1、Designation: D2386 18Designation: 16/15Standard Test Method forFreezing Point of Aviation Fuels1This standard is issued under the fixed designation D2386; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript 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 th
3、e tem-perature below which solid hydrocarbon crystals may form inaviation turbine fuels and aviation gasoline. If no crystalliza-tion point or freezing point can be measured this test can beused to determine the lowest measurable temperature beforethe crystallization point.NOTE 1The interlaboratory
4、program that generated the precisions forthis test method did not include aviation gasoline.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, ass
5、ociated with its use. It is theresponsibility 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.For specific warning statements, see 5.4, Section 6, and 8.3.1.4 This international
6、 standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee
7、.2. Referenced Documents2.1 ASTM Standards:2D910 Specification for Leaded Aviation GasolinesD1655 Specification for Aviation Turbine FuelsD3117 Test Method for Wax Appearance Point of DistillateFuels (Withdrawn 2010)3D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice
8、 for Automatic Sampling of Petroleum andPetroleum ProductsE1 Specification for ASTM Liquid-in-Glass ThermometersE77 Test Method for Inspection and Verification of Ther-mometers2.2 Energy Institute Standard:IP Standards for Petroleum and Its Products IP 16/1543. Terminology3.1 Definitions of Terms Sp
9、ecific to This Standard:3.1.1 freezing point, nin aviation fuels, the fuel tempera-ture at which solid hydrocarbon crystals, formed on cooling,disappear when the temperature of the fuel is allowed to riseunder specified conditions of test.3.1.2 crystallization point, nthe temperature at whichcrystal
10、s of hydrocarbons first appear when the test sample iscooled.4. Significance and Use4.1 The freezing point of an aviation fuel is the lowesttemperature at which the fuel remains free of solid hydrocar-bon crystals that can restrict the flow of fuel through filters ifpresent in the fuel system of the
11、 aircraft.The temperature of thefuel in the aircraft tank normally falls during flight dependingon aircraft speed, altitude, and flight duration. The freezingpoint of the fuel must always be lower than the minimumoperational tank temperature.4.2 Freezing point is a requirement in Specifications D910
12、and D1655.5. Apparatus5.1 Jacketed Sample TubeA double-walled, unsilveredvessel, similar to a Dewar flask, the space between the inner1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D
13、02.07 on Flow Properties.Current edition approved Dec. 1, 2018. Published January 2019. Originallyapproved in 1965. Last previous edition approved in 2015 as D2386 151. DOI:10.1520/D2386-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servi
14、ceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K., http:/www
15、.energyinst.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on stan
16、dardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1and outer tube walls being filled at atmospheric pressure withdry nitrogen or air. The m
17、outh of the sample tube shall beclosed with a stopper supporting the thermometer andmoisture-proof collar through which the stirrer passes (Fig. 1).A cork stopper is recommended.5.2 CollarsMoisture-proof collars as shown in Fig. 2 shallbe used to prevent condensation of moisture.5.3 StirrerShall be
18、made of 1.6 mm brass or stainless steelrod bent into a smooth three-loop spiral at the bottom.NOTE 2The stirrer may be mechanically actuated as described in theapparatus section of Test Method D3117.5.4 Vacuum FlaskAn unsilvered vacuum flask(WarningImplosion hazard) having the minimum dimen-sions sh
19、own in Fig. 1 shall be used to hold an adequate volumeof cooling liquid and permit the necessary depth of immersionof the jacketed sample tube.5.5 ThermometerA total immersion type, having a rangefrom 80 C to +20 C, designated as ASTM No. 114C/IP No.14C. (See Specification E1, or Appendix A, IP Stan
20、dardThermometers, Volume 2, IP Standard Methods for Analysisand Testing of Petroleum and Related Products.)NOTE 3The accuracy of this thermometer is to be checked inaccordance with Test Method E77, at temperatures of 0 C, 40 C,60 C, and 75 C.56. Reagents and Materials6.1 AcetoneTechnical Grade aceto
21、ne is suitable for thecooling bath, provided it does not leave a residue on drying.(WarningExtremely flammable.)6.2 Ethanol or Ethyl AlcoholA commercial or technicalgrade of dry ethanol is suitable for the cooling bath.(WarningExtremely flammable.)6.3 Isopropyl AlcoholA commercial or technical grade
22、 ofdry isopropyl alcohol is suitable. (WarningExtremely flam-mable.)6.4 Methanol or Methyl AlcoholA commercial or techni-cal grade of dry methanol is suitable for the cooling bath.(WarningExtremely flammable and toxic.)6.5 Carbon Dioxide (Solid) or Dry IceA commercialgrade of dry ice is suitable for
23、 use in the cooling bath.(WarningExtremely cold, 78 C. Carbon dioxide (solid)liberates gases that can cause suffocation. Contact with skincauses burns, freezing, or both.)5The U.S. National Bureau of Standards, Gaithersburg, MD, and the BritishNational Physical Laboratory, Teddington, England are ab
24、le to certify thermometersat these temperatures.FIG. 1 Freezing Point ApparatusD2386 1826.6 Liquid NitrogenA commercial or technical grade ofliquid nitrogen is suitable for the cooling bath when thefreezing point is lower than 65 C. (WarningExtremelycold, 196 C. Liquid nitrogen liberates gases that
25、can causesuffocation. Contact with skin causes burns, freezing, or both.)6.7 Fiberglasscommercial grade, for use in moisture-proof collar B.6.8 Dehydrating AgentUse one of the following:6.8.1 Calcium sulfate (CaS04), granulated anhydrous cal-cium sulfate, for use as a desiccant in moisture-proof col
26、lar B,or to assist in drying the nitrogen gas or air (5.2) used withcollar 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. (WarningSilica gel dyed with cadmiumsalts can cause cancer by inhalation.)
27、7. Sampling7.1 Obtain a sample in accordance with Practice D4057 orPractice 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 ambientroom temperature to minimize introduction of any moisture.Minimize exposure of the sample to sources
28、of heat.8. Procedure8.1 CollarAssemble the collar (5.2), thermometer (5.5)and stirrer (5.3) into the cork. To prevent the ingress of waterinto the test portion, it is important that an effective moisture-proof collar as prepared in accordance with 8.1.1 or 8.1.2 isused.8.1.1 Collar type A, flush wit
29、h nitrogen or dry air beforefitting to the jacketed sample tube, and throughout the entiredetermination.NOTE 4The air can be effectively dried by passing through absorbenttubes filled with dehydrating agents (6.8.1 and 6.8.2).8.1.2 Collar type B, fill with fiberglass (6.7) and a suitabledehydrating
30、agent (6.8.1 and 6.8.2) as shown in Fig. 2. Thefiberglass shall be replaced every fourth test. The dehydratingNOTE 1All dimensions are in mm and 60.1 mm glass wall thickness is 1 mm.FIG. 2 Moistureproof Collars for Freezing Point ApparatusD2386 183agent should be renewed at intervals of not more tha
31、n 3 monthsor when a color change shows it to be ineffective8.2 Measure out 25 mL 6 1 mL of the fuel and transfer it tothe clean, dry, jacketed sample tube. Close the tube tightly withthe cork holding the stirrer, thermometer, and moisture proofcollar and adjust the thermometer position so that its b
32、ulb doesnot touch the walls of the tube flask and is approximately in thecenter. The bulb of the thermometer should be 10 mm to15 mm from the bottom of the sample tube. (WarningDonot add solid carbon dioxide to liquid nitrogen.)NOTE 5Performance of this test method can be difficult, since thespecime
33、n tube is immersed in a coolant medium that evolves gas bubblesduring the test. This can interfere with visual observations. In addition, thecrystals that are formed in the specimen can be difficult to recognize, andthey can appear in a variety of manifestations. It is strongly suggested thatoperato
34、rs seek guidance from experienced operators of this test method toassist them in the correct recognition of these crystals.NOTE 6This test method should be performed under laboratoryconditions where there is an ample supply of light. Some crystals can bevery faint in appearance and difficult to obse
35、rve under inadequate lightingconditions.8.3 Clamp the jacketed sample tube so that it extends as faras possible into the vacuum flask (WarningImplosion haz-ard) containing the cooling medium (Note 7). The surface ofthe sample should be approximately 15 mm to 20 mm belowthe level of the coolant. Unle
36、ss the medium is cooled bymechanical refrigeration, add solid carbon dioxide as necessarythroughout the test to maintain the coolant level in the vacuumflask.NOTE 7Acetone and either methyl, ethyl, or isopropyl alcohols aresuitable. All of these require cautious handling. Liquid nitrogen may alsobe
37、used as a coolant instead of liquids cooled with solid carbon dioxide forfuel samples which have a freezing point below 65 C. Mechanicalrefrigeration is permitted. Where used the refrigerant temperature shouldbe 70 C to 80 C.8.4 Stir the fuel continuously, moving the stirrer up anddown at the rate o
38、f 1 cycless to 1.5 cycless, taking care thatthe stirrer loops approach the bottom of the flask on thedownstroke and remain below the specimen surface on theupstroke. It is permissible for momentary interruption ofstirring while performing some operations of the procedure(see Note 8). Observe the spe
39、cimen continuously for theappearance of hydrocarbon crystals. Disregard any cloud thatappears at approximately 10 C and does not increase inintensity as the temperature decreases, because this cloud isdue to water. Record the temperature at which hydrocarboncrystals appear. This is the crystallizati
40、on point. Remove thejacketed sample tube from the coolant and allow the specimento warm by ambient air, stirring it continuously at 1 cycless to1.5 cycless. Continue to observe the specimen continuouslyfor the disappearance of hydrocarbon crystals. Record thetemperature at which the hydrocarbon crys
41、tals completelydisappear. If the crystallization point cannot be reached bycontinuously cooling the fuel to the lowest temperature achiev-able by the apparatus (between 65 C and 70 C), record thelowest temperature that the fuel reaches.NOTE 8Because the gases released by the coolant can obscureobser
42、vations, the sample tube can be removed from the coolant forobservations. The tube can be removed for periods no longer than 10 s. Ifcrystals are observed to have already formed, the specimen temperatureshould be noted and the specimen allowed to be warmed by ambient air,with continued stirring, to
43、at least 5 C above the temperature at which thecrystals disappear. The specimen should then be re-immersed in thecoolant and allowed to cool. Remove the specimen from the coolantslightly above the noted temperature, and observe for appearance of thecrystals.NOTE 9It is recommended to compare the cry
44、stal appearance tem-perature with the crystal disappearance temperature. The appearancetemperature should be colder than the disappearance temperature. If this isnot the case, this is an indication that the crystals were not correctlyrecognized. Also, the difference between these temperatures should
45、typically be no greater than 6 C.9. Report9.1 If determined, the observed freezing point determined inSection 8 shall be corrected by applying the relevant thermom-eter correction resulting from the checks described in Note 3.Where the observed freezing point falls between two calibra-tion temperatu
46、res, the correction at the observed temperatureshall be obtained by linear interpolation. Report the correctedtemperature of crystal disappearance to the nearest 0.5 C asthe freezing point, Test Method D2386. If the crystallizationpoint temperature of the fuel is not determined during cooling,report
47、 the freezing point as less than the lowest temperature ofthe fuel measured.NOTE 10False results can be obtained if the temperature of the testportion is not uniform during the cooling and warming cycles. To obtaina uniform temperature, the test portion must be stirred strictly inaccordance with the
48、 procedure described.NOTE 11Contamination by other petroleum products can causecrystals to appear at much higher temperatures than normally expected foraviation fuel freeze points. In order to identify such contamination, it isimportant that observations are made throughout the test, both in thecool
49、ing and warming cycles.NOTE 12When results are desired in degrees Fahrenheit, test resultsobtained in degrees Celsius should be converted to the nearest wholedegree Fahrenheit. Interim Celsius freezing points should carry the bestprecision available for subsequent conversion to degrees Fahrenheit.10. Precision and Bias610.1 PrecisionThe precision of this test method wasobtained by the statistical examination of the results of 13samples of fuel consisting of JetA, JetA1, JP-5 and JP-8 testedby 15 laboratori
