ASTM D7397-21

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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 − 20 D7397 − 21
Standard Test Method for
Cloud Point of Petroleum Products and Liquid Fuels
(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*
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, 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
D5773 Test Method for Cloud Point of Petroleum Products and Liquid Fuels (Constant Cooling Rate Method)
D6751 Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels
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:
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 2007. Last previous edition approved in 20172020 as
D7397 – 17.D7397 – 20. DOI: 10.1520/D7397-20. 10.1520/D7397-21.
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
D7397 − 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 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 °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.
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, which you may attend.
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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 30 °C 6 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 15 °C 6 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 6 °C
6 3 °C ⁄min. When crystals first appear under this slower cooling rate, the temperature of the specimen is recorded to 0.1 °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.
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.
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 3 °C to 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 °C to +20 °C at a resolution of 0.1 °C.
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.
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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 descript
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