ASTM D7683 - 21

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Designation: 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 appro-

priate safety, health, and environmental practices and deter-

mine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accor-

dance with internationally recognized principles on standard-

ization established in the Decision on Principles for the

Development of International Standards, Guides and Recom-

mendations 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:

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 (BXX), n—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 rep-

resents 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 tem-

perature of the specimen is low enough to cause wax crystals

to precipitate. In a homogeneous liquid, the cloud is always

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 Jan. 1, 2021. Published January 2021. Originally

approved in 2011. Last previous edition approved in 2020 as D7683 – 20. DOI:

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

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.

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 de-

scribed in 11.4, the specimen receptacle is described in 6.3, and

the optical system for detection of crystal formation is de-

scribed 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 hydro-

carbon crystals with a light emitter and a light receiver through

coaxial-type optical ﬁbers. (See A1.2.3.) When the crystalliza-

tion 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 measure-

ment 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 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 appa-

ratus 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 em-

bedded 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 tem-

perature. 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 a tempera-

ture 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 for operation in accordance with

the manufacturer’s instructions.

D7683 − 21

10. Calibration and Standardization

10.1 Ensure that all of the manufacturer’s instructions for

calibrating, checking, and operating the apparatus are fol-

lowed.

10.2 A sample with a well-documented cloud point can be

used to verify the performance of the automatic apparatus.

Alternatively, a sample that has been extensively tested in a

cloud point cross-check program can be used. Such veriﬁcation

materials can also be prepared from intracompany cross-

checks.

11. Procedure

11.1 Pour the sample specimen into the test jar to the scribed

mark. When necessary, heat the sample in a bath or oven until

it is just sufficiently ﬂuid to pour into the test jar. Samples with

an expected cloud point above 36 °C or samples which appear

solid at room temperature can be heated above 45 °C, but they

shall not be heated above 60 °C.

11.2 Insert the charged test jar into the metallic block bath,

and install the test jar cap assembly snugly.

11.3 Enter the expected cloud point and start the operation

of the apparatus according to the manufacturer’s instructions.

From this point on, the apparatus automatically controls the

series of procedures, which includes the sample preheating

function if the apparatus is so programmed prior to the start of

the automatic procedure. (Warning—Exercise care when se-

lecting 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.)

11.4 After the sample preheating is completed, the metallic

block bath is cooled down automatically at a typical rate of

3 °C to 4 °C ⁄min. At a temperature at least 20 °C above the

expected cloud point, the cooling rate slows down to 0.8 °C to

1.1 °C ⁄min. During the cooling, the optical system monitors

for appearance of the crystals.

11.5 In the event a cloud point is detected prematurely

during the fast cooling rate, as determined by the apparatus, the

specimen shall be reheated to a higher temperature, at least

30 °C warmer than the temperature of premature detection, and

then cooled as described in 11.4, while the optical system

monitors for appearance of the crystals.

11.6 At the detection of the cloud point, the specimen

temperature is displayed to the nearest 0.1 °C and held on the

digital display. The metallic block bath starts heating automati-

cally for the next test.

12. Report

12.1 Report the temperature recorded in 11.6 to 0.1 °C as

the cloud point D7683 (Small Test Jar Method).

12.2 When speciﬁed, correct the results recorded in 11.6

with the relative bias in accordance with 13.3, then round to the

next lower integer (a colder temperature) and report as the Test

Method D2500 equivalent cloud point in accordance with Test

Method D7683.

13. Precision and Bias

13.1 Precision—The precision of this test method as deter-

mined by the statistical examination of the interlaboratory test

results is as follows:

13.1.1 Repeatability—The difference between successive

test results, obtained by the same operator using the same

apparatus under constant operating conditions on identical test

material, would in the long run, in the normal and correct

operation of this test method, exceed the following only in one

case in twenty.

1.47 °C, valid range –50 °C to +6 °C

13.1.2 Reproducibility—The difference between two single

and independent test results, obtained by different operators

working in different laboratories on identical test material,

would in the long run, in normal and correct operation of this

test method, exceed the following only in one case in twenty.

2.45 °C, valid range –50 °C to +6 °C

13.2 Bias—Since there is no accepted reference material

suitable for determining the bias for the procedure in this test

method, bias has not been determined.

13.3 Relative Bias—The Degree of Agreement between

results by Test Method D7683 and Test Method D2500/

IP219—Results on the same materials produced by Test

Method D7683 and Test Method D2500 have been assessed in

accordance with procedures outlined in Practice D6708. The

ﬁndings are:

The degree of agreement between results from Test Method

D7683 and Test Method D2500/IP219 can be further improved

by applying the bias correction outlined in Eq 1. Sample-

speciﬁc bias, as deﬁned in Practice D6708, was observed for

some samples after applying the bias correction.

Predicted Y

D2500

5bias 2corrected X

D7683

11.68°C (1)

where:

X= result obtained by Test Method D7683,

and

bias-corrected X = predicted Y= result that would have

been obtained by Test Method D2500/

IP219 on the same sample.

Differences between bias-corrected results from Eq 1 and

Test Method D2500/IP219, for the sample types and property

ranges studied, are expected to exceed the following between

method reproducibility (R

), as deﬁned in Practice D6708,

about 5 % of the time.

53.51 °C (2)

13.4 The precision statements were derived from a 2009

interlaboratory cooperative test program.

Participants ana-

lyzed 21 sample sets comprised of six distillate fuels, six base

oil stocks, three biodiesel (derived from soy, canola, and

tallow), and six blends of biodiesel in distillate fuel represent-

ing B5, B10, and B20 blends. The cloud point temperature

Supporting data have been ﬁled at ASTM International Headquarters and may

be obtained by requesting Research Report RR:D02-1715. Contact ASTM Customer

Service at service@astm.org.

D7683 − 21

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摘要：

ASTM D7683 - 21 是一项由美国材料与试验协会发布的关于用自动气相色谱法测定汽车制动液湿平衡回流沸点的标准试验方法。该标准适用于所有类型的汽车制动液，包括基于乙二醇醚、硅酮及其他合成基液的产品，旨在通过一个更为高效、精确且自动化的气相色谱分析过程，替代传统的手动回流沸点测定方法，以减少人为误差并提高测试一致性。遵循ASTM D7683-21版本的操作规范，能够帮助汽车制造厂、制动液生产商及质量检测机构有效评估制动液在吸收水分后的高温性能表现，其测得的湿平衡回流沸点是衡量制动液抗气阻能

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