ASTM D4007-11(2016)e1

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.

General Information

• Status: Historical
• Publication Date: 31-May-2016
• 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)

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
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.
ε NOTE—Subsection X1.3.3.2 was revised editorially in November 2016.
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
MPMS Chapter 10.6)
NOTE 1—Test Method D4006 (API MPMS Chapter 10.2) has been
determined to be the preferred and most accurate method for the D4006Test Method for Water in Crude Oil by Distillation
determination of water.
(API MPMS Chapter 10.2)
D4057Practice for Manual Sampling of Petroleum and
1.2 The values stated in SI units are to be regarded as
Petroleum Products (API MPMS Chapter 8.1)
standard.
D4177Practice for Automatic Sampling of Petroleum and
1.2.1 Exception—The values given in parentheses are for
Petroleum Products (API MPMS Chapter 8.2)
information only.
D4928Test Method forWater in Crude Oils by Coulometric
Karl Fischer Titration (API MPMS Chapter 10.9)
1.3 This standard does not purport to address all of the
D5854Practice for Mixing and Handling of Liquid Samples
safety concerns, if any, associated with its use. It is the
of Petroleum and Petroleum Products (API MPMS Chap-
responsibility of the user of this standard to establish appro-
ter 8.3)
priate safety and health practices and determine the applica-
E969Specification for Glass Volumetric (Transfer) Pipets
bility of regulatory limitations prior to use. Specific warning
2.2 API Standards:
statements appear in 6.1, 8.3, and A1.5.4.
MPMS Chapter 8.1Manual Sampling of Petroleum and
Petroleum Products (ASTM Practice D4057)
MPMS Chapter 8.2Automatic Sampling of Petroleum and
Petroleum Products (ASTM Practice D4177)
MPMSChapter8.3MixingandHandlingofLiquidSamples
of Petroleum and Petroleum Products (ASTM Practice
This test method is under the jurisdiction of ASTM Committee D02 on
D5854)
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
CurrenteditionapprovedJune1,2016.PublishedJuly2016.Originallyapproved the ASTM website.
ɛ1 3
in 1981. Last previous edition approved in 2011 as D4007–11 . DOI: 10.1520/ Available from American Petroleum Institute (API), 1220 L. St., NW,
D4007-11R16E01. Washington, DC 20005-4070, www.api.org.
© 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
´1
D4007 − 11 (2016)
MPMS Chapter 10.1Determination of Sediment in Crude eredbythepowersource.Thetrunnioncupsandcushionsshall
Oils and Fuel Oils by the Extraction Method (ASTMTest firmly support the tubes when the centrifuge is in motion. The
Method D473)
centrifuge shall be enclosed by a metal shield or case strong
MPMSChapter10.2DeterminationofWaterinCrudeOilby
enough to eliminate danger if any breakage occurs.
Distillation (ASTM Test Method D4006)
5.1.3 The centrifuge shall be heated and controlled thermo-
MPMS Chapter 10.4Determination of Sediment and Water
statically to avoid unsafe conditions. It shall be capable of
in Crude Oil by the Centrifuge Method (Field Procedure)
maintaining the sample temperature during the entire run at
MPMS Chapter 10.5Determination of Water in Petroleum
60°C 6 3°C (140°F 6 5°F). The thermostatic control shall
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-
zenes (Toluenes)
rcf = relative centrifugal force and
2.4 ISO Standard: d = diameter of swing measured between tips of opposite
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
3.1 Equal volumes of crude oil and water-saturated toluene where:
are placed into a cone-shaped centrifuge tube. After
rcf = relative centrifugal force and
centrifugation, the volume of the higher density water and
d = diameter of swing measured between tips of opposite
sediment layer at the bottom of the tube is read.
tubes when in rotating position, in.
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.
4.2 This test method may not be suitable for crude oils that
where:
contain alcohols that are soluble in water. In cases where the
d = diameter of swing measured between tips of opposite
impact on the results may be significant, the user is advised to
tubes when in rotating position, in.
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
5. Apparatus
given in Fig. 1 and made of thoroughly annealed glass. The
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
shown in Fig. 2), and at the 0.5mL, 1.0mL, 1.5mL, 2.0mL,
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
50.0mL, and 100mLmarks. The tube shall not be used if the
U.K., http://www.energyinst.org.uk.
5 scale error at any mark exceeds the applicable tolerance from
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. Table 1.
´1
D4007 − 11 (2016)
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.)
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
FIG. 1 Eight-Inch (203 mm) Centrifuge Tube
7.1 Sampling is defined as all steps required to obtain an
TABLE 1 Centrifuge Tube Calibration Tolerances
aliquotofthecontentsofanypipe,tank,orothersystemandto
for 203 mm (8 in.) Tube
place the sample into the laboratory test container.
Range, mL Subdivision, mL Volume Tolerance, mL
7.2 Only representative samples obtained as specified in
0 to 0.1 0.05 ±0.02
Above 0.1 to 0.3 0.05 ±0.03
PracticesD4057(API MPMSChapter8.1)andPracticeD4177
Above 0.3 to 0.5 0.05 ±0.05
(API MPMS Chapter 8.2) shall be used for this test method.
Above 0.5 to 1.0 0.10 ±0.05
Above 1.0 to 2.0 0.10 ±0.10
7.3 Sample Mixing—is typically required to obtain a test
Above 2.0 to 3.0 0.20 ±0.10
portion representative of the bulk sample to be tested, but
Above 3.0 to 5.0 0.5 ±0.20
Above 5.0 to 10 1.0 ±0.50
precautions shall be taken to maintain the integrity of the
Above 10 to 25 5.0 ±1.00
sample during this operation. Mixing of volatile crude petro-
Above 25 to 100 25.0 ±1.00
leum containing water or sediments, or both, may result in the
lossoflightcomponents.Additionalinformationonthemixing
andhandlingofliquidsamplescanbefoundinPracticeD5854
(API MPMS Chapter 8.3).
5.3 Bath—The bath shall be either a solid metal block bath
oraliquidbathofsufficientdepthforimmersingthecentrifuge
8. Procedure
tube in the vertical position to the 100mL mark. Means shall
8.1 Filleachoftwocentrifugetubes(5.2)tothe50mLmark
be provided for maintaining the temperature at 60°C 63°C
with sample directly from the sample container. Using a pipet
(140°F 65°F).Forsomecrudeoils,temperaturesof71°C 6
orothersuitablevolumetransferdevice(see5.4),add50mL 6
3°C (160°F 6 5°F) may be required to melt wax crystals in
0.05mL of toluene, which has been water saturated at 60°C
crude oils. For these crude oils, the test temperature shall be
(140°F) or 71°C (160°F) (see 5.3). Read the top of the
maintained high enough to ensure the absence of wax crystals.
meniscusatboththe50mLand100mLmarks.Add0.2mLof
5.4 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. 6
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
6. Solvent listed by the American Chemical Society, see Annual Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
6.1 Toluene—Reagent grade conforming to the specifica-
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
tionsoftheCommitteeonAnalyticalReagentsoftheAmerican MD.
´1
D4007 − 11 (2016)
FIG. 2 Procedure for Reading Water and Sediment When Using an ASTM 100-mm Cone-Shaped Centrifuge Tube
´1
D4007 − 11 (2016)
TABLE 2 Expression of Results, mL
demulsifier solution (6.2) to each tube, using a 0.2mLpipet or
other suitable volume transfer device, such as an automatic Total Percent Water and
Tube 1 Tube 2
Sediment, % (V/V)
pipettor. Stopper the tube tightly and invert the tubes ten times
No visible water and No visible water and 0.00
to ensure that the oil and solvent are uniformly mixed.
sediment sediment
No visible water and 0.025 0.025
8.2 In the case where the crude oil is very viscous and
sediment
mixingofthesolventwiththeoilwouldbedifficult,thesolvent
0.025 0.025 0.05
may be added to the centrifuge tube first to facilitate mixing.
0.025 0.05 0.075
0.05 0.05 0.10
Take care to not fill the centrifuge tube past the 100mL mark
0.05 0.075 0.125
with the sample.
0.075 0.075 0.15
0.075 0.10 0.175
8.3 Loosen the stoppers slightly and immerse the tubes to
0.10 0.10 0.20
the 100mL mark for at least 15min in the bath maintained at
0.10 0.15 0.25
60°C 6 3°C (140°F 6 5°F) (see 5.3). Secure the stoppers
and again invert the tubes ten
...

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 − 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—Subsection X1.3.3.2 was revised editorially in November 2016.
1. 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.
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.
ɛ1
Current edition approved June 1, 2016. Published July 2016. Originally approved in 1981. Last previous edition approved in 2011 as D4007 – 11 . DOI:
10.1520/D4007-16.10.1520/D4007-11R16E01.
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.
Available from American Petroleum Institute (API), 1220 L. St., NW, Washington, DC 20005-4070, www.api.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
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.) 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 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.
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.
´1
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.) 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.
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 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.
5.4 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.
FIG. 1 Eight-Inch (203 mm) Centrifuge Tube
´1
D4007 − 11 (2016)
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. 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)
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 6 3 °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 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) to the 50 mL mark with sample directly from the sample container. Using a pipet or
other suitable volume transfer device (see 5.4), 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 5.3). Read the top of the meniscus at both the 50 mL and 100 mL marks. Add 0.2 mL of demulsifier solution
(6.2) 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.
8.2 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.
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. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
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D4007 − 11 (2016)
FIG. 2 Procedure for Reading Water and Sediment When Using an ASTM 100-mm Cone-Shaped Centrifu
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