ASTM D2500-02
(Test Method)Standard Test Method for Cloud Point of Petroleum Products
Standard Test Method for Cloud Point of Petroleum Products
SCOPE
1.1 This test method covers only petroleum products and biodiesel fuels that are transparent in layers 40 mm in thickness, and with a cloud point below 49°C.
Note 1—The interlaboratory program consisted of petroleum products of Test Method D 1500 color of 3.5 and lower. The precisions stated in this test method may not apply to samples with ASTM color higher than 3.5.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Section 7.
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An American National Standard
Designation: D 2500 – 02 British Standard 4458
Designation: 219/82
Standard Test Method for
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Cloud Point of Petroleum Products
This standard is issued under the fixed designation D 2500; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope * name of the test method. The cloud appears when the tempera-
ture of the specimen is low enough to cause wax crystals to
1.1 This test method covers only petroleum products and
form. For many specimens, the crystals first form at the lower
biodiesel fuels that are transparent in layers 40 mm in
circumferential wall of the test jar where the temperature is
thickness, and with a cloud point below 49°C.
lowest. The size and position of the cloud or cluster at the cloud
NOTE 1—The interlaboratory program consisted of petroleum products
point varies depending on the nature of the specimen. Some
of Test Method D 1500 color of 3.5 and lower. The precisions stated in this
samples will form large, easily observable, clusters, while
test method may not apply to samples with ASTM color higher than 3.5.
others are barely perceptible.
1.2 This standard does not purport to address all of the
3.1.1.2 Discussion—Upon cooling to temperatures lower
safety concerns, if any, associated with its use. It is the
than the cloud point, clusters of crystals will grow in multiple
responsibility of the user of this standard to establish appro-
directions; for example, around the lower circumference of the
priate safety and health practices and determine the applica-
test jar, towards the center of the jar, or vertically upwards. The
bility of regulatory limitations prior to use. For specific hazard
crystals can develop into a ring of cloud along the bottom
statements, see Section 7.
circumference, followed by extensive crystallization across the
bottom of the test jar as temperature decreases. Nevertheless,
2. Referenced Documents
the cloud point is defined as the temperature at which the
2.1 ASTM Standards:
crystals first appear, not when an entire ring or full layer of wax
D 1500 Test Method for ASTM Color of Petroleum Prod-
has been formed at the bottom of the test jar.
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ucts (ASTM Color Scale)
3.1.1.3 Discussion—In general, it is easier to detect the
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E 1 Specification for ASTM Thermometers
cloud point of samples with large clusters that form quickly,
2.2 IP Standard:
such as paraffinic samples. The contrast between the opacity of
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Specifications for IP Standard Thermometers
the cluster and the liquid is also sharper. In addition, small
brightly-reflective spots can sometimes be observed inside the
3. Terminology
cluster when the specimen is well illuminated. For other more
3.1 Definitions of Terms Specific to This Standard:
difficult samples, such as naphthenic, hydrocracked, and those
3.1.1 cloud point, n—in petroleum products and biodiesel
samples whose cold flow behavior have been chemically
fuels, the temperature of a liquid specimen when the smallest
altered, the appearance of the first cloud can be less distinct.
observable cluster of wax crystals first appears upon cooling
The rate of crystal growth is slow, the opacity contrast is weak,
under prescribed conditions.
and the boundary of the cluster is more diffuse. As the
3.1.1.1 Discussion—To many observers, the cluster of wax
temperature of these specimens decrease below the cloud
crystals looks like a patch of whitish or milky cloud, hence the
point, the diffuse cluster will increase in size and can form a
general haze throughout. A slight haze throughout the entire
sample, which slowly becomes more apparent as the tempera-
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This test method is under the jurisdiction of ASTM Committee D02 on
ture of the specimen decreases, can also be caused by traces of
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.07 on Flow Properties.
water in the specimen instead of crystal formation (see Note 4).
Current edition approved April 10, 2002. Published July 2002. Originally
With these difficult samples, drying the sample prior to testing
published as D 2500–66. Last previous edition D 2500–99.
2 can eliminate this type of interference.
Annual Book of ASTM Standards, Vol 05.01.
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Annual Book of ASTM Standards, Vol 14.03.
4
Available from Institute for Petroleum, 61 New Cavendish St., London,
England WIM 8AR.
*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.
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