1、Designation: D2386 151Designation: 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.
2、A 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.1NOTEA mercury caveat was removed from the scope editoriall
3、y in July 2015.1. Scope*1.1 This test method covers the determination of the tem-perature below which solid hydrocarbon crystals may form inaviation turbine fuels and aviation gasoline.NOTE 1The interlaboratory program that generated the precisions forthis test method did not include aviation gasoli
4、ne.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, associated with its use. It is theresponsibility of the user of this standard to establish a
5、ppro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificwarning statements, see 5.4, Section 6, and 8.3.2. Referenced Documents2.1 ASTM Standards:2D910 Specification for Leaded Aviation GasolinesD1655 Specification for Aviation Tur
6、bine FuelsD3117 Test Method for Wax Appearance Point of DistillateFuels (Withdrawn 2010)3D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsE1 Specification for ASTM Liquid-in-Glass ThermometersE77 Test Method
7、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 Specific to This Standard:3.1.1 freezing point, nin aviation fuels, the fuel tempera-ture at which solid hydrocarbon crystals, for
8、med 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 whichcrystals of hydrocarbons first appear when the test sample iscooled.4. Significance and Use4.1 The freezing point of an aviation fuel i
9、s 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 aircraft.The temperature of thefuel in the aircraft tank normally falls during flight dependingon aircraft speed, altitude, and
10、 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 D910and D1655.5. Apparatus5.1 Jacketed Sample TubeA double-walled, unsilveredvessel, similar to a Dewar flask, the space between the
11、 innerand outer tube walls being filled at atmospheric pressure withdry nitrogen or air. The mouth 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.1This test method is under t
12、he jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.07 on Flow Properties.Current edition approved June 1, 2015. Published June 2015. Originallyapproved in 1965. Last previous edition approved in 2012 as D2386 0
13、6 (2012).DOI: 10.1520/D2386-15E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version
14、of this historical standard is referenced onwww.astm.org.4Available 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 standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
15、hohocken, PA 19428-2959. United States15.2 CollarsMoisture-proof collars as shown in Fig. 2 shallbe used to prevent condensation of moisture.5.3 StirrerShall be 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 actuate
16、d as described in theapparatus section of Test Method D3117.5.4 Vacuum FlaskAn unsilvered vacuum flask(WarningImplosion hazard) having the minimum dimen-sions shown in Fig. 1 shall be used to hold an adequate volumeof cooling liquid and permit the necessary depth of immersionof the jacketed sample t
17、ube.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 StandardThermometers, Volume 2, IP Standard Methods for Analysisand Testing of Petroleum and Related Products.)NOTE 3The accuracy of this therm
18、ometer 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 acetone is suitable for thecooling bath, provided it does not leave a residue on drying.(WarningExtremely flammable.)6.2 Ethanol or Ethyl Alcoho
19、lA commercial or technicalgrade of dry ethanol is suitable for the cooling bath.(WarningExtremely flammable.)6.3 Isopropyl AlcoholA commercial or technical grade ofdry isopropyl alcohol is suitable. (WarningExtremely flam-mable.)6.4 Methanol or Methyl AlcoholA commercial or techni-cal grade of dry m
20、ethanol 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 use in the cooling bath.(WarningExtremely cold, 78 C. Carbon dioxide (solid)liberates gases that can cause suffocation. Contact with skinc
21、auses burns, freezing, or both.)6.6 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 can causesuffocation. Contact with skin causes burns, fr
22、eezing, or both.)5The U.S. National Bureau of Standards, Gaithersburg, MD, and the BritishNational Physical Laboratory, Teddington, England are able to certify thermometersat these temperatures.FIG. 1 Freezing Point ApparatusD2386 15126.7 Fiberglasscommercial grade, for use in moisture-proof collar
23、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 collar 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-
24、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.)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
25、.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 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 water
26、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 isused.8.1.1 Collar type A, flush with nitrogen or dry air beforefitting to the jacketed sample tube, and throughout the entiredetermination.NOTE 4The air can be effectively d
27、ried 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 agent (6.8.1 and 6.8.2) as shown in Fig. 2. Thefiberglass shall be replaced every fourth test. The dehydratingagent should be renewed at i
28、ntervals of not more than 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 proofNOTE 1All dimensions are in mm a
29、nd 60.1 mm glass wall thickness is 1 mm.FIG. 2 Moistureproof Collars for Freezing Point ApparatusD2386 1513collar and adjust the thermometer position so that its bulb 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
30、 the bottom of the sample tube. (WarningDonot add solid carbon dioxide to liquid nitrogen.)NOTE 5Performance of this test method can be difficult, since thespecimen tube is immersed in a coolant medium that evolves gas bubblesduring the test. This can interfere with visual observations. In addition,
31、 thecrystals that are formed in the specimen can be difficult to recognize, andthey can appear in a variety of manifestations. It is strongly suggested thatoperators seek guidance from experienced operators of this test method toassist them in the correct recognition of these crystals.NOTE 6This tes
32、t method should be performed under laboratoryconditions where there is an ample supply of light. Some crystals can bevery faint in appearance and difficult to observe under inadequate lightingconditions.8.3 Clamp the jacketed sample tube so that it extends as faras possible into the vacuum flask (Wa
33、rningImplosion 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. Unless the medium is cooled bymechanical refrigeration, add solid carbon dioxide as necessarythroughout the test to maintain the coolant leve
34、l in the vacuumflask.NOTE 7Acetone and either methyl, ethyl, or isopropyl alcohols aresuitable. All of these require cautious handling. Liquid nitrogen may alsobe used as a coolant instead of liquids cooled with solid carbon dioxide forfuel samples which have a freezing point below 65 C. Mechanicalr
35、efrigeration 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 of 1 cycless to 1.5 cycless, taking care thatthe stirrer loops approach the bottom of the flask on thedownstroke and remain below the spec
36、imen surface on theupstroke. It is permissible for momentary interruption ofstirring while performing some operations of the procedure(see Note 8). Observe the specimen continuously for theappearance of hydrocarbon crystals. Disregard any cloud thatappears at approximately 10 C and does not increase
37、 inintensity as the temperature decreases, because this cloud isdue to water. Record the temperature at which hydrocarboncrystals appear. Remove the jacketed sample tube from thecoolant and allow the specimen to warm by ambient air,stirring it continuously at 1 cycless to 1.5 cycless. Continueto obs
38、erve the specimen continuously for the disappearance ofhydrocarbon crystals. Record the temperature at which thehydrocarbon crystals completely disappear.NOTE 8Because the gases released by the coolant can obscureobservations, the sample tube can be removed from the coolant forobservations. The tube
39、 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 at least 5 C above the temperature at which thecrystals disappear. The specimen sh
40、ould 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 crystal appearance tem-perature with the crystal disappearance temperature. The appea
41、rancetemperature 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 shouldtypically be no greater than 6 C.9. Report9.1 The observed freezing point determin
42、ed in Section 8shall be corrected by applying the relevant thermometercorrection resulting from the checks described in Note 3.Where the observed freezing point falls between two calibra-tion temperatures, the correction at the observed temperatureshall be obtained by linear interpolation. Report th
43、e correctedtemperature of crystal disappearance to the nearest 0.5 C asthe freezing point, Test Method D2386.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 stirr
44、ed strictly inaccordance with the 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 thr
45、oughout the test, both in thecooling 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 co
46、nversion 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 laboratories.10.1.1 RepeatabilityThe difference between two test r
47、e-sults obtained by the same operator with the same apparatusunder constant operating conditions on identical test materialwould, in the long run, in the normal and correct operation ofthe test method, exceed 1.5 C only in one case in twenty.10.1.2 ReproducibilityThe difference between two singleand
48、 independent results obtained by different operators work-ing in different laboratories on identical test material would, inthe long run, in the normal and correct operation of the testmethod, exceed 2.5 C only in one case in twenty.10.2 BiasBecause there are no liquid hydrocarbon mix-tures of “know
49、n” freezing point, which simulate aviation fuels,bias cannot be established.11. Keywords11.1 aviation gasoline; aviation turbine fuels; crystallizationpoint; determination; freezing point; low temperature tests;manual method; petroleum products; physical tests6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1572.D2386 1514SUMMARY OF CHANGESSubcommittee D02.07 has identified the location of selected changes to this standard s
