ASTM D8420-21

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: D8420 − 21
Standard Test Method for
Wax Appearance Temperature and Wax Disappearance
Temperature of Petroleum Products and Liquid Fuels
This standard is issued under the fixed designation D8420; 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 D4057 Practice for Manual Sampling of Petroleum and
Petroleum Products
1.1 This test method covers the determination of the wax
D4177 Practice for Automatic Sampling of Petroleum and
appearance temperature and the wax disappearance tempera-
Petroleum Products
ture of petroleum products and liquid fuels by an automatic
D5773 Test Method for Cloud Point of Petroleum Products
instrument using optical light scattering detection.
and Liquid Fuels (Constant Cooling Rate Method)
1.2 This test method is applicable to such materials as:
D6300 Practice for Determination of Precision and Bias
crude oil, distillate fuels, residual fuels such as No. 6 Fuel Oil,
Data for Use in Test Methods for Petroleum Products,
marine fuels such as VLSFO, and including mixtures of these
Liquid Fuels, and Lubricants
fuels and liquid biofuels.
1.3 This test method covers the range of temperatures from 3. Terminology
–30 °C to +75 °C with temperature resolution of 0.1 °C.
3.1 Definitions:
1.4 This test method contains interim precision with repeat-
3.1.1 cloud point, n—in petroleum products and biodiesel
ability only; a full ILS will be completed within five years of
fuels, the temperature of a liquid specimen when the smallest
its approval.
observable cluster of wax crystals first occurs upon cooling
under prescribed conditions.
1.5 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
3.2 Definitions of Terms Specific to This Standard:
standard.
3.2.1 wax appearance temperature, WAT, n—when the ap-
pearance of wax crystals in the specimen is determined under
1.6 This standard does not purport to address all of the
the conditions of this test method.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.2.1.1 Discussion—The wax appearance temperature in
priate safety, health, and environmental practices and deter- this test method is determined by an automatic instrument
mine the applicability of regulatory limitations prior to use. using an optical device for detection of the crystal formation.
1.7 This international standard was developed in accor-
3.2.2 wax disappearance temperature, WDT, n—when the
dance with internationally recognized principles on standard-
disappearance of wax crystals is determined under the condi-
ization established in the Decision on Principles for the
tions of this test method.
Development of International Standards, Guides and Recom-
3.2.2.1 Discussion—The wax disappearance temperature in
mendations issued by the World Trade Organization Technical
this test method is determined by an automatic instrument
Barriers to Trade (TBT) Committee.
using an optical device for detection of the crystal formation.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 Aspecimen in a chamber cooled by a Peltier device at a
constant rate of 1.5 °C⁄min 6 0.5 °C⁄min while continuously
being illuminated by a near infrared (NIR) light source. The
This test method is under the jurisdiction of ASTM Committee D02 on
specimen is continuously monitored by an array of optical
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
detectors for the appearance of wax crystals. The detectors are
Subcommittee D02.07 on Flow Properties.
sufficient in number to ensure that any solid phase wax crystals
Current edition approved Nov. 1, 2021. Published December 2021. DOI:
10.1520/D8420-21.
that may form are detected. The temperature at which the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
appearance of wax crystals is detected in the specimen, as
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
determinedbytheapparatus,isrecordedto0.1 °Cresolutionas
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the wax appearance temperature. Once the wax appearance
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8420 − 21
temperature is detected, when the wax disappearance tempera- 7. Reagents and Materials
ture is desired, the specimen is warmed at a constant rate of
7.1 Sample syringe (Luer type), capable of dispensing 3 mL
1.5 °C⁄min 6 0.5 °C⁄min while continuously being illumi-
to 5 mL of sample.
nated by a NIR light source until the crystals in the specimen
7.2 Syringe filter (optional), 2.7 µm disposable syringe filter
disappear. The temperature at which the disappearance of the
(Luer type).
wax crystals is detected in the specimen, as determined by the
apparatus, is recorded as the wax disappearance temperature.
8. Sampling
5. Significance and Use
8.1 Obtain a sample in accordance with Practices D4057 or
5.1 The wax appearance temperature of petroleum products D4177.
and liquid fuels is an indicator of the lowest temperature of
8.2 Samples of very viscous materials may be warmed until
their utility for certain applications. Wax crystals of sufficient
they are reasonably fluid before they are tested. However, no
quantity can plug filters or impede flow in some fuel systems.
sample should be heated more than absolutely necessary.
5.2 The wax disappearance temperature of petroleum prod-
8.3 Thesampleshouldnotbeheatedabove75 °C.Whenthe
ucts and liquid fuels is an indicator of the warmest temperature
sample is heated above 75 °C, allow the sample to cool below
to remove thermal history. Wax crystals of sufficient quantity
75 °C before filtering or inserting into the apparatus.
can plug filters or impede flow in some fuel systems.
8.4 When moisture or particulates, or both, are present in
5.3 NIR light scattering technology is useful for recognition
the sample, remove the moisture by a method, such as
of wax crystal formation in dark and opaque fuels, and the
centrifugation for opaque fuels, or filtration through dry
cloud point in transparent fuels.
lint-free filter paper for transparent fuels until the oil is clear,
5.4 The wax appearance temperature is an earlier indicator but make such filtration at a temperature at least 14 °C above
of wax crystal formation than pour point and has better the expected cloud point.
resolution than pour point.
9. Preparation of Apparatus
5.5 This test method can determine the temperature of the
9.1 Prepare the instrument for operation in accordance with
test specimen at which wax crystals have formed sufficiently to
the manufacturer’s instructions
be observed with a resolution of 0.1 °C.
6. Apparatus
10. Calibration and Standardization
3,4
6.1 Automatic Apparatus —The automatic apparatus de-
10.1 Ensure that all of the manufacturer’s instructions for
scribed in this test method consists of a specimen chamber
calibrating, checking, and operating the apparatus are fol-
controlled by a microprocessor that is capable of adjusting a
lowed.
Peltier device for the heating and the cooling of the test
10.2 Verify the performance of the apparatus at least once
specimen, optically observing the appearance and disappear-
per year by determining the wax appearance temperature of a
ance of wax crystals, and recording the temperature of the
certified reference material (CRM) such as those for cloud
specimen, described in detail in Annex A1.
point (Test Method D5773), or other suitable material with a
6.2 The apparatus shall be equipped with a specimen
mutually agreed cloud point. For transparent liquids, wax
chamber, optical detector array, NIR light source, digital
appearance temperature is synonymous with cloud point.
display, Peltier device, and a specimen temperature measuring
device.
11. Procedure
6.3 The Peltier device shall be capable of heating or cooling
11.1 When necessary, heat the sample in a bath or oven to a
thetestspecimenataconstantrateof1.5 °C⁄min 60.5 °C⁄min.
temperature above the expected wax disappearance tempera-
ture and maintain this temperature for approximately thirty to
6.4 The temperature measuring device in the specimen
sixty minutes to erase the thermal history. Samples with an
chamber shall be capable of measuring the temperature of the
expected wax appearance temperature (cloud point) above
test specimen from –30 °C to +75 °C at a resolution of 0.1 °C.
35 °C or samples which appear solid at room temperature can
6.5 The apparatus shall be equipped with a dry air system
be heated above 65 °C, but should not be heated above 75 °C.
for transferring the test specimen into the specimen chamber,
11.2 Draw approximately 3 mL to 5 mL of sample into the
and drying the specimen chamber.
Luer type sample syringe, when necessary, preheat the syringe
to the same temperature as the sample.
The automatic wax appearance and wax disappearance apparatus is covered by
a patent. Interested parties are invited to submit information regarding the
11.3 When necessary, attach a 2.7 µm disposable Luer type
identification of an alternative(s) to this patented item to the ASTM International
syringe filter to the sample syringe to remove particulates.
Headquarters.Your comments will receive careful consideration at a meeting of the
Samples
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