1、Designation: D381 12 (Reapproved 2017)Standard Test Method forGum Content in Fuels by Jet Evaporation1This standard is issued under the fixed designation D381; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. 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.1. Scope1.1 This test method covers the determination o
3、f the existentgum content of aviation fuels, and the gum content of motorgasolines or other volatile distillates in their finished form,(including those containing alcohol and ether type oxygenatesand deposit control additivessee Note 7 for additionalinformation) at the time of test.1.2 Provisions a
4、re made for the determination of the heptaneinsoluble portion of the residue of non-aviation fuels.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3.1 The accepted SI unit of pressure is the Pascal (Pa); theaccepted SI uni
5、t for temperature is degrees Celsius.1.4 WARNINGMercury has been designated by manyregulatory agencies as a hazardous material that can causecentral nervous system, kidney and liver damage. Mercury, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handl
6、ing mercury andmercury containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAswebsitehttp:/www.epa.gov/mercury/faq.htmfor addi-tional information. Users should be aware that selling mercuryand/or mercury containing products into your state or countryma
7、y be prohibited by law.1.5 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 the applica-bility of regulatory limitations prior
8、 to use. For specificwarning statements, see 6.4, 7.4, and 9.1.1.6 This international 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-mendati
9、ons issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1655 Specification for Aviation Turbine FuelsD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsE1 Specification for ASTM Liquid-in-Glass ThermometersE2
10、9 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 Energy Institute Standard:3IP Standard Methods for Analysis and Testing of PetroleumProductsIP540 Determination of the existent gum content of aviationturbine fuel jet evaporation method3. Terminology
11、3.1 Definitions of Terms Specific to This Standard:3.1.1 existent gum, nthe evaporation residue of aviationfuels, without any further treatment.3.2 For non-aviation fuels, the following definitions apply.3.3 solvent washed gum content, nthe residue remainingwhen the evaporation residue (see 3.4) has
12、 been washed withheptane and the washings discarded.3.3.1 DiscussionFor motor gasoline or non-aviationgasoline, solvent washed gum content was previously referredto as existent gum.3.4 unwashed gum content, nthe evaporation residue ofthe product or component under test, without any furthertreatment.
13、4. Summary of Test Method4.1 When testing either aviation or motor gasoline, a 50 mL6 0.5 mL quantity of fuel is evaporated under controlled1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommi
14、ttee D02.14 on on Stability, Cleanliness and Compatibility of LiquidFuels.Current edition approved July 1, 2017. Published July 2017. Originally approvedin 1934. Last previous edition approved in 2012 as D381 12. DOI: 10.1520/D0381-12R17.2For referenced ASTM standards, visit the ASTM website, www.as
15、tm.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.3Available from Energy Institute, 61 New Cavendish St., London, W1G 7AR,U.K., http:/www.energyinst.org.*A Summary of Change
16、s 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 standardization established in the Decis
17、ion on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1conditions of temperature and flow of air (see Table 1). Whentesting aviation turbine fuel, a 50 mL 6 0.5 mLquantity of fuel
18、is evaporated under controlled conditions of temperature andflow of steam (see Table 1). For aviation gasoline and aviationturbine fuel, the resulting residue is weighed and reported asmilligrams per 100 mL. For motor gasoline, the residue isweighed before and after extracting with heptane and there
19、sults reported as milligrams per 100 mL.NOTE 1Specification D1655 allows the existent gum of aviationturbine fuels to be determined by either Test Method D381 or IP 540, withTest Method D381 identified as the referee test method.Test Method D381specifically requires the use of steam as the evaporati
20、ng medium foraviation turbine fuels, whereas IP 540 allows either air or steam as theevaporating medium for aviation turbine fuels.5. Significance and Use5.1 The true significance of this test method for determininggum in motor gasoline is not firmly established. It has beenproved that high gum can
21、cause induction-system deposits andsticking of intake valves, and in most instances, it can beassumed that low gum will ensure absence of induction-systemdifficulties. The user should, however, realize that the testmethod is not of itself correlative to induction-system deposits.The primary purpose
22、of the test method, as applied to motorgasoline, is the measurement of the oxidation products formedin the sample prior to or during the comparatively mildconditions of the test procedure. Since many motor gasolinesare purposely blended with nonvolatile oils or additives, theheptane extraction step
23、is necessary to remove these from theevaporation residue so that the deleterious material, gum, maybe determined. With respect to aviation turbine fuels, largequantities of gum are indicative of contamination of fuel byhigher boiling oils or particulate matter and generally reflectpoor handling prac
24、tices in distribution downstream of therefinery.6. Apparatus6.1 Balance, capable of weighing test specimens to thenearest 0.1 mg.6.2 Beakers, of 100 mL capacity, as illustrated in Fig. 1.Arrange the beakers in sets, the number in each set dependingupon the number of beaker wells in the evaporating b
25、ath. Markeach beaker in the set, including the tare beaker, with anidentifying number or letter.6.3 Cooling VesselA tightly covered vessel, such as adesiccator without desiccant, for cooling the beakers beforeweighing.NOTE 2The use of a desiccant could lead to erroneous results.6.4 Evaporation Bath
26、(WarningIf a liquid-filled evapo-ration bath is used, care must be taken that the flash point of theliquid used is at least 30 C higher than the highest bathtemperature expected.) Either a solid metal block bath or aliquid bath, electrically heated, and constructed in accordancewith the general prin
27、ciples shown in Fig. 1 may be used.(Although all dimensions are given in SI units, older bathsconforming to Test Method D381 94, or earlier, are suitable.)The bath should have wells and jets for two or more beakers.The rate of flow from each outlet when fitted with the conicaladapters with 500 m to
28、600 m copper or stainless steelscreens should not differ from 1000 mLs by more than 15 %.Aliquid bath, if used, shall be filled to within 25 mm of the topwith a suitable liquid. Temperature shall be maintained bymeans of thermostatic controls or by refluxing liquids ofsuitable composition.6.5 Flow I
29、ndicator, as illustrated in Fig. 1, such as aflowmeter, capable of metering a flow of air or steam equiva-lent to 1000 mLs for each outlet.NOTE 3Alternatively, a pressure gage may be used to meter the flowof air or steam equivalent to 1000 mL s 6 150 mL s for each outlet.6.6 Sintered Glass Filtering
30、 Funnel, coarse porosity,150 mL capacity.6.7 SteamSupply by suitable means capable of deliveringto the bath inlet the required amount of steam at 232 C to246 C.6.8 Temperature Sensor, liquid-in-glass thermometer con-forming to the requirements in the specification(s) for ASTM3C/IP73C, found in Speci
31、fication E1, or another temperaturemeasuring device or system, or both, of at least equivalentaccuracy and precision over a temperature range from 5 C to400 C.6.9 Graduated Cylinders, with spout, capable of measuring50 mL 6 0.5 mL.6.10 Handling Equipment, forceps (stainless steel, spadeended) or ton
32、gs (stainless steel) for use in handling the beakersand conical jets, as required by this test method.TABLE 1 Schedule of Test ConditionsSample TypeVaporizingMediumOperating TemperatureBath Test WellAviation and motor gasoline air 160 C to165 C150 C to160 CAviation turbine fuel steam 232 C to246 C22
33、9 C to235 CFIG. 1 Apparatus for Determining Gum Content by Jet Evapora-tionD381 12 (2017)27. Materials7.1 AirSupply of filtered air at a pressure not more than35 kPa.7.2 Gum SolventA mixture of equal volumes of tolueneand acetone.7.3 HeptaneMinimum purity of 99.7 %.7.4 SteamSupply of steam free of o
34、ily residue and at apressure not less than 35 kPa. (WarningIf a steam super-heater is used, there may be exposed hot surfaces on the steamsuperheater. Avoid contact with exposed skin by use ofprotective equipment as required.)8. Assembly of Air-Jet Apparatus8.1 Assemble the air-jet apparatus as show
35、n in Fig. 1. Withthe apparatus at room temperature, adjust the air flow to give arate of 600 mLs 6 90 mLs for the outlet under test. Checkthe remaining outlets for uniform air flow.NOTE 4A rate of 600 mL s 6 90 mL s from each outlet, at roomtemperature and atmospheric pressure, will ensure delivery
36、of 1000 mL s6 150 mL s at the temperature of 155 C 6 5 C for each outlet. It isrecommended to follow the manufacturers instructions to verify totalflow/s (600 mL s air flow number of outlets = total flow/s) anduniformity from each outlet.8.2 Apply heat to the evaporation bath (see 6.4) until thetemp
37、erature of the bath is between 160 C and 165 C.Introduce air into the apparatus at a rate indicated on the flowindicator (see 6.5) from the exercise carried out in 8.1. Measurethe temperature in each well with the temperature sensor (see6.8) placed with the bulb or sensor tip resting on the bottom o
38、fthe beaker in the well. Do not use any well having a recordedtemperature outside the range from 150 C to 160 C.9. Assembly of Steam-Jet Apparatus9.1 Assemble the steam-jet apparatus as shown in Fig. 1.(WarningThe sample and solvent vapors evaporated duringthe performance of this test procedure can
39、be extremelyflammable or combustible and hazardous from the inhalationstandpoint. The evaporation bath must be provided with aneffective exhaust hood to control such vapors and reduce therisk of thermal explosion.)9.2 To place the apparatus in operation, apply heat to thebath. When the temperature r
40、eaches 232 C, slowly introducedry steam into the system until a rate of 1000 mLs 6150 mLs for each outlet is reached (see 10.2). Regulate thetemperature of the bath to a range from 232 C to 246 C toprovide a well temperature of 232 C 6 3 C. Measure thetemperature with the temperature sensor, placed
41、resting on thebottom of a beaker in one of the bath wells with the conicaladapter in place. Any well having a temperature that differs bymore than 3 C from 232 C is not suitable for standard tests.10. Calibration and Standardization10.1 Air Flow:10.1.1 Verify or calibrate the air flow to ensure all
42、outletsmeet the 600 mLs 6 90 mLs air flow requirement as mea-sured at room temperature and atmospheric pressure. Refer tothe instrument manufacturer instructions for specific guidanceon performing the air flow calibration procedure. Note thesetting of the flow indicator device for use with air and u
43、se thissetting for subsequent tests.10.1.1.1 One way to calibrate the air flow is to use acalibrated flow indicator device, such as a flowmeter, separatefrom the device specified in 6.5, to check the air flow rate ateach outlet directly at room temperature and atmosphericpressure. To obtain accurate
44、 results, ensure that the backpressure of the flowmeter is less than 1 kPa.10.1.1.2 Alternatively, another way to calibrate the air flowis to measure and adjust as appropriate the total air flow rate(mL/s) supplied to the outlets. The total air flow rate equals theexpected air flow rate at each outl
45、et times the number or outletpositions (for example, instrument has 5 positions and a totalair flow rate measurement of 3000 mLs, indicating an ex-pected air flow rate of 600 mLs at each outlet). Once verifyingthe total flow supplied to the outlets is at the appropriate rate,perform uniformity check
46、s by comparing the relative air flowrates at each outlet position versus the requirements in 10.1.1.10.2 Steam Flow:10.2.1 Verify or calibrate the steam flow to ensure all outletsmeet the 1000 mLs 6 150 mLs steam flow requirement.Refer to the instrument manufacturer instructions for specificguidance
47、 on performing the steam flow calibration procedure.Note the setting of the flow indicator device for use with steamand use this setting for subsequent tests.10.2.1.1 One way to calibrate the steam flow, is to attach acopper tube to a steam outlet and extend the tube into a 2 Lgraduated cylinder tha
48、t has been filled with crushed ice andwater that has been previously weighed. Exhaust the steam intothe cylinder for approximately 60 s. Adjust the position of thecylinder so that the end of the copper tube is immersed in thewater to a depth of less than 50 mm to prevent excessive backpressure. Afte
49、r the appropriate time has elapsed, remove thecopper tube from the cylinder and weigh the cylinder. The gainin mass represents the amount of steam condensed. Calculatethe steam rate (mL/s) as follows:R 5 M 2 m!1000/kt (1)where:R = steam rate (mL/s),M = mass of graduated cylinder with condensed steam, g,m = mass of graduated cylinder and ice, g,k = mass of 1000 mL of steam at 232 C at atmosphericpressure = 0.434 g, andt = condensing time, s.11. Procedure11.1 Wash the beakers, including the tare, with the
