ASTM D6822-02

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An American National Standard
Designation:D6822–02
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 D 6822; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 Adjunct:
Adjunct to D 1250 Guide for Petroleum Measurement
1.1 This test method covers the determination, using a glass
Tables (API MPMS Chapter 11.1)
thermohydrometer, of the density, relative density (specific
2.3 API Standards:
gravity), or API gravity of crude petroleum and liquid petro-
MPMS Chapter 9.1 Hydrometer Test Method for Density,
leum products with Reid vapor pressures of 101.325 kPa
Relative Density (Specific Gravity) or API Gravity of
(14.696 psi) or less.Values are determined at existing tempera-
Crude Petroleum and Liquid Petroleum Products (ASTM
tures and corrected to 15°C or 60°F by means of international
Test Method D 1298)
standard tables.
MPMS Chapter 11.1 Volume Correction Factors
1.2 The values stated in either SI units or inch pound-units
are to be regarded separately as standard. The values stated in
3. Terminology
each system may not be exact equivalents; therefore, each
3.1 Definitions of Terms Specific to This Standard:
system shall be used independently of the other. Combining
3.1.1 API gravity (°API), n—a special function of relative
values from the two systems may result in nonconformance
density 60/60°F, represented by:
with the standard.
°API 5 141.5 / relative density 60/60°F 2 131.5 (1)
1.3 This standard does not purport to address all of the @ ~ !#
safety concerns, if any, associated with its use. It is the
3.1.1.1 Discussion—No statement of reference temperature
responsibility of the user of this standard to establish appro-
is required, as 60°F is included in the definition.
priate safety and health practices and determine the applica-
3.1.2 density, n—the mass of liquid per unit volume at 15°C
bility of regulatory limitations prior to use.
and 101.325 kPa with the standard unit of measurement being
kilograms per cubic metre (kg/m ).
2. Referenced Documents
3.1.2.1 Discussion—Other reference temperatures, such as
2.1 ASTM Standards:
20°Cmaybeusedforsomeproductsorinsomelocations.Less
D 1298 Test Method for Density, Relative Density (Specific
preferredunitsofmeasurement;forexample,kg/Lorg/mL,are
Gravity), or API Gravity of Crude Petroleum and Liquid
still in use.
Petroleum Products by Hydrometer Method (API MPMS
3.1.3 observed values, n—hydrometer readings observed at
Chapter 9.1)
a temperature other than the defined reference temperature.
D 6300 Practice for Determination of Precision and Bias
3.1.3.1 Discussion—These values are only hydrometer
Data for Use in Test Methods for Petroleum Products and
readings and not density, relative density, orAPI gravity at the
Lubricants
temperature.
E 100 Specification for ASTM Hydrometers
3.1.4 relative density, n—the ratio of the mass of a given
volume of liquid at a specific temperature to the mass of an
equal volume of pure water at the same or different tempera-
This test method is under the jurisdiction of ASTM Committee D02 on
ture. Both reference temperatures shall be explicitly stated.
Petroleum Products and Lubricants and theAPI Committee on Petroleum Measure-
ment, and is the direct responsibility of Subcommittee D02.02/COMQ, the joint
ASTM-API Committee on Static Petroleum Measurement.
Current edition approved Aug. 10, 2002. Published November 2002. Annual Book of ASTM Standards, Vol 05.01.
2 5
Annual Book of ASTM Standards, Vol 05.04. AvailablefromAmericanPetroleumInstitute,1220LSt.,NW,Washington,DC
Annual Book of ASTM Standards, Vol 14.03. 20005.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6822–02
TABLE 1 Density Thermohydrometers
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 ASTM Hydrometer No. Density, Range, kg/m
term specific gravity may still be found.
300H 600 to 650
301H 650 to 700
3.1.5 thermohydrometer, n—a glass hydrometer with a
302H 700 to 750
self-contained thermometer.
303H 750 to 800
304H 800 to 850
305H 850 to 900
4. Summary of Test Method
306H 900 to 950
4.1 The density or API gravity, after temperature equilib-
307H 950 to 1000
308H 1000 to 1050
rium has been reached, is read by observing the freely floating
309H 1050 to 1100
thermohydrometer and noting the graduation nearest to the
Hydrometer
apparent intersection of the horizontal plane surface of the
Total length, mm 374 to 387
liquid with the vertical scale of the hydrometer after tempera-
Body diameter, mm 18 to 25
ture equilibrium has been reached. The observed thermohy-
Stem diameter, mm, min 4.0
drometer reading is reduced to the reference temperature value
Hydrometer Scale
by means of the Petroleum Measurement Tables (the appropri-
Standard temperature, °C 15
ate adjunct to Guide D 1250/API MPMS Chapter 11.1) and
Subdivisions, kg/m 0.5
observed temperature from the enclosed thermometer.
Short intermediate lines at, kg/m 1
Long intermediate lines at, kg/m 5
Main (numbered) lines at, kg/m 10
5. Significance and Use
Scale error at any point not to exceed, kg/m 0.5
Length of nominal scale, mm 125 to 145
5.1 Density and API gravity are used in custody transfer
Scale extension beyond nominal range limits, kg/m 2.5
quantity calculations and to satisfy transportation, storage, and
Thermometer Scale
regulatory requirements. Accurate determination of density or
Range, °C
API gravity of crude petroleum and liquid petroleum products
Designation L −20 to +65
is necessary for the conversion of measured volumes to
Designation M 0 to +85
volumes at the standard temperatures of 15°C or 60°F.
Designation H +20 to +105
Immersion total
5.2 DensityandAPIgravityarealsofactorsthatindicatethe
Subdivisions, °C 1.0
quality of crude petroleum. Crude petroleum prices are fre-
Intermediate lines at, °C 5
quently posted against values in kg/m or in degrees API. Main (numbered) lines at, °C 10
Scale error at any point not to exceed, °C 1.0
However, this property of petroleum is an uncertain indication
Scale length, mm 80 to 100
of its quality unless correlated with other properties.
5.3 Field of Application—Because the thermohydrometer
incorporates both the hydrometer and thermometer in one
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 D 1298 (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
E 100 (shown in Fig. 1), and graduated in:
shown in Table 3.
6.1.1 Kilograms/cubic metre (kg/m ) and degrees Celsius
7.1.2 If the test temperature is significantly different from
for density hydrometers, as shown in Table 1.
the reference temperature of 15°C or 60°F, the expansion or
6.1.2 Degrees API (°API) and degrees Fahrenheit for hy-
contraction of the glass may affect the calibration of the
drometers measuring in API Gravity, as shown in Table 2.
thermohydrometer.Ahydrometer correction factor (HYC) may
6.2 Hydrometer Cylinders, clear glass, plastic, or metal. For
be applied to the measured density value to provide a corrected
convenience of pouring, the cylinder may have a pouring lip.
reading. Historically, the following equations have been used
The inside diameter shall be at least 25 mm (1 in.) greater than
within volume correction factor tables.
the outside diameter of the thermohydrometer used.The height
of the cylinder shall be such that the bottom of the thermohy- r 5r 3 HYC (2)
corrected test
D6822–02
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
D6822–02
FIG. 1 Typical Thermohydrometer Designs
D6822–02
loss and in such a manner that the stem will not be wetted
where:
higher than the approximate floating position.
HYC = hydrometer thermal correction factor,
r = test density, corrected for the effects of tem-
corrected 7.2.3.1 Keep the rest of the stem dry, as unnecessary liquid
perature on the thermohydrometer, and
on the stem changes the effective weight of the instrument, and
r = test density, as observed by reading the ther-
test
so affects the reading obtained.
mohydrometer.
7.2.3.2 Gently lower the thermohydrometer into the center
HYC 5 1 2 0.00001278~t 2 60! 2 0.0000000062~t 2 60! (3) of the hydrometer cylinder. When the thermohydrometer has
settled, ensure it is not resting on the bottom of the cylinder by
where:
depressing it about two scale divisions into the liquid. Give the
t = observed temperature (°F) or
thermohydrometeraslightspin,allowingittofloatfreelyaway
HYC 5 1 2 0.000023 t 2 15! 2 0.00000002 t 2 15! (4)
~ ~ from the walls of the hydrometer cylinder.
7.2.3.3 Allow enough time for the thermohydrometer to
where:
come to rest, all air bubbles to come to the surface, and the
t = observed temperature (°C).
thermohydrometer temperature to stabilize, usually 3 to 5 min.
7.1.2.1 All parties affected by the measurement should
This is particularly necessary in the case of more viscous
agree upon the need for and the method of correction.
samples. Use a temperature bath if control of the sample
7.1.3 When the thermohydrometer value is used to select
temperature is required.
factors for correcting volumes to standard temperatures, the
7.2.4 Read the thermohydrometer to the nearest scale divi-
thermohydrometer reading preferably should be made at a
sion (see 7.2.7 for details). The correct reading is that point on
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,
NOTE 1—Volume and density correction tables are based on average
appearstobecomeastraightlinecuttingthethermohydrometer
expansion for a number of typical materials. Since the same coefficients
scale. See Fig. 2 for details on reading the meniscus.
were used in computing both sets of tables, corrections made over the
7.2.5 To make a reading with opaque liquids, observe the
same temperature interval minimize errors arising from possible differ-
ences between the coefficien
...