1、Designation: D 7462 08An American National StandardStandard Test Method forOxidation Stability of Biodiesel (B100) and Blends ofBiodiesel with Middle Distillate Petroleum Fuel (AcceleratedMethod)1This standard is issued under the fixed designation D 7462; the number immediately following the designa
2、tion indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a measure
3、ment of the oxidationstability of biodiesel (B100) and blends of biodiesel withmiddle distillate petroleum fuels under specified oxidizingconditions at 95C. Specifically, the oxidation stability isassessed by the formation and measurement of insolubledegradation materials.NOTE 1Biodiesel B100, compo
4、sed of alkyl esters, can have goodsolubility for some products of oxidative degradation. Thus some B100samples could undergo significant degradation, but show little or nosediment formation. By contrast, many petroleum diesel fuels haverelatively poor solubility for products of oxidative degradation
5、, so Bxxblends, such as B20, could show higher sediment levels. Refer toAppendix X1 for a suggested paraffinic dilution procedure to evaluateoxidative degradation of B100 for degradation materials that are soluble inB100, but insoluble in iso-octane.1.2 The values stated in SI units are to be regard
6、ed 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 appro-priate safety and health practices and determine
7、 the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 381 Test Method for Gum Content in Fuels by JetEvaporationD 943 Test Method for Oxidation Characteristics of Inhib-ited Mineral OilsD 1193 Specification for Reagent WaterD 2274 Test Method for Oxi
8、dation Stability of DistillateFuel Oil (Accelerated Method)D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 4625 Test Method for Middle Distillate Fuel StorageStability at 43C (110F)3. Terminology3.1 Defi
9、nitions:3.1.1 adherent insolubles (formerly adherent gum),nmaterial that is produced in the course of stressing distillatefuel under the conditions of this test and which adheres to theglassware after fuel has been flushed from the system.3.1.2 filterable insolubles, nmaterial that is produced inthe
10、 course of stressing the sample fuel under the conditions ofthis test and can be removed from the fuel by filtration. Thisincludes both material suspended in the fuel and material easilyremoved from the oxidation cell and oxygen delivery tube withhydrocarbon solvent.3.1.3 total insolubles, nsum of t
11、he adherent and filterableinsolubles.3.2 Definitions of Terms Specific to This Standard:3.2.1 zero time, ntime the first of a batch of oxidationcells is placed in the heating bath.3.2.1.1 DiscussionThis is the time taken as the start of the16 h of residence in the heating bath.4. Summary of Test Met
12、hod4.1 A 350-mL volume of filtered sample is aged at 95C for16 h while oxygen is bubbled through the sample at a rate of3 L/h. After aging, the sample is cooled to approximately roomtemperature before filtering to obtain the filterable insolublesquantity. The interior of the oxidation cell is also w
13、ashed withhydrocarbon solvent to remove any filterable insolubles andliquid that can be removed by the solvent. These washings arealso filtered and included as filterable insolubles.4.2 Adherent insolubles are then removed from the oxida-tion cell and associated glassware with trisolvent. The trisol
14、-vent is evaporated to obtain the quantity of adherent insolubles.4.3 The sum of the filterable and adherent insolubles,expressed as milligrams per 100 mL, is reported as totalinsolubles.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the
15、direct responsibility of SubcommitteeD02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved Nov. 1, 2008. Published December 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta
16、ndards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Significance and Use5.1 This test method provides a measurement of the oxida-tion stability
17、 of biodiesel and biodiesel blends.5.2 The test method may not provide a prediction of thequantity of insolubles that will form in field storage over anygiven period of time. The amount of insolubles formed in suchfield storage is subject to the specific storage conditions, whichare too variable for
18、 this test method to predict accurately.5.3 This test method yields results more rapidly than TestMethod D 4625, the 43C bottle test. However, as a result ofthe significantly elevated temperature and the pure oxygenatmosphere, the nature and amount of insolubles may deviateto a greater extent than T
19、est Method D 4625 from those formedin field storage.6. Interferences6.1 Oxidation is a major chemical process causing adherentand filterable insolubles to form. Any substances, such ascopper or chromium, that catalyze oxidation reactions willcause more rapid or greater quantities of insoluble materi
20、al, orboth, to form. Since the apparatus used in this test can also beused in Test Method D 943, where coils of copper and steel areused, it is important that any residues that could contain thesemetals be eliminated from the apparatus by thorough cleaningprior to use. Similarly, to preclude the pre
21、sence of chromiumions, as well as to protect laboratory personnel from potentialharm, chromic acid shall not be used for cleaning glassware inthe practice of this test method.6.2 Ultraviolet light exposure has been found to increase theamount of total insolubles. Therefore, the fuel being testedshal
22、l be shielded from direct exposure to ultraviolet light(sunlight or fluorescent). Conduct all sampling, measuring,filtration, and weighing away from direct sunlight and in asdark an area as would be compatible with other laboratoryoperations. Storage before stress, the stress period and cool-down af
23、ter stressing shall be in the dark.7. Apparatus7.1 Oxidation Cell, of borosilicate glass, as shown in Fig. 1,shall consist of a test tube, condenser, and oxygen deliverytube. This cell is identical to that used in Test Method D 2274.7.2 Heating Bath/Block, shall be capable of maintaining auniform te
24、mperature at 95 6 1C. It shall be large enough tohold the desired number of oxidation cells immersed to a depthof approximately 350 mm. Further, the construction mustpermit shielding the fuel samples in the oxidation cells fromlight while they are undergoing oxidation.37.3 Flow Meters, shall have a
25、capability of measuring 3 60.3 L/h of oxygen. One flow meter shall be provided for eachoxidation cell.7.4 Filter Drying Oven, shall be capable of safely evapo-rating the solvent at 90 6 2C for the drying of filter materials.7.5 Glassware Drying Oven, shall be capable of dryingglassware at 105 6 5C.7
26、.6 Filter Assembly, see Fig. 2, shall be capable of holdingthe filters described in 7.7.7.7 Filter Media, 47-mm diameter glass fiber membranefilters with a nominal pore size of 0.7 m.7.8 Evaporating Beaker, borosilicate glass beaker, of 100 to200-mL capacity.7.9 Hot Plate or Heating Block, capable o
27、f heating a liquidin the evaporating vessel (7.8) to 135C.7.10 ALL equipment should be calibrated according to themanufacturers instructions on a periodic basis to ensureconsistency of results.8. Reagents and Materials8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless ot
28、herwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high
29、purity to permit its use without lessening theaccuracy of the determination.8.2 Purity of WaterUnless otherwise indicated, referenceto water shall be understood to mean reagent water as definedby Type III of Specification D 1193.8.3 2.2,4-trimethylpentane (isooctane), 99.75 % purity pre-filtered thr
30、ough a filter medium of the type specified in 7.7.8.4 Oxygen, 99.5 % purity or better. When the oxygen isdelivered through a plant system of piping, a filter shall beprovided adjacent to the constant temperature bath to preventthe introduction of line debris or moisture into the oxidationcells; a pr
31、essure regulator adequate to maintain a constant flowof gas through the apparatus shall also be used. A tank ofoxygen of the specified purity can be used provided it isequipped with a two-stage pressure regulator.8.5 Trisolvent, a mixture of equal volumes of acetone,methanol, and toluene. See 8.1. I
32、t has been found thatcommercial grades of acetone, if used in the trisolvent, canhave impurities that cause an apparently greater level ofadherent insolubles to be measured. It is particularly importantthat technical, commercial, practical, or industrial grades(however they are designated by the par
33、ticular manufacturer)are not to be used, as their use may lead to apparently increasedlevels of adherent insolubles. (WarningFire hazard; toxic.)9. Samples and Sampling9.1 When obtaining samples for the laboratory, followPractices D 4057 or D 4177, or other standard practice capableof providing repr
34、esentative samples.9.2 Analyze fuel samples as soon as possible after receipt.When a fuel cannot be tested within one day, blanket it with aninert gas such as oxygen-free nitrogen, argon, or helium. It ispreferable to store the sample at a temperature of 5 to 10C.3This apparatus is available from su
35、ppliers of specialty petroleum testingequipment.4Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Pool
36、e, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D74620829.3 Test SamplesReduction of the laboratory sample totest sample size (about 400 mL for each determination)depends upon the size of sample received by the labor
37、atory. Ifthe laboratory sample is stored in a tank, drum, or 19-L orlarger can, use the pertinent procedures of Practice D 4057.Thoroughly mix smaller laboratory samples by shaking, roll-ing, or other techniques before taking an aliquot portion bypouring, pipetting, or other means. Clean any tube, t
38、hief,pipette, beaker, or other substance that is to contact thelaboratory sample with trisolvent and dry it prior to use. Priorto mixing thoroughly and taking an aliquot, allow samples thathave been stored at reduced temperatures to warm to roomtemperature or heat above the cloud point for sampling.
39、10. Preparation of Apparatus10.1 Preparation of Glassware Other Than OxidationCellsRinse all glassware thoroughly with trisolvent followedby water, then wash with a mildly alkaline or neutral laboratorydetergent. Rinse three times with deionized or distilled water.FIG. 1 Oxidation CellD7462083Dry th
40、e glassware in an oven or rinse it with acetone andair-dry it to remove water.10.2 Preparation of Oxidation Cells and AccessoriesAfter completion of 10.1, soak the oxidation cells and acces-sories in laboratory detergent in water. Allow the glassware tosoak at least two hours. Wash, drain, and then
41、rinse theglassware five times with tap water followed by three rinseswith distilled or deionized water. Rinse with acetone; drain andallow the oxidation cell and oxygen delivery tube to dry.10.3 Preparation of Evaporating BeakersDry the cleanedbeakers (10.1)for1hinanoven at 105 6 5C. Place thebeaker
42、s near the balance being careful to prevent contamina-tion of the beakers from airborne particles or other contami-nants. Allow the beakers to cool for 1 h. Weigh beakers to thenearest 0.1 mg.11. Procedure11.1 Preparing the SamplePlace one filter (described in7.7) on the filter support and clamp the
43、 filter funnel to thesupport as shown in Fig. 2. Apply suction (approximately 80kPa). Pour 400 mL of the fuel through the filter (see 7.7) intoa clean (10.1) 500-mL glass suction flask. Repeat preparationfor each sample to be run. After filtration is complete, discardthe filter media. Never use the
44、same filters for a secondincrement of fuel, because any material deposited on the filtersby a previous increment of fuel can result in a greater removalof solids from the next increment.11.2 Assembling the Oxidation Apparatus:11.2.1 Place a clean oxygen delivery tube into a cleanoxidation cell (Sect
45、ion 10) and pour 350 6 5 mL of the filteredfuel into the cell. As soon thereafter as possible, but in no casegreater than 1 h after measuring the sample, immerse the testcell in the 95C heating bath. During any interim period storethe cells in the dark. Keep the level of sample in the oxidationcell
46、below the level of the liquid medium in the heating bath.11.2.2 Place a condenser over the oxygen delivery tube andoxidation cell; connect the condenser to the cooling water.Connect the oxygen delivery tube to the oxygen supply throughthe flow meter and adjust the oxygen flow to 3 6 0.3 L/h. Makesur
47、e samples are protected from light. When the number of testcells is less than the capacity of the heating bath, fill the emptypositions with dummy oxidation cells containing 350 mL of astable petroleum liquid with physical properties similar tothose of the fuel being tested.11.2.3 Record the time th
48、e first oxidation cell is placed inthe bath as zero time.11.3 Cool the Sample:11.3.1 After 16 6 0.25 h from zero time, remove thesamples from the heating bath in the same sequence as theywere placed therein. Cover the opening of each cell with apiece of aluminum foil or plastic to prevent entrance o
49、f dirt,dust, or moisture. Record the time the first cell is removed.11.3.2 Place the oxidation cells in a dark, ventilated site atroom temperature until the fuel attains room temperature butfor no longer than 4 h.11.4 Determining Filterable Insolubles:11.4.1 For each sample to be filtered, use a single, pre-weighed, glass fiber filter. In addition, for each set of samplesto be analyzed at one time, use a single glass fiber filter as amoisture blank or control.NOTE 2The stacked filter method used in test methods such as TestMethod D 2274 has been found to i
