ASTM D5772-21

Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Linear Cooling Rate Method)

SIGNIFICANCE AND USE
5.1 For petroleum products and diesel fuels, the cloud point is an index of the lowest temperature of its utility for certain applications. Wax crystals of sufficient quantity can plug filters used in some fuel systems.  
5.2 Petroleum blending operations require 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 when rounded to the next lower integer are equivalent to Test Method D2500.  
5.5 This test method is more precise than Test Method D2500.
SCOPE
1.1 This test method covers the description of 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 using a linear cooling rate.  
1.2 This test method covers the range of temperatures from −60 °C to 49 °C with temperature resolution of 0.1 °C, however, the range of temperatures included in the 1997 interlaboratory cooperative test program only covered the temperature range of –56 °C to +34 °C.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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: 31-Dec-2020
• ICS: 75.080 - Petroleum products in general
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.07 - Flow Properties

Relations

• Refers: ASTM D6751-18 - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Oct-2018
• Refers: ASTM D2500-16 - Standard Test Method for Cloud Point of Petroleum Products
• Effective Date: 01-Jan-2016
• Refers: ASTM D6751-15c - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Dec-2015
• Refers: ASTM D6751-15b - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Oct-2015
• Refers: ASTM D6751-15a - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Jun-2015
• Refers: ASTM D6751-15 - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Jan-2015
• Refers: ASTM D6751-14 - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Oct-2014
• Refers: ASTM D6751-12 - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Aug-2012
• Refers: ASTM D6751-11b - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 15-Jul-2011
• Refers: ASTM D4057-06(2011) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• Effective Date: 01-Jun-2011
• Refers: ASTM D6751-11a - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 15-Feb-2011
• Refers: ASTM D6751-11 - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 15-Feb-2011
• Refers: ASTM D6751-10 - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Aug-2010
• Refers: ASTM D6751-09a - Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• Effective Date: 01-Dec-2009
• Refers: ASTM D2500-09 - Standard Test Method for Cloud Point of Petroleum Products
• Effective Date: 15-Apr-2009

Overview

ASTM D5772-21 is the internationally recognized standard test method for determining the cloud point of petroleum products and liquid fuels, including biodiesel fuels and their blends. Developed by ASTM International, this test method utilizes an automatic instrument operating at a linear cooling rate, providing a precise and reliable measurement of the temperature at which wax crystals first appear as a cloud in transparent fuel samples.

This method covers cloud point determinations over a temperature range from −60 °C to +49 °C with a resolution of 0.1 °C, making it suitable for a wide variety of fuel types and ensuring accuracy in cold flow property assessments. The standard is directly relevant for fuel producers, refineries, quality control labs, and end-users who require verified fuel performance under lower temperature conditions.

Key Topics

• Significance of Cloud Point: The cloud point is a crucial indicator of the lowest temperature at which a fuel remains suitable for certain applications. Below the cloud point, wax crystals may form in sufficient quantities to clog fuel system filters and lines, impacting fuel operability.
• Automatic Linear Cooling Method: The procedure specifies the use of an automatic device with controlled cooling, an optical detection system for identifying the first appearance of wax crystals, and precise temperature measurement.
• Measurement Precision: Results are reported with 0.1 °C resolution. When rounded down to the next lower integer, results are equivalent to those from the older Test Method D2500, but with improved repeatability and reproducibility.
• Applicable Fuels: The method is applicable to petroleum products and biodiesel fuels that are transparent in a 40 mm sample layer, including blends. It ensures accurate cloud point detection for both conventional fuels and modern biodiesel components.
• Safety and Compliance: The standard emphasizes the importance of following proper safety, health, and environmental procedures, and complying with relevant regulations when executing the test.

Applications

ASTM D5772-21 is essential in the following areas:

• Fuel Blending Operations: Accurate cloud point measurements are critical during fuel blending to ensure products meet specifications for flow properties and winter operability.
• Quality Control in Refineries and Production: Regular cloud point testing helps maintain product consistency and safety, especially for diesel fuels, heating oils, and biodiesel blends.
• Specification Compliance: The method supports compliance with industry and regulatory specifications that reference cloud point as a quality criterion.
• Prevention of Engine and Equipment Issues: By identifying the temperature at which wax precipitates form, the method helps avoid operational problems like blocked filters and flow lines in storage and distribution systems.
• Research and Development: The precision and automation of this method make it suitable for R&D applications, allowing for comparative studies of fuel formulations and additives.

Related Standards

For broader context and complementary guidance, consult these relevant standards:

• ASTM D2500 - Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (manual method)
• ASTM D4057 - Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4177 - Practice for Automatic Sampling of Petroleum and Petroleum Products
• ASTM D6751 - Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
• IP 219 - Energy Institute Test Method for Cloud Point of Petroleum Products

ASTM D5772-21 provides a reliable, automated approach to cloud point determination, supporting the needs of the petroleum and biofuels industries for precision, safety, and regulatory compliance in fuel performance testing.

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: D5772 − 21
Designation: IP 445/09
Standard Test Method for
Cloud Point of Petroleum Products and Liquid Fuels (Linear
Cooling Rate Method)
This standard is issued under the fixed designation D5772; 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.
INTRODUCTION
This test method describes an alternative procedure for the determination of cloud point of
petroleum products of Test Method D2500/IP 219 using an automatic apparatus. The temperature
results from this test method have been found to be equivalent to Test Method D2500/IP 219. When
specification requires Test Method D2500/IP 219, do not substitute this test method or any other
method without obtaining comparative data and agreement from the specifier.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the description of the determi-
D2500Test Method for Cloud Point of Petroleum Products
nation of the cloud point of petroleum products and biodiesel
and Liquid Fuels
fuels that are transparent in layers 40mm in thickness by an
D4057Practice for Manual Sampling of Petroleum and
automatic instrument using a linear cooling rate.
Petroleum Products
1.2 This test method covers the range of temperatures from
D4177Practice for Automatic Sampling of Petroleum and
−60°C to 49°C with temperature resolution of 0.1°C,
Petroleum Products
however, the range of temperatures included in the 1997
D6751Specification for Biodiesel Fuel Blend Stock (B100)
interlaboratory cooperative test program only covered the
for Middle Distillate Fuels
temperature range of –56°C to +34°C.
2.2 Energy Institute Standard:
1.3 The values stated in SI units are to be regarded as
IP219Test Method for Cloud Point of Petroleum Products
standard. No other units of measurement are included in this
standard.
3. Terminology
1.4 This standard does not purport to address all of the
3.1 Definitions:
safety concerns, if any, associated with its use. It is the
3.1.1 biodiesel, n—fuel comprised of mono-alkyl esters of
responsibility of the user of this standard to establish appro-
long chain fatty acids derived from vegetable oils or animal
priate safety, health, and environmental practices and deter-
fats, designated B100.
mine the applicability of regulatory limitations prior to use.
3.1.1.1 Discussion—Biodiesel is typically produced by a
1.5 This international standard was developed in accor-
reactionofavegetableoiloranimalfatwithanalcoholsuchas
dance with internationally recognized principles on standard- methanol or ethanol in the presence of a catalyst to yield
ization established in the Decision on Principles for the
mono-alkylestersandglycerin,whichisremoved.Thefinished
Development of International Standards, Guides and Recom-
biodiesel derives approximately 10% of its mass from the
mendations issued by the World Trade Organization Technical
reacted alcohol. The alcohol used in the reaction may or may
Barriers to Trade (TBT) Committee.
not come from renewable resources.
1 2
This test method is under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Subcommittee D02.07 on Flow Properties. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Jan. 1, 2021. Published January 2021. Originally the ASTM website.
approved in 1995. Last previous edition approved in 2020 as D5772–20. DOI: Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
10.1520/D5772-21. U.K., http://www.energyinst.org.uk.
*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
D5772 − 21
3.1.2 biodiesel blend (BXX), n—a homogeneous mixture of 0.1°C resolution. Should the user wish to provide results with
hydrocarbon oils and mono-alkyl esters of long chain fatty a similar format to Test Method D2500, then this calculation
acids. canbeperformed.Someapparatuscanperformthiscalculation
3.1.2.1 Discussion—In the abbreviation, BXX, the XX rep- automatically.
resents the volume percentage of biodiesel fuel in the blend.
4. Summary of Test Method
3.1.2.2 Discussion—The mono-alkyl esters of long chain
fattyacids(thatis,biodiesel)usedinthemixtureshallmeetthe 4.1 After insertion of the specimen into the apparatus and
requirements of Specification D6751. initiation of the program, the prescribed specimen test cell
3.1.2.3 Discussion—Diesel fuel, fuel oil, and non-aviation (Annex A1) is heated and then linearly cooled at a specified
rate (11.6). The specimen is continuously monitored by an
gas turbine oil are examples of hydrocarbon oils.
opposingopticallightbarrier(AnnexA1andFig.A1.3)forthe
3.1.3 biodiesel fuel, n—synonym for biodiesel.
crystal structure formation.The temperature, when the crystal-
3.1.4 cloud point, n—in petroleum products and biodiesel
lization of the wax in the specimen is detected by the optical
fuels, the temperature of a liquid specimen when the smallest
barrier, is recorded with a resolution of 0.1°C. The specimen
observable cluster of wax crystals first occurs upon cooling
is then heated to the original starting temperature.
under prescribed conditions.
3.1.4.1 Discussion—The cloud point occurs when the tem- 5. Significance and Use
perature of the specimen is low enough to cause wax crystals
5.1 For petroleum products and diesel fuels, the cloud point
to precipitate. In a homogeneous liquid, the cloud is always
is an index of the lowest temperature of its utility for certain
noted first at the location in the specimen where the specimen
applications.Waxcrystalsofsufficientquantitycanplugfilters
temperatureisthelowest.Thecloudpointisthetemperatureat
used in some fuel systems.
whichthecrystalsfirstoccur,regardlessoftheirlocationinthe
5.2 Petroleum blending operations require precise measure-
specimen, and not after extensive crystallization has taken
ment of the cloud point.
place. The wax crystals that precipitate at lower temperatures
are typically, but not excluded to, straight-chain hydrocarbons 5.3 This test method can determine the temperature of the
and lipids.
testspecimenatwhichwaxcrystalshaveformedsufficientlyto
3.1.4.2 Discussion—The purpose of the cloud point method be observed as a cloud, with a resolution of 0.1°C.
is to detect the presence of the wax crystals in the specimen;
5.4 This test method provides results that when rounded to
however, trace amounts of water and inorganic compounds
the next lower integer are equivalent to Test Method D2500.
may also be present.The intent of the cloud point method is to
5.5 This test method is more precise than Test Method
capturethetemperatureatwhichtheliquidfuelinthespecimen
D2500.
begins to change from a single liquid phase to a two-phase
system containing solid and liquid. It is not the intent of this
6. Apparatus
test method to monitor the phase transition of the trace
6.1 Automatic Apparatus —The automatic cloud point ap-
components, such as water.
paratus described in Annex A1 consists of a microprocessor-
3.2 Definitions of Terms Specific to This Standard:
controlled measuring unit that is capable of heating, cooling,
3.2.1 automatic cloud point, n—the temperature of a speci-
optically observing the appearance of the automatic cloud
men when the appearance of the cloud is determined under the
point, and recording the temperature of the specimen. The
conditions of this test method.
apparatus shall be equipped with a digital display, cooling/
3.2.1.1 Discussion—The cloud point in this test method is
heating block assembly, optical light barrier assembly, and a
determined by an automatic instrument using an optical device
testcelloftheapproximatedimensionslistedinAnnexA1,and
for detection of the crystal formation. The apparatus and the
contain a temperature measuring device.
conditionsaredifferentfromthoseestablishedforTestMethod
6.2 Beaker, glass or plastic (disposable) (50mL), for con-
D2500,although,accordingtointerlaboratoryexamination,the
taining the sample prior to introduction into the test cell.
results have been determined to be equivalent to Test Method
D2500.
6.3 Circulating Bath, a refrigeration unit equipped with a
circulating pump capable of maintaining a temperature at least
3.2.2 linear cooling rate method, n—in cloud point test
20°C lower than the lowest expected cloud point to be
methods, test procedure using prescribed cooling rate, speci-
measured.
men receptacle, and optical system for detection of crystal
formation.
7. Reagents and Materials
3.2.2.1 Discussion—The prescribed cooling rate is de-
7.1 Cleaning Solvents, suitable for cleaning and drying the
scribed in 11.6; the specimen receptacle is described in Annex
test cell, such as petroleum naphtha and acetone. (Warning—
A1, and the optical system for the detection of crystal forma-
tion is described in Annex A1.
The sole source of supply of the Herzog Model SC 815 and SC 819 known to
3.2.3 D2500/IP 219 equivalent cloud point, n—thetempera-
the committee at this time is Walter Herzog, Lauda, Germany. If you are aware of
ture of a specimen, in integers, calculated by rounding the
alternative suppliers, please provide this information to ASTM International
results of this test method to the next lower integer.
Headquarters.Your comments will receive careful consideration at a meeting of the
3.2.3.1 Discussion—This test method produces results with responsible technical committee, which you may attend.
D5772 − 21
Flammable.Liquidcauseseyeburns.Vaporisharmful.Maybe expected cloud point. The lowest starting temperature that can
fatal or cause blindness if swallowed or inhaled.) be programmed is 20°C.
7.2 Methyl Alcohol, anhydrous, for use as cooling medium 11.5 When the expected cloud point is not known, preselect
in circulating bath. a starting temperature of 40°C. The apparatus automatically
heatsthetestspecimentoapproximately40°Cwhenastarting
7.3 Lint-free filter paper may be used as a drying medium.
temperature is not selected. When the expected cloud point is
not known and the sample needs to be heated before transfer-
8. Sampling
ringintothetestspecimenbeaker,preselectastartingtempera-
8.1 Obtain a sample in accordance with Practice D4057 or
ture of 70°C.
D4177.
11.6 A portion of the sample is drawn into the test cell.
8.2 Samples of very viscous materials may be warmed until
Initially, the specimen is heated to 40°C or to a starting
theyarereasonablyfluidbeforetheyaresampled.However,no
temperature preselected by the operator between 20°C and
sample should be heated more than absolutely necessary.
70°C. The flow of the cooling fluid from the circulating bath
8.3 The sample shall not be heated above 70°C. When the isthenr
...

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: D5772 − 20 D5772 − 21
Designation: IP 445/09
Standard Test Method for
Cloud Point of Petroleum Products and Liquid Fuels (Linear
Cooling Rate Method)
This standard is issued under the fixed designation D5772; 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.
INTRODUCTION
This test method describes an alternative procedure for the determination of cloud point of
petroleum products of Test Method D2500/IP 219 using an automatic apparatus. The temperature
results from this test method have been found to be equivalent to Test Method D2500/IP 219. When
specification requires Test Method D2500/IP 219, do not substitute this test method or any other
method without obtaining comparative data and agreement from the specifier.
1. Scope*
1.1 This test method covers the description of 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 using a linear cooling rate.
1.2 This test method covers the range of temperatures from −60 °C to 49 °C with temperature resolution of 0.1 °C, however, the
range of temperatures included in the 1997 interlaboratory cooperative test program only covered the temperature range of –56 °C
to +34 °C.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.5 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:
D2500 Test Method for Cloud Point of Petroleum Products and Liquid Fuels
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 June 1, 2020Jan. 1, 2021. Published June 2020January 2021. Originally approved in 1995. Last previous edition approved in 20172020 as
D5772 – 17.D5772 – 20. DOI: 10.1520/D5772-20. 10.1520/D5772-21.
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
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5772 − 21
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6751 Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
2.2 Energy Institute Standard:
IP 219 Test Method for Cloud Point of Petroleum Products
3. Terminology
3.1 Definitions:
3.1.1 biodiesel, n—fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats,
designated B100.
3.1.1.1 Discussion—
Biodiesel is typically produced by a reaction of a vegetable oil or animal fat with an alcohol such as methanol or ethanol in the
presence of a catalyst to yield mono-alkyl esters and glycerin, which is removed. The finished biodiesel derives approximately
10 % of its mass from the reacted alcohol. The alcohol used in the reaction may or may not come from renewable resources.
3.1.2 biodiesel blend, blend (BXX), n—blend of biodiesel fuel with diesel fuels and fuel oils.a homogeneous mixture of
hydrocarbon oils and mono-alkyl esters of long chain fatty acids.
3.1.2.1 Discussion—
In the abbreviation, BXX, the XX represents the volume percentage of biodiesel fuel in the blend.
3.1.2.2 Discussion—
The mono-alkyl esters of long chain fatty acids (that is, biodiesel) used in the mixture shall meet the requirements of Specification
D6751.
3.1.2.3 Discussion—
Diesel fuel, fuel oil, and non-aviation gas turbine oil are examples of hydrocarbon oils.
3.1.3 biodiesel fuel, n—synonym for biodiesel.
3.1.4 cloud point, n—in petroleum products and biodiesel fuels, the temperature of a liquid specimen when the smallest observable
cluster of wax crystals first occurs upon cooling under prescribed conditions.
3.1.4.1 Discussion—
The cloud point occurs when the temperature of the specimen is low enough to cause wax 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 wax crystals that precipitate at lower temperatures are typically, but not excluded to,
straight-chain hydrocarbons and lipids.
3.1.4.2 Discussion—
The purpose of the cloud point method is to detect the presence of the wax crystals in the specimen; however, trace amounts of
water and inorganic compounds may also be present. The intent of the cloud point method is to capture the temperature at which
the liquid fuel in the specimen begins to change from a single liquid phase to a two-phase system containing solid and liquid. It
is not the intent of this test method to monitor the phase transition of the trace components, such as water.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 automatic cloud point, n—the temperature of a specimen when the appearance of the cloud is determined under the
conditions of this test method.
3.2.1.1 Discussion—
The cloud point in this test method is determined by an automatic instrument using an optical device for detection of the crystal
formation. The apparatus and the conditions are different from those established for Test Method D2500, although, according to
interlaboratory examination, the results have been determined to be equivalent to Test Method D2500.
3.2.2 linear cooling rate method, n—in cloud point test methods, test procedure using prescribed cooling rate, specimen receptacle,
and optical system for detection of crystal formation.
3.2.2.1 Discussion—
The prescribed cooling rate is described in 11.6; the specimen receptacle is described in Annex A1, and the optical system for the
detection of crystal formation is described in Annex A1.
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.uk.
D5772 − 21
3.2.3 D2500/IP 219 equivalent cloud point, n—the temperature of a specimen, in integers, calculated by rounding the results of
this test method to the next lower integer.
3.2.3.1 Discussion—
This test method produces results with 0.1 °C resolution. Should the user wish to provide results with a similar format to Test
Method D2500, then this calculation can be performed. Some apparatus can perform this calculation automatically.
4. Summary of Test Method
4.1 After insertion of the specimen into the apparatus and initiation of the program, the prescribed specimen test cell (Annex A1)
is heated and then linearly cooled at a specified rate (11.6). The specimen is continuously monitored by an opposing optical light
barrier (Annex A1 and Fig. A1.3) for the crystal structure formation. The temperature, when the crystallization of the wax in the
specimen is detected by the optical barrier, is recorded with a resolution of 0.1 °C. The specimen is then heated to the original
starting temperature.
5. Significance and Use
5.1 For petroleum products and diesel fuels, the cloud point is an index of the lowest temperature of its utility for certain
applications. Wax crystals of sufficient quantity can plug filters used in some fuel systems.
5.2 Petroleum blending operations require 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 when rounded to the next lower integer are equivalent to Test Method D2500.
5.5 This test method is more precise than Test Method D2500.
6. Apparatus
6.1 Automatic Apparatus —The automatic cloud point apparatus described in Annex A1 consists of a microprocessor-controlled
measuring unit that is capable of heating, cooling, optically observing the appearance of the automatic cloud point, and recording
the temperature of the specimen. The apparatus shall be equipped with a digital display, cooling/heating block assembly, optical
light barrier assembly, and a test cell of the approximate dimensions listed in Annex A1, and contain a temperature measuring
device.
6.2 Beaker, glass or plastic (disposable) (50 mL), for containing the sample prior to introduction into the test cell.
6.3 Circulating Bath, a refrigeration unit equipped with a circulating pump capable of maintaining a temperature at least 20 °C
lower than the lowest expected cloud point to be measured.
7. Reagents and Materials
7.1 Cleaning Solvents, suitable for cleaning and drying the test cell, such as petroleum naphtha and acetone. (Warning—
Flammable. Liquid causes eye burns. Vapor is harmful. May be fatal or cause blindness if swallowed or inhaled.)
7.2 Methyl Alcohol, anhydrous, for use as cooling medium in circulating bath.
7.3 Lint-free filter paper may be used as a drying medium.
The sole source of supply of the Herzog Model SC 815 and SC 819 known to the committee at this time is Walter Herzog, Lauda, Germany. 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.
D5772 − 21
8. Sampling
8.1 Obtain a sample in accordance with Practice D4057 or D4177.
8.2 Samples of very viscous materials may be warmed until they are reasonably fluid before they are sampled. However, no sample
should be heated more than absolutely necessary.
8.3 The sample shall not be heated above 70 °C. When the sample is heated above 70 °C, allow the sample to cool below 70 °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 oil is perfectly clear. Make such filtration at a temperature at least 14 °C above the expected cloud point.
NOTE 1—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
...