ASTM D5002-22

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Designation: D5002 − 19 D5002 − 22
Standard Test Method for
Density, Relative Density, and API Gravity of Crude Oils by
Digital Density Analyzer
This standard is issued under the fixed designation D5002; 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.
1. Scope*
1.1 This test method covers the determination of the density, relative density, and API gravity of crude oils that may be handled
in a normal fashion as liquids at test temperatures between 15 °C and 35 °C utilizing either manual or automated sample injection
equipment. This test method applies to crude oils with high vapor pressures provided appropriate precautions are taken to prevent
vapor loss during transfer of the sample to the density analyzer.
1.2 This test method was evaluated in interlaboratory study testing using crude oils in the 0.75 g ⁄mL to 0.95 g ⁄mL range. Lighter
crude oil may require special handling to prevent vapor losses.
1.3 The values stated in SI units are to be regarded as standard. Other units of measurement are included in this standard. The
accepted units of measurement of density are grams per millilitre and kilograms per cubic metre.
1.4 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. Specific warning statements are given in 7.4, 7.5, and 7.6.
1.5 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:
D287 Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)
D941 Test Method for Density and Relative Density (Specific Gravity) of Liquids by Lipkin Bicapillary Pycnometer (Withdrawn
1993)
D1193 Specification for Reagent Water
D1217 Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham Pycnometer
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
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.04.0D on Physical and Chemical Methods.
Current edition approved Dec. 1, 2019July 1, 2022. Published January 2020August 2022. Originally approved in 1989. Last previous edition approved in 20182019 as
ɛ1
D5002 – 18D5002 – 19. . DOI: 10.1520/D5002-19.10.1520/D5002-22.
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.
The last approved version of this historical standard is referenced on www.astm.org.
*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
D5002 − 22
D1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by
Hydrometer Method
D4052 Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D4377 Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration (Withdrawn 2020)
3. Terminology
3.1 Definitions:
3.1.1 density, n—mass per unit volume at a specified temperature.
3.1.1.1 Discussion—
3 3
The SI unit of density is kg/m ; the unit of measure g/cm is commonly used in industry. Less preferred units, for example, kg/L
or g/mL, are still in use.
3.1.2 relative density, n—the ratio of the density of a material at a stated temperature to the density of water at a stated temperature.
3.1.2.1 Discussion—
Relative density is also commonly known as specific gravity. Commonly used stated temperatures are 20 °C ⁄20 °C, 15 °C ⁄15 °C,
20 °C ⁄4 °C and 60 °F ⁄60 °F. “Relative density” was historically known as the deprecated term “specific gravity”.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 API gravity, n—a special function of relative density 60 °F ⁄60 °F, represented by:
141.5
°API = 2 131.5 (1)
relative density
3.2.1.1 Discussion—
No statement of reference temperature is required since 60 °F is included in the definition.
3.2.2 test specimen, n—the volume of the sample aliquot residing in the U-tube during the measurement cycle.
3.2.2.1 Discussion—
Sample material residing in filling nozzles, tubing and valve manifolds is not considered “Test Specimen.” A test specimen may
be measured only once.
4. Summary of Test Method
4.1 Approximately 1 mL to 2 mL of crude oil sample is introduced into an oscillating U-tube and the change in oscillating
frequency caused by the change in the mass of the tube is used in conjunction with adjustment data to determine the density,
relative density, and API gravity of the sample. Both manual and automated injection techniques are described.
5. Significance and Use
5.1 Density is a fundamental physical property that may be used in conjunction with other properties to characterize the quality
of crude oils.
5.2 The density or relative density of crude oils is used for the conversion of measured volumes to volumes at the standard
temperatures of 15 °C or 60 °F and for the conversion of crude mass measurements into volume units.
5.3 The application of the density result obtained from this test method, for fiscal or custody transfer accounting calculations, may
require measurements of the water and sediment contents obtained on similar specimens of the crude oil parcel.
6. Apparatus
6.1 Digital Density Analyzer—A digital analyzer consisting of a U-shaped, oscillating tube, U-tube, and a system for electronic
excitation, frequency counting, and display. The analyzer shall accommodate the accurate measurement of the sample temperature
during measurement or shall control the sample temperature. The instrument shall be capable of meeting the precision requirements
described in 6.1 of Test Method D4052.
D5002 − 22
6.2 Syringes, at least 2 mL in volume with a tip or an adapter tip that will fit the inlet of the density analyzer.
6.3 Flow-Through or Pressure Adapter, for use as an alternative means of introducing the sample into the density meter.
6.4 Autosampler, required for use in automated injection analyses. The autosampler shall be designed to ensure the integrity of
the test specimen prior to and during the analysis and be equipped to transfer a representative portion of test specimen to the digital
density analyzer.
7. Reagents and Materials
7.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type
II of Specification D1193 or better.
7.3 Water, reagent water, freshly boiled, to remove dissolved gasses, for use as a primary calibration standard. (Warning—
Handling water at boiling or near boiling temperature can present a safety hazard. Wear appropriate personal protective
equipment.)
7.4 Acetone, for flushing and drying the sample tube. (Warning—Extremely flammable.)
7.5 Petroleum Naphtha, for flushing viscous petroleum samples from the sample tube. (Warning—Extremely flammable.)
NOTE 1—Suitable solvent naphthas are marketed under various designations such as “petroleum ether,” “ligroine,” or “precipitation naphtha.”
7.6 n-Nonane, n-tridecane or cyclohexane, 99 % purity or better, or similar pure material for which the density is known precisely
from literature references or by direct determination in accordance with Test Method D941 or D1217. (Warning—Extremely
flammable.)
8. Sampling, Test Specimens, and Test Units
8.1 Sampling is defined as all the steps required to obtain an aliquot of the contents of any pipe, tank or other system, and to place
the sample into the laboratory test container. The laboratory test container and sample volume shall be of sufficient dimensions to
allow mixing as described in 8.3.1. Mixing is required to obtain a homogeneous sample for analysis.
8.2 Laboratory Sample—Use only representative samples obtained as specified in Practices D4057 or D4177 for this test method.
8.3 Test Specimen—A portion or volume of sample obtained from the laboratory sample and delivered to the density analyzer
U-tube. Obtain the test specimen as follows:
8.3.1 Mix the sample of crude oil to homogenize any sediment and water present. The mixing may be accomplished as described
in Practice D4177 or Test Method D4377. Mixing at room temperature in an open container can result in the loss of light ends,
so mixing in closed, pressurized containers or at sub-ambient temperatures is recommended.
8.3.2 Draw the test specimen from a properly mixed laboratory sample using an appropriate syringe. Alternatively, if the proper
density analyzer attachments and connecting tubes are used then the test specimen may be delivered directly to the analyzer’s
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, American Chemical Society, Washington, DC. For Suggestionssuggestions on the testing of reagents not listed by the American Chemical Society, see
AnnualAnalar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial
Convention, Inc. (USPC), Rockville, MD.
D5002 − 22
A
TABLE 1 Density of Water
NOTE 1—Several metrological entities have issued water density tables
and alternative water density data is referenced in publications external to
ASTM and this test method. Using water density data from an alternative
recognized source does not pose a compliance issue with this test method
as the variation in the data typically is limited to the sixth decimal place.
Tempera- Density, Tempera- Density, Tempera- Density,
ture, °C g/mL ture, °C g/mL ture,° C g/mL
0.01 0.999844 21.0 0.997996 40.0 0.992216
3.0 0.999967 22.0 0.997773 45.0 0.990213
4.0 0.999975 23.0 0.997541 50.0 0.988035
5.0 0.999967 24.0 0.997299 55.0 0.985693
10.0 0.999703 25.0 0.997048 60.0 0.983196
15.0 0.999103 26.0 0.996786 65.0 0.980551
15.56 0.999016 27.0 0.996516 70.0 0.977765
16.0 0.998946 28.0 0.996236 75.0 0.974843
17.0 0.998778 29.0 0.995947 80.0 0.971790
18.0 0.998599 30.0 0.995650 85.0 0.968611
19.0 0.998408 35.0 0.994033 90.0 0.965310
20.0 0.998207 37.78 0.993046 99.9 0.958421
A
Densities conforming to the International Temperature Scale 1990 (ITS 90) were
extracted from Lemmon, E. W., McLinden, M. O., and Friend, D. G., “Thermo-
physical Properties of Fluid Systems,”NIST Chemistry WebBook, NIST Standard
Reference Database No. 68, Eds. P.J. Linstrom and W.G. Mallard, National
Institute of Standards and Technology, Gaithersburg, MD, http://webbook.nist.gov.
(retrieved July 24, 2013).
U-tube from the mixing container. For automated injections, it is necessary to first transfer a portion of sample by appropriate
means from a properly mixed laboratory sample to the autosampler vials and take the necessary steps to ensure the integrity of
the test specimen prior to and during the analysis. Sample vials for the autosampler shall be sealed immediately after filling up
to 80 % 6 5 % and shall be kept closed until the auto sampler transfers the test specimen into the U-tube.
9. Preparation of Apparatus
9.1 Set up the density analyzer following the manufacturer’s instructions. Set the internal temperature control so that the desired
test temperature is established and maintained in the U-tube compartment of the analyzer. Verify the calibration of the instrument
at the same temperature at which the density or relative density of the sample is to be measured.
10. Verification and Adjustment
10.1 As a minimum requirement, calibration verification of the instrument is required when first set up and whenever the test
temperature is changed. Thereafter, conduct calibration verification at least weekly during routine operation or more frequently as
may be dictated by the nature of the crude oils being measured. Whenever the apparatus fails a calibration verification without
discernible cause, the apparatus shall be adjusted.
10.1.1 For non-calculating density meters, see Appendix X1 for adjustment procedure.
10.2 The adjustment routine for digital density meters involves using a minimum of two reference media. Typically, this will be
air and freshly boiled reagent water under atmospheric conditions. (Warning—Handling water at boiling or near boiling
temperature may present a safety hazard. Wear appropriate personal protective equipment.) Other materials such as n-nonane,
n-tridecane, cyclohexane, and n-hexadecane (for high temperature applications) may also be used as appropriate adjustment
materials, provided the reference materials have density values that are certified and traceable to national standards.
10.3 Follow the manufacturer’s instructions for the proper adjustment of the apparatus. If the apparatus is adjusted using air and
reagent water, observe the proper entries of air and water density values (see Table 1).
10.3.1 The density of air varies with pressure and relative humidity. Therefore, it is important that the dewpoint of ambient air
is below the adjustment temperature of the instrument as to avoid condensation of water in the U-tube. This may be achieved by
flushing ambient air through a desiccant container and into the U-tube.
10.3.2 The density of air varies with ambient pressure as a consequence of site elevation and atmospheric changes in pressure.
The air density may be calculated using this formula:
D5002 − 22
ρ 5 0.001293 273.15 ⁄ T P/101.325 g/mL (2)
@ #@ #
air
where:
ρ = density of air,
air
T = temperature, K, and
P = site atmospheric pressure at the time of adjustment, kPa.
NOTE 2—P should preferably be determined by direct measurement of the barometric pressure at the site of calibration. If direct measurement is not
available, and common sources providing weather data are consulted, the pressure reported is typically corrected to Sea Level, P . Therefore, such
SL
pressure data shall be corrected back to site pressure, P. For correction of P to P:
SL
P5 P 2 Site Elevation meters ⁄82.3 (3)
@ ~ ! #
SL2
NOTE 3—In the International Standard Atmosphere, ISA, the pressure drops 1 kPa per 82.3 m of elevation
10.3.3 The water density values are given in Table 1. Water density values are considered constant with respect to pressure in the
range of normally occurring atmospheric pressure.
NOTE 4—The need for a change in adjustment is generally attributable to deposits in the sample tube that are not removed by the routine flushing
procedure. Although this condition may be compensated for by adjusting the apparatus, it is good practice to clean the tube with warm chromic acid
solution (Warning—Causes severe burns. A recognized carcinogen.) whenever a major adjustment is required. Chromic acid solution is the most effective
cleaning agent; however, surfactant-type cleaning fluids have also been used successfully.
11. Procedure
11.1 Introduce a minimum of 1 mL to 2 mL of crude oil into the clean, dry, U-tube of the instrument using a suitable syringe.
Leave the syringe in place.
11.1.1 Ensure that the U-tube is properly filled and that no gas bubbles are present. The sample shall be homogeneous and free
of even the smallest gas bubbles. Check the integrity of the filled sample by using optical or physical methods to verify absence
of gas bubbles. If gas bubbles are detected, empty and refill the sample tube, and recheck for gas bubbles.
11.1.2 Allow the sample to equilibrate to the test temperature before proceeding to evaluate the test sample for the presence of
unseen air or gas bubbles.
11.1.3 For dark crude oil samples the observation of air or gas bubbles in the U-tube is very difficult. The presence of bubbles
may often be detected, however, by observing the fluctuations of the digital display of the density value. Air or gas bubbles cause
large random variations in the third and fourth significant figures for density reading. When bubbles are absent and the sample is
at equilibrium with the test temperature, the displayed values are stable, do not drift, and show only small variations of the order
of 61 to 2 units in the last significant figure. If stable values are not observed after a few minutes, then repeat the injection of a
new test specimen into the U-tube.
NOTE 5—When viscous liquids are being measured, a stable reading may be achieved even when air or gas bubbles are present. Careful injection of fresh
sample will often eliminate bubbles. Since bubbles contribute to lower density readings, an observed increase in the density of the liquid after injection
of fresh test specimen tends to suggest that bubbles were previously present.
11.1.4 After the instrument displays a steady reading to four significant figures for density, relative density, and two significant
figures for AP
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