ASTM D4007-22

Standard Test Method for Water and Sediment in Crude Oil by the Centrifuge Method (Laboratory Procedure)

SIGNIFICANCE AND USE
5.1 The water and sediment content of crude oil is significant because it can cause corrosion of equipment and problems in processing. A determination of water and sediment content is required to measure accurately net volumes of actual oil in sales, taxation, exchanges, and custody transfers. It is not anticipated that this test method, which is written with a dedicated laboratory facility in mind, is likely to be used in field test rooms or sample rooms due to safety concerns for proper ventilation and handling.  
5.2 This test method may not be suitable for crude oils that contain alcohols that are soluble in water. In cases where the impact on the results may be significant, the user is advised to consider using another test method, such as Test Method D4928 (API MPMS Chapter 10.9).
SCOPE
1.1 This test method describes the laboratory determination of water and sediment in crude oils by means of the centrifuge procedure. This centrifuge method for determining water and sediment in crude oils is not entirely satisfactory. The amount of water detected is almost always lower than the actual water content. When a highly accurate value is required, the revised procedures for water by distillation, Test Method D4006 (API MPMS Chapter 10.2) (Note 1), and sediment by extraction, Test Method D473 (API MPMS Chapter 10.1), shall be used.  
Note 1: Test Method D4006 (API MPMS Chapter 10.2) has been determined to be the preferred and most accurate method for the determination of water.  
1.2 The values stated in SI units are to be regarded as standard.  
1.2.1 Exception—The values given in parentheses are for information only.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific warning statements appear in 7.1, 9.3, and A1.5.4.  
1.4 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-Sep-2022
• ICS: 75.040 - Crude petroleum
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.02 - Hydrocarbon Measurement for Custody Transfer (Joint ASTM-API)

Relations

• Refers: ASTM D4175-23a - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 15-Dec-2023
• Refers: ASTM D665-23 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 01-Dec-2023
• Refers: ASTM D4175-23e1 - Standard Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Jul-2023
• Refers: ASTM D665-19 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 01-Dec-2019
• Refers: ASTM E969-02(2019) - Standard Specification for Glass Volumetric (Transfer) Pipets
• Effective Date: 01-Jul-2019
• Refers: ASTM D665-14 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 01-Oct-2014
• Refers: ASTM D665-12 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 01-Nov-2012
• Refers: ASTM E969-02(2012) - Standard Specification for Glass Volumetric (Transfer) Pipets
• Effective Date: 01-Nov-2012
• Refers: ASTM E969-02(2007) - Standard Specification for Glass Volumetric (Transfer) Pipets
• Effective Date: 01-Nov-2007
• Refers: ASTM D665-06 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 01-May-2006
• Refers: ASTM D665-03 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 01-Nov-2003
• Refers: ASTM D665-02 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 10-Nov-2002
• Refers: ASTM E969-02 - Standard Specification for Glass Volumetric (Transfer) Pipets
• Effective Date: 10-Oct-2002
• Refers: ASTM D665-99 - Standard Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
• Effective Date: 10-Dec-1999
• Refers: ASTM E969-95(1999) - Standard Specification for Glass Volumetric (Transfer) Pipets
• Effective Date: 10-Dec-1999

Overview

ASTM D4007-22 is the internationally recognized standard test method for determining the amount of water and sediment in crude oil using the laboratory centrifuge method. Published by ASTM International, this method is essential for the petroleum industry to quantify impurities that directly affect processing, equipment integrity, and the financial aspects of oil sales, taxation, exchanges, and custody transfers. Proper measurement of water and sediment ensures accuracy in calculating net volumes of crude oil and helps prevent operational issues such as equipment corrosion and refining inefficiencies.

Key Topics

• Purpose and Significance

  • Accurately determines water and sediment content to reduce the risk of corrosion and equipment problems.
  • Supports net oil volume calculations for custody transfer, sales, and regulatory compliance.
  • Primarily designed for laboratory use; not intended for field or sample room application due to ventilation and safety requirements.

• Test Method Summary

  • Equal parts of crude oil and water-saturated toluene are placed in a cone-shaped centrifuge tube.
  • The mixture is centrifuged, and the volume of water and sediment settling at the bottom is measured visually.
  • Demulsifiers may be used to enhance phase separation.

• Precision and Limitations

  • The centrifuge method may yield slightly lower water values compared to actual content.
  • For highly accurate results, refer to complementary methods like ASTM D4006 (distillation) and ASTM D473 (extraction).
  • Not recommended for crude oils containing water-soluble alcohols, as results may be impacted.

• Safety and Compliance

  • Requires proper ventilation, handling of flammable and toxic solvents (primarily toluene), and adherence to laboratory safety protocols.
  • Users must establish safety, health, and environmental practices per regulatory requirements.

Applications

• Petroleum Production and Refining

  • Enables reliable quality control by quantifying undesirable water and solid contents prior to refining or further processing.
  • Prevents premature wear and unplanned downtime by identifying potential for corrosion in pipelines and equipment.

• Custody Transfer and Commerce

  • Used for verifying oil quality and quantity during sales transactions and exchanges.
  • Helps in meeting contractual and legal specifications for crude oil shipments, and in accurate taxation and royalty calculations.

• Regulatory and Environmental Compliance

  • Supports documentation needed to meet local and international regulations regarding crude oil specifications.

• Laboratory Quality Assurance

  • Ensures comparability and repeatability of test results across laboratories using standardized procedures.
  • Provides reference data for disputes or validation during oil custody transfer.

Related Standards

• ASTM D4006 - Test Method for Water in Crude Oil by Distillation; a more precise alternative for water determination.
• ASTM D473 - Test Method for Sediment in Crude Oils and Fuel Oils by Extraction.
• ASTM D4928 - Determination of Water in Crude Oils by Coulometric Karl Fischer Titration; applicable if alcohols are present.
• ASTM D1796 - Test Method for Water and Sediment in Fuel Oils by Centrifuge Method (Lab Procedure).
• ASTM D4057 and D4177 - Practices for Manual and Automatic Sampling of Petroleum and Petroleum Products.
• API MPMS Chapter 10.x series – Reference methods for measuring water and sediment content in petroleum products.

Summary

ASTM D4007-22 provides a standardized laboratory procedure for measuring water and sediment in crude oil using the centrifuge method. This method plays a critical role in the petroleum industry by safeguarding process integrity, ensuring fair commerce, and supporting accurate financial transactions. While highly valuable in routine quality control, users should be aware of its limitations and consider complementary methods for higher accuracy or specific sample characteristics. Compliance with related ASTM and API methods, as well as robust safety practices, ensures reliable and defendable results.

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: D4007 − 22
Manual of Petroleum Measurement Standards (MPMS), Chapter 10.3
Standard Test Method for
Water and Sediment in Crude Oil by the Centrifuge Method
(Laboratory Procedure)
This standard is issued under the fixed designation D4007; 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.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method describes the laboratory determination
D95Test Method for Water in Petroleum Products and
of water and sediment in crude oils by means of the centrifuge
BituminousMaterialsbyDistillation(API MPMSChapter
procedure. This centrifuge method for determining water and
10.5)
sediment in crude oils is not entirely satisfactory. The amount
D473TestMethodforSedimentinCrudeOilsandFuelOils
of water detected is almost always lower than the actual water
by the Extraction Method (API MPMS Chapter 10.1)
content. When a highly accurate value is required, the revised
D665Test Method for Rust-Preventing Characteristics of
procedures for water by distillation, Test Method D4006 (API
Inhibited Mineral Oil in the Presence of Water
MPMS Chapter 10.2) (Note 1), and sediment by extraction,
D1796Test Method for Water and Sediment in Fuel Oils by
Test Method D473 (API MPMS Chapter 10.1), shall be used.
the Centrifuge Method (Laboratory Procedure) (API
NOTE 1—Test Method D4006 (API MPMS Chapter 10.2) has been
MPMS Chapter 10.6)
determined to be the preferred and most accurate method for the
D4006Test Method for Water in Crude Oil by Distillation
determination of water.
(API MPMSChapter 10.2)
1.2 The values stated in SI units are to be regarded as
D4057Practice for Manual Sampling of Petroleum and
standard.
Petroleum Products (API MPMS Chapter 8.1)
1.2.1 Exception—The values given in parentheses are for
D4175Terminology Relating to Petroleum Products, Liquid
information only.
Fuels, and Lubricants
D4177Practice for Automatic Sampling of Petroleum and
1.3 This standard does not purport to address all of the
Petroleum Products (API MPMS Chapter 8.2)
safety concerns, if any, associated with its use. It is the
D4928Test Method forWater in Crude Oils by Coulometric
responsibility of the user of this standard to establish appro-
Karl Fischer Titration (API MPMS Chapter 10.9)
priate safety, health, and environmental practices and deter-
D5854Practice for Mixing and Handling of Liquid Samples
mine the applicability of regulatory limitations prior to use.
of Petroleum and Petroleum Products (API MPMS Chap-
Specific warning statements appear in 7.1, 9.3, and A1.5.4.
ter 8.3)
1.4 This international standard was developed in accor-
E969Specification for Glass Volumetric (Transfer) Pipets
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
2.2 API Standards:
Development of International Standards, Guides and Recom-
MPMS Chapter 1Terms and Definitions Database
mendations issued by the World Trade Organization Technical
MPMS Chapter 8.1Manual Sampling of Petroleum and
Barriers to Trade (TBT) Committee.
Petroleum Products (ASTM Practice D4057)
MPMS Chapter 8.2Automatic Sampling of Petroleum and
Petroleum Products (ASTM Practice D4177)
MPMSChapter8.3MixingandHandlingofLiquidSamples
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and the API Committee on
Petroleum Measurement and is the direct responsibility of Subcommittee D02.02
/COMQ the joint ASTM-API Committee on Hydrocarbon Measurement for
Custody Transfer (Joint ASTM-API). This test method has been approved by the For referenced ASTM standards, visit the ASTM website, www.astm.org, or
sponsoring committees and accepted by the Cooperating Societies in accordance contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
with established procedures. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Oct. 1, 2022. Published December 2022. Originally the ASTM website.
ɛ1 3
approved in 1981. Last previous edition approved in 2016 as D4007–11 (2016) . Available from American Petroleum Institute (API), 1220 L. St., NW,
DOI: 10.1520/D4007-22. Washington, DC 20005-4070, www.api.org.
*A Summary of Changes section appears at the end of this standard
© Jointly copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA and the American Petroleum Institute (API), 1220 L Street NW, Washington DC 20005, USA
D4007 − 22
of Petroleum and Petroleum Products (ASTM Practice 6. Apparatus
D5854)
6.1 Centrifuge:
MPMS Chapter 10.1Determination of Sediment in Crude
6.1.1 A centrifuge capable of spinning two or more filled
Oils and Fuel Oils by the Extraction Method (ASTMTest
cone-shaped, 203mm (8in.) centrifuge tubes at a speed that
Method D473)
can be controlled to give a relative centrifugal force (rcf) of a
MPMSChapter10.2DeterminationofWaterinCrudeOilby
minimumof600atthetipofthetubesshallbeused(see6.1.6).
Distillation (ASTM Test Method D4006)
6.1.2 Therevolvinghead,trunnionrings,andtrunnioncups,
MPMS Chapter 10.4Determination of Sediment and Water
including the cushions, shall be soundly constructed to with-
in Crude Oil by the Centrifuge Method (Field Procedure)
stand the maximum centrifugal force capable of being deliv-
MPMS Chapter 10.5Determination of Water in Petroleum
eredbythepowersource.Thetrunnioncupsandcushionsshall
Products and Bituminous Materials by Distillation
firmly support the tubes when the centrifuge is in motion. The
(ASTM Test Method D95)
centrifuge shall be enclosed by a metal shield or case strong
MPMS Chapter 10.6Determination of Water and Sediment
enough to eliminate danger if any breakage occurs.
in Fuel Oils by the Centrifuge Method (Laboratory Pro-
6.1.3 The centrifuge shall be heated and controlled thermo-
cedures) (ASTM Test Method D1796)
statically to avoid unsafe conditions. It shall be capable of
MPMSChapter10.9TestMethodforWaterinCrudeOilsby
maintaining the sample temperature during the entire run at
Coulometric Karl Fischer Titration (ASTM Test Method
60°C 6 3°C (140°F 6 5°F). The thermostatic control shall
D4928)
be capable of maintaining the temperature within these limits
2.3 IP Standard:
and operate safely if there is a flammable atmosphere.
Methods Book, Appendix BSpecification for Methylben-
6.1.4 Electricpoweredandheatedcentrifugesmustmeetall
zenes (Toluenes)
safety requirements for use in hazardous areas.
6.1.5 Calculate the necessary minimum speed of the rotat-
2.4 ISO Standard:
ing head in revolutions per minute (r/min) as follows:
ISO 5272:1979Toluene for Industrial Use—Specifications
r/min 51335 =rcf/d (1)
3. Terminology
where:
3.1 Definitions:
rcf = relative centrifugal force and
3.1.1 For definitions of terms used in this test method, refer
d = diameter of swing measured between tips of opposite
to Terminology D4175 and the API MPMS Chapter 1 Terms
tubes when in rotating position, mm, or
and Definitions Database.
r/min 5265 =rcf/d (2)
4. Summary of Test Method
where:
4.1 Equal volumes of crude oil and water-saturated toluene
rcf = relative centrifugal force and
are placed into a cone-shaped centrifuge tube. After
d = diameter of swing measured between tips of opposite
centrifugation, the volume of the higher density water and
tubes when in rotating position, in.
sediment layer at the bottom of the tube is read.
6.1.6 Calculate the relative centrifugal force from a mea-
5. Significance and Use sured speed (r/min) as follows:
5.1 The water and sediment content of crude oil is signifi- r/min
rcf 5 d (3)
S D
cantbecauseitcancausecorrosionofequipmentandproblems 1335
inprocessing.Adeterminationofwaterandsedimentcontentis
where:
required to measure accurately net volumes of actual oil in
d = diameter of swing measured between tips of opposite
sales, taxation, exchanges, and custody transfers. It is not
tubes when in rotating position, mm, or
anticipated that this test method, which is written with a
dedicated laboratory facility in mind, is likely to be used in r/min
rcf 5 d (4)
S D
field test rooms or sample rooms due to safety concerns for 265
proper ventilation and handling.
where:
5.2 This test method may not be suitable for crude oils that
d = diameter of swing measured between tips of opposite
contain alcohols that are soluble in water. In cases where the
tubes when in rotating position, in.
impact on the results may be significant, the user is advised to
6.2 Centrifuge Tubes—Each centrifuge tube shall be a
consider using another test method, such as Test Method
203mm (8in.) cone-shaped tube, conforming to dimensions
D4928 (API MPMS Chapter 10.9).
given in Fig. 1 and made of thoroughly annealed glass. The
graduations, numbered as shown in Fig. 1, shall be clear and
distinct,andthemouthshallbeconstrictedinshapeforclosure
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
withacork.Scaleerrortolerancesandthesmallestgraduations
U.K., http://www.energyinst.org.uk.
between various calibration marks are given in Table 1 and
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. applytocalibrationsmadewithair-freewaterat20°C(68°F),
D4007 − 22
6.4 50 mL Pipet, Class A, or equivalent volume dispensing
device, capable of delivering a volume of 50mL 6 0.05mL
(see Specification E969) for use in the test.
7. Solvent
7.1 Toluene—Reagent grade conforming to the specifica-
tionsoftheCommitteeonAnalyticalReagentsoftheAmerican
Chemical Society (ACS) or to Grade 2 of ISO 5272 or
conforming to the EI Specification for Methylbenzenes (Tolu-
enes). (Warning—Flammable. Keep away from heat, sparks,
and open flame. Vapor harmful. Toluene is toxic. Particular
care must be taken to avoid breathing the vapor and to protect
theeyes.Keepcontainerclosed.Usewithadequateventilation.
Avoid prolonged or repeated contact with the skin.)
7.1.1 Typical characteristics for this reagent are:
Assay 99.5+ %
Color (APHA) 10
Boiling range (initial to dry point) 2.0 °C
(Recorded boiling point 110.6°C)
Residue after evaporation 0.001 % max – wt/wt
Substances darkened by H SO passes test
2 4
Sulfur compounds (as S) 0.003 % max – wt/wt
Water (H O) (by Karl Fischer titration) 0.03 % max – wt/wt
7.1.2 The solvent shall be water-saturated at 60°C 63°C
(140°F 6 5°F) (see 6.3) but shall be free of suspended water.
See Annex A1 for the solvent-water saturation procedure.
7.2 Demulsifier—A demulsifier should be used to promote
the separation of water from the sample and to prevent its
clinging to the walls of the centrifuge tube.The recommended
FIG. 1 Eight-Inch (203 mm) Centrifuge Tube
stock solution is 25% demulsifier to 75% toluene. For some
crude oils a different ratio of demulsifier to toluene may be
TABLE 1 Centrifuge Tube Calibration Tolerances
required. Demulsifiers used in the concentration and quantity
for 203 mm (8 in.) Tube
recommended will not add to the water and sediment volume
Range, mL Subdivision, mL Volume Tolerance, mL
determined.The solution must be stored in a dark bottle that is
0 to 0.1 0.05 ±0.02
Above 0.1 to 0.3 0.05 ±0.03 tightly closed.
Above 0.3 to 0.5 0.05 ±0.05
Above 0.5 to 1.0 0.10 ±0.05
8. Sampling
Above 1.0 to 2.0 0.10 ±0.10
Above 2.0 to 3.0 0.20 ±0.10
8.1 Sampling is defined as all steps required to obtain an
Above 3.0 to 5.0 0.5 ±0.20
Above 5.0 to 10 1.0 ±0.50 aliquotofthecontentsofanypipe,tank,orothersystemandto
Above 10 to 25 5.0 ±1.00
place the sample into the laboratory test container.
Above 25 to 100 25.0 ±1.00
8.2 Only representative samples obtained as specified in
PracticesD4057(API MPMSChapter8.1)andPracticeD4177
(API MPMS Chapter 8.2) shall be used for this test method.
whenreadingthebottomoftheshadedmeniscus.Theaccuracy
of the graduations on the centrifuge tube shall be volumetri-
8.3 Sample Mixing—is typically required to obtain a test
cally verified, before use of the tube. The verification shall portion representative of the bulk sample to be tested, but
include calibration at each mark up to the 0.25mL mark (as
precautions shall be taken to maintain the integrity of the
shown in Fig. 2), and at the 0.5mL, 1.0mL, 1.5mL, 2.0mL, sample during this operation. Mixing of volatile crude petro-
50.0mL, and 100mLmarks. The tube shall not be used if the
leum containing water or sediments, or both, may result in the
scale error at any mark exceeds the applicable tolerance from lossoflightcomponents.Additionalinformationonthemixing
Table 1.
andhandlingofliquidsamplescanbefoundinPracticeD5854
(API MPMS Chapter 8.3).
6.3 Bath—The bath shall be either a solid metal block bath
oraliquidbathofsufficientdepthforimmersingthecentrifuge
tube in the vertical position to the 100mL mark. Means shall
be provided for maintaining the temperature at 60°C 63°C
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington,
(140°F 65°F).Forsomecrudeoils,temperaturesof71°C 6
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
3°C (160°F 6 5°F) may be required to melt wax crystals in
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
crude oils. For these crude oils, the test temperature shall be
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
maintained high enough to ensure the absence of wax crystals. copeial Convention, Inc. (USPC), Rockville, MD.
D4007 − 22
FIG. 2 Procedure for Reading Water and Sediment When Using an ASTM 100-mm Cone-Shaped Centrifuge Tube
D4007 − 22
9. Procedure one subdivision on the centrifuge tube (see Table 1)or
0.025mLfor readings of 0.10mLand below, the readings are
9.1 Filleachoftwocentrifugetubes(6.2)tothe50mLmark
inadmissible and the determination shall be repeated.
with sample directly from the sample container. Using a pipet
orothersuitablevolumetransferdevice(see6.4),add50mL 6 10.2 Express the sum of the two admissible readings as the
0.05mL of toluene, which has been water saturated at 60°C percentagebyvolumeofwaterandsediment;reporttheresults
(140°F) or 71°C (160°F) (see 6.3). Read the top of the as shown in Table 2.
meniscusatboththe50mLand100mLmarks.Add0.2mLof
11. Precision and Bias
demulsifier solution (7.2) to each tube, using a 0.2mLpipet or
11.1 Precision—The precision of this test method, as deter-
other suitable volume transfer device, such as an automatic
mined by statistical examination of interlaboratory test results
pipettor. Stopper the tube tightly and invert the tubes ten times
in the range from 0.01% to 1.0%, is described in 11.1.1 and
to ensure that the oil and solvent are uniformly mixed.
11.1.2.
9.2 In the case where the crude oil is very viscous and
11.1.1 Repeatability—The difference between two test
mixingofthesolventwiththeoilwouldbedifficult,thesolvent
results, obtained by the same operator with the same apparatus
may be added to the centrifuge tube first to facilitate mixing.
under constant operating conditions on identical test material,
Take care to not fill the centrifuge tube past the 100mL mark
would, in the long run, in the normal and correct operation of
with the sample.
thetestmethod,exceedthefollowingvalueinonlyonecasein
9.3 Loosen the stoppers slightly and immerse the tubes to
twenty:
the 100mL mark for at least 15min in the bath maintained at
60°C 6 3°C (140°F 6 5°F) (see 6.3). Secure the stoppers
From 0.0% to 0.3% water, see Fig. 3.
and again invert the tubes ten times to ensure uniform mixing
From 0.3% to 1.0% water, repeatability is constant at 0.12.
of oil and solvent. (Warning—The vapor pressure at 60°C
(140°F) is approximately double that at 40°C (104°F).)
11.1.2 Reproducibility—The difference between two single
and independent test results obtained by different operators
9.4 Placethetubesinthetrunnioncupsonoppositesidesof
working in different laboratories on identical test material,
the centrifuge to establish a balanced condition. (If the tubes
would, in the long run, in the normal and correct operation of
cannot be counter-balanced by eye, place them, in their
thetestmethod,exceedthefollowingvalueinonlyonecasein
trunnion cups, on either side of a balance and equalize their
twenty:
masses by the addition of water to the trunnion cups.) Re-
tighten the corks and spin for 10 min at a minimum relative
From 0.0% to 0.3% water, see Fig. 3.
centrifugal force of 600 calculated from the equation given in
From 0.3% to 1.0% water, reproducibility is constant at
6.1.6.
0.28.
9.5 Immediatelyafterthecentrifugecomestorestfollowing
the spin, read and record the combined volume of water and
11.2 Bias—The procedure in this test method has no bias
sediment at the bottom of each tube, to the nearest 0.05mL
becausethevalueofwaterandsedimentcanbedefinedonlyin
from 0.1mL to 1mL graduations, and to the nearest 0.1mL
terms of a test method.
above1mLgraduations.Below0.1mL,estimatetothenearest
0.025mL(refertoFig.2).Returnthetubeswithoutagitationto
12. Keywords
the centrifuge and spin for another 10min at the same rate.
12.1 centrifuge; centrifuge tube; crude oil; laboratory pro-
9.6 Repeat this operation until the combined volume of
cedure; sampling; sediment and water; solvent
water and sediment remains constant for two consecutive
readings.Ingeneral,notmorethantwospinningsarerequired.
TABLE 2 Expression of Results, mL
Total Percent Water and
9.7 The temperature of the sample during the entire centri-
Tube 1 Tube 2
Sediment, % (V/V)
fuging procedure shall be maintained at 60°C 6 3°C (140°F
No visible water and No visible water and 0.00
6 5°F) (see 6.3).
sediment sediment
No visible water and 0.025 0.025
9.8 To avoid the danger of tubes breaking in the cups, care
sediment
must be taken that the tubes are bedded onto the bottom
0.025 0.025 0.05
cushion so that no part of the tube is in contact with the rim of 0.025 0.05 0.075
0.05 0.05 0.10
the cup.
0.05 0.075 0.125
0.075 0.075 0.15
10. Calculation
0.075 0.10 0.175
0.10 0.10 0.20
10.1 Record the final volume of water and sediment in each
0.10 0.15 0.25
tube. If the difference between the two readings is greater than
D4007 − 22
FIG. 3 Basic Sediment and Water Precision
ANNEX
(Mandatory Information)
A1. PROCEDURE TO WATER-SATURATE TOLUENE
A1.1 Scope A1.2 Significance
A1.1.1 This method is satisfactory for the water saturation A1.2.1 Fig.A1.1 shows that water is soluble in toluene to a
of toluene to be used for determination of water and sediment significant extent. The percentage of water that will dissolve
in crude oils by the centrifuge method. increases as the temperature is increased from about 0.03% at
FIG. A1.1 Solubility of Water in Toluene
D4007 − 22
21°C (70°F) to about 0.17% at 70°C (158°F). Toluene, as A1.5.2 Fill the glass bottle with 700mL to 800mL of
normally supplied, is relatively dry and if used in an as- toluene.Add sufficient water (at least 2mL but not more than
receivedcondition,willdissolveaportionoforevenallofany
25mL) to maintain a visual indication of excess water. Screw
water present in a crude oil sample. This would reduce the
the cap on the bottle and shake vigorously for 30s.
apparent sediment and water level in the crude sample. To
A1.5.3 Loosen the cap and place the bottle in the bath for
determine water and sediment accurately by centrifuge on a
30min. Remove the bottle, tighten the cap, and shake cau-
crude oil sample, the toluene must first be saturated at the
tiously for 30s.
centrifuge test temperature.
A1.5.4 Repeat the above procedure (A1.5.3) 3 times.
A1.3 Reagents
(Warning—Thevaporpressureoftolueneat60°C(140°F)is
A1.3.1 Toluene—Reagent grade conforming to the specifi-
approximately twice that at 38°C (100°F).)
cations of the Committee on Analytical Reagents of the
A1.5.5 Allow the bottle with the water-toluene mixture to
American Chemical Society (ACS) or to Grade 2 of ISO
5272, or conforming to the EI Specification for Methylben- sit in the bath 48h before using. This will ensure complete
zenes (Toluenes).
equilibrium between the toluene and the free water as well as
complete saturation at the desired temperature. If it is neces-
A1.3.2 Water, either distilled or tap water.
sary to use the water-saturated toluene before the 48h equili-
A1.4 Apparatus
bration time has been completed, the solvent must be poured
into centrifuge tubes and centrifuged in the same equipment at
A1.4.1 Liquid-Heating Bath,ofsufficientdepthforimmers-
the same relative centrifuge force and temperature that is used
inga1qtor1Lbottletoitsshoulder.Meansshallbeprovided
for the centrifuge test. The toluene must be carefully pipetted
for maintaining the temperature at 60°C 6 3°C (140°F 6
5°F) (see 6.3). from the centrifuge tube so that any free water that may be in
the bottom of the tube is not disturbed.
A1.4.2 Glass Bottle, 1qt or 1L, with screw top.
A1.5.6 Saturation is time- and temperature-dependent. It is
A1.5 Procedure
recommendedthatbottlesof
...

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.
´1
Designation: D4007 − 11 (Reapproved 2016) D4007 − 22
Manual of Petroleum Measurement Standards (MPMS), Chapter 10.3
Standard Test Method for
Water and Sediment in Crude Oil by the Centrifuge Method
(Laboratory Procedure)
This standard is issued under the fixed designation D4007; 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.
ε NOTE—Subsection X1.3.3.2 was revised editorially in November 2016.
1. Scope Scope*
1.1 This test method describes the laboratory determination of water and sediment in crude oils by means of the centrifuge
procedure. This centrifuge method for determining water and sediment in crude oils is not entirely satisfactory. The amount of
water detected is almost always lower than the actual water content. When a highly accurate value is required, the revised
procedures for water by distillation, Test Method D4006 (API MPMS Chapter 10.2) (Note 1), and sediment by extraction, Test
Method D473 (API MPMS Chapter 10.1), shall be used.
NOTE 1—Test Method D4006 (API MPMS Chapter 10.2) has been determined to be the preferred and most accurate method for the determination of water.
1.2 The values stated in SI units are to be regarded as standard.
1.2.1 Exception—The values given in parentheses are for information only.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific warning statements appear in 6.17.1, 8.39.3, and A1.5.4.
1.4 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:
D95 Test Method for Water in Petroleum Products and Bituminous Materials by Distillation (API MPMS Chapter 10.5)
D473 Test Method for Sediment in Crude Oils and Fuel Oils by the Extraction Method (API MPMS Chapter 10.1)
D665 Test Method for Rust-Preventing Characteristics of Inhibited Mineral Oil in the Presence of Water
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and the API Committee on Petroleum
Measurement and is the direct responsibility of Subcommittee D02.02 /COMQ the joint ASTM-API Committee on Hydrocarbon Measurement for Custody Transfer (Joint
ASTM-API). This test method has been approved by the sponsoring committees and accepted by the Cooperating Societies in accordance with established procedures.
Current edition approved June 1, 2016Oct. 1, 2022. Published July 2016December 2022. Originally approved in 1981. Last previous edition approved in 20112016 as
ɛ1
D4007 – 11 (2016) . DOI: 10.1520/D4007-11R16E01.10.1520/D4007-22.
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.
*A Summary of Changes section appears at the end of this standard
© Jointly copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, USA and the American Petroleum Institute (API), 1220 L Street NW, Washington DC 20005, USA
D4007 − 22
D1796 Test Method for Water and Sediment in Fuel Oils by the Centrifuge Method (Laboratory Procedure) (API MPMS Chapter
10.6)
D4006 Test Method for Water in Crude Oil by Distillation (API MPMSChapter 10.2)
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products (API MPMS Chapter 8.1)
D4175 Terminology Relating to Petroleum Products, Liquid Fuels, and Lubricants
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products (API MPMS Chapter 8.2)
D4928 Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration (API MPMS Chapter 10.9)
D5854 Practice for Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products (API MPMS Chapter 8.3)
E969 Specification for Glass Volumetric (Transfer) Pipets
2.2 API Standards:
MPMS Chapter 1 Terms and Definitions Database
MPMS Chapter 8.1 Manual Sampling of Petroleum and Petroleum Products (ASTM Practice D4057)
MPMS Chapter 8.2 Automatic Sampling of Petroleum and Petroleum Products (ASTM Practice D4177)
MPMS Chapter 8.3 Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products (ASTM Practice D5854)
MPMS Chapter 10.1 Determination of Sediment in Crude Oils and Fuel Oils by the Extraction Method (ASTM Test Method
D473)
MPMS Chapter 10.2 Determination of Water in Crude Oil by Distillation (ASTM Test Method D4006)
MPMS Chapter 10.4 Determination of Sediment and Water in Crude Oil by the Centrifuge Method (Field Procedure)
MPMS Chapter 10.5 Determination of Water in Petroleum Products and Bituminous Materials by Distillation (ASTM Test
Method D95)
MPMS Chapter 10.6 Determination of Water and Sediment in Fuel Oils by the Centrifuge Method (Laboratory Procedures)
(ASTM Test Method D1796)
MPMS Chapter 10.9 Test Method for Water in Crude Oils by Coulometric Karl Fischer Titration (ASTM Test Method D4928)
2.3 IP Standard:
Methods Book, Appendix B Specification for Methylbenzenes (Toluenes)
2.4 ISO Standard:
ISO 5272:1979 Toluene for Industrial Use—Specifications
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology D4175 and the API MPMS Chapter 1 Terms and
Definitions Database.
4. Summary of Test Method
4.1 Equal volumes of crude oil and water-saturated toluene are placed into a cone-shaped centrifuge tube. After centrifugation,
the volume of the higher density water and sediment layer at the bottom of the tube is read.
5. Significance and Use
5.1 The water and sediment content of crude oil is significant because it can cause corrosion of equipment and problems in
processing. A determination of water and sediment content is required to measure accurately net volumes of actual oil in sales,
taxation, exchanges, and custody transfers. It is not anticipated that this test method, which is written with a dedicated laboratory
facility in mind, is likely to be used in field test rooms or sample rooms due to safety concerns for proper ventilation and handling.
5.2 This test method may not be suitable for crude oils that contain alcohols that are soluble in water. In cases where the impact
on the results may be significant, the user is advised to consider using another test method, such as Test Method D4928 (API MPMS
Chapter 10.9).
6. Apparatus
6.1 Centrifuge:
Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, www.api.org.
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.uk.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
D4007 − 22
6.1.1 A centrifuge capable of spinning two or more filled cone-shaped, 203 mm (8 in.) centrifuge tubes at a speed that can be
controlled to give a relative centrifugal force (rcf) of a minimum of 600 at the tip of the tubes shall be used (see 5.1.66.1.6).
6.1.2 The revolving head, trunnion rings, and trunnion cups, including the cushions, shall be soundly constructed to withstand the
maximum centrifugal force capable of being delivered by the power source. The trunnion cups and cushions shall firmly support
the tubes when the centrifuge is in motion. The centrifuge shall be enclosed by a metal shield or case strong enough to eliminate
danger if any breakage occurs.
6.1.3 The centrifuge shall be heated and controlled thermostatically to avoid unsafe conditions. It shall be capable of maintaining
the sample temperature during the entire run at 60 °C 6 3 °C (140 °F 6 5 °F). The thermostatic control shall be capable of
maintaining the temperature within these limits and operate safely if there is a flammable atmosphere.
6.1.4 Electric powered and heated centrifuges must meet all safety requirements for use in hazardous areas.
6.1.5 Calculate the necessary minimum speed of the rotating head in revolutions per minute (r/min) as follows:
r/min 5 1335 =rcf/d (1)
where:
rcf = relative centrifugal force and
d = diameter of swing measured between tips of opposite tubes when in rotating position, mm, or
r/min 5 265 =rcf/d (2)
where:
rcf = relative centrifugal force and
d = diameter of swing measured between tips of opposite tubes when in rotating position, in.
6.1.6 Calculate the relative centrifugal force from a measured speed (r/min) as follows:
r/min
rcf 5 d (3)
S D
where:
d = diameter of swing measured between tips of opposite tubes when in rotating position, mm, or
r/min
rcf 5 d (4)
S D
where:
d = diameter of swing measured between tips of opposite tubes when in rotating position, in.
6.2 Centrifuge Tubes—Each centrifuge tube shall be a 203 mm (8 in.) cone-shaped tube, conforming to dimensions given in Fig.
1 and made of thoroughly annealed glass. The graduations, numbered as shown in Fig. 1, shall be clear and distinct, and the mouth
shall be constricted in shape for closure with a cork. Scale error tolerances and the smallest graduations between various calibration
marks are given in Table 1 and apply to calibrations made with air-free water at 20 °C (68 °F), when reading the bottom of the
shaded meniscus. The accuracy of the graduations on the centrifuge tube shall be volumetrically verified, before use of the tube.
The verification shall include calibration at each mark up to the 0.25 mL mark (as shown in Fig. 2), and at the 0.5 mL, 1.0 mL,
1.5 mL, 2.0 mL, 50.0 mL, and 100 mL marks. The tube shall not be used if the scale error at any mark exceeds the applicable
tolerance from Table 1.
6.3 Bath—The bath shall be either a solid metal block bath or a liquid bath of sufficient depth for immersing the centrifuge tube
in the vertical position to the 100 mL mark. Means shall be provided for maintaining the temperature at 60 °C 6 3 °C (140 °F 6
5 °F). For some crude oils, temperatures of 71 °C 6 3 °C (160 °F 6 5 °F) may be required to melt wax crystals in crude oils. For
these crude oils, the test temperature shall be maintained high enough to ensure the absence of wax crystals.
D4007 − 22
FIG. 1 Eight-Inch (203 mm) Centrifuge Tube
TABLE 1 Centrifuge Tube Calibration Tolerances
for 203 mm (8 in.) Tube
Range, mL Subdivision, mL Volume Tolerance, mL
0 to 0.1 0.05 ±0.02
Above 0.1 to 0.3 0.05 ±0.03
Above 0.3 to 0.5 0.05 ±0.05
Above 0.5 to 1.0 0.10 ±0.05
Above 1.0 to 2.0 0.10 ±0.10
Above 2.0 to 3.0 0.20 ±0.10
Above 3.0 to 5.0 0.5 ±0.20
Above 5.0 to 10 1.0 ±0.50
Above 10 to 25 5.0 ±1.00
Above 25 to 100 25.0 ±1.00
6.4 50 mL Pipet, Class A, or equivalent volume dispensing device, capable of delivering a volume of 50 mL 6 0.05 mL (see
Specification E969) for use in the test.
7. Solvent
7.1 Toluene—Reagent grade conforming to the specifications of the Committee on Analytical Reagents of the American Chemical
Society (ACS) or to Grade 2 of ISO 5272 or conforming to the EI Specification for Methylbenzenes (Toluenes). (Warning—
Flammable. Keep away from heat, sparks, and open flame. Vapor harmful. Toluene is toxic. Particular care must be taken to avoid
breathing the vapor and to protect the eyes. Keep container closed. Use with adequate ventilation. Avoid prolonged or repeated
contact with the skin.)
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.
D4007 − 22
FIG. 2 Procedure for Reading Water and Sediment When Using an ASTM 100-mm Cone-Shaped Centrifuge Tube
D4007 − 22
7.1.1 Typical characteristics for this reagent are:
Assay 99.5+ %
Color (APHA) 10
Boiling range (initial to dry point) 2.0 °C
(Recorded boiling point 110.6°C)
Residue after evaporation 0.001 % max – wt/wt
Substances darkened by H SO passes test
2 4
Sulfur compounds (as S) 0.003 % max – wt/wt
Water (H O) (by Karl Fischer titration) 0.03 % max – wt/wt
7.1.2 The solvent shall be water-saturated at 60 °C 6 3 °C (140 °F 6 5 °F) (see 5.36.3) but shall be free of suspended water. See
Annex A1 for the solvent-water saturation procedure.
7.2 Demulsifier—A demulsifier should be used to promote the separation of water from the sample and to prevent its clinging to
the walls of the centrifuge tube. The recommended stock solution is 25 % demulsifier to 75 % toluene. For some crude oils a
different ratio of demulsifier to toluene may be required. Demulsifiers used in the concentration and quantity recommended will
not add to the water and sediment volume determined. The solution must be stored in a dark bottle that is tightly closed.
8. Sampling
8.1 Sampling is defined as all 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.
8.2 Only representative samples obtained as specified in Practices D4057 (API MPMS Chapter 8.1) and Practice D4177 (API
MPMS Chapter 8.2) shall be used for this test method.
8.3 Sample Mixing—is typically required to obtain a test portion representative of the bulk sample to be tested, but precautions
shall be taken to maintain the integrity of the sample during this operation. Mixing of volatile crude petroleum containing water
or sediments, or both, may result in the loss of light components. Additional information on the mixing and handling of liquid
samples can be found in Practice D5854 (API MPMS Chapter 8.3).
9. Procedure
9.1 Fill each of two centrifuge tubes (5.26.2) to the 50 mL mark with sample directly from the sample container. Using a pipet
or other suitable volume transfer device (see 5.46.4), add 50 mL 6 0.05 mL of toluene, which has been water saturated at 60 °C
(140 °F) or 71 °C (160 °F) (see 5.36.3). Read the top of the meniscus at both the 50 mL and 100 mL marks. Add 0.2 mL of
demulsifier solution (6.27.2) to each tube, using a 0.2 mL pipet or other suitable volume transfer device, such as an automatic
pipettor. Stopper the tube tightly and invert the tubes ten times to ensure that the oil and solvent are uniformly mixed.
9.2 In the case where the crude oil is very viscous and mixing of the solvent with the oil would be difficult, the solvent may be
added to the centrifuge tube first to facilitate mixing. Take care to not fill the centrifuge tube past the 100 mL mark with the sample.
9.3 Loosen the stoppers slightly and immerse the tubes to the 100 mL mark for at least 15 min in the bath maintained at 60 °C
6 3 °C (140 °F 6 5 °F) (see 5.36.3). Secure the stoppers and again invert the tubes ten times to ensure uniform mixing of oil and
solvent. (Warning—The vapor pressure at 60 °C (140 °F) is approximately double that at 40 °C (104 °F).)
9.4 Place the tubes in the trunnion cups on opposite sides of the centrifuge to establish a balanced condition. (If the tubes cannot
be counter-balanced by eye, place them, in their trunnion cups, on either side of a balance and equalize their masses by the addition
of water to the trunnion cups.) Retighten the corks and spin for 10 min at a minimum relative centrifugal force of 600 calculated
from the equation given in 5.1.66.1.6.
9.5 Immediately after the centrifuge comes to rest following the spin, read and record the combined volume of water and sediment
at the bottom of each tube, to the nearest 0.05 mL from 0.1 mL to 1 mL graduations, and to the nearest 0.1 mL above 1 mL
graduations. Below 0.1 mL, estimate to the nearest 0.025 mL (refer to Fig. 2). Return the tubes without agitation to the centrifuge
and spin for another 10 min at the same rate.
D4007 − 22
9.6 Repeat this operation until the combined volume of water and sediment remains constant for two consecutive readings. In
general, not more than two spinnings are required.
9.7 The temperature of the sample during the entire centrifuging procedure shall be maintained at 60 °C 6 3 °C (140 °F 6 5 °F)
(see 5.36.3).
9.8 To avoid the danger of tubes breaking in the cups, care must be taken that the tubes are bedded onto the bottom cushion so
that no part of the tube is in contact with the rim of the cup.
10. Calculation
10.1 Record the final volume of water and sediment in each tube. If the difference between the two readings is greater than one
subdivision on the centrifuge tube (see Table 1) or 0.025 mL for readings of 0.10 mL and below, the readings are inadmissible and
the determination shall be repeated.
10.2 Express the sum of the two admissible readings as the percentage by volume of water and sediment; report the results as
shown in Table 2.
11. Precision and Bias
11.1 Precision—The precision of this test method, as determined by statistical examination of interlaboratory test results in the
range from 0.01 % to 1.0 %, is described in 10.1.111.1.1 and 10.1.211.1.2.
11.1.1 Repeatability—The difference between two test results, obtained by the same operator with the same apparatus under
constant operating conditions on identical test material, would, in the long run, in the normal and correct operation of the test
method, exceed the following value in only one case in twenty:
From 0.0 % to 0.3 % water, see Fig. 3.
From 0.3 % to 1.0 % water, repeatability is constant at 0.12.
11.1.2 Reproducibility—The difference between two single and independent test results obtained by different operators working
in different laboratories on identical test material, would, in the long run, in the normal and correct operation of the test method,
exceed the following value in only one case in twenty:
From 0.0 % to 0.3 % water, see Fig. 3.
From 0.3 % to 1.0 % water, reproducibility is constant at 0.28.
11.2 Bias—The procedure in this test method has no bias because the value of water and sediment can be defined only in terms
of a test method.
TABLE 2 Expression of Results, mL
Total Percent Water and
Tube 1 Tube 2
Sediment, % (V/V)
No visible water and No visible water and 0.00
sediment sediment
No visible water and 0.025 0.025
sediment
0.025 0.025 0.05
0.025 0.05 0.075
0.05 0.05 0.10
0.05 0.075 0.125
0.075 0.075 0.15
0.075 0.10 0.175
0.10 0.10 0.20
0.10 0.15 0.25
D4007 − 22
FIG. 3 Basic Sediment and Water Precision
12. Keywords
12.1 centrifuge; centrifuge tube; crude oil; laboratory procedure; sampling; sediment and water; solvent
ANNEX
(Mandatory Information)
A1. PROCEDURE TO WATER-SATURATE TOLUENE
A1.1 Scope
A1.1.1 This method is satisfactory for the water saturation of toluene to be used for determination of water and sediment in crude
oils by the centrifuge method.
A1.2 Significance
A1.2.1 Fig. A1.1 shows that water is soluble in toluene to a significant extent. The percentage of water that will dissolve increases
as the temperature is increased from about 0.03 % at 21 °C (70 °F) to about 0.17 % at 70 °C (158 °F). Toluene, as normally
supplied, is relatively dry and if used in an as-received condition, will dissolve a portion of or even all of any water present in a
crude oil sample. This would reduce the apparent sediment and water level in the crude sample. To determine water and sediment
accurately by centrifuge on a crude oil sample, the toluene must first be saturated at the centrifuge test temperature.
A1.3 Reagents
A1.3.1 Toluene—Reagent grade conforming to the specifications of the Committee on Analytical Reagents of the American
Chemical Society (ACS) or to Grade 2 of ISO 5272, or conforming to the EI Specification for Methylbenzenes (Toluenes).
D4007 − 22
FIG. A1.1 Solubility of Water in Toluene
A1.3.2 Water, either distilled or tap water.
A1.4 Apparatus
A1.4.1 Liquid-Heating Bath, of sufficient depth for immersing a 1 qt or 1 L bottle to its shoulder. Means shall be provided for
maintaining the temperature at 60 °C 6 3 °C (140 °F 6 5 °F) (see 5.36.3).
A1.4.2 Glass Bottle, 1 qt or 1 L, with screw top.
A1.5 Procedure
A1.5.1 Adjust the heating bath to the temperature at which the centrifuge test is to be run. Maintain the bath temperature to 63 °C
(65 °F).
A1.5.2 Fill the glass bottle with 700 mL to 800 mL of toluene. Add sufficient water (at least 2 mL but not more than 25 mL) to
maintain a visual indication of excess water. Screw the cap on the bottle and shake vigorously for 30 s.
A1.5.3 Loosen the cap and place the bottle in the bath for 30 min. Remove the bottle, tighten the cap, and shake cautiously for
30 s.
D4007 − 22
A1.5.4 Repeat the above procedure (A1.5.3) 3 times. (Warning—The vapor pressure of toluene at 60 °C (140 °F) is
approximately twice that at 38 °C (100 °F).)
A1.5.5 Allow the bottle with the water-toluene mixture to sit in the bath 48 h before using. This will ensure complete equilibrium
between the toluene and the free water as well as complete saturation at the desired temperature. If it is necessary to use the
water-saturated toluene before the 48 h equilibration time has been
...