 to +85
ate adjunct to Guide /API MPMS Chapter 11.1) and observed
Designation H +20 to +105
temperature from the enclosed thermometer.
Immersion total
Subdivisions, °C 1.0
Intermediate lines at, °C 5
5. Significance and Use
Main (numbered) lines at, °C 10
Scale error at any point not to exceed, °C 1.0
5.1 Density and API gravity are used in custody transfer
Scale length, mm 80 to 100
quantity calculations and to satisfy transportation, storage, and
regulatory requirements. Accurate determination of density or
API gravity of crude petroleum and liquid petroleum products
is necessary for the conversion of measured volumes to
6.1.1 Kilograms/cubic metre (kg/m ) and degrees Celsius
volumes at the standard temperatures of 15°C or 60°F.
for density hydrometers, as shown in Table 1.
5.2 DensityandAPIgravityarealsofactorsthatindicatethe
6.1.2 Degrees API (°API) and degrees Fahrenheit for hy-
quality of crude petroleum. Crude petroleum prices are fre-
drometers measuring in API Gravity, as shown in Table 2.
quently posted against values in kg/m or in degrees API.
6.2 Hydrometer Cylinders, clear glass, plastic, or metal. For
However, this property of petroleum is an uncertain indication
convenience of pouring, the cylinder may have a pouring lip.
of its quality unless correlated with other properties.
The inside diameter shall be at least 25 mm (1 in.) greater than
5.3 Field of Application—Because the thermohydrometer
the outside diameter of the thermohydrometer used.The height
incorporates both the hydrometer and thermometer in one
of the cylinder shall be such that the bottom of the thermohy-
device, it is more applicable in field operations for determining
drometer clears the bottom of the cylinder by at least 25 mm
density or API gravity of crude petroleum and other liquid
(1 in.) when suspended in the sample test portion.
petroleum products. The procedure is convenient for gathering
6.2.1 For field testing, a sample thief of suitable dimensions
main trunk pipelines and other field applications where limited
may be more convenient than a hydrometer cylinder. The
laboratory facilities are available. The thermohydrometer
liquid level shall be level with the top of the thief.
method may have limitations in some petroleum density
6.3 Temperature Bath, to control temperature close to the
determinations. When this is the case, other methods such as
bulk hydrocarbon temperature or to control temperature close
Test Method D1298 (API MPMS Chapter 9.1) may be used.
to the reference temperature of 15°C or 60°F.
5.4 This test method is suitable for determining the density,
relative density, or API gravity of low viscosity transparent or 7. Procedure
opaque liquids, or both. This test method, when used for
7.1 Effect of Test Temperature:
opaque liquids, requires the use of a meniscus correction (see
7.1.1 The density orAPI gravity determined by the thermo-
7.2).
hydrometer method is most accurate at or near the reference
temperature of 15°C or 60°F. Other temperatures within the
6. Apparatus
range of the enclosed thermometer may be used, if consistent
6.1 Glass Thermohydrometers, as specified in Specification with the type of sample and the necessary limiting conditions
E100 (shown in Fig. 1), and graduated in: shown in Table 3.
D6822–02 (2008)
TABLE 2 API Gravity Thermohydrometers
NOTE—For petroleum products and other liquids of similar surface tensions (33 dynes/cm or less).
Thermometer Scale in Body Thermometer Scale in Stem
ASTM Hydrometer Nominal API Gravity ASTM Hydrometer Nominal API Gravity
No. Range, degrees No. Range, degrees
41H-66 15 to 23 71H-62 −1 to +11
42H-66 22 to 30 72H-62 9 to 21
43H-66 29 to 37 73H-62 19 to 31
44H-66 36 to 44 74H-62 29 to 41
45H-66 43 to 51
51H-62 −1 to +11
52H-62 9 to 21
53H-62 19 to 31
54H-62 29 to 41
55H-62 39 to 51
56H-62 49 to 61
57H-62 59 to 71
58H-62 69 to 81
59H-62 79 to 91
60H-62 89 to 101
Hydrometer
Thermometer Scale Thermometer Scale
in Body in Stem
Total length, mm 374 to 387 374 to 387
Body diameter, mm 18 to 25 23 to 27
Stem diameter, mm, min 4.0 6.0
Hydrometer Scale
Standard temperature, °F 60
Subdivisions, °API 0.1
Intermediate lines at, °API 0.5
Main (numbered) lines at, °API 1.0
Scale error at any point not to exceed, °API 0.1
Length of nominal scale, mm 125 to 145
Thermometer Scale
Thermometer Scale Thermometer Scale
in Body in Stem
A
Range, °F
Designation L 0 to 150
Designation M 30 to 180 30 to 220
Designation H 60 to 220
Immersion Total Total
Subdivisions, °F 2 2
Intermediate lines at, °F 10 10
Main (numbered) lines at, °F 20 20
Scale error at any point not to exceed, °F 1 1
Scale length, mm 80 to 110 105 to 145
A
Indication of the thermometer range is made by the use of the listed designation used as a suffix to the ASTM hydrometer number. For example, 54HL is an instrument
with an API gravity range of 29 to 41°API and a thermometer range of 0 to 150°F. An instrument with the same gravity range but a thermometer range of 60 to 220°F would
be designated 54HH. The number 57HM would identify an instrument with an API gravity range of 59 to 71°API and a thermometer range of 30 to 180°F.
TABLE 3 Limiting Conditions and Test Temperatures
Sample Type Initial Boiling Point Other Limits Test Temperature
Volatile 120°C (250°F) or lower Cool in original closed container to 18°C (65°F) or lower
Volatile and viscous 120°C (250°F) or lower Viscosity too high Heat to minimum temperature to obtain sufficient fluidity
at 18°C (65°F)
Non-volatile Above 120°C (250°F) Use any temperature between −18°C and 90°C (0 and 195°F)
as convenient
Mixture with non-petroleum products . . . Test at 15 6 0.2°C or 60 6 0.5°F
7.1.2 If the test temperature is significantly different from thermohydrometer.Ahydrometer correction factor (HYC) may
the reference temperature of 15°C or 60°F, the expansion or
be applied to the measured density value to provide a corrected
contraction of the glass may affect the calibration of the
D6822–02 (2008)
FIG. 1 Typical Thermohydrometer Designs
reading. Historically, the following equations have been used
where:
within volume correction factor tables.
t = observed temperature (°F) or
r 5r 3 HYC (2)
corrected test
HYC 5 1 2 0.000023~t 2 15! 2 0.00000002~t 2 15! (4)
where:
where:
HYC = hydrometer thermal correction factor,
t = observed temperature (°C).
ρ = test density, corrected for the effects of tem-
corrected
7.1.2.1 All parties affected by the measurement should
perature on the thermohydrometer, and
agree upon the need for and the method of correction.
ρ = test density, as observed by reading the ther-
test
7.1.3 When the thermohydrometer value is used to select
mohydrometer.
factors for correcting volumes to standard temperatures, the
HYC 5 1 2 0.00001278~t 2 60! 2 0.0000000062~t 2 60! (3) thermohydrometer reading preferably should be made at a
D6822–02 (2008)
temperature within 63°C (65°F) of the temperature at which the thermohydrometer scale at which the surface of the liquid
the bulk volume of the oil was measured (see Note 1). cuts the scale. To make a reading for transparent liquids in a
However, when appreciable amounts of light fractions may be transparent hydrometer cylinder, determine this point by plac-
lost during determination at the bulk oil temperature, the limits ing the eye slightly below the level of the liquid and slowly
given in Table 3 shall be applied. raising it until the surface, first seen as a distorted ellipse,
appearstobecomeastraightlinecuttingthethermohydrometer
NOTE 1—Volume and density correction tables are based on average
scale. See Fig. 2 for details on reading the meniscus.
expansion for a number of typical materials. Since the same coefficients
7.2.5 To make a reading with opaque liquids, observe the
were used in computing both sets of tables, corrections made over the
point on the thermohydrometer scale to which the sample rises
same temperature interval minimize errors arising from possible differ-
ences between the coefficients of the material under test and the standard above its main surface, placing the eye slightly above the plane
coefficients. This effect becomes more important as temperatures diverge
surface of the liquid.This reading requires meniscus correction
significantly from 15°C or 60°F.
(see Note 2). Determine this correction for the particular
thermohydrometer in use by observing the height above the
7.2 Density Measurement:
main surface of the liquid to which the sample rises on the
7.2.1 Adjust the temperature of the sample in accordance
thermohydrometer scale
...
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