ASTM D7683-21

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Designation: D7683 − 20 D7683 − 21
Standard Test Method for
Cloud Point of Petroleum Products and Liquid Fuels (Small
Test Jar Method)
This standard is issued under the fixed designation D7683; 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*
1.1 This test method covers the determination of the cloud point of petroleum products, biodiesel, and biodiesel blends that are
transparent in layers 40 mm in thickness, using an automatic instrument.
1.2 The measuring range of the apparatus is from –65 °C to +51 °C, however the precision statements were derived only from
samples with cloud point temperatures from –50 °C to +6 °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
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
D6751 Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
2.2 Energy Institute Standards:
IP219 Test Method for Cloud Point of Petroleum Products
3. Terminology
3.1 Definitions:
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 2011. Last previous edition approved in 20172020 as
D7683 – 17.D7683 – 20. DOI: 10.1520/D7683-20.10.1520/D7683-21.
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.
*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
D7683 − 21
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.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 small test jar method, n—in cloud point test methods, automatic test procedure using a small sample size, prescribed cooling
rate, specimen receptacle, and optical system for detection of crystal formation.
3.2.1.1 Discussion—
The prescribed cooling rate is described in 11.4, the specimen receptacle is described in 6.3, and the optical system for detection
of crystal formation is described in A1.2.3.
3.2.2 D2500/IP219 equivalent cloud point, n—temperature of a specimen, in integers, calculated by applying a bias and rounding
the results of this test method to the next lower integer (see 12.2).
3.2.2.1 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 inserting the glass test jar containing the specimen into the automatic apparatus and initiating the test program, the
specimen is heated, if necessary, to the designated temperature and then cooled by prescribed rates. (See 11.4.) The test specimen
is continuously monitored for appearance of hydrocarbon crystals with a light emitter and a light receiver through coaxial-type
optical fibers. (See A1.2.3.) When the crystallization in the specimen is detected by the optical system, the temperature is recorded
to 0.1 °C resolution. The specimen is then heated to facilitate the start of the next test.
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 precise measurement of the cloud point.
D7683 − 21
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 corrected for bias and rounded to the next lower integer (see 12.2), have been
found equivalent to Test Method D2500.
5.5 This test method determines the cloud point in a shorter time period than required by Test Method D2500.
6. Apparatus
6.1 Automatic Apparatus—The automatic cloud point apparatus described in this test method is a microprocessor-controlled
apparatus that is capable of heating and cooling a test specimen at prescribed rates, optically observing the first appearance of
hydrocarbon wax crystals, and recording the temperature of the test specimen. A detailed description of the apparatus is provided
in Annex A1.
6.2 Temperature-Measuring Device—The temperature-measuring device in the specimen chamber shall be capable of measuring
the temperature from –65 °C to 51 °C at a resolution of 0.1 °C.
6.3 Test Jar—Clear, cylindrical borosilicate glass with a flat bottom with an approximate capacity of 12 mL. Approximately 4.5
mL of sample specimen is contained when filled to the scribed line. During the test, the test jar is fitted with a test jar cap assembly
on its top. See A1.1.2 for more details on the test jar.
6.4 Metallic Block Bath—Metallic block with a cylindrical hole to fit the test jar. The metallic block assembly shall have a
provision for cooling/heating. A temperature sensor is embedded in the metallic block to monitor its temperature.
7. Reagents and Materials
7.1 Cleaning Agents—Capable of cleaning and drying the test jar and test jar cap assembly, after each test. Chemical agents such
as alcohol and petroleum-based solvents have been found suitable to use. (Warning—Flammable.) (Warning— May be harmful
by itself or when evaporated.)
8. Sampling
8.1 Obtain a sample in accordance with Practice D4057 or by Practice D4177.
8.2 A minimum volume of 4.5 mL of sample is required for each test.
8.3 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 is absolutely necessary to facilitate pouring the sample into the instrument test jar. (Warning—
Exercise care when selecting the preheating temperature. Samples which are fluid at ambient room temperature can also have a
low flash point. Use higher preheating temperatures only on samples known to be solid near ambient room temperature.)
8.4 The sample shall not be heated above 60 °C. When the sample is heated above 60 °C allow the sample to cool below 60 °C
before filtering or inserting into the apparatus.
8.5 When moisture is present, 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
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