ASTM D4007-11(2016)
(Test Method)Standard Test Method for Water and Sediment in Crude Oil by the Centrifuge Method (Laboratory Procedure)
Standard Test Method for Water and Sediment in Crude Oil by the Centrifuge Method (Laboratory Procedure)
SIGNIFICANCE AND USE
4.1 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.
4.2 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 and health practices and determine the applicability of regulatory limitations prior to use. Specific warning statements appear in 6.1, 8.3, and A1.5.4.
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Designation: D4007 − 11 (Reapproved 2016)
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 BituminousMaterialsbyDistillation(API MPMSChapter
10.5)
1.1 This test method describes the laboratory determination
D473TestMethodforSedimentinCrudeOilsandFuelOils
of water and sediment in crude oils by means of the centrifuge
by the Extraction Method (API MPMS Chapter 10.1)
procedure. This centrifuge method for determining water and
D665Test Method for Rust-Preventing Characteristics of
sediment in crude oils is not entirely satisfactory. The amount
Inhibited Mineral Oil in the Presence of Water
of water detected is almost always lower than the actual water
D1796Test Method for Water and Sediment in Fuel Oils by
content. When a highly accurate value is required, the revised
the Centrifuge Method (Laboratory Procedure) (API
procedures for water by distillation, Test Method D4006 (API
MPMS Chapter 10.6)
MPMS Chapter 10.2) (Note 1), and sediment by extraction,
D4006Test Method for Water in Crude Oil by Distillation
Test Method D473 (API MPMS Chapter 10.1), shall be used.
(API MPMS Chapter 10.2)
NOTE 1—Test Method D4006 (API MPMS Chapter 10.2) has been
D4057Practice for Manual Sampling of Petroleum and
determined to be the preferred and most accurate method for the
Petroleum Products (API MPMS Chapter 8.1)
determination of water.
D4177Practice for Automatic Sampling of Petroleum and
1.2 The values stated in SI units are to be regarded as
Petroleum Products (API MPMS Chapter 8.2)
standard.
D4928Test Method forWater in Crude Oils by Coulometric
1.2.1 Exception—The values given in parentheses are for
Karl Fischer Titration (API MPMS Chapter 10.9)
information only.
D5854Practice for Mixing and Handling of Liquid Samples
1.3 This standard does not purport to address all of the
of Petroleum and Petroleum Products (API MPMS Chap-
safety concerns, if any, associated with its use. It is the
ter 8.3)
responsibility of the user of this standard to establish appro- E969Specification for Glass Volumetric (Transfer) Pipets
priate safety and health practices and determine the applica-
2.2 API Standards:
bility of regulatory limitations prior to use. Specific warning
MPMS Chapter 8.1Manual Sampling of Petroleum and
statements appear in 6.1, 8.3, and A1.5.4.
Petroleum Products (ASTM Practice D4057)
MPMS Chapter 8.2Automatic Sampling of Petroleum and
2. Referenced Documents
Petroleum Products (ASTM Practice D4177)
2.1 ASTM Standards:
MPMSChapter8.3MixingandHandlingofLiquidSamples
D95Test Method for Water in Petroleum Products and
of Petroleum and Petroleum Products (ASTM Practice
D5854)
MPMS Chapter 10.1Determination of Sediment in Crude
This test method is under the jurisdiction of ASTM Committee D02 on
Oils and Fuel Oils by the Extraction Method (ASTMTest
Petroleum Products, Liquid Fuels, and Lubricants and the API Committee on
Method D473)
Petroleum Measurement and is the direct responsibility of Subcommittee D02.02
/COMQ the joint ASTM-API Committee on Hydrocarbon Measurement for
MPMSChapter10.2DeterminationofWaterinCrudeOilby
Custody Transfer (Joint ASTM-API). This test method has been approved by the
Distillation (ASTM Test Method D4006)
sponsoring committees and accepted by the Cooperating Societies in accordance
MPMS Chapter 10.4Determination of Sediment and Water
with established procedures.
in Crude Oil by the Centrifuge Method (Field Procedure)
CurrenteditionapprovedJune1,2016.PublishedJuly2016.Originallyapproved
ɛ1
in 1981. Last previous edition approved in 2011 as D4007–11 . DOI: 10.1520/
MPMS Chapter 10.5Determination of Water in Petroleum
D4007-16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American Petroleum Institute (API), 1220 L. St., NW,
the ASTM website. Washington, DC 20005-4070, www.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4007 − 11 (2016)
Products and Bituminous Materials by Distillation be capable of maintaining the temperature within these limits
(ASTM Test Method D95) and operate safely if there is a flammable atmosphere.
MPMS Chapter 10.6Determination of Water and Sediment
5.1.4 Electricpoweredandheatedcentrifugesmustmeetall
in Fuel Oils by the Centrifuge Method (Laboratory Pro-
safety requirements for use in hazardous areas.
cedures) (ASTM Test Method D1796)
5.1.5 Calculate the necessary minimum speed of the rotat-
MPMSChapter10.9TestMethodforWaterinCrudeOilsby
ing head in revolutions per minute (r/min) as follows:
Coulometric Karl Fischer Titration (ASTM Test Method
D4928) r/min 51335 =rcf/d (1)
2.3 IP Standard:
where:
Methods Book, Appendix BSpecification for Methylben-
rcf = relative centrifugal force and
zenes (Toluenes)
d = diameter of swing measured between tips of opposite
2.4 ISO Standard:
tubes when in rotating position, mm, or
ISO 5272:1979Toluene for Industrial Use—Specifications
r/min 5265 =rcf/d (2)
3. Summary of Test Method
where:
3.1 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.
5.1.6 Calculate the relative centrifugal force from a mea-
4. Significance and Use
sured speed (r/min) as follows:
4.1 The water and sediment content of crude oil is signifi-
r/min
cantbecauseitcancausecorrosionofequipmentandproblems
rcf 5 d (3)
S D
inprocessing.Adeterminationofwaterandsedimentcontentis
required to measure accurately net volumes of actual oil in where:
sales, taxation, exchanges, and custody transfers. It is not
d = diameter of swing measured between tips of opposite
anticipated that this test method, which is written with a
tubes when in rotating position, mm, or
dedicated laboratory facility in mind, is likely to be used in
r/min
field test rooms or sample rooms due to safety concerns for
rcf 5 d (4)
S D
proper ventilation and handling.
where:
4.2 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
consider using another test method, such as Test Method
5.2 Centrifuge Tubes—Each centrifuge tube shall be a
D4928 (API MPMS Chapter 10.9).
203mm (8in.) cone-shaped tube, conforming to dimensions
given in Fig. 1 and made of thoroughly annealed glass. The
5. Apparatus
graduations, numbered as shown in Fig. 1, shall be clear and
5.1 Centrifuge:
distinct,andthemouthshallbeconstrictedinshapeforclosure
5.1.1 A centrifuge capable of spinning two or more filled
withacork.Scaleerrortolerancesandthesmallestgraduations
cone-shaped, 203mm (8in.) centrifuge tubes at a speed that
between various calibration marks are given in Table 1 and
can be controlled to give a relative centrifugal force (rcf) of a
applytocalibrationsmadewithair-freewaterat20°C(68°F),
minimumof600atthetipofthetubesshallbeused(see5.1.6).
whenreadingthebottomoftheshadedmeniscus.Theaccuracy
5.1.2 Therevolvinghead,trunnionrings,andtrunnioncups,
of the graduations on the centrifuge tube shall be volumetri-
including the cushions, shall be soundly constructed to with-
cally verified, before use of the tube. The verification shall
stand the maximum centrifugal force capable of being deliv-
include calibration at each mark up to the 0.25mL mark (as
eredbythepowersource.Thetrunnioncupsandcushionsshall
shown in Fig. 2), and at the 0.5mL, 1.0mL, 1.5mL, 2.0mL,
firmly support the tubes when the centrifuge is in motion. The
50.0mL, and 100mLmarks. The tube shall not be used if the
centrifuge shall be enclosed by a metal shield or case strong
scale error at any mark exceeds the applicable tolerance from
enough to eliminate danger if any breakage occurs.
Table 1.
5.1.3 The centrifuge shall be heated and controlled thermo-
5.3 Bath—The bath shall be either a solid metal block bath
statically to avoid unsafe conditions. It shall be capable of
oraliquidbathofsufficientdepthforimmersingthecentrifuge
maintaining the sample temperature during the entire run at
tube in the vertical position to the 100mL mark. Means shall
60°C 6 3°C (140°F 6 5°F). The thermostatic control shall
be provided for maintaining the temperature at 60°C 63°C
(140°F 65°F).Forsomecrudeoils,temperaturesof71°C 6
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
3°C (160°F 6 5°F) may be required to melt wax crystals in
U.K., http://www.energyinst.org.uk.
crude oils. For these crude oils, the test temperature shall be
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. maintained high enough to ensure the absence of wax crystals.
D4007 − 11 (2016)
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.)
6.1.1 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
6.1.2 The solvent shall be water-saturated at 60°C 63°C
(140°F 6 5°F) (see 5.3) but shall be free of suspended water.
See Annex A1 for the solvent-water saturation procedure.
6.2 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.
7. Sampling
7.1 Sampling is defined as all steps required to obtain an
aliquotofthecontentsofanypipe,tank,orothersystemandto
FIG. 1 Eight-Inch (203 mm) Centrifuge Tube
place the sample into the laboratory test container.
7.2 Only representative samples obtained as specified in
TABLE 1 Centrifuge Tube Calibration Tolerances
for 203 mm (8 in.) Tube PracticesD4057(API MPMSChapter8.1)andPracticeD4177
(API MPMS Chapter 8.2) shall be used for this test method.
Range, mL Subdivision, mL Volume Tolerance, mL
0 to 0.1 0.05 ±0.02
7.3 Sample Mixing—is typically required to obtain a test
Above 0.1 to 0.3 0.05 ±0.03
Above 0.3 to 0.5 0.05 ±0.05 portion representative of the bulk sample to be tested, but
Above 0.5 to 1.0 0.10 ±0.05
precautions shall be taken to maintain the integrity of the
Above 1.0 to 2.0 0.10 ±0.10
sample during this operation. Mixing of volatile crude petro-
Above 2.0 to 3.0 0.20 ±0.10
Above 3.0 to 5.0 0.5 ±0.20
leum containing water or sediments, or both, may result in the
Above 5.0 to 10 1.0 ±0.50
lossoflightcomponents.Additionalinformationonthemixing
Above 10 to 25 5.0 ±1.00
andhandlingofliquidsamplescanbefoundinPracticeD5854
Above 25 to 100 25.0 ±1.00
(API MPMS Chapter 8.3).
8. Procedure
5.4 50 mL Pipet, Class A, or equivalent volume dispensing
device, capable of delivering a volume of 50mL 6 0.05mL
8.1 Filleachoftwocentrifugetubes(5.2)tothe50mLmark
(see Specification E969) for use in the test.
with sample directly from the sample container. Using a pipet
orothersuitablevolumetransferdevice(see5.4),add50mL 6
6. Solvent
0.05mL of toluene, which has been water saturated at 60°C
6.1 Toluene—Reagent grade conforming to the specifica- (140°F) or 71°C (160°F) (see 5.3). Read the top of the
tionsoftheCommitteeonAnalyticalReagentsoftheAmerican meniscusatboththe50mLand100mLmarks.Add0.2mLof
Chemical Society (ACS) or to Grade 2 of ISO 5272 or demulsifier solution (6.2) to each tube, using a 0.2mLpipet or
conforming to the EI Specification for Methylbenzenes (Tolu- other suitable volume transfer device, such as an automatic
enes). (Warning—Flammable. Keep away from heat, sparks, pipettor. Stopper the tube tightly and invert the tubes ten times
to ensure that the oil and solvent are uniformly mixed.
8.2 In the case where the crude oil is very viscous and
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
mixingofthesolventwiththeoilwouldbedifficult,thesolvent
listed by the American Chemical Society, see Annual Standards for Laboratory
may be added to the centrifuge tube first to facilitate mixing.
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Take care to not fill the centrifuge tube past the 100mL mark
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. with the sample.
D4007 − 11 (2016)
FIG. 2 Procedure for Reading Water and Sediment When Using an ASTM 100-mm Cone-Shaped Centrifuge Tube
D4007 − 11 (2016)
8.3 Loosen the stoppers slightly and immerse the tubes to 10. Precision and Bias
the 100mL mark for at least 15min in the bath maintained at
10.1 Precision—The precision of this test method, as deter-
60°C 6 3°C (140°F 6 5°F) (see 5.3). Secure the stoppers
mined by statistical examination of interlaboratory test results
and again invert the tubes ten times to ensure uniform mixing
in the range from 0.01% to 1.0%, is described in 10.1.1 and
of oil and solvent. (Warning—The vapor pressure at 60°C
10.1.2.
(140°F) is approximately double that at 40°C (104°F).)
10.1.1 Repeatability—The difference between two test
8.4 Placethetubesinthetrunnioncupsonoppositesidesof
results, obtained by the same operator with t
...
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 D4007 − 11 (Reapproved 2016)
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—Referenced Documents and API information was editorially corrected in July 2013.
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. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory
limitations prior to use. Specific warning statements appear in 6.1, 8.3, and A1.5.4.
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
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 MPMS Chapter 10.2)
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products (API MPMS Chapter 8.1)
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 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)
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, 2011June 1, 2016. Published August 2011July 2016. Originally approved in 1981. Last previous edition approved in 20082011 as
ɛ1
D4007D4007 – 11 –08. DOI: 10.1520/D4007-11E01.10.1520/D4007-16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, www.api.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4007 − 11 (2016)
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. Summary of Test Method
3.1 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.
4. Significance and Use
4.1 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.
4.2 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).
5. Apparatus
5.1 Centrifuge:
5.1.1 A centrifuge capable of spinning two or more filled cone-shaped, 203-mm (8-in.)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 5.1.6).
5.1.2 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.
5.1.3 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 6060 °C 6 3°C (1403 °C (140 °F 6 5°F).5 °F). The thermostatic
control shall be capable of maintaining the temperature within these limits and operate safely if there is a flammable atmosphere.
5.1.4 Electric powered and heated centrifuges must meet all safety requirements for use in hazardous areas.
5.1.5 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.
5.1.6 Calculate the relative centrifugal force from a measured speed (r/min) as follows:
r/min
rcf 5 d (3)
S D
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 − 11 (2016)
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.
5.2 Centrifuge Tubes—Each centrifuge tube shall be a 203-mm (8-in.)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),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 0.25 mL
mark (as shown in Fig. 2), and at the 0.5, 1.0, 1.5, 2.0, 50.0, and 100 mL 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.
5.3 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-mL100 mL mark. Means shall be provided for maintaining the temperature at 6060 °C 6 3°C
(1403 °C (140 °F 6 5°F).5 °F). For some crude oils, temperatures of 7171 °C 6 3°C (1603 °C (160 °F 6 5°F)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.
5.4 50 mL 50 mL Pipet, Class A, or equivalent volume dispensing device, capable of delivering a volume of 5050 mL 6 0.05
mL 0.05 mL (see Specification E969) for use in the test.
FIG. 1 Eight-Inch (203-mm)(203 mm) Centrifuge Tube
D4007 − 11 (2016)
TABLE 1 Centrifuge Tube Calibration Tolerances
for 203-mm (8-in.)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. Solvent
6.1 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.)
6.1.1 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)
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
6.1.2 The solvent shall be water-saturated at 6060 °C 6 3°C (1403 °C (140 °F 6 5°F)5 °F) (see 5.3) but shall be free of
suspended water. See Annex A1 for the solvent-water saturation procedure.
6.2 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.
7. Sampling
7.1 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.
7.2 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.
7.3 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).
8. Procedure
8.1 Fill each of two centrifuge tubes (5.2)(5.2) to the 50-mL50 mL mark with sample directly from the sample container. Using
a pipet or other suitable volume transfer device (see 5.4), add 5050 mL 6 0.05 mL 0.05 mL of toluene, which has been water
saturated at 60°C (140°F) or 71°C (160°F)60 °C (140 °F) or 71 °C (160 °F) (see 5.3). Read the top of the meniscus at both the
5050 mL and 100-mL100 mL marks. Add 0.2 mL 0.2 mL of demulsifier solution (6.2) to each tube, using a 0.2-mL0.2 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.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed by
the American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmac
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