ASTM D4052-22

Standard Test Method for Density, Relative Density, and API Gravity of Liquids by Digital Density Meter

SIGNIFICANCE AND USE
5.1 Density is a fundamental physical property that can be used in conjunction with other properties to characterize both the light and heavy fractions of petroleum and petroleum products.  
5.2 Determination of the density or relative density of petroleum and its products is necessary for the conversion of measured volumes to volumes at the standard temperature of 15 °C.
SCOPE
1.1 This test method covers the determination of the density, relative density, and API Gravity of petroleum distillates and viscous oils that can be handled in a normal fashion as liquids at the temperature of test, utilizing either manual or automated sample injection equipment. Its application is restricted to liquids with total vapor pressures (see Test Method D5191) typically below 100 kPa and viscosities (see Test Method D445 or D7042) typically below about 15 000 mm2/s at the temperature of test. The total vapor pressure limitation however can be extended to >100 kPa provided that it is first ascertained that no bubbles form in the U-tube, which can affect the density determination. Some examples of products that may be tested by this procedure include: gasoline and gasoline-oxygenate blends, diesel, jet, basestocks, waxes, and lubricating oils.  
1.1.1 Waxes and highly viscous samples were not included in the 1999 interlaboratory study (ILS) sample set that was used to determine the current precision statements of the method, since all samples evaluated at the time were analyzed at a test temperature of 15 °C. Wax and highly viscous samples require a temperature cell operated at elevated temperatures necessary to ensure a liquid test specimen is introduced for analysis. Consult instrument manufacturer instructions for appropriate guidance and precautions when attempting to analyze wax or highly viscous samples. Refer to the Precision and Bias section of the method and Note 9 for more detailed information about the 1999 ILS that was conducted.  
1.2 In cases of dispute, the referee method is the one where samples are introduced manually as in 6.2 or 6.3, as appropriate for sample type.  
1.3 When testing opaque samples, and when not using equipment that is capable of automatic bubble detection, proper procedure shall be established so that the absence of air bubbles in the U-tube can be established with certainty. For the determination of density in crude oil samples use Test Method D5002.  
1.4 The values stated in SI units are regarded as the standard, unless stated otherwise. The accepted units of measure for density are grams per millilitre (g/mL) or kilograms per cubic metre (kg/m3).  
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 statements, see 3.2.1, Section 7, 9.1, 10.2, and Appendix X1.  
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

• Status: Published
• Publication Date: 30-Apr-2022
• ICS: 17.060 - Measurement of volume, mass, density, viscosity
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.04.0D - Physical and Chemical Methods

Relations

• Refers: ASTM D445-24 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Apr-2024
• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D445-23 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Nov-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D1250-19e1 - Standard 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
• Effective Date: 01-May-2019
• Refers: ASTM D5191-18a - Standard Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method)
• Effective Date: 01-Dec-2018
• Refers: ASTM D445-16 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 15-Dec-2016
• Refers: ASTM D5002-15 - Standard Test Method for Density and Relative Density of Crude Oils by Digital Density Analyzer
• Effective Date: 15-Dec-2015
• Refers: ASTM D445-14e1 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM D445-14 - Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
• Effective Date: 01-Jul-2014
• Refers: ASTM D7042-14 - Standard Test Method for Dynamic Viscosity and Density of Liquids by Stabinger Viscometer (and the Calculation of Kinematic Viscosity)
• Effective Date: 01-May-2014
• Refers: ASTM D5191-13 - Standard Test Method for Vapor Pressure of Petroleum Products (Mini Method)
• Effective Date: 01-Dec-2013
• Refers: ASTM D5002-13 - Standard Test Method for Density and Relative Density of Crude Oils by Digital Density Analyzer
• Effective Date: 01-Oct-2013
• Refers: ASTM D7042-12a - Standard Test Method for Dynamic Viscosity and Density of Liquids by Stabinger Viscometer (and the Calculation of Kinematic Viscosity)
• Effective Date: 01-Nov-2012
• Refers: ASTM D5191-12 - Standard Test Method for Vapor Pressure of Petroleum Products (Mini Method)
• Effective Date: 01-Sep-2012

Overview

ASTM D4052-22, published by ASTM International, specifies the standard test method for the determination of density, relative density, and API gravity of liquids, specifically petroleum products and distillates, using a digital density meter. This method delivers reliable and precise measurements critical for the characterization, classification, and conversion of petroleum and petroleum-based liquids. It addresses both manual and automated means of sample introduction, with particular considerations for the handling and preparation of various sample types, including gasoline blends, diesel, jet fuel, base stocks, waxes, and lubricating oils.

Key Topics

• Density and Relative Density: Quantifying mass per unit volume at a specific temperature is essential for petroleum product analysis and standardization.
• API Gravity: Important for classifying petroleum liquids, API gravity is calculated from the measured density and provides information about the product’s quality and suitability for various applications.
• Digital Density Meters: The method utilizes oscillating U-tube digital density analyzers, which offer high accuracy, reproducibility, and automation potential in both laboratory and industrial settings.
• Sample Suitability: Applies to samples that behave as liquids at the test temperature and have typical vapor pressures below 100 kPa and viscosities below approximately 15,000 mm²/s. Adaptations are recommended for highly viscous or waxy samples.
• Calibration and Quality Control: Stringent calibration procedures using certified standards such as air and freshly boiled reagent water are necessary. Regular quality control checks are recommended to ensure data reliability.
• Measurement Units: Results are reported in grams per millilitre (g/mL), kilograms per cubic metre (kg/m³), or API gravity units, with clear indication of test and reference temperatures.

Applications

• Petroleum Refining and Blending: Accurate density and API gravity measurements are fundamental for process control, product classification, and regulatory compliance in refineries.
• Quality Assurance: Laboratories employ this test method to ensure products meet required specifications for transport, processing, and sale.
• Volume Correction: Density data allows for conversion of measured volumes to standardized conditions (typically 15 °C), which is vital for commercial transactions and logistical management.
• Fuel Characterization: The method supports classification and standardization of a broad range of liquid petroleum products including gasoline, jet fuel, diesel, lubricants, and base stocks.
• Regulatory Testing: Recognized by industries and government agencies for determination of density and API gravity in disputed cases or when referee methods are mandated.
• Routine and Advanced Laboratory Analysis: Adaptable for both high-throughput automated laboratories and smaller facilities relying on manual methods.

Related Standards

• ASTM D287: Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)
• ASTM D445, D7042: Test Methods for Viscosity, often referenced for ensuring sample suitability
• ASTM D1298: Density tests by hydrometer method for crude oil
• ASTM D5002: Standard Test Method for Density, Relative Density, and API Gravity of Crude Oils by Digital Density Analyzer
• ASTM D4057, D4177: Recommended practices for manual and automatic sampling of petroleum products
• ASTM D5191: Test Method for Vapor Pressure of Petroleum Products

Practical Value

Implementing ASTM D4052-22 helps laboratories and industries achieve accurate, repeatable, and standardized results vital for the efficient operation and regulatory compliance of petroleum supply chains. Its digital approach minimizes operator error, facilitates automation, and enhances safety in sample handling and analysis. The internationally recognized method supports trade, inventory management, and quality control across a wide range of petroleum and liquid fuel applications.

Keywords: ASTM D4052, digital density meter, API gravity, density measurement of petroleum, petroleum products testing, relative density, laboratory standard, fuel analysis, quality control, refinery test methods.

Standards Content (Sample)

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.
Designation: D4052 − 22
Standard Test Method for
Density, Relative Density, and API Gravity of Liquids by
Digital Density Meter
This standard is issued under the fixed designation D4052; 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* bubblesintheU-tubecanbeestablishedwithcertainty.Forthe
determination of density in crude oil samples use Test Method
1.1 Thistestmethodcoversthedeterminationofthedensity,
D5002.
relative density, and API Gravity of petroleum distillates and
1.4 The values stated in SI units are regarded as the
viscous oils that can be handled in a normal fashion as liquids
standard, unless stated otherwise. The accepted units of mea-
at the temperature of test, utilizing either manual or automated
sure for density are grams per millilitre (g/mL) or kilograms
sample injection equipment. Its application is restricted to
per cubic metre (kg/m ).
liquids with total vapor pressures (see Test Method D5191)
typicallybelow100kPaandviscosities(seeTestMethodD445
1.5 This standard does not purport to address all of the
orD7042)typicallybelowabout15000mm /satthetempera-
safety concerns, if any, associated with its use. It is the
tureoftest.Thetotalvaporpressurelimitationhowevercanbe
responsibility of the user of this standard to establish appro-
extended to >100kPa provided that it is first ascertained that
priate safety, health, and environmental practices and deter-
no bubbles form in the U-tube, which can affect the density
mine the applicability of regulatory limitations prior to use.
determination. Some examples of products that may be tested
Forspecificwarningstatements,see3.2.1,Section7,9.1,10.2,
by this procedure include: gasoline and gasoline-oxygenate
and Appendix X1.
blends, diesel, jet, basestocks, waxes, and lubricating oils.
1.6 This international standard was developed in accor-
1.1.1 Waxes and highly viscous samples were not included
dance with internationally recognized principles on standard-
in the 1999 interlaboratory study (ILS) sample set that was
ization established in the Decision on Principles for the
used to determine the current precision statements of the
Development of International Standards, Guides and Recom-
method, since all samples evaluated at the time were analyzed
mendations issued by the World Trade Organization Technical
atatesttemperatureof15°C.Waxandhighlyviscoussamples
Barriers to Trade (TBT) Committee.
require a temperature cell operated at elevated temperatures
2. Referenced Documents
necessary to ensure a liquid test specimen is introduced for
analysis. Consult instrument manufacturer instructions for
2.1 ASTM Standards:
appropriate guidance and precautions when attempting to
D287Test Method forAPI Gravity of Crude Petroleum and
analyze wax or highly viscous samples. Refer to the Precision
Petroleum Products (Hydrometer Method)
and Bias section of the method and Note 9 for more detailed
D445Test Method for Kinematic Viscosity of Transparent
information about the 1999 ILS that was conducted.
and Opaque Liquids (and Calculation of DynamicViscos-
ity)
1.2 In cases of dispute, the referee method is the one where
D1193Specification for Reagent Water
samples are introduced manually as in 6.2 or 6.3, as appropri-
D1250Guide for the Use of the Joint API and ASTM
ate for sample type.
Adjunct for Temperature and Pressure Volume Correction
1.3 When testing opaque samples, and when not using
FactorsforGeneralizedCrudeOils,RefinedProducts,and
equipment that is capable of automatic bubble detection,
Lubricating Oils: API MPMS Chapter 11.1
proper procedure shall be established so that the absence of air
D1298Test Method for Density, Relative Density, or API
Gravity of Crude Petroleum and Liquid Petroleum Prod-
ucts by Hydrometer Method
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. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2022. Published May 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1981. Last previous edition approved in 2018 as D4052–18a. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4052-22. 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
D4052 − 22
D4057Practice for Manual Sampling of Petroleum and 3.2.4 sample aliquot, n—the fraction of the original labora-
Petroleum Products tory sample dedicated for this test.
D4175Terminology Relating to Petroleum Products, Liquid
3.2.4.1 Discussion—Thesamplealiquotistypicallyresiding
Fuels, and Lubricants
insyringes,samplevials,beakers,orcontainersforthepurpose
D4177Practice for Automatic Sampling of Petroleum and
of transferring a representative test specimen into the appara-
Petroleum Products
tus’U-tube.
D4377TestMethodforWaterinCrudeOilsbyPotentiomet-
3 3.2.5 test specimen, n—the volume of the sample aliquot
ric Karl Fischer Titration (Withdrawn 2020)
residing in the U-tube during the measurement cycle.
D5002Test Method for Density, Relative Density, and API
Gravity of Crude Oils by Digital Density Analyzer
3.2.5.1 Discussion—Sample material residing in filling
D5191Test Method for Vapor Pressure of Petroleum Prod-
nozzles, tubing and valve manifolds is not considered “Test
ucts and Liquid Fuels (Mini Method)
Specimen.” A test specimen can be measured only once.
D7042Test Method for Dynamic Viscosity and Density of
Liquids by Stabinger Viscometer (and the Calculation of
4. Summary of Test Method
Kinematic Viscosity)
4.1 A volume of approximately 1mL to 2mL of liquid
sample is introduced into an oscillating U-tube and the change
3. Terminology
inoscillatingfrequencycausedbythechangeinthemassofthe
3.1 Definitions:
U-tube is used in conjunction with calibration data to deter-
3.1.1 For definitions of terms used in this test method, refer
minethedensity,relativedensity,orAPIGravityofthesample.
to Terminology D4175.
Bothmanualandautomatedinjectiontechniquesaredescribed.
3.1.2 density, n—mass per unit volume.
3 5. Significance and Use
3.1.2.1 Discussion—TheSIunitofdensityiskg/m ;theunit
of measure g/cm is commonly used in industry. 5.1 Density is a fundamental physical property that can be
3.1.3 relative density, n—the ratio of the density of a used in conjunction with other properties to characterize both
material at a stated temperature to the density of water at a the light and heavy fractions of petroleum and petroleum
stated temperature. products.
5.2 Determination of the density or relative density of
3.1.3.1 Discussion—Relative density is also commonly
petroleum and its products is necessary for the conversion of
knownasspecificgravity.Commonlyusedstatedtemperatures
measured volumes to volumes at the standard temperature of
are 20°C⁄20°C, 15°C⁄15°C, 20°C⁄4°C and 60°F⁄60°F.
15°C.
“Relative density” was historically known as the deprecated
term “specific gravity.”
6. Apparatus
3.2 Definitions of Terms Specific to This Standard:
3.2.1 adjustment, v—the operation of bringing the instru-
6.1 Digital Density Analyzer—Adigital analyzer consisting
menttoastateofperformancesuitableforitsuse,bysettingor
of a U-shaped, oscillating tube, U-tube, and a system for
adjusting the density meter constants.
electronic excitation, frequency counting, and display. The
3.2.1.1 Discussion—On some digital density analyzer
analyzer shall accommodate the accurate measurement of the
instruments,anadjustmentmaybemaderatherthancalibrating
sample temperature during measurement or shall control and
the instrument. The adjustment procedure uses air and freshly
keepthesampletemperatureconstantto 60.05°C.Theinstru-
boiled reagent water (Warning—Handling water at boiling or
ment shall be capable of meeting the precision requirements
near boiling temperature can present a safety hazard. Wear
described in this test method.
appropriate personal protective equipment.) as standards to
6.2 Syringes, for use primarily in manual injections, at least
establish the linearity of measurements over a range of
2mL in volume with a tip or an adapter tip that will fit the
operating temperatures.
opening of the U-tube.
3.2.2 API gravity, n—a special function of relative density
6.3 Flow-Through or Pressure Adapter, for use as an alter-
60°F⁄60°F, represented by:
native means of introducing the sample into the density
141.5
analyzer either by a pump, by pressure, or by vacuum.
°API= 2131.5 (1)
relativedensity
NOTE 1—It is highly recommended that a vacuum not be applied to
samples prone to light-end loss, as it can easily lead to the formation of
3.2.2.1 Discussion—No statement of reference temperature
bubbles in the U-tube. It is recommended to fabricate a special cap or
is required since 60°F is included in the definition.
stopper for sample containers so that air, such as from a squeeze pump, is
3.2.3 calibration, v—set of operations that establishes the
used to displace a test specimen to the U-tube measuring cell by the
flow-through method.
relationshipbetweenthereferencedensityofstandardsandthe
corresponding density reading of the instrument.
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 sample
The last approved version of this historical standard is referenced on
www.astm.org. aliquot to the digital density analyzer.
D4052 − 22
6.5 Ultrasonic Bath, Unheated, (optional), of suitable di- D4377. Mixing at room temperature in an open container can
mensions to hold container(s) placed inside of bath, for use in result in the loss of volatile material from certain sample types
effectively dissipating and removing air or gas bubbles that (for example, gasoline samples), so mixing in closed, pressur-
may be entrained in viscous sample types prior to analysis. ized containers or at least 10°C below ambient temperature is
required for such sample types where loss of volatile material
7. Reagents and Materials
is a potential concern. For some sample types, such as viscous
lube oils that are prone to having entrained air or gas bubbles
7.1 Purity of Reagents—Reagent grade chemicals shall be
present in the sample, the use of an ultrasonic bath (see 6.5)
used in all tests. Unless otherwise indicated, it is intended that
without the heater turned on (if so equipped), has been found
all reagents shall conform to the specifications of the Commit-
effective in dissipating bubbles typically within 10min.
tee onAnalytical Reagents of theAmerican Chemical Society,
where such specifications are available. Other grades may be
NOTE2—Whenmixingsampleswithvolatilecomponents,considerthe
used, provided it is first ascertained that the reagent is of
sample properties in relation to both ambient temperature and pressure.
sufficiently high purity to permit its use without lessening the
8.3.2 For manual injections, draw the test specimen from a
accuracy of the determination.
properly mixed laboratory sample using an appropriate sy-
7.2 Purity of Water—Unless otherwise indicated, references
ringe. If the proper density analyzer attachments and connect-
to water shall be understood to mean reagent water as defined
ing tubes are used, as described in 6.3, then the test specimen
by Type II of Specification D1193 or higher.
can be delivered directly to the analyzer’s U-tube from the
7.3 Water,reagentwater,freshlyboiledtoremovedissolved mixing container. For automated injections, it is necessary to
gasses, for use as primary calibration standard. (Warning—
first transfer a portion of sample by appropriate means from a
Handling water at boiling or near boiling temperature can properlymixedlaboratorysampletotheautosamplervials,and
present a safety hazard. Wear appropriate personal protective
take the necessary steps to ensure the integrity of the test
equipment.) specimen prior to and during the analysis. Sample vials for the
autosampler shall be sealed immediately after filling up to
7.4 Cleaning Solvent,suchaspetroleumnaphtha orsolvent
80% 6 5% and shall be kept closed until the auto sampler
knowntobemisciblewiththesamplematerialwithoutcausing
transfers the test specimen into the measuring cell. For highly
corrosion of the sample cell. Consult manufacturer’s informa-
volatilesamples,coolthesamplepriortomeasurement.Follow
tion for details. (Warning—Petroleum naphtha is extremely
the manufacturer’s instructions.
flammable.)
NOTE 3—Overfilled sample vials can result in cross-contamination
7.5 Acetone,orotherhighlyvolatilesolventforflushingand
between sample vials.
drying the U-tube. (Warning—Extremely flammable.)
7.6 Dry Air, for drying the U-tube.
9. Preparation of Apparatus
8. Sampling, Test Specimens, and Test Units
9.1 Setupthedensityanalyzerfollowingthemanufacturer’s
instructions. Set the internal temperature control so that the
8.1 Samplingisdefinedasallthestepsrequiredtoobtainan
desired test temperature is established and maintained in the
aliquot of the contents of any pipe, tank, or other system, and
U-tube of the analyzer. Verify the instrument’s calibration at
to place the sample into the laboratory test container. The
thesametemperatureatwhichthedensityorrelativedensityof
laboratory test container and sample volume shall be of
the sample is to be measured or perform an adjustment (see
sufficient capacity to mix the sample and obtain a homoge-
3.2.1–Discussion) in preparation of analyzing samples.
neous sample for analysis.
(Warning—Precise setting and control of the test temperature
8.2 Laboratory Sample—Use only representative samples
in the U-tube is extremely important. An error of 0.1°C can
obtained as specified in Practices D4057 or D4177 for this test
result in a change in density of one in the fourth decimal when
method.
measuring in units of grams per millilitre.)
8.3 Test Specimen—A portion or volume of sample aliquot
obtained from the laboratory sample and delivered to the
10. Verification and Adjustment
density analyzer U-tube. The test specimen is obtained as
10.1 As a minimum requirement, calibration verification of
follows:
the instrument is required when first set up and whenever the
8.3.1 Mixthesampleifrequiredtohomogenize,takingcare
test temperature is changed. Whenever the apparatus fails a
to avoid the introduction of air bubbles. The mixing may be
calibrationverificationwithoutdiscerniblecause,theapparatus
accomplished as described in Practice D4177 or Test Method
must be adjusted. See 3.2.1.
10.2 The adjustment routine for digital density meters
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
involves using a minimum of two reference media. Typically,
Standard-Grade Reference Materials, American Chemical Society, Washington,
this will be air and freshly boiled reagent water under atmo-
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
spheric conditions. (Warning—Handling water at boiling or
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
near boiling temperature can present a safety hazard. Wear
copeial Convention, Inc. (USPC), Rockville, MD.
appropriate personal protective equipment.) Other materials
Suitable solvent naphthas are marketed under various designations such as
“Petroleum Ether,” “Ligroine,” or “Precipitation Naphtha.” such as n-nonane, n-tridecane, cyclohexane, and n-hexadecane
D4052 − 22
(for high temperature applications) can also be used as appro- 11. Quality Control Checks
priate adjustment materials, provided the reference materials
11.1 Confirm the instrument is in statistical control at least
have density values that are certified and traceable to national
once a week when it is in use, by analyzing a quality control
standards.
(QC) sample that is representative of samples typically ana-
10.3 Follow the manufacturer’s instructions for the proper lyzed. Analysis of a single QC sample can be sufficient.
adjustment of the apparatus. If the apparatus is adjusted using Analysis of QC sample results can be carried out using control
air and reagent water, observe the proper entries of air and chart techniques. If the QC sample result determined causes
water density values. the laboratory to be in an out-of-control situation, such as
10.3.1 The density of air varies with pressure and relative exceeding the laboratory’s control limits, instrument adjust-
humidity (see Table 1). Therefore, it is important that the ment is required. An ample supply of QC sample material
dewpointofambientairisbelowtheadjustmenttemperatureof shouldbeavailablefortheintendedperiodofuse,andmustbe
theinstrumentastoavoidcondensationofwaterintheU-tube. homogeneous and stable under the anticipated storage condi-
This can be achieved by flushing ambient air through a tions.Priortomonitoringthemeasurementprocess,theuserof
desiccant container and into the U-tube. themethodneedstodeterminetheaverageandcontrollimitsof
10.3.2 The density of air varies with ambient pressure as a the QC sample. The QC sample precision should be checked
consequence of site elevation and atmospheric changes in against the method precision to ensure data quality.
pressure. The air density can be calculated using this formula:
11.2 Although not mandatory, it is recommended that peri-
ρ 50.001293 273.15 ⁄ T P/101.325 g/mL (2) odicanalysesofcertifieddensitystandards(thatis,traceableto
@ #@ #
air
national standards) that are separate from those that may be
where:
used in adjusting the instrument, be used to confirm testing
ρ = density of air,
air
accuracy.
T = temperature, K, and
P = site atmospheric pressure at the time of adjustment,
12. Procedure
kPa.
12.1 Manual Injection:
NOTE 4—P should preferably be determined by direct measurement of
the barometric pressure at the site of calibration. If direct measurement is 12.1.1 Introduceavolumeofabout1mLto2mL,ofsample
not available, and common sources providing weather data are consulted,
into the clean, dry U-tube of the instrument using a suitable
the pressure reported is typically corrected to Sea Level, P . Therefore,
SL
syringe or alternative, as described in 6.3.
such pressure data must be corrected back to site pressure, P. For
12.1.2 The sample can also be introduced by siphoning.
correction of P to P:
SL
Plug the external TFE-fluorocarbon capillary tube into the
P=P 2 @SiteElevation ~meters!/82.3# (3)
SL
entryportoftheU-tube.Immersetheotherendofthecapillary
NOTE 5—In the International Standard Atmosphere, ISA, the pressure
in the sample and apply suction to the other port using a
drops 1kPa per 82.3m of elevation.
syringe or vacuum line until the U-tube is properly filled (see
10.3.3 The water density values are given in Table 1.Water
Note 1).
density values are considered constant with respect to pressure
12.1.3 Ensure that the U-tube is properly filled and that no
in the range of normally occurring atmospheric pressure.
gasbubblesarepresent.Thesamplemustbehomogeneousand
freeofeventhesmallestgasbubbles.Checktheintegrityofthe
A
TABLE 1 Density of Water
filled sample by using optical or physical methods to verify
NOTE 1—Several metrological entities have issued water density tables absence of gas bubbles. If gas bubbles are detected, empty and
and alternative water density data is referenced in publications external to
refill the U-tube, and recheck for gas bubbles.
ASTM and this test method. Using water density data from an alternative
recognized source does not pose a compliance issue with this test method NOTE 6—If the sample is too dark in color to determine the absence of
bubbles with certainty, the density cannot be measured within the stated
as the variation in the data typically is limited to the sixth decimal place.
precision limits of Section 15.
Temperature, Density, g/mL Temperature, Density, Temperature, Density,
°C °C g/mL °C g/mL
12.1.4 For most instrument models, it is recommended to
0.01 0.999844 21.0 0.997996 40.0 0.992216
turn the illumination light off with minimal delay after sample
3.0 0.999967 22.0 0.997773 45.0 0.990213
introduction and checking for bubbles because the heat gener-
4.0 0.999975 23.0 0.997541 50.0 0.988035
5.0 0.999967 24.0 0.997299 55.0 0.985693 atedcanaffectthemeasurementtemperature.Forsomemodels
10.0 0.999703 25.0 0.997048 60.0 0.983196
however, the cell light may be left on without affecting results.
15.0 0.999103 26.0 0.996786 65.0 0.980551
Refer to the manufacturer’s recommendations concerning
15.56 0.999016 27.0 0.996516 70.0 0.977765
16.0 0.998946 28.0 0.996236 75.0 0.974843 whether to leave the illumination light off or on.
17.0 0.998778 29.0 0.995947 80.0 0.971790
12.1.5 Aftertheinstrumentdisplaysasteadyreadingtofour
18.0 0.998599 30.0 0.995650 85.0 0.968611
significant figures for density, relative density, orAPI Gravity,
19.0 0.998408 35.0 0.994033 90.0 0.965310
and five for T-values, indicating that temperature equilibrium
20.0 0.998207 37.78 0.993046 99.9 0.958421
A
has been reached, record the density, relative density, API
DensitiesconformingtotheInternationalTemperatureScale1990(ITS90)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
ASTM MNL 7, Manual on Presentation of Data Control Chart Analysis,
Institute of Standards andTechnology, Gaithersburg, MD, http://webbook.nist.gov.
Section 3: Control Charts for Individuals, 6th ed., ASTM International, W.
(retrieved July 24, 2013).
Conshohocken, PA.
D4052 − 22
Gravity or T-values, or both, as appropriate. For instrument
...

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: D4052 − 18a D4052 − 22
Standard Test Method for
Density, Relative Density, and API Gravity of Liquids by
Digital Density Meter
This standard is issued under the fixed designation D4052; 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*
1.1 This test method covers the determination of the density, relative density, and API Gravity of petroleum distillates and viscous
oils that can be handled in a normal fashion as liquids at the temperature of test, utilizing either manual or automated sample
injection equipment. Its application is restricted to liquids with total vapor pressures (see Test Method D5191) typically below
100 kPa and viscosities (see Test Method D445 or D7042) typically below about 15 000 mm /s at the temperature of test. The total
vapor pressure limitation however can be extended to >100 kPa provided that it is first ascertained that no bubbles form in the
U-tube, which can affect the density determination. Some examples of products that may be tested by this procedure include:
gasoline and gasoline-oxygenate blends, diesel, jet, basestocks, waxes, and lubricating oils.
1.1.1 Waxes and highly viscous samples were not included in the 1999 interlaboratory study (ILS) sample set that was used to
determine the current precision statements of the method, since all samples evaluated at the time were analyzed at a test
temperature of 15 °C. Wax and highly viscous samples require a temperature cell operated at elevated temperatures necessary to
ensure a liquid test specimen is introduced for analysis. Consult instrument manufacturer instructions for appropriate guidance and
precautions when attempting to analyze wax or highly viscous samples. Refer to the Precision and Bias section of the method and
Note 9 for more detailed information about the 1999 ILS that was conducted.
1.2 In cases of dispute, the referee method is the one where samples are introduced manually as in 6.2 or 6.3, as appropriate for
sample type.
1.3 When testing opaque samples, and when not using equipment that is capable of automatic bubble detection, proper procedure
shall be established so that the absence of air bubbles in the U-tube can be established with certainty. For the determination of
density in crude oil samples use Test Method D5002.
1.4 The values stated in SI units are regarded as the standard, unless stated otherwise. The accepted units of measure for density
are grams per millilitre (g/mL) or kilograms per cubic metre (kg/m ).
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 statements, see 3.2.1, Section 7, 9.1, 10.2, and Appendix X1.
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.
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. 15, 2018May 1, 2022. Published February 2019May 2022. Originally approved in 1981. Last previous edition approved in 2018 as
D4052 – 18.D4052 – 18a. DOI: 10.1520/D4052-18A.10.1520/D4052-22.
*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
D4052 − 22
2. Referenced Documents
2.1 ASTM Standards:
D287 Test Method for API Gravity of Crude Petroleum and Petroleum Products (Hydrometer Method)
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D1193 Specification for Reagent Water
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
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
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)
D5002 Test Method for Density, Relative Density, and API Gravity of Crude Oils by Digital Density Analyzer
D5191 Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method)
D7042 Test Method for Dynamic Viscosity and Density of Liquids by Stabinger Viscometer (and the Calculation of Kinematic
Viscosity)
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175.
3.1.2 density, n—mass per unit volume at a specified temperature.volume.
3.1.2.1 Discussion—
3 3
The SI unit of density is kg/m ; the unit of measure g/cm is commonly used in industry.
3.1.3 relative density, n—the ratio of the density of a material at a stated temperature to the density of water at a stated temperature.
3.1.3.1 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 adjustment, v—the operation of bringing the instrument to a state of performance suitable for its use, by setting or adjusting
the density meter constants.
3.2.1.1 Discussion—
On some digital density analyzer instruments, an adjustment may be made rather than calibrating the instrument. The adjustment
procedure uses air and freshly boiled reagent water (Warning—Handling water at boiling or near boiling temperature can present
a safety hazard. Wear appropriate personal protective equipment.) as standards to establish the linearity of measurements over a
range of operating temperatures.
3.2.2 API gravity, n—a special function of relative density 60 °F ⁄60 °F, represented by:
141.5
°API= 2 131.5 (1)
relative density
3.2.2.1 Discussion—
No statement of reference temperature is required since 60 °F is included in the definition.
3.2.3 calibration, v—set of operations that establishes the relationship between the reference density of standards and the
corresponding density reading of the instrument.
3.2.4 sample aliquot, n—the fraction of the original laboratory sample dedicated for this test.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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.
D4052 − 22
3.2.4.1 Discussion—
The sample aliquot is typically residing in syringes, sample vials, beakers, or containers for the purpose of transferring a
representative test specimen into the apparatus’ U-tube.
3.2.5 test specimen, n—the volume of the sample aliquot residing in the U-tube during the measurement cycle.
3.2.5.1 Discussion—
Sample material residing in filling nozzles, tubing and valve manifolds is not considered “Test Specimen.” A test specimen can
be measured only once.
4. Summary of Test Method
4.1 A volume of approximately 1 mL to 2 mL of liquid sample is introduced into an oscillating U-tube and the change in
oscillating frequency caused by the change in the mass of the U-tube is used in conjunction with calibration data to determine the
density, relative density, or 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 can be used in conjunction with other properties to characterize both the light
and heavy fractions of petroleum and petroleum products.
5.2 Determination of the density or relative density of petroleum and its products is necessary for the conversion of measured
volumes to volumes at the standard temperature of 15 °C.
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 and keep the sample temperature constant to 60.05 °C. The instrument shall be capable of
meeting the precision requirements described in this test method.
6.2 Syringes, for use primarily in manual injections, at least 2 mL in volume with a tip or an adapter tip that will fit the opening
of the U-tube.
6.3 Flow-Through or Pressure Adapter, for use as an alternative means of introducing the sample into the density analyzer either
by a pump, by pressure, or by vacuum.
NOTE 1—It is highly recommended that a vacuum not be applied to samples prone to light-end loss, as it can easily lead to the formation of bubbles in
the U-tube. It is recommended to fabricate a special cap or stopper for sample containers so that air, such as from a squeeze pump, is used to displace
a test specimen to the U-tube measuring cell by the flow-through method.
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 sample aliquot to the
digital density analyzer.
6.5 Ultrasonic Bath, Unheated, (optional), of suitable dimensions to hold container(s) placed inside of bath, for use in effectively
dissipating and removing air or gas bubbles that may be entrained in viscous sample types prior to analysis.
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.
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 suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. PharmaceuticalPharmacopeial Convention, Inc.
(USPC), Rockville, MD.
D4052 − 22
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 higher.
7.3 Water, reagent water, freshly boiled to remove dissolved gasses, for use as primary calibration standard. (Warning—Handling
water at boiling or near boiling temperature can present a safety hazard. Wear appropriate personal protective equipment.)
7.4 Cleaning Solvent, such as petroleum naphtha (orWarning—Petroleum naphtha is extremely flammable), or other materials
that are capable of flushing and removing samples entirely from the U-tube. solvent known to be miscible with the sample material
without causing corrosion of the sample cell. Consult manufacturer’s information for details. (Warning—Petroleum naphtha is
extremely flammable.)
7.5 Acetone, or other highly volatile solvent for flushing and drying the U-tube. (Warning—Extremely flammable.)
7.6 Dry Air, for drying the U-tube.
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 capacity to mix
the sample and 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 aliquot obtained from the laboratory sample and delivered to the density
analyzer U-tube. The test specimen is obtained as follows:
8.3.1 Mix the sample if required to homogenize, taking care to avoid the introduction of air bubbles. 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 volatile material from certain sample types (for example, gasoline samples), so mixing in closed, pressurized
containers or at least 10 °C below ambient temperature is required for such sample types where loss of volatile material is a
potential concern. For some sample types, such as viscous lube oils that are prone to having entrained air or gas bubbles present
in the sample, the use of an ultrasonic bath (see 6.5) without the heater turned on (if so equipped), has been found effective in
dissipating bubbles typically within 10 min.
NOTE 2—When mixing samples with volatile components, consider the sample properties in relation to both ambient temperature and pressure.
8.3.2 For manual injections, draw the test specimen from a properly mixed laboratory sample using an appropriate syringe. If the
proper density analyzer attachments and connecting tubes are used, as described in 6.3, then the test specimen can be delivered
directly to the analyzer’s 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
measuring cell. For highly volatile samples, cool the sample prior to measurement. Follow the manufacturer’s instructions.
NOTE 3—Overfilled sample vials can result in cross-contamination between sample vials.
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 of the analyzer. Verify the instrument’s calibration at the same
temperature at which the density or relative density of the sample is to be measured or perform an adjustment (see
Suitable solvent naphthas are marketed under various designations such as “Petroleum Ether,” “Ligroine,” or “Precipitation Naphtha.”
D4052 − 22
3.2.1–Discussion) in preparation of analyzing samples. (Warning—Precise setting and control of the test temperature in the U-tube
is extremely important. An error of 0.1 °C can result in a change in density of one in the fourth decimal when measuring in units
of grams per millilitre.)
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. Whenever the apparatus fails a calibration verification without discernible cause, the apparatus must be
adjusted. See 3.2.1.
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 can 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) can 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.
10.3.1 The density of air varies with pressure and relative humidity (see Table 1). 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 can 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 can be calculated using this formula:
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 4—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
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.
Temperature, Density, g/mL Temperature, Density, Temperature, Density,
°C °C g/mL °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).
D4052 − 22
pressure data must be corrected back to site pressure, P. For correction of P to P:
SL
P=P 2 @Site Elevation ~meters!/82.3# (3)
SL
NOTE 5—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.
11. Quality Control Checks
11.1 Confirm the instrument is in statistical control at least once a week when it is in use, by analyzing a quality control (QC)
sample that is representative of samples typically analyzed. Analysis of a single QC sample can be sufficient. Analysis of QC
sample results can be carried out using control chart techniques. If the QC sample result determined causes the laboratory to be
in an out-of-control situation, such as exceeding the laboratory’s control limits, instrument adjustment is required. An ample supply
of QC sample material should be available for the intended period of use, and must be homogeneous and stable under the
anticipated storage conditions. Prior to monitoring the measurement process, the user of the method needs to determine the average
and control limits of the QC sample. The QC sample precision should be checked against the method precision to ensure data
quality.
11.2 Although not mandatory, it is recommended that periodic analyses of certified density standards (that is, traceable to national
standards) that are separate from those that may be used in adjusting the instrument, be used to confirm testing accuracy.
12. Procedure
12.1 Manual Injection:
12.1.1 Introduce a volume of about 1 mL to 2 mL, of sample into the clean, dry U-tube of the instrument using a suitable syringe
or alternative, as described in 6.3.
12.1.2 The sample can also be introduced by siphoning. Plug the external TFE-fluorocarbon capillary tube into the entry port of
the U-tube. Immerse the other end of the capillary in the sample and apply suction to the other port using a syringe or vacuum
line until the U-tube is properly filled (see Note 1).
12.1.3 Ensure that the U-tube is properly filled and that no gas bubbles are present. The sample must 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 U-tube, and recheck for gas bubbles.
NOTE 6—If the sample is too dark in color to determine the absence of bubbles with certainty, the density cannot be measured within the stated precision
limits of Section 15.
12.1.4 For most instrument models, it is recommended to turn the illumination light off with minimal delay after sample
introduction and checking for bubbles because the heat generated can affect the measurement temperature. For some models
however, the cell light may be left on without affecting results. Refer to the manufacturer’s recommendations concerning whether
to leave the illumination light off or on.
12.1.5 After the instrument displays a steady reading to four significant figures for density, relative density, or API Gravity, and
five for T-values, indicating that temperature equilibrium has been reached, record the density, relative density, API Gravity or
T-values, or both, as appropriate. For instruments that can print out results from the display, the print out can be used to meet the
recording requirements.
12.1.6 Based on the 1999 ILS testing protocols (see Note 9), precision determinations involving a single manual injection, as well
as taking the average of two
...