1、Designation:D52512 Designation: D525 12aDesignation: 40/97British Standard 4347Standard Test Method forOxidation Stability of Gasoline (Induction Period Method)1This standard is issued under the fixed designation D525; the number immediately following the designation indicates the year oforiginal ad
2、option 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.This standard has been approved for use by agencies of the Department of Defense.1
3、. Scope*1.1 This test method covers the determination of the stability of gasoline in finished form only, under accelerated oxidationconditions. (WarningThis test method2is not intended for determining the stability of gasoline components, particularly thosewith a high percentage of low boiling unsa
4、turated compounds, as these may cause explosive conditions within the apparatus.However, because of the unknown nature of certain samples, the pressure vessel assembly shall include a safety burst-disc in orderto safeguard the operator.)NOTE 1For measurement of oxidation stability of gasoline by mea
5、surement of potential gum, refer to Test Method D873, or IP Test Method 138.NOTE 2The precision data were developed with gasolines derived from hydrocarbon sources only without oxygenates.1.2 The accepted SI unit of pressure is the kilo Pascal (kPa), and of temperature is C.1.3 WARNINGMercury has be
6、en designated by many regulatory agencies as a hazardous material that can cause centralnervous system, kidney and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Cautionshould be taken when handling mercury and mercury containing products. See the applica
7、ble product Material Safety Data Sheet(MSDS) for details and EPAs websitehttp:/www.epa.gov/mercury/faq.htmfor additional information. Users should be awarethat selling mercury and/or mercury containing products into your state or country may be prohibited by law.1.4 This standard does not purport to
8、 address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D873 Test M
9、ethod for Oxidation Stability of Aviation Fuels (Potential Residue Method)D4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsE1 Specification for ASTM Liquid-in-Glass Thermometers2.2 Energy Institute Standards:4IP-138 Test Method for Oxidation Stability, Aviation GasolinePart IV P
10、etroleum and its Products53. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 break point, nthe point in the pressure-time curve that is preceded by a pressure drop of exactly 14 kPa within 15 minand succeeded by a drop of not less than 14 kPa in 15 min.1This test method is under
11、the jurisdiction of ASTM Committee D02 on Petroleum Products and Lubricants and is the direct responsibility of Subcommittee D02.14 onStability and Cleanliness of Liquid Fuels.This test method has been approved by the sponsoring committees and accepted by the Cooperating Societies in accordance with
12、 established procedures.Current edition approved April 15,Sept. 1, 2012. Published MayNovember 2012. Originally approved in 1939. Last previous edition approved in 20052012 asD52505.D52512. DOI: 10.1520/D0525-12A.2Further information can be found in the June 1978, January 1979, and June 1986 edition
13、s of the Institute of Petroleum Review.3For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4Available from Ener
14、gy Institute, 61 New Cavendish St., London WIM, 8AR U.K.5A convenient template for measuring the breakpoint is described in the paper by Korb, E. L., “Induction Period Calculator,” ASTM Bulletin, No. 153, August 1948, pp.99102.1This document is not an ASTM standard and is intended only to provide th
15、e user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit 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 versionof the standa
16、rd as published by ASTM is to be considered the official document.*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.3.1.2 induction period, nthe time elapsed between the
17、placing of the pressure vessel in the bath and the break point at 100C.4. Summary of Test Method4.1 The sample is oxidized in a pressure vessel initially filled at 15 to 25C with oxygen pressure at 690 to 705 kPa and heatedat a temperature between 98 and 102C. The pressure is recorded continuously o
18、r read at stated intervals until the breakpoint isreached. The time required for the sample to reach this point is the observed induction period at the temperature of test, from whichthe induction period at 100C can be calculated. (WarningIn addition to other precautions, to provide protection again
19、st thepossibility of explosive rupture of the pressure vessel, the pressure vessel should be operated behind an appropriate safety shield.)5. Significance and Use5.1 The induction period may be used as an indication of the tendency of motor gasoline to form gum in storage. It should berecognized, ho
20、wever, that its correlation with the formation of gum in storage may vary markedly under different storageconditions and with different gasolines.6. Apparatus6.1 Oxidation Pressure Vessel, Glass Sample Container and Cover, Accessories, Pressure Gage, and Oxidation Bath,asdescribed in Annex A1.6.2 Th
21、ermometer, having a range as shown as follows and conforming to the requirements as prescribed in Specification E1 orin the specifications for IP thermometers:NOTE 3Other temperature sensing devices that cover the temperature range of interest, such as thermocouples or platinum resistance thermomete
22、rs,that can provide equivalent or better accuracy and precision, may be used in place of thermometers specified in 6.2.Thermometer NumberTemperature Range ASTM IP95 to 103C 22C 24C7. Reagents and Materials7.1 Gum SolventMixture of equal volumes of toluene and acetone, both of which shall be of 99 %
23、minimum purity.7.2 OxygenCommercially-available extra-dry oxygen of not less than 99.6 % purity.8. Sampling8.1 Sample in accordance with the procedure for oxidation stability as described in Practice D4057.9. Preparation of Apparatus9.1 Wash the glass sample container with gum solvent until free fro
24、m gum. Rinse thoroughly with water and immerse thesample container and cover in detergent cleaning solution. The type of detergent and conditions for its use shall match thecleanliness obtained by the use of a strongly oxidizing agent such as chromosulfuric acid, ammonium peroxydisulfate inconcentra
25、ted sulfuric acid at approximately 8 G./L, or sulfuric acid itself, soaking for at least 12 h, followed by rinses in tap water,distilled water and then acetone. For comparison, visual appearance and weight loss on heating the glassware under test conditionsmay be used. Glassware needs to show no sig
26、ns of discoloration or particulates on the surface. The weight of glassware must notchange by more than 60.5 mg between cleaning and heating/cooling cycles. Detergent cleaning avoids the potential hazards andinconveniences related to handling corrosive chromic acid solutions; this procedure remains
27、the reference cleaning practice andas such may function as an alternate to the preferred procedure, cleaning with detergent solutions.9.2 Remove container and cover from the cleaning solution by means of corrosion-resistant steel forceps and handle only withforceps thereafter. Wash thoroughly, first
28、 with tap water, then with distilled water, and dry in an oven at 100 to 150C for at least1h.9.3 Drain any gasoline from the pressure vessel and wipe the inside of the pressure vessel and pressure vessel closure, first witha clean cloth moistened with gum solvent and then with a clean dry cloth. Rem
29、ove the filler rod from the stem and carefully cleanany gum or gasoline from the stem, rod, and needle valve with gum solvent. The pressure vessel, the valve, and all connectinglines shall be thoroughly dry before each test is started. (WarningVolatile peroxides which may have formed during a previo
30、ustest may accumulate in the equipment, producing a potentially explosive environment. Special care in cleaning after each test isneeded to ensure the filler rod, stem, and needle valve are free of these peroxides.)10. Procedure10.1 Bring the pressure vessel and the gasoline to be tested to a temper
31、ature of 15 to 25C. Place the glass sample containerin the pressure vessel and add 50 6 1 mL of test specimen.Alternatively, transfer 50 6 1 mL of test specimen into the glass samplecontainer first, before placing the glass sample container into the pressure vessel. Cover the sample container, close
32、 the pressurevessel, and using a quick release air coupling introduce oxygen until a pressure of 690 to 705 kPa is attained. Allow the gas inthe bomb to escape slowly in order to flush out the air originally present (Release the pressure at a slow uniform rate through theneedle valve at a rate not t
33、o exceed 345 kPa per min). Introduce oxygen again until a pressure of 690 to 705 kPa is attained andD525 12a2observe for leaks, ignoring an initial rapid drop in pressure (generally not over 40 kPa) which may be observed because of thesolution of oxygen in the sample. When the rate of pressure drop
34、does not exceed 7 kPa in 10 min, assume the absence of leaksand proceed with the test without repressuring.10.2 Place the charged pressure vessel in the vigorously boiling water bath, or appropriate liquid bath equipped with mechanicalstirring, being careful to avoid shaking, and record the time of
35、immersion as the starting time. Maintain the temperature of theliquid bath between 98 and 102C. Observe the temperature to the nearest 0.1C at intervals during the test, and record the averagetemperature to the nearest 0.1C as the temperature of the test. Make a continuous record of the pressures in
36、 the pressure vessel,or if an indicating pressure gage is used, take pressure readings at 15-min intervals or less. If, during the initial 30 min of the test,a leak develops (as indicated by a steady drop in pressure considerably in excess of 14 kPa in 15 min) discard the test. Continuethe test unti
37、l reaching a point preceded by a pressure drop of exactly 14 kPa in 15 min and succeeded by a drop of not less than14 kPa in 15 min or until the induction period exceeds the product specification. If no breakpoint is observed at the terminationof the test, refer to Section 12 for reporting the resul
38、t. (WarningIf a boiling water bath is used and the test is made in a regionwhere the atmospheric pressure is consistently below normal (101.3 kPa), it is permissible to add a liquid with higher boiling point,such as ethylene glycol, to the water in order to maintain the operating temperature of the
39、bath in the neighborhood of 100C. Ifa liquid other than water is used, be sure the liquid is compatible with the seals in the pressure vessel.)10.3 Record the number of minutes from the time the pressure vessel is placed in the bath until the breakpoint has been reachedas the observed induction peri
40、od at the temperature of the test.10.4 Cool the pressure vessel to approximately room temperature within 30 min after removal from the bath, using ambient airor water 35C, before releasing the pressure slowly from the pressure vessel through the needle valve at a rate not exceeding345 kPa per minute
41、. Wash the pressure vessel and sample container in preparation for the next test.11. Calculation11.1 The number of minutes from the time the pressure vessel is placed in the bath until the breakpoint has been reached is theobserved induction period at the temperature of the test.11.2 Method of Calcu
42、lationCalculate the induction period at 100C from one of the following equations: When the testtemperature is above 100C:Induction period at 100C 5 IPt!1 1 0.101ta2 100! (1)D0525-12A_1When the test temperature is below 100C:D0525-12A_2where:IPt= induction period, min, at the temperature of the test,
43、ta= test temperature when above 100C, C, andtb= test temperature when below 100C, C.12. Report12.1 Report the Induction period at 100C, calculated as in 11.2 to the nearest 1 min.12.2 If the test was stopped prior to observing the pressure drop required in 10.2, but after the product specification w
44、asexceeded, then report the result as being greater than N min, where N is the product specification in min.12.3 If a slow oxidation of the sample is occurring rather than a breakpoint as defined in 10.2, then report the sample as a slowoxidizing fuel with the total time for the test and the overall
45、 pressure drop from the start of the test. A precision and bias statementhas not been determined for this case.13. Precision and Bias13.1 The precision of the test method as determined by statistical examination of interlaboratory test results is as follows:13.1.1 RepeatabilityThe difference between
46、 two test results, obtained by the same operator with the same apparatus underconstant operating conditions on identical test material, would in the long run, in the normal and correct operation of the testmethod, exceed the following values only in one case in twenty: 5 %.13.1.2 ReproducibilityThe
47、difference between two single and independent results obtained by different operators working indifferent laboratories on identical test material would, in the long run, in the normal and correct operation of the test method,exceed the following values only in one case in twenty: 10 %.13.2 BiasThere
48、 being no criteria for measuring bias in these test-product combinations, no statement of bias can be made.NOTE 4The precision values given above for induction period were obtained using a boiling water bath only as the heat source. Therefore, theseprecision values are not necessarily applicable to
49、induction period results obtained using other heat sources.14. Keywords14.1 breakpoint; gasoline; induction period; oxidation stabilityD525 12a3ANNEX(Mandatory Information)A1. APPARATUSA1.1 ApparatusA1.1.1 Pressure VesselThe pressure vessel shall be made of corrosion-resistant steel with the inside dimensions of the portionthat encloses the reacting gasoline-oxygen mixture conforming substantially to those shown in Fig. A1.1. Fig. A1.1 is a compositedrawing of specific pressure vessels and related apparatus for performing Test M
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