ASTM D5972-23

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
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: D5972 − 16 D5972 − 23
Designation: 435/15435/22
Standard Test Method for
Freezing Point of Aviation Fuels (Automatic Phase
1,2
Transition Method)
This standard is issued under the fixed designation D5972; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This test method covers the determination of the temperature below which solid hydrocarbon crystals form in aviation turbine
fuels.
1.2 This test method is designed to cover the temperature range of −80 °C to 20 °C; however, 2003 Joint ASTM/IP Interlaboratory
Cooperative Test Program mentioned in 12.4 has only demonstrated the test method with fuels having freezing points in the range
of −42 °C to −60 °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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use. For specific warning statements, see 7.1, 7.3, and 7.5.
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:
D2386 Test Method for Freezing Point of Aviation Fuels
3. Terminology
3.1 Definitions:
3.1.1 freezing point, n—in aviation fuels, the fuel temperature at which solid hydrocarbon crystals, formed on cooling, disappear
when the temperature of the fuel is allowed to rise under specified conditions of test.
This test method is under the jurisdiction of ASTM International Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility
of Subcommittee D02.07 on Flow Properties. The technically equivalent standard as referenced is under the jurisdiction of the Energy Institute Subcommittee SC-B-7.
Current edition approved June 1, 2016March 1, 2023. Published June 2016March 2023. Originally approved in 1996. Last previous edition approved in 20152016 as
D5972 – 15.D5972 – 16. DOI: 10.1520/D5972-16.10.1520/D5972-23.
This test method has been developed through the cooperative effort between ASTM and the Energy Institute, London. ASTM and IP standards were approved by ASTM
and EI technical committees as being technically equivalent but that does not imply both standards are identical.
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.
*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
D5972 − 23
3.2 Definitions of Terms Specific to This Standard:
3.2.1 automatic phase transition method, n—in this test method, the procedures of automatically cooling a liquid aviation fuel
specimen until solid hydrocarbon crystals appear, followed by controlled warming and recording of the temperature at which the
solid hydrocarbon crystals completely redissolve into the liquid phase.
3.2.2 Peltier device, n—a solid-state thermoelectric device constructed with dissimilar semiconductor materials, configured in
such a way that it will transfer heat to and away from a test specimen dependent on the direction of electric current applied to the
device.
4. Summary of Test Method
4.1 A specimen is cooled at a rate of 15 °C ⁄min 6 5 °C ⁄min by a Peltier device while continuously being illuminated by a light
source. The specimen is continuously monitored by an array of optical detectors for the first formation of solid hydrocarbon
crystals. Once the hydrocarbon crystals are formed, the specimen is then warmed at a rate of 10 °C ⁄min 6 0.5 °C ⁄min until the
last hydrocarbon crystals return to the liquid phase. The detectors are sufficient in number to ensure that any solid hydrocarbon
crystals are detected. The specimen temperature at which the last hydrocarbon crystals return to the liquid phase is recorded as the
freezing point.
5. Significance and Use
5.1 The freezing point of an aviation fuel is the lowest temperature at which the fuel remains free of solid hydrocarbon crystals.
These crystals can restrict the flow of fuel through the fuel system of the aircraft. The temperature of the fuel in the aircraft tank
normally decreases during flight depending on aircraft speed, altitude, and flight duration. The freezing point of the fuel must
always be lower than the minimum operational fuel temperature.
5.2 Petroleum blending operations require precise measurement of the freezing point.
5.3 This test method produces results which have been found to be equivalent to Test Method D2386 and expresses results to the
nearest 0.1 °C, with improved precision over Test Method D2386. This test method also eliminates most of the operator time and
judgment required by Test Method D2386.
5.4 When specification requires Test Method D2386, do not substitute this test method or any other test method.
6. Apparatus
6.1 Automatic Apparatus —This apparatus consists of a microprocessor-controlled test chamber that is capable of cooling and
heating the test specimen, optically observing the appearance and disappearance of solid hydrocarbon crystals, and recording the
temperature of the specimen. A detailed description of the apparatus is provided in Annex A1.
6.2 The apparatus shall be equipped with a specimen cup, optical detector array, light source, digital display, Peltier device, and
a specimen temperature measuring device.
6.3 The temperature measuring device in the specimen cup shall be capable of measuring the temperature of the test specimen
from −80 °C to +20 °C at a resolution of 0.1 °C and accuracy of 0.1 °C.
6.4 The apparatus shall be equipped with fittings to permit the circulation of a liquid medium to remove heat generated by the
Peltier device and other electronic components of the apparatus.
6.5 The apparatus shall be equipped with fittings to permit the circulation of purge gas to purge the test chamber containing the
specimen cup of any atmospheric moisture.
The sole source of supply of the Phase Technology Freezing Point Analyzer Model Series 70, 70V, and 70X known to the committee at this time is Phase Technology,
No. 135-11960 Hammersmith Way, Richmond, B.C. Canada, V7A 5C9. All the model series previously mentioned have identical test chambers and electronics. The distinction
between different model series is the low temperature limit. Refer to manufacturer’s product information on the low-temperature limit of various models. 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.
D5972 − 23
7. Reagents and Materials
7.1 n-Octane—Reagent grade is suitable. (Warning—Flammable. Harmful if inhaled. Keep away from heat, sparks, and open
flame.)
7.2 Cooling Medium—Liquid heat exchange medium to remove the heat generated by the Peltier device and other electronic
components from the apparatus.
NOTE 1—Some apparatus are designed to use tap water as a cooling medium to bring the specimen temperature to −60 °C. To achieve cooling of the
specimen to −80 °C, provide circulation of the cooling medium at −30 °C or lower to the apparatus. Since water freezes at 0 °C, a commercial or technical
grade isopropanol is suitable as the cooling medium. Refer to the manufacturer’s operating instructions on the relationship between the cooling medium
temperature and the minimum specimen temperature.
7.3 Purge Gas—A gas such as air, nitrogen, helium, or argon with a dew point below the lowest temperature attained by the
specimen under the conditions of the test. (Warning—Compressed gas under high pressure.) (Warning—Inert gas can be an
asphyxiant when inhaled.)
7.4 Pipette, capable of dispensing 0.15 mL 6 0.01 mL of sample.
7.5 Cotton Swabs—Plastic- or paper-shaft cotton swabs to clean the specimen cup. (Warning—The use of swabs with wooden
shafts may damage the mirrored surface of the specimen cup.)
8. Preparation of Apparatus
8.1 Install the analyzer for operation in accordance with the manufacturer’s instructions.
8.2 Turn on the liquid cooling medium and ensure its temperature is appropriate for the specimen being tested in accordance with
the manufacturer’s instructions (see Note 1).
8.3 Turn on the purge gas and ensure that it is regulated to the appropriate pressure in accordance with the manufacturer’s
instructions.
8.4 Turn on the main power switch of the analyzer.
NOTE 2—Some apparatus are capable of generating a source of dry purge gas, thus eliminating the need for an external supply of a compressed gas.
9. Calibration and Standardization
9.1 Ensure that all of the manufacturer’s instructions for calibrating, checking, and operating the apparatus are followed. Verify
cooling rate is in line with test method and manufacturer’s instructions.
9.2 To verify the performance of the apparatus, an aviation turbine fuel sample for which extensive data has been obtained by
freeze point, Test Method D2386, may be used. Samples such as those used in the ASTM interlaboratory cross-check program
would meet this criterion. Such verification materials can also be prepared from intracompany cross-checks. Alternatively,
high-purity n-octane or n-nonane with known freezing points can be used to verify the calibration of the temperature-measuring
device in the apparatus.
10. Procedure
10.1 Open the test chamber lid and clean the specimen cup inside the test chamber with a cotton swab.
10.2 Rinse the specimen cup by pipetting 0.15 mL 6 0.01 mL of specimen into the cup. Clean the specimen out of the cup by
using a cotton swab. The cup should be cleaned to the point where no visible droplets of specimen remain in the cup.
10.3 Rinse the cup a second time by repeating 10.2.
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