ASTM D5773-21

Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Constant Cooling Rate 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 D2500.
Note 1: This is based on the Test Method D2500 equivalent cloud point in which the 0.1 °C result is rounded to the next lower integer.  
5.5 This test method determines the cloud point in a shorter period of time than Test Method D2500.
Note 2: In cases of samples with cloud points near ambient temperatures, time savings may not be realized.  
5.6 This test method eliminates most of the operator time required of Test Method D2500.  
5.7 This test method does not require the use of a mechanical refrigeration apparatus.
Note 3: In certain cases of high ambient temperature, a source of cooling water may be required to measure low-temperature cloud points (see 7.1).
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 using a constant 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: 75.160.20 - Liquid fuels
• 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 D5773-21, titled Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Constant Cooling Rate Method), is a globally recognized test procedure for determining the cloud point of petroleum products and biodiesel fuels. This standard, developed by ASTM International, specifies an automated method using a constant cooling rate and optical detection to identify the temperature at which wax crystals first appear in liquid fuels. Cloud point is a critical quality indicator in fuel production, blending, and practical use, as wax crystal formation can impede flow and cause filter plugging in engines and fuel systems.

Key Topics

• Cloud Point Determination: Measures the lowest temperature at which waxing becomes detectable.
• Automatic Instrumentation: Employs an automatic apparatus with a Peltier device for temperature control, optical detectors for cloud detection, and digital result reporting.
• Test Range and Resolution: Covers temperatures from −60 °C to +49 °C with a high resolution of 0.1 °C.
• Sample Requirements: Applicable to petroleum products and biodiesel fuels that are transparent in layers up to 40 mm.
• Comparison to Manual Methods: Provides results equivalent to ASTM D2500 but with improved efficiency and reduced operator involvement.
• Operator Efficiency: The method is less labor-intensive and faster than traditional manual tests.
• No Refrigeration Necessary: Eliminates the need for bulky mechanical refrigeration systems.

Applications

Fuel Quality Control

• Petroleum and Diesel Fuels: Ensures suitability for low-temperature climates; essential for preventing wax-induced filter plugging.
• Biodiesel and Blends: Used to assess and optimize the low-temperature operability of biodiesel and biodiesel blends with diesel.
• Blending Operations: Supports precise formulation by identifying the cloud point of blend stocks and finished fuels.

Laboratory and Industrial Use

• Quality Assurance: Integral for refineries, fuel distributors, and testing laboratories to validate fuel compliance with industry specifications.
• Research and Development: Facilitates the development of new fuel formulations and additives to improve cold flow properties.

Regulatory Compliance

• Specification Testing: Meets requirements for reporting cloud point results in fuel specifications for transportation and heating fuels.
• Global Acceptance: Conforms to internationally recognized testing practices and ensures consistency across laboratories and jurisdictions.

Related Standards

• ASTM D2500: Standard Test Method for Cloud Point of Petroleum Products and Liquid Fuels - equivalent results to D5773 but uses a manual observation approach.
• 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.
• Energy Institute IP 219: Test Method for Cloud Point of Petroleum Products.
• Energy Institute IP 446: Determination of the Cloud Point of Petroleum Products - Automatic Constant Cooling Rate Method.

Practical Value

Adopting ASTM D5773-21 ensures laboratories, refineries, and fuel distributors can rapidly and reliably determine the cloud point of petroleum-based and biodiesel fuels with minimal operator intervention. This results in improved throughput, better data consistency, and enhanced product quality control, especially for fuels intended for cold climate use. The automated approach significantly reduces manual labor and the risk of human error, making this method a preferred choice for modern fuel testing and compliance programs.

Keywords: ASTM D5773, cloud point, petroleum products, biodiesel, liquid fuels, automatic test method, constant cooling rate, fuel quality, low temperature operability, wax crystals.

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: D5773 − 21
Designation: IP 446/09
Standard Test Method for
Cloud Point of Petroleum Products and Liquid Fuels
(Constant Cooling Rate Method)
This standard is issued under the fixed designation D5773; 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 productsTest MethodD2500/IP219 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 determination of the cloud
D2500Test Method for Cloud Point of Petroleum Products
point of petroleum products and biodiesel fuels that are
and Liquid Fuels
transparent in layers 40mm in thickness by an automatic
D4057Practice for Manual Sampling of Petroleum and
instrument using a constant 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
IP 219Test Method for Cloud Point of Petroleum Products
standard. No other units of measurement are included in this
IP 446Determination of the Cloud Point of Petroleum
standard.
Products—Automatic Constant Cooling Rate Method
1.4 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.1 Definitions:
priate safety, health, and environmental practices and deter-
3.1.1 biodiesel, n—fuel comprised of mono-alkyl esters of
mine the applicability of regulatory limitations prior to use.
long chain fatty acids derived from vegetable oils or animal
1.5 This international standard was developed in accor-
fats, designated B100.
dance with internationally recognized principles on standard- 3.1.1.1 Discussion—Biodiesel is typically produced by a
ization established in the Decision on Principles for the
reactionofavegetableoiloranimalfatwithanalcoholsuchas
Development of International Standards, Guides and Recom-
methanol or ethanol in the presence of a catalyst to yield
mendations issued by the World Trade Organization Technical
mono-alkylestersandglycerin,whichisremoved.Thefinished
Barriers to Trade (TBT) Committee.
biodiesel derives approximately 10% of its mass from the
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 D5773–20. DOI: Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
10.1520/D5773-21. 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
D5773 − 21
reacted alcohol. The alcohol used in the reaction may or may figured in such a way that it will transfer heat to or away from
not come from renewable resources. a test specimen dependent on the direction of electric current
applied to the device.
3.1.2 biodiesel blend (BXX), n—a homogeneous mixture of
hydrocarbon oils and mono-alkyl esters of long chain fatty
3.2.4 D2500/IP 219 equivalent cloud point, n—thetempera-
acids.
ture of a specimen, in integers, calculated by rounding the
3.1.2.1 Discussion—In the abbreviation, BXX, the XX rep-
results of this test method to the next lower integer.
resents the volume percentage of biodiesel fuel in the blend.
3.2.4.1 Discussion—This test method produces results with
3.1.2.2 Discussion—The mono-alkyl esters of long chain
0.1°C resolution. Should the user wish to provide results with
fattyacids(thatis,biodiesel)usedinthemixtureshallmeetthe
a similar format to Test Method D2500, then this calculation
requirements of Specification D6751.
canbeperformed.Someapparatuscanperformthiscalculation
3.1.2.3 Discussion—Diesel fuel, fuel oil, and non-aviation
automatically.
gas turbine oil are examples of hydrocarbon oils.
3.1.3 biodiesel fuel, n—synonym for biodiesel.
4. Summary of Test Method
3.1.4 cloud point, n—in petroleum products and biodiesel
4.1 A prescribed specimen (11.5) is cooled by a Peltier
fuels, the temperature of a liquid specimen when the smallest
device (A1.1) at a constant rate of 1.5°C⁄min 6 0.1°C⁄min
observable cluster of wax crystals first occurs upon cooling
while continuously being illuminated by a light source
under prescribed conditions.
(A1.1.4). The specimen is continuously monitored by an array
3.1.4.1 Discussion—The cloud point occurs when the tem-
of optical detectors (A1.1.5, Fig.A1.1) for the first appearance
perature of the specimen is low enough to cause wax crystals
of a cloud of wax crystals. The detectors are sufficient in
to precipitate. In a homogeneous liquid, the cloud is always
number to ensure that any solid-phase hydrocarbon crystals
noted first at the location in the specimen where the specimen
that may form are detected. The temperature at which the
temperatureisthelowest.Thecloudpointisthetemperatureat
appearance of a cloud of wax crystals is first detected in the
whichthecrystalsfirstoccur,regardlessoftheirlocationinthe
specimen is recorded to 0.1°C resolution. When the recorded
specimen, and not after extensive crystallization has taken
temperatureisroundedtothenextlowerintegertemperature,it
place. The wax crystals that precipitate at lower temperatures
is designated as the D2500/IP219 equivalent cloud point per
are typically, but not excluded to, straight-chain hydrocarbons
Test Method D5773.
and lipids.
3.1.4.2 Discussion—The purpose of the cloud point is to
5. Significance and Use
measure the wax crystals in the specimen; however, trace
amounts of water and inorganic compounds may also be
5.1 The cloud point of petroleum products and biodiesel
present.Theintentofthecloudpointmeasurementistocapture
fuels is an index of the lowest temperature of their utility for
thetemperatureatwhichtheliquidfuelinthespecimenbegins
certain applications. Wax crystals of sufficient quantity can
to change from a single liquid phase to a two-phase system
plug filters used in some fuel systems.
containing solid and liquid. It is not the intent of this test
methodtomonitorthephasetransitionofthetracecomponents
5.2 Petroleum blending operations require a precise mea-
such as water.
surement of the cloud point.
3.2 Definitions of Terms Specific to This Standard:
5.3 This test method can determine the temperature of the
3.2.1 automatic cloud point, n—the temperature of a
testspecimenatwhichwaxcrystalshaveformedsufficientlyto
specimen, when the appearance of the cloud is determined
be observed as a cloud with a resolution of 0.1°C.
under the conditions of this test method.
5.4 This test method provides results that are equivalent to
3.2.1.1 Discussion—The cloud point in this test method is
Test Method D2500.
determinedbyanautomaticinstrumentusinganopticaldevice
for detection of the crystal formation. The apparatus and the
NOTE 1—This is based on the Test Method D2500 equivalent cloud
conditionsaredifferentfromthoseestablishedforTestMethod
point in which the 0.1°C result is rounded to the next lower integer.
D2500, although according to interlaboratory examination, the
5.5 This test method determines the cloud point in a shorter
results have been determined to be equivalent to Test Method
period of time than Test Method D2500.
D2500.
3.2.2 constant cooling rate method, n—in cloud point test
NOTE 2—In cases of samples with cloud points near ambient
temperatures, time savings may not be realized.
methods, test procedure using prescribed cooling rate, speci-
men receptacle, and optical system for detection of crystal
5.6 This test method eliminates most of the operator time
formation.
required of Test Method D2500.
3.2.2.1 Discussion—The prescribed cooling rate is de-
5.7 This test method does not require the use of a mechani-
scribed in 4.1, the specimen receptacle is described in Annex
A1, and the optical system for the detection of crystal forma- cal refrigeration apparatus.
tion is described in Annex A1.
NOTE 3—In certain cases of high ambient temperature, a source of
3.2.3 Peltier device, n—a solid-state thermoelectric device
cooling water may be required to measure low-temperature cloud points
constructed with dissimilar semiconductor materials and con- (see 7.1).
D5773 − 21
6. Apparatus 7.4 Cotton Swabs—Plastic or paper shaft cotton swabs used
4 to clean the sample cup. (Warning—The use of swabs with
6.1 Automatic Apparatus —The automatic cloud point ap-
wooden shafts may damage the mirrored surface of the
paratusdescribedinthistestmethodconsistsofatestchamber
specimen cup.)
controlled by a microprocessor that is capable of controlling
the heating and cooling of the test specimen, optically observ-
8. Sampling
ing the first appearance of a cloud of wax crystals and
8.1 Obtain a sample in accordance with Practice D4057 or
recording the temperature of the specimen described in detail
D4177.
in Annex A1.
8.2 Samples of very viscous materials may be warmed until
6.2 The apparatus shall be equipped with a specimen cup,
they are reasonably fluid before they are tested. However, no
optical detector array, light source, digital display, Peltier
sample should be heated more than absolutely necessary.
device, and a specimen temperature measuring device.
8.3 The sample shall not be heated above 70°C. When the
6.3 ThePeltierdeviceshallbecapableofheatingorcooling
sample is heated above 70°C, allow the sample to cool below
the test specimen at a constant rate of 1.5 °C⁄min 6
70°C before filtering or inserting into the apparatus.
0.1°C⁄min.
8.4 When moisture is present in the sample, remove the
6.4 The temperature-measuring device in the specimen cup
moisture by a method such as filtration through dry, lint-free
shall be capable of measuring the temperature of the test
filter paper until the oil is perfectly clear, but make such
specimen from −40°C to +70°C at a resolution of 0.1°C.
filtration at a temperature at least 14°C above the expected
6.5 The apparatus shall be equipped with fittings to permit
cloud point.
the circulation of a liquid cooling medium, if required, to
remove heat generated by the Peltier device and other elec- NOTE 5—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
tronic components of the apparatus.
interfere with the detection of the wax cloud.
NOTE 4—Some apparatus are designed to use ambient air as a cooling
medium. In such cases, a built-in fan is available to provide circulation of
9. Preparation of Apparatus
air and there is no need for fittings as described for a liquid cooling
9.1 Prepare the instrument for operation in accordance with
medium. The function of the cooling medium is to remove heat from the
electronic components. The choice of the cooling medium has no impact
the manufacturer’s instructions.
whatsoever on the test results.
9.2 Make liquid cooling medium connections if required
6.6 The apparatus shall be equipped with fittings to permit
(see Note 4) and ensure that they do not leak.
the circulation of purge gas to purge the test chamber contain-
9.3 Makepurgegasconnectionsandensurethattheydonot
ing the specimen cup of any atmospheric moisture.
leak.
7. Reagents and Materials
9.4 Turnontheliquidcoolingmediumifrequired(seeNote
4).
7.1 Cooling Medium—Air, tap water, or other liquid heat
exchange medium sufficient to remove heat generated by the
9.5 Turn on the purge gas.
Peltier device and other electronic components from the
9.6 Turnonthemainpowerswitchoftheanalyzer.Afterthe
apparatus. To achieve specimen cooling to −40°C, supply
automatic self diagnostics startup sequence is completed, the
circulation of liquid cooling medium at +25°C or lower to the
instrument will display a READY message.
apparatus. For an apparatus which relies on air as cooling
medium,theambientairtemperaturehastobebelow+30°Cto
10. Calibration and Standardization
achieve specimen cooling to −40°C.
10.1 Ensure that all of the manufacturer’s instructions for
7.2 Purge Gas—A gas such as air, nitrogen, helium, or
calibrating, checking, and operating the apparatus are fol-
argonwithadewpointbelowthelowestoperatingtemperature
lowed.
of the analyzer. (Warning—Compressed gas under high pres-
10.2 Asample with a mutually agreed upon cloud point can
sure.) (Warning—Inert gas can be an asphyxiant when in-
be used to verify performance of the apparatus.
haled.)
7.3 Precision Volume Dispensing Device, capable of dis-
11. Procedure
pensing 0.15mL 6 0.01mL of sample.
11.1 Inspect the specimen cup to ensure it is clean and dry.
If not, clean the cup (see 11.3).
11.2 Deliver 0.15mL 6 0.01mL of specimen into the
ThesolesourceofsupplyofthePhaseTechnologyCloudPointAnalyzermodel
series 10, 30, 70, 70V, and 70X known to the committee at this time is Phase
specimen cup. Pipette, syringe, or precision positive-
Technology, 11168 Hammersmith Gate, Richmond, B.C. Canada V7A 5H8. The
displacement devices are suitable for use in delivering the
various model series mentioned above are differentiated by their cooling capacities
specimen.
and user interfaces; however, all o
...

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: D5773 − 20 D5773 − 21
Designation: IP 446/09
Standard Test Method for
Cloud Point of Petroleum Products and Liquid Fuels
(Constant Cooling Rate Method)
This standard is issued under the fixed designation D5773; 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 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 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 constant 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
ɛ1
D5773 – 17D5773 – 20. . DOI: 10.1520/D5773-20.10.1520/D5773-21.
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
D5773 − 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
IP 446 Determination of the Cloud Point of Petroleum Products—Automatic Constant Cooling Rate Method
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 is to measure the wax crystals in the specimen; however, trace amounts of water and inorganic
compounds may also be present. The intent of the cloud point measurement 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 constant 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—
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.uk.
D5773 − 21
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.
3.2.3 Peltier device, n—a 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.
3.2.4 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.
3.2.4.1 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 A prescribed specimen (11.5) is cooled by a Peltier device (A1.1) at a constant rate of 1.5 °C ⁄min 6 0.1 °C ⁄min while
continuously being illuminated by a light source (A1.1.4). The specimen is continuously monitored by an array of optical detectors
(A1.1.5, Fig. A1.1) for the first appearance of a cloud of wax crystals. The detectors are sufficient in number to ensure that any
solid-phase hydrocarbon crystals that may form are detected. The temperature at which the appearance of a cloud of wax crystals
is first detected in the specimen is recorded to 0.1 °C resolution. When the recorded temperature is rounded to the next lower
integer temperature, it is designated as the D2500/IP 219 equivalent cloud point per Test Method D5773.
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.
5.4 This test method provides results that are equivalent to Test Method D2500.
NOTE 1—This is based on the Test Method D2500 equivalent cloud point in which the 0.1 °C result is rounded to the next lower integer.
5.5 This test method determines the cloud point in a shorter period of time than Test Method D2500.
NOTE 2—In cases of samples with cloud points near ambient temperatures, time savings may not be realized.
5.6 This test method eliminates most of the operator time required of Test Method D2500.
5.7 This test method does not require the use of a mechanical refrigeration apparatus.
NOTE 3—In certain cases of high ambient temperature, a source of cooling water may be required to measure low-temperature cloud points (see 7.1).
6. Apparatus
6.1 Automatic Apparatus —The automatic cloud point apparatus described in this test method consists of a test chamber controlled
The sole source of supply of the Phase Technology Cloud Point Analyzer model series 10, 30, 70, 70V, and 70X known to the committee at this time is Phase Technology,
11168 Hammersmith Gate, Richmond, B.C. Canada V7A 5H8. The various model series mentioned above are differentiated by their cooling capacities and user interfaces;
however, all of them are capable of covering the entire temperature range specified in the scope. 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.
D5773 − 21
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 cup, optical detector array, light source, 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 constant rate of 1.5 °C ⁄min 6 0.1 °C ⁄min.
6.4 The temperature-measuring device in the specimen cup shall be capable of measuring the temperature of the test specimen
from −40 °C to +70 °C at a resolution of 0.1 °C.
6.5 The apparatus shall be equipped with fittings to permit the circulation of a liquid cooling medium, if required, to remove heat
generated by the Peltier device and other electronic components of the apparatus.
NOTE 4—Some apparatus are designed to use ambient air as a cooling medium. In such cases, a built-in fan is available to provide circulation of air and
there is no need for fittings as described for a liquid cooling medium. The function of the cooling medium is to remove heat from the electronic
components. The choice of the cooling medium has no impact whatsoever on the test results.
6.6 The apparatus shall be equipped with fittings to permit the circulation of purge gas to purge the test chamber containing the
specimen cup of any atmospheric moisture.
7. Reagents and Materials
7.1 Cooling Medium—Air, tap water, or other liquid heat exchange medium sufficient to remove heat generated by the Peltier
device and other electronic components from the apparatus. To achieve specimen cooling to −40 °C, supply circulation of liquid
cooling medium at +25 °C or lower to the apparatus. For an apparatus which relies on air as cooling medium, the ambient air
temperature has to be below +30 °C to achieve specimen cooling to −40 °C.
7.2 Purge Gas—A gas such as air, nitrogen, helium, or argon with a dew point below the lowest operating temperature of the
analyzer. (Warning—Compressed gas under high pressure.) (Warning—Inert gas can be an asphyxiant when inhaled.)
7.3 Precision Volume Dispensing Device, capable of dispensing 0.15 mL 6 0.01 mL of sample.
7.4 Cotton Swabs—Plastic or paper shaft cotton swabs used to clean the sample cup. (Warning—The use of swabs with wooden
shafts may damage the mirrored surface of the specimen cup.)
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 tested. 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, but make such filtration at a temperature at least 14 °C above the expected cloud point.
NOTE 5—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.
D5773 − 21
9.2 Make liquid cooling medium connections if required (see Note 4) and ensure that they do not leak.
9.3 Make purge gas connections and ensure that they do not leak.
9.4 Turn on the liquid cooling medium if required (see Note 4).
9.5 Turn on the purge gas.
9.6 Turn on the main power switch of the analyzer. After the automatic self diagnostics startup sequence is completed, the
instrument will display a READY message.
10. Calibration and Standardization
10.1 Ensure that all of the manufacturer’s instructions for calibrating, checking, and operating the appa
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