1、Designation: D 381 04Designation: 131/99An American National StandardStandard Test Method forGum Content in Fuels by Jet Evaporation1This standard is issued under the fixed designation D 381; the number immediately following the designation indicates the year oforiginal adoption or, in the case of r
2、evision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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. Scope*1.1 This test meth
3、od covers the determination of 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 additives) at the time of test.1.2 Provisions are made
4、 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 as thestandard. The accepted SI unit of pressure is the Pascal (Pa);the accepted SI unit for temperature is degrees Celsius.1.4 This standard does not purp
5、ort 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 to use. For specificwarning statements, see 6.4, 7.4,
6、 and 9.1.2. Referenced Documents2.1 ASTM Standards:2D 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsE 1 Specification for ASTM Liquid-in-Glass ThermometersE 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications2.2 Energy Institute Sta
7、ndard:IP Standard Methods for Analysis and Testing of PetroleumProducts33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 existent gumthe evaporation residue of aviationfuels, without any further treatment.3.2 For non-aviation fuels, the following definitions apply.3.3 solvent w
8、ashed gum contentthe residue remainingwhen the evaporation residue (see 3.4) has been washed withheptane and the washings discarded.3.3.1 DiscussionFor motor gasoline or non-aviation gaso-line, solvent washed gum content was previously referred to asexistent gum.3.4 unwashed gum contentthe evaporati
9、on residue of theproduct or component under test, without any further treat-ment.4. Summary of Test Method4.1 A measured quantity of fuel is evaporated under con-trolled conditions of temperature and flow of air or steam. Foraviation gasoline and aviation turbine fuel, the resultingresidue is weighe
10、d and reported as milligrams per 100 mL. Formotor gasoline, the residue is weighed before and afterextracting with heptane and the results reported as milligramsper 100 mL.5. Significance and Use5.1 The true significance of this test method for determininggum in motor gasoline is not firmly establis
11、hed. It has beenproved that high gum can 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 induc
12、tion-system deposits.The primary purpose 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
13、or additives, theheptane extraction step is necessary to remove these from theevaporation residue so that the deleterious material, gum, maybe determined. With respect to aviation turbine fuels, large1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricant
14、s and is the direct responsibility of SubcommitteeD02.14 on Stability and Cleanliness of Liquid Fuels.Current edition approved Nov. 1, 2004. Published November 2004. Originallyapproved in 1934. Last previous edition approved in 2003 as D 381 03.In the IP, this test method is under the jurisdiction o
15、f the StandardizationCommittee. This test method was issued as a joint ASTM-IP standard in 1965.2For 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 Docume
16、nt Summary page onthe ASTM website.3Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,U.K.1*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.quantiti
17、es of gum are indicative of contamination of fuel byhigher boiling oils or particulate matter and generally reflectpoor handling practices 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 il
18、lustrated in Fig. 1.Arrange the beakers in sets, the number in each set dependingupon the number of beaker wells in the evaporating bath. 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
19、 desiccant, for cooling the beakers beforeweighing.NOTE 1The use of a desiccant could lead to erroneous results.6.4 Evaporation Bath (WarningIf a liquid-filled evapo-ration bath is used, care must be taken that the flash point of theliquid used is at least 30C higher than the highest bathtemperature
20、 expected.) Either a solid metal block bath or aliquid bath, electrically heated, and constructed in accordancewith the general principles shown in Fig. 1 may be used.(Although all dimensions are given in SI units, older bathsconforming to Test Method D 381 94, or earlier, are suitable.)The bath sho
21、uld have wells and jets for two or more beakers.The rate of flow from each outlet when fitted with the conicaladapters with 500 to 600 micron copper or stainless steelscreens should not differ from 1000 mL/s by more than 15 %.A liquid bath, if used, shall be filled to within 25 mm of the topwith a s
22、uitable liquid. Temperature shall be maintained bymeans of thermostatic controls or by refluxing liquids ofsuitable composition.6.5 Flow Indicator, as illustrated in Fig. 1, such as aflowmeter, capable of metering a flow of air or steam equiva-lent to 1000 mL/s for each outlet.NOTE 2Alternatively, a
23、 pressure gage may be used to meter the flowof air or steam equivalent to 1000 6 150 mL/s for each outlet.6.6 Sintered Glass Filtering 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 to 246C.6.8 Temp
24、erature Sensor, liquid-in-glass thermometer con-forming to the requirements in the specification(s) for ASTM3C/IP73C, found in Specification E 1, or another temperaturemeasuring device or system, or both, of at least equivalentaccuracy and precision over a temperature range from 5 to400C.6.9 Graduat
25、ed Cylinders, with spout, capable of measuring50 6 0.5 mL.6.10 Handling Equipment, forceps (stainless steel, spadeended) or tongs (stainless steel) for use in handling the beakersand conical jets, as required by this test method.7. Materials7.1 AirSupply of filtered air at a pressure not more than35
26、 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 oily 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 cont
27、act with exposed skin by use ofprotective equipment as required.)8. Assembly of Air-Jet Apparatus8.1 Assemble the air-jet apparatus as shown in Fig. 1. Withthe apparatus at room temperature, adjust the air flow to give arate of 600 6 90 mL/s for the outlet under test. Check theremaining outlets for
28、uniform air flow.NOTE 3A rate of 600 6 90 mL/s from each outlet, at roomtemperature and atmospheric pressure, will ensure delivery of 1000 6 150mL/s at the temperature of 155 6 5C for each outlet. It is recommendedto follow the manufacturers instructions to verify total flow/s (600 mL/sair flow 3 nu
29、mber of outlets = total flow/s) and uniformity from eachoutlet.8.2 Apply heat to the evaporation bath (see 6.4) until thetemperature of the bath is between 160 and 165C. Introduceair into the apparatus at a rate indicated on the flow indicator(see 6.5) from the exercise carried out in 8.1. Measure t
30、hetemperature in each well with the temperature sensor (see 6.8)placed with the bulb or sensor tip resting on the bottom of thebeaker in the well. Do not use any well having a recordedtemperature outside the range from 150 to 160C.9. Assembly of Steam-Jet Apparatus9.1 Assemble the steam-jet apparatu
31、s as shown in Fig. 1.(WarningThe sample and solvent vapors evaporated duringthe performance of this test procedure can be extremelyflammable or combustible and hazardous from the inhalationstandpoint. The evaporation bath must be provided with aneffective exhaust hood to control such vapors and redu
32、ce therisk of thermal explosion.)9.2 To place the apparatus in operation, apply heat to thebath. When the temperature reaches 232C, slowly introducedry steam into the system until a rate of 1000 6 150 mL/s foreach outlet is reached (see 10.2). Regulate the temperature ofFIG. 1 Apparatus for Determin
33、ing Gum Content by JetEvaporationD381042the bath to a range from 232 to 246C to provide a welltemperature of 232 6 3C. Measure the temperature with thetemperature sensor, placed resting on the bottom of a beaker inone of the bath wells with the conical adapter in place. Anywell having a temperature
34、that differs by more than 3C from232C 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 outletsmeet the 600 6 90 mL/s air flow requirement as measured atroom temperature and atmospheric pressure. Refer to theinst
35、rument manufacturer instructions for specific guidance onperforming the air flow calibration procedure. Note the settingof the flow indicator device for use with air and use this settingfor subsequent tests.10.1.1.1 One way to calibrate the air flow is to use acalibrated flow indicator device, such
36、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 results, ensure that the backpressure of the flowmeter is less than 1 kPa.10.1.1.2 Alternatively, another way to calibrate the a
37、ir 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 outlet times the number or outletpositions (for example, instrument has 5 positions and a totalair flow rate measurement of 3000 mL/s
38、, indicating an ex-pected air flow rate of 600 mL/s at each outlet). Once verifyingthe total flow supplied to the outlets is at the appropriate rate,perform uniformity checks by comparing the relative air flowrates at each outlet position versus the requirements in 10.1.1.10.2 Steam Flow:10.2.1 Veri
39、fy or calibrate the steam flow to ensure all outletsmeet the 1000 6 150 mL/s steam flow requirement. Refer tothe instrument manufacturer instructions for specific guidanceon performing the steam flow calibration procedure. Note thesetting of the flow indicator device for use with steam and usethis s
40、etting 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 that has been filled with crushed ice andwater that has been previously weighed. Exhaust the steam intothe cylinder for approximately
41、 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. After the appropriate time has elapsed, remove thecopper tube from the cylinder and weigh the cylinder. The gainin mass represents the
42、 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 232C at atmosphericpressure = 0.434 g, andt = conden
43、sing time, s.11. Procedure11.1 Wash the beakers, including the tare, with the gumsolvent until free of gum. Rinse thoroughly with water andimmerse in a mildly alkaline or neutral pH laboratory detergentcleaning solution.11.1.1 The type of detergent and conditions for its use needto be established in
44、 each laboratory. The criterion for satisfac-tory cleaning shall be a matching of the quality of that obtainedwith chromic acid cleaning solutions on used beakers (freshchromic acid, 6-h soaking period, rinsing with distilled waterand drying). For this comparison visual appearance and massloss on he
45、ating the glassware under test conditions may beused. Detergent cleaning avoids the potential hazards andinconveniences related to handling corrosive chromic acidsolutions. The latter remains as the reference cleaning practiceand as such may function as an alternate to the preferredprocedure-cleanin
46、g with detergent solutions.11.1.2 Remove the beakers from the cleaning solution bymeans of stainless steel forceps or tongs (see 6.10) and handleonly with forceps or tongs thereafter. Wash the beakersthoroughly, first with tap water and then with distilled water,and dry in an oven at 150C for at lea
47、st 1 h. Cool the beakersfor at least2hinthecooling vessel placed in the vicinity of thebalance.11.2 Select the operating conditions, corresponding to theaviation motor gasoline or aircraft turbine fuel under test, fromthe data given in Table 1. Heat the bath to the prescribedoperating temperature. I
48、ntroduce air or steam to the apparatusand adjust the total flow to that established in 8.1 or 9.2. If anexternal preheater is used, regulate the temperature of thevaporizing medium to give the prescribed test well tempera-ture.11.3 Weigh the tare and test beakers to the nearest 0.1 mg.Record the mas
49、ses.11.4 If suspended or settled solid matter is present, mix orshake the contents of the sample container thoroughly using anappropriate method. At atmospheric pressure, immediatelyfilter a quantity of the sample through a sintered-glass funnel ofcoarse porosity (see 13.3). Treat the filtrate as described in11.5-11.7.11.5 Measure a 50 6 0.5 mL test specimen in a graduatedcylinder (see 6.9), and transfer it to a weighed beaker (see 6.2).(See Practice D 4057 regarding sampling.) Use one beaker foreach test specimen to be tested, and fill each beaker exc
