ASTM D7397-10(2016)
(Test Method)Standard Test Method for Cloud Point of Petroleum Products (Miniaturized Optical Method)
Standard Test Method for Cloud Point of Petroleum Products (Miniaturized Optical Method)
SIGNIFICANCE AND USE
5.1 The cloud point of petroleum products and biodiesel fuels is an index of the lowest temperature of their utility for certain applications. Wax crystals of sufficient quantity can plug filters used in some fuel systems.
5.2 Petroleum blending operations require a precise measurement of the cloud point.
5.3 This test method can determine the temperature of the test specimen at which wax crystals have formed sufficiently to be observed as a cloud with a resolution of 0.1°C.
5.4 This test method provides results that are equivalent to Test Method D5773/IP 446. The temperature results of this test method have been found to be warmer than those of Test Method D2500/IP 219 by an average of 0.49 °C; however, no sample specific bias was observed.
5.5 Similar to Test Method D5773/IP 446, this test method determines cloud point in a shorter period of time than Test Method D2500/IP 219.
Note 1: In cases of samples with cloud points near ambient temperatures, time savings may not be realized.
Note 2: This test method eliminates most of the operator time required of Test Method D2500/IP 219.
Note 3: The only utility required by the apparatus described in this test method is electricity with power consumption of approximately 20 W. The electric power can come from an alternating current source (wall receptacle) or direct current source such as a battery or a cigarette lighter plug in a vehicle.
Note 4: The apparatus described by this test method can be made much smaller and lighter than that of Test Methods D5773/IP 446 and D2500/IP 219, allowing full portability.
Note 5: The apparatus used in the 2006 interlaboratory study weighed approximately 1 kg and occupied the space of a small lunch box. See Section 13.
SCOPE
1.1 This test method covers the determination of the cloud point of petroleum products and biodiesel fuels that are transparent in layers 40 mm in thickness by an automatic instrument.
1.2 This test method covers the range of temperatures from –60 °C to +20 °C with temperature resolution of 0.1 °C; however, the range of temperatures included in the 2006 interlaboratory cooperative test program only covered the temperature range of –35 °C to +12 °C. See Section 13.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D7397 − 10 (Reapproved 2016)
Standard Test Method for
Cloud Point of Petroleum Products (Miniaturized Optical
Method)
This standard is issued under the fixed designation D7397; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers the determination of the cloud 3.1 Definitions:
point of petroleum products and biodiesel fuels that are
3.1.1 biodiesel, n—fuel comprising mono-alkyl esters of
transparent in layers 40 mm in thickness by an automatic
long-chain fatty acids derived from vegetable oils or animal
instrument.
fats, designated B100.
3.1.1.1 Discussion—Biodiesel is typically produced by a
1.2 This test method covers the range of temperatures from
reaction of vegetable oil or animal fat with an alcohol such as
–60 °C to +20 °C with temperature resolution of 0.1 °C;
methanol or ethanol in the presence of a catalyst to yield
however, the range of temperatures included in the 2006
mono-esters and glycerin.The fuel typically may contain up to
interlaboratory cooperative test program only covered the
14differenttypesoffattyacidsthatarechemicallytransformed
temperature range of –35 °C to +12 °C. See Section 13.
into fatty acid methyl esters (FAME).
1.3 The values stated in SI units are to be regarded as
3.1.2 biodiesel blend (BXX), n—blend of biodiesel fuel with
standard. No other units of measurement are included in this
petroleum-based diesel fuel designated BXX, where XX is the
standard.
volume percentage (as a whole number without the percentage
1.4 This standard does not purport to address all of the
sign) of biodiesel.
safety concerns, if any, associated with its use. It is the
3.1.3 cloud point, n—in petroleum products and biodiesel
responsibility of the user of this standard to establish appro-
fuels, the temperature of a liquid specimen when the smallest
priate safety and health practices and determine the applica-
observable cluster of hydrocarbon crystals first occurs upon
bility of regulatory limitations prior to use.
cooling under prescribed conditions.
2. Referenced Documents
3.1.3.1 Discussion—The cloud point occurs when the tem-
perature of the specimen is low enough to cause hydrocarbon
2.1 ASTM Standards:
D2500 Test Method for Cloud Point of Petroleum Products crystals to precipitate. In a homogeneous liquid, the cloud is
always noted first at the location in the specimen where the
D4057 Practice for Manual Sampling of Petroleum and
specimen temperature is the lowest. The cloud point is the
Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and temperature at which the crystals first occur, regardless of their
location in the specimen, and not after extensive crystallization
Petroleum Products
D5773 Test Method for Cloud Point of Petroleum Products has taken place. The hydrocarbon crystals that precipitate at
lower temperatures are typically, but not excluded to, straight
(Constant Cooling Rate Method)
2.2 Energy Institute Standards: chain hydrocarbons commonly called “wax crystals.”
IP 219 Test Method for Cloud Point of Petroleum Products
3.2 Definitions of Terms Specific to This Standard:
IP 446 Test Method for Cloud Point of Petroleum Products
3.2.1 D2500/IP 219 equivalent cloud point, n—temperature
of a specimen, in integers, calculated by applying a bias and
This test method is under the jurisdiction of ASTM Committee D02 on
rounding the result to the next lower integer (see 12.2).
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
3.2.1.1 Discussion—This test method produces results with
Subcommittee D02.07 on Flow Properties.
0.1 °C resolution. Should the user wish to provide results with
Current edition approved April 1, 2016. Published May 2016. Originally
approved in 2007. Last previous edition approved in 2010 as D7397 – 10. DOI:
a similar format to Test Method D2500, then this calculation
10.1520/D7397-10R16.
can be performed (see 12.2). Some apparatus can perform this
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
calculation automatically.
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
3.2.2 automatic cloud point, n—temperature of a specimen,
the ASTM website.
3 when the appearance of the cloud is determined under the
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
U.K., http://www.energyinst.org.uk. conditions of this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7397 − 10 (2016)
3.2.2.1 Discussion—The cloud point in this test method is 5.5 Similar to Test Method D5773/IP 446, this test method
determined by an automatic instrument using a miniaturized determines cloud point in a shorter period of time than Test
test receptacle equipped with two optical fibers, one to bring Method D2500/IP 219.
light into the test receptacle and the other to receive light
NOTE 1—In cases of samples with cloud points near ambient
scattered from the specimen.
temperatures, time savings may not be realized.
NOTE2—Thistestmethodeliminatesmostoftheoperatortimerequired
3.2.3 miniaturized optical method, n— in cloud point test
of Test Method D2500/IP 219.
methods, test procedure using prescribed cooling rate, speci-
NOTE3—Theonlyutilityrequiredbytheapparatusdescribedinthistest
men receptacle, and optical system for detection of crystal
methodiselectricitywithpowerconsumptionofapproximately20 W.The
formation.
electric power can come from an alternating current source (wall recep-
tacle) or direct current source such as a battery or a cigarette lighter plug
3.2.3.1 Discussion—The prescribed cooling rate is de-
in a vehicle.
scribed in 4.1, the specimen receptacle is described in Annex
NOTE 4—The apparatus described by this test method can be made
A1, and the optical system for the detection of crystal forma-
much smaller and lighter than that of Test Methods D5773/IP 446 and
tion is described in Annex A1.
D2500/IP 219, allowing full portability.
NOTE 5—The apparatus used in the 2006 interlaboratory study weighed
3.2.4 Peltier device, n—solid state thermoelectric device
approximately 1 kg and occupied the space of a small lunch box. See
constructed with dissimilar semiconductor materials and con-
Section 13.
figured in such a way that it will transfer heat to or away from
a test specimen dependent on the direction of electric current 6. Apparatus
4, 5
applied to the device.
6.1 Automatic Apparatus —The automatic cloud point
apparatus described in this test method consists of a test
4. Summary of Test Method
chamber controlled by a microprocessor that is capable of
controlling the heating and cooling of the test specimen,
4.1 A specimen is cooled by a Peltier device in a miniatur-
optically observing the first appearance of a cloud of wax
ized specimen receptacle (A1.1.1) at a rate of 30 °C 6
crystals and recording the temperature of the specimen de-
5 °C⁄min, while continuously being illuminated by a light
scribed in detail in Annex A1.
source (A1.1.4). The specimen is continuously monitored by
an optical detector (A1.1.5) for the first appearance of a cloud
6.2 The apparatus shall be equipped with a specimen
of wax crystals. Once crystals are first detected, as manifested
receptacle, optical detector, light source, optical fibers, digital
by an increase in scattered light level received by the optical
display, Peltier device, and a specimen temperature measuring
detector, the specimen is warmed at a rate of 15 °C 6
device.
5 °C⁄min.As soon as all the crystals have re-dissolved into the
6.3 The Peltier device shall be capable of heating or cooling
liquid specimen, warming is halted and the specimen is cooled
the test specimen at a rate of 3 °C to 35 °C⁄min.
again; but this time at a slower rate of 6 °C 6 3 °C⁄min.When
6.4 The temperature measuring device in the specimen
crystals first appear under this slower cooling rate, the tem-
receptacle shall be capable of measuring the temperature of the
perature of the specimen is recorded to 0.1 °C resolution as
test specimen from –60 °C to +20 °C at a resolution of 0.1 °C.
cloud point.
NOTE 6—The apparatus described above is covered by patents. If you
5. Significance and Use
are aware of an alternative(s) to the patented items, please attach to your
ballot return a description of the alternative(s). All suggestions will be
5.1 The cloud point of petroleum products and biodiesel
considered by the committee.
fuels is an index of the lowest temperature of their utility for
certain applications. Wax crystals of sufficient quantity can 7. Reagents and Materials
plug filters used in some fuel systems.
7.1 Disposable syringe that is capable of dispensing at least
10 mL 60.5 mLperfulldischargeofsampleintothespecimen
5.2 Petroleum blending operations require a precise mea-
receptacle.
surement of the cloud point.
NOTE 7—The apparatus can also be connected to a sample supply line
5.3 This test method can determine the temperature of the
to receive new sample. The amount of sample required per analysis is the
test specimen at which wax crystals have formed sufficiently to
same as that for the syringe injection procedure (that is, 20 mL 6 1.0 mL
be observed as a cloud with a resolution of 0.1°C.
per analysis). In such cases, a disposable syringe would not be needed.
5.4 This test method provides results that are equivalent to
8. Sampling
Test Method D5773/IP446.The temperature results of this test
method have been found to be warmer than those of Test
8.1 Obtain a sample in accordance with Practices D4057 or
Method D2500/IP 219 by an average of 0.49 °C; however, no D4177.
sample specific bias was observed.
The sole source of supply of the apparatus known to the committee at this time
is Phase Technology Miniature Cloud Point Analyzer available from Phase
ThePeltierdeviceiscoveredbyapatent.Interestedpartiesareinvitedtosubmit Technology, 11168 Hammersmith Gate, Richmond, B.C., Canada V7A-5H8. If you
information regarding the identification of an alternative(s) to this patented item to are aware of alternative suppliers, please provide this information to ASTM
the ASTM International Headquarters. Your comments will receive careful consid- I
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7397 − 10 D7397 − 10 (Reapproved 2016)
Standard Test Method for
Cloud Point of Petroleum Products (Miniaturized Optical
Method)
This standard is issued under the fixed designation D7397; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*Scope
1.1 This test method covers the determination of the cloud point of petroleum products and biodiesel fuels that are transparent
in layers 40 mm 40 mm in thickness by an automatic instrument.
1.2 This test method covers the range of temperatures from –60–60 °C to +20°C+20 °C with temperature resolution of
0.1°C;0.1 °C; however, the range of temperatures included in the 2006 interlaboratory cooperative test program only covered the
temperature range of –35–35 °C to +12°C.+12 °C. See Section 13.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D2500 Test Method for Cloud Point of Petroleum Products
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D5773 Test Method for Cloud Point of Petroleum Products (Constant Cooling Rate Method)
2.2 Energy Institute Standards:
IP 219 Test Method for Cloud Point of Petroleum Products
IP 446 Test Method for Cloud Point of Petroleum Products
3. Terminology
3.1 Definitions:
3.1.1 biodiesel, n—fuel comprising mono-alkyl esters of long-chain fatty acids derived from vegetable oils or animal fats,
designated B100.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.07 on Flow Properties.
Current edition approved May 1, 2010April 1, 2016. Published August 2010May 2016. Originally approved in 2007. Last previous edition approved in 20082010 as
D7397D7397 – 10.–08. DOI: 10.1520/D7397-10.10.1520/D7397-10R16.
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 Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.uk.
3.1.1.1 Discussion—
Biodiesel is typically produced by a reaction of vegetable oil or animal fat with an alcohol such as methanol or ethanol in the
presence of a catalyst to yield mono-esters and glycerin. The fuel typically may contain up to 14 different types of fatty acids that
are chemically transformed into fatty acid methyl esters (FAME).
3.1.2 biodiesel blend (BXX), n—blend of biodiesel fuel with petroleum-based diesel fuel designated BXX, where XX is the
volume percentage (as a whole number without the percentage sign) of biodiesel.
*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
D7397 − 10 (2016)
3.1.3 cloud point, n—in petroleum products and biodiesel fuels, the temperature of a liquid specimen when the smallest
observable cluster of hydrocarbon crystals first occurs upon cooling under prescribed conditions.
3.1.3.1 Discussion—
The cloud point occurs when the temperature of the specimen is low enough to cause hydrocarbon crystals to precipitate. In a
homogeneous liquid, the cloud is always noted first at the location in the specimen where the specimen temperature is the lowest.
The cloud point is the temperature at which the crystals first occur, regardless of their location in the specimen, and not after
extensive crystallization has taken place. The hydrocarbon crystals that precipitate at lower temperatures are typically, but not
excluded to, straight chain hydrocarbons commonly called “wax crystals.”
3.2 Definitions of Terms Specific to This Standard:
3.2.1 D2500/IP 219 equivalent cloud point, n—temperature of a specimen, in integers, calculated by applying a bias and
rounding the result to the next lower integer (see 12.2).
3.2.1.1 Discussion—
This test method produces results with 0.1°C0.1 °C resolution. Should the user wish to provide results with a similar format to Test
Method D2500, then this calculation can be performed (see 12.2). Some apparatus can perform this calculation automatically.
3.2.2 automatic cloud point, n—temperature of a specimen, when the appearance of the cloud is determined under the conditions
of this test method.
3.2.2.1 Discussion—
The cloud point in this test method is determined by an automatic instrument using a miniaturized test receptacle equipped with
two optical fibers, one to bring light into the test receptacle and the other to receive light scattered from the specimen.
3.2.3 miniaturized optical method, n— in cloud point test methods, test procedure using prescribed cooling rate, specimen
receptacle, and optical system for detection of crystal formation.
3.2.3.1 Discussion—
The prescribed cooling rate is described in 4.1, the specimen receptacle is described in Annex A1, and the optical system for the
detection of crystal formation is described in Annex A1.
3.2.4 Peltier device, n—solid state thermoelectric device constructed with dissimilar semiconductor materials and configured in
such a way that it will transfer heat to or away from a test specimen dependent on the direction of electric current applied to the
device.
4. Summary of Test Method
4.1 A specimen is cooled by a Peltier device in a miniaturized specimen receptacle (A1.1.1) at a rate of 3030 °C 6
5°C/min,5 °C ⁄min, while continuously being illuminated by a light source (A1.1.4). The specimen is continuously monitored by
an optical detector (A1.1.5) for the first appearance of a cloud of wax crystals. Once crystals are first detected, as manifested by
an increase in scattered light level received by the optical detector, the specimen is warmed at a rate of 1515 °C 6
5°C/min.5 °C ⁄min. As soon as all the crystals have re-dissolved into the liquid specimen, warming is halted and the specimen is
cooled again; but this time at a slower rate of 66 °C 6 3°C/min.3 °C ⁄min. When crystals first appear under this slower cooling
rate, the temperature of the specimen is recorded to 0.1°C0.1 °C resolution as cloud point.
5. Significance and Use
5.1 The cloud point of petroleum products and biodiesel fuels is an index of the lowest temperature of their utility for certain
applications. Wax crystals of sufficient quantity can plug filters used in some fuel systems.
5.2 Petroleum blending operations require a precise measurement of the cloud point.
5.3 This test method can determine the temperature of the test specimen at which wax crystals have formed sufficiently to be
observed as a cloud with a resolution of 0.1°C.
The Peltier device is covered by a patent. Interested parties are invited to submit information regarding the identification of an alternative(s) to this patented item to the
ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee.
D7397 − 10 (2016)
5.4 This test method provides results that are equivalent to Test Method D5773/IP 446. The temperature results of this test
method have been found to be warmer than those of Test Method D2500/IP 219 by an average of 0.49°C;0.49 °C; however, no
sample specific bias was observed.
5.5 Similar to Test Method D5773/IP 446, this test method determines cloud point in a shorter period of time than Test Method
D2500/IP 219.
NOTE 1—In cases of samples with cloud points near ambient temperatures, time savings may not be realized.
NOTE 2—This test method eliminates most of the operator time required of Test Method D2500/IP 219.
NOTE 3—The only utility required by the apparatus described in this test method is electricity with power consumption of approximately 20 watts.
20 W. The electric power can come from an alternating current source (wall receptacle) or direct current source such as a battery or a cigarette lighter
plug in a vehicle.
NOTE 4—The apparatus described by this test method can be made much smaller and lighter than that of Test Methods D5773/IP 446 and D2500/IP
219, allowing full portability.
NOTE 5—The apparatus used in the 2006 interlaboratory study weighed approximately 1 kg 1 kg and occupied the space of a small lunch box. See
Section 13.
6. Apparatus
4, 5
6.1 Automatic Apparatus —The automatic cloud point apparatus described in this test method consists of a test chamber
controlled by a microprocessor that is capable of controlling the heating and cooling of the test specimen, optically observing the
first appearance of a cloud of wax crystals and recording the temperature of the specimen described in detail in Annex A1.
6.2 The apparatus shall be equipped with a specimen receptacle, optical detector, light source, optical fibers, digital display,
Peltier device, and a specimen temperature measuring device.
6.3 The Peltier device shall be capable of heating or cooling the test specimen at a rate of 33 °C to 35°C/min.35 °C ⁄min.
6.4 The temperature measuring device in the specimen receptacle shall be capable of measuring the temperature of the test
specimen from –60–60 °C to +20°C+20 °C at a resolution of 0.1°C.0.1 °C.
NOTE 6—The apparatus described above is covered by patents. If you are aware of an alternative(s) to the patented items, please attach to your ballot
return a description of the alternative(s). All suggestions will be considered by the committee.
7. Reagents and Materials
7.1 Disposable syringe that is capable of dispensing at least 1010 mL 6 0.5 mL 0.5 mL per full discharge of sample into the
specimen receptacle.
NOTE 7—The apparatus can also be connected to a sample supply line to receive new sample. The amount of sample required per analysis is the same
as that for the syringe injection procedure (that is, 2020 mL 6 1.0 mL 1.0 mL per analysis). In such cases, a disposable syringe would not be needed.
8. Sampling
8.1 Obtain a sample in accordance with Practices D4057 or D4177.
8.2 Samples of very viscous materials may be warmed until they are reasonably fluid before they are tested. However, no sample
should be heated more than absolutely necessary.
8.3 The sample shall not be heated above 70°C.70 °C. When the sample is heated above 70 °C, allow the sample to cool below
70°C70 °C before filtering or inserting into the apparatus.
8.4 When moisture is present in the sample, remove the moisture by a method, such as filtration through dry lint-free filter paper,
until the specimen is perfectly clear, but make such filtration at a temperature at least 14°C14 °C above the expected cloud point.
NOTE 8—Moisture will be noticed in the sample as a separate phase or as a haze throughout the entire sample. Generally, a slight haze will not interfere
with the detection of the wax cloud.
9. Preparation of Apparatus
9.1 Prepare the instrument for operation in accordance with the manufacturer’s instructions.
9.2 Turn on the main power switch of the analyzer.
10. Calibration and Standardization
10.1 Ensure that all of the manufacturer’s instructions for calibrating, checking, and operating the apparatus are followed.
10.2 A sample with a mutually agreed upon cloud point can be used to verify performance of the apparatus.
The sole source of supply of the apparatus known to the committee at this time is Phase Technology Miniature Cloud Point Analyzer available from Phase Technology,
11168 Hammersmith Gate, Richmond, B.C., Canada V7A-5H8. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters.
Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D7397 − 10 (2016)
TABLE 1 Typical Repeatability at Different Cloud Points
Cloud Point °C Repeatability °C
15 0.4
10 0.5
5 0.7
0 0.8
-5 0.9
-10 1.1
-15 1.2
-20 1.3
-25 1.5
-30 1.6
-35 1.7
11. Procedure
11.1 Draw 1010 mL 6 0.5 mL 0.5 mL of bubble-free sample into a new disposable syringe. Connect the syringe to the inlet
port, and inject the full charge of sample into the test receptacle. The specimen excess will flow into a waste-receiving container.
11.2 Draw another 1010 mL 6 0.5 mL 0.5 mL of bubble-free sample into the syringe. Connect the syringe to the inlet port, and
inject the full charge of sample into the test receptacle. The specimen excess will flow into a waste-receiving container. The total
amount of sample (that is, 2020 mL 6 1.0 mL) 1.0 mL) is sufficient in quantity to flush out any previous sample in the specimen
receptacle and fill it with the fresh sample.
NOTE 9—Follow manufacturer’s instructions for sample injection if the specimen receptacle is connected to a sample supply line as described in Note
7.
11.3 Start the operation of the apparatus according to the manufacturer’s instructions. From this point on, the apparatus
automatically controls the procedure.
11.4 Cool the sample at a rate of 3030 °C 6 5°C/min,5 °C ⁄min, while continuously illuminating the sample with the light
source. Monitor the specimen continuously with the optical detector. Once crystals are first detected, as manifested by an increase
in light level received by the optical detector, warm the specimen at a rate of 1515 °C 6 5°C/min.5 °C ⁄min. As soon as all the
crystals have re-dissolved into the liquid specimen in accordance with this test method, stop the warming and cool the specimen
again at a slower rate of 66 °C 6 3°C/min.3 °C ⁄min. When crystals first appear under this slower cooling rate, record the
temperature of the specimen as the cloud point.
11.5 The measurement is automatically terminated once the cloud point is detected.
11.6 When the measurement is complete, the cloud point value
...
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