ASTM D2386-19

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Designation: D2386 − 18 D2386 − 19
Designation: 16/15
Standard Test Method for
Freezing Point of Aviation Fuels
This standard is issued under the fixed designation D2386; 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 may form in aviation
turbine fuels and aviation gasoline. If no crystallization point or freezing point can be measured, this test can be used to
determinereport the lowest measurable temperature reached before the crystallization point.
NOTE 1—The interlaboratory program that generated the precisions for this test method did not include aviation gasoline.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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. For specific warning statements, see 5.4, Section 6, and 8.3.
1.4 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:
D910 Specification for Leaded Aviation Gasolines
D1655 Specification for Aviation Turbine Fuels
D3117 Test Method for Wax Appearance Point of Distillate Fuels (Withdrawn 2010)
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
E1 Specification for ASTM Liquid-in-Glass Thermometers
E77 Test Method for Inspection and Verification of Thermometers
2.2 Energy Institute Standard:
IP Standards for Petroleum and Its Products IP 16/15
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
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.
3.1.2 crystallization point, n—the temperature at which crystals of hydrocarbons first appear when the test sample is cooled.
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 Dec. 1, 2018May 1, 2019. Published January 2019June 2019. Originally approved in 1965. Last previous edition approved in 20152018 as
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D2386 – 15D2386 – 18. . DOI: 10.1520/D2386-18.10.1520/D2386-19.
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volume information, refer to the standard’s Document Summary page on the ASTM website.
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Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http://www.energyinst.org.
*A Summary of Changes section appears at the end of this standard
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D2386 − 19
4. Significance and Use
4.1 The freezing point of an aviation fuel is the lowest temperature at which the fuel remains free of solid hydrocarbon crystals
that can restrict the flow of fuel through filters if present in the fuel system of the aircraft. The temperature of the fuel in the aircraft
tank normally falls during flight depending on aircraft speed, altitude, and flight duration. The freezing point of the fuel must
always be lower than the minimum operational tank temperature.
4.2 Freezing point is a requirement in Specifications D910 and D1655.
5. Apparatus
5.1 Jacketed Sample Tube—A double-walled, unsilvered vessel, similar to a Dewar flask, the space between the inner and outer
tube walls being filled at atmospheric pressure with dry nitrogen or air. The mouth of the sample tube shall be closed with a stopper
supporting the thermometer and moisture-proof collar through which the stirrer passes (Fig. 1). A cork stopper is recommended.
5.2 Collars—Moisture-proof collars as shown in Fig. 2 shall be used to prevent condensation of moisture.
5.3 Stirrer—Shall be made of 1.6 mm brass or stainless steel rod bent into a smooth three-loop spiral at the bottom.
NOTE 2—The stirrer may be mechanically actuated as described in the apparatus section of Test Method D3117.
5.4 Vacuum Flask—An unsilvered vacuum flask (Warning—Implosion hazard) having the minimum dimensions shown in Fig.
1 shall be used to hold an adequate volume of cooling liquid and permit the necessary depth of immersion of the jacketed sample
tube.
5.5 Thermometer—A total immersion type, having a range from −80 °C to +20 °C, designated as ASTM No. 114C/IP No. 14C.
(See Specification E1, or Appendix A, IP Standard Thermometers, Volume 2, IP Standard Methods for Analysis and Testing of
Petroleum and Related Products.)
FIG. 1 Freezing Point Apparatus
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NOTE 1—All dimensions are in mm and 60.1 mm glass wall thickness is 1 mm.
FIG. 2 Moistureproof Collars for Freezing Point Apparatus
NOTE 3—The accuracy of this thermometer is to be checked in accordance with Test Method E77, at temperatures of 0 °C, −40 °C, −60 °C, and
−75 °C.
6. Reagents and Materials
6.1 Acetone—Technical Grade acetone is suitable for the cooling bath, provided it does not leave a residue on drying.
(Warning—Extremely flammable.)
6.2 Ethanol or Ethyl Alcohol—A commercial or technical grade of dry ethanol is suitable for the cooling bath. (Warning—
Extremely flammable.)
6.3 Isopropyl Alcohol—A commercial or technical grade of dry isopropyl alcohol is suitable. (Warning—Extremely
flammable.)
6.4 Methanol or Methyl Alcohol—A commercial or technical grade of dry methanol is suitable for the cooling bath.
(Warning—Extremely flammable and toxic.)
6.5 Carbon Dioxide (Solid) or Dry Ice—A commercial grade of dry ice is suitable for use in the cooling bath.
(Warning—Extremely cold, −78 °C. Carbon dioxide (solid) liberates gases that can cause suffocation. Contact with skin causes
burns, freezing, or both.)
The U.S. National Bureau of Standards, Gaithersburg, MD, and the British National Physical Laboratory, Teddington, England are able to certify thermometers at these
temperatures.
D2386 − 19
6.6 Liquid Nitrogen—A commercial or technical grade of liquid nitrogen is suitable for the cooling bath when the freezing point
is lower than −65 °C. (Warning—Extremely cold, −196 °C. Liquid nitrogen liberates gases that can cause suffocation. Contact
with skin causes burns, freezing, or both.)
6.7 Fiberglass—commercial grade, for use in moisture-proof collar B.
6.8 Dehydrating Agent—Use one of the following:
6.8.1 Calcium sulfate (CaS0 ), granulated anhydrous calcium sulfate, for use as a desiccant in moisture-proof collar B, or to
assist in drying the nitrogen gas or air (5.2) used with collar A.
6.8.2 Silica gel, 1.7 mm, for use as a desiccant in moisture-proof collar B, or to assist in drying the nitrogen gas or air (5.2) used
with collar A. (Warning—Silica gel dyed with cadmium salts can cause cancer by inhalation.)
7. Sampling
7.1 Obtain a sample in accordance with Practice D4057 or Practice D4177.
7.2 At least 25 mL of specimen is required for each test.
7.3 Keep the sample in a tightly sealed container at ambient room temperature to minimize introduction of any moisture.
Minimize exposure of the sample to sources of heat.
8. Procedure
8.1 Collar—Assemble the collar (5.2), thermometer (5.5) and stirrer (5.3) into the cork. To prevent the ingress of water into the
test portion, it is important that an effective moisture-proof collar as prepared in accordance with 8.1.1 or 8.1.2 is used.
8.1.1 Collar type A, flush with nitrogen or dry air before fitting to the jacketed sample tube, and throughout the entire
determination.
NOTE 4—The air can be effectively dried by passing through absorbent tubes filled with dehydrating agents (6.8.1 and 6.8.2).
8.1.2 Collar type B, fill with fiberglass (6.7) and a suitable dehydrating agent (6.8.1 and 6.8.2) as shown in Fig. 2. The fiberglass
shall be replaced every fourth test. The dehydrating agent should be renewed at intervals of not more than 3 months or when a
color change shows it to be ineffective
8.2 Measure out 25 mL 6 1 mL of the fuel and transfer it to the clean, dry, jacketed sample tube. Close the tube tightly with
the cork holding the stirrer, thermometer, and moisture proof collar and
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