1、Designation: D4308 10An American National StandardStandard Test Method forElectrical Conductivity of Liquid Hydrocarbons by PrecisionMeter1This standard is issued under the fixed designation D4308; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e 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. Scope*1.1 This test
3、 method covers and applies to the determinationof the “rest” electrical conductivity of aviation fuels and othersimilar low-conductivity hydrocarbon liquids in the range from0.1 to 2000 pS/m (see 3.2). This test method can be used in thelaboratory or in the field.1.2 The values stated in SI units ar
4、e to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 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 corros
5、ive tomaterials. Caution should be taken when handling 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 mercu
6、ry containing products into your state or countrymay be prohibited by law.1.4 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. For specificwarning statements, see 7.1.1, 7.2, 8.3, and Annex A1.2. Referenced Documents2.1 ASTM Standards:2D150 Test Methods for AC Loss Characteristics and Per-mittivity (Dielectric Constant) of Solid Electrical Insula-tionD2624 Test Met
8、hods for Electrical Conductivity ofAviationand Distillate FuelsD4306 Practice for Aviation Fuel Sample Containers forTests Affected by Trace ContaminationE1 Specification for ASTM Liquid-in-Glass Thermometers3. Terminology3.1 picosiemens per metrethe unit of electrical conductiv-ity is also called a
9、 conductivity unit (CU). A siemen is the SIdefinition of reciprocal ohm sometimes called mho.1 pS/m 5 1 3 10212V21m215 1cu5 1 picomho/m (1)3.2 rest conductivitythe reciprocal of the resistance ofuncharged fuel in the absence of ionic depletion or polariza-tion. It is the electrical conductivity at t
10、he initial instant ofcurrent measurement after a dc voltage is impressed betweenelectrodes.4. Summary of Test Method4.1 A sample of liquid hydrocarbon is introduced into aclean conductivity cell which is connected in series to a batteryvoltage source and a sensitive dc ammeter. The conductivity,auto
11、matically calculated from the observed peak current read-ing dc voltage and cell constant using Ohms law, appears as adigital value in either a manual or automatic mode of meteroperation.5. Significance and Use5.1 The generation and dissipation of electrostatic charge infuel due to handling depend l
12、argely on the ionic species presentwhich may be characterized by the rest or equilibrium electri-cal conductivity. The time for static charge to dissipate isinversely related to conductivity. This test method can supple-ment Test Method D2624 which is limited to fuels containingstatic dissipator add
13、itive.NOTE 1For low-conductivity fluids below 1 pS/m in conductivity, anac measurement technique is preferable to a dc test method for sensing theelectrical conductivity of bulk fluid. This dc test method can be used atconductivities from 0.1 to 1 pS/m if precautions are observed in cell1This test m
14、ethod is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.J0.04 on Additives and Electrical Properties.Current edition approved Oct. 1, 2010. Published November 2010. Originallyapproved in 1983. Last previous edition
15、 approved in 2010 as D430895(2010).DOI: 10.1520/D4308-10.2For 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.1*A
16、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.cleaning and sample handling.Awaiting period of 15 min is required afterfilling the cell before measuring dc conductivities
17、 below 1 pS/m. Asingle-laboratory program was conducted comparing this test method withac Test Methods D150.36. Apparatus6.1 Conductivity ApparatusComponents of the dc con-ductivity apparatus are shown in Fig. 1.4,56.1.1 The conductivity cell shown in Fig. 1 consists of aninner electrode and an oute
18、r electrode separated by an insula-tor. The outer electrode and cap provide a ground path andelectrostatic (Faraday) shield.6.1.2 The electrometer shown in Fig. 1 contains a batterywhich supplies a voltage to the cell and a bridge circuit whichsenses the flow of current and converts the output signa
19、ldirectly into conductivity units, that is, pS/m. A pushbuttonselector allows selection of zero reading, calibration, and fourrange selections.6.1.3 The cell and electrometer are connected by a triaxialcable as shown in Fig. 1.6.2 Thermometer, general purpose type, having a range of 0to 60C (see Spe
20、cification E1). Temperature measuring devicesthat cover the temperature range of interest, such as an ASTM1C thermometer, or liquid-in-glass thermometers, thermo-couples, or platinum resistance thermometers that provideequivalent or better accuracy and precision than ASTM 1Cthermometers may be used.
21、7. Reagents7.1 Cleaning Solvent, The following may be used:7.1.1 Toluene-Isopropyl Alcohol Mixture(WarningFlammable. Vapor harmful. See Annex A1.1.) Mix two vol-umes of toluene and three volumes of isopropyl alcohol both ofreagent grade and distill. Discard the first 20 % and last 5 %fractions.7.2 n
22、-Heptane(WarningFlammable. Harmful if in-haled. See Annex A1.2.) Prepare by percolating ASTM refer-ence fuel grade n-heptane through silica gel5,6as follows:7.2.1 Activate approximately 2000 g of 100 to 200 meshsilica gel by heating at 180C for 24 h. Allow it to cool in adesiccator under nitrogen or
23、 in vacuum. Soak approximately0.5 g of glass wool5,7for 24 h in clean n-heptane.7.2.2 Take a tube of borosilicate glass having an insidediameter of 60 to 70 mm, a length 1500 mm, with a conicallyshaped lower end provided with a glass cock. Place a perfo-rated porcelain disk (diameter 25 mm) in the l
24、ower end of thetube and put the soaked glass wool on top of the disk. Fill thetube with the activated silica gel while tapping to achieve3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1241.4The sole source of supply of the
25、apparatus, the KSLA Cell and PrecisionConductivity Meter System, Emcee Model #1154, known to the committee at thistime is Emcee Electronics, Inc., 520 Cypress Ave., Venice, FL 34285.5If you are aware of alternative suppliers, please provide this information toASTM International Headquarters. Your co
26、mments will receive careful consider-ation at a meeting of the responsible technical committee,1which you may attend.6The sole source of supply known to the committee at this time is Code 923,from W. R. Grace pipet instead.The sample should be clean and bright when tested.9. Preparation of Apparatus
27、9.1 Cleaning the CellThe cleaning procedure to be useddepends on the estimated conductivity of the sample to betested.9.1.1 For samples that are expected to exhibit conductivitiesbelow 1 pS/m, the KSLA cell should be completely disas-sembled, the parts cleaned and the cell reassembled usingprotectiv
28、e gloves.9.1.1.1 Dismantle the cell by removing the loose batterycap, the outer electrode electrical connector and the bottomscrew-on cap. Press the inner electrode towards the bottom ofthe outer electrode and remove the inner electrode TFE-fluorocarbon insulator assembly.9.1.1.2 Each part of the ce
29、ll should be rinsed thoroughly fivetimes with cleaning solvent followed by rinsing with treatedn-heptane. The parts should be dried with a stream of nitrogengas.9.1.1.3 After reassembly, the cell should be rinsed withtreated n-heptane.9.1.1.4 After cleaning, check the cleanliness of the cell bymeasu
30、ring the conductivity of treated n-heptane in accordancewith Section 11. The corrected value should be lower than 0.05pS/m.9.1.2 For samples that are expected to exhibit conductivitiesabove 1 pS/m, the KSLA cell still assembled should be rinsedfive times with cleaning solvent, followed by rinsing wi
31、thtreated n-heptane. The cell should be dried with a stream ofnitrogen gas.9.1.2.1 After cleaning, check the cleanliness of the cell bymeasuring the conductivity of treated n-heptane in accordancewith Section 11. The corrected value should be lower than 0.1pS/m.9.2 Cleaning of Auxiliary Equipment:9.
32、2.1 Pipets used to transfer samples should be rinsed insideand outside with cleaning solvent using a non-contaminatingsqueeze bottle, then blown dry with clean, dry nitrogen.Thermometers should be similarly rinsed and maintained.NOTE 5If a cell has been used to test samples of high-conductivity,that
33、 is, more than 1000 pS/m, it should be disassembled for thoroughcleaning. Very thorough cleaning may also be accomplished by placing thedisassembled cell in a Soxhlet apparatus containing boiling toluene/isopropyl alcohol for several hours.NOTE 6If testing is to be done on both low-conductivity (100
34、0 pS/m) samples, separate cells are recom-mended.10. Calibration and Standardization10.1 Checking the Test Equipment:10.1.1 Remove cell and cable from the meter.10.1.2 Depress the 20 pS/m switch. The digital readingshould indicate 0.00 6 0.01 pS/m after 3 s. If readings exceed60.01 either adjust zer
35、o or record the zero error for calculatingfinal report value.10.1.3 Depress the calibrate switch. The digital readingshould indicate 1000 6 3 pS/m.10.1.4 If low battery indicator is displayed during measureor calibration, the internal batteries should be replaced.10.2 Checking the Cell Constant:10.2
36、.1 A check on the cell constant is necessary only if thecell has been damaged. Two capacitance measurements arerequired with a precision ac bridge. Make a rigid two-terminalconnection between the cell assembly and the bridge. Measurethe total capacitance, CE(picofarad) of the empty assembly.Without
37、disturbing the connection, add 100 mL of a hydrocar-bon standard and measure the new total capacitance, CS(picofarad) and the temperature in the cell. Alternatively, thecell can be sent to the manufacturer for recalibration.10.2.2 Calculate the actual capacitance, CA, of the emptycell as follows:CA5
38、 CS2 CE!/k21! (2)where:k = dielectric constant of the hydrocarbon at test tempera-tures.10.2.3 Calculate the cell constant as follows:K 5 8.854/CA(3)8A standard, such as cyclohexane, with certified dielectric constant, may beobtained from the National Bureau of Standards, Washington, DC 20234.D4308
39、10310.2.4 The cell constant of a new KSLAcell is 1.0. Becauseof its configuration, the cell constant cannot change signifi-cantly unless there is gross damage.11. Procedure11.1 Attach the cleaned cell to the meter as shown in Fig. 2.11.1.1 Depress the ZERO switch, the digital reading shouldindicate
40、the same value recorded in 10.1.2.11.1.2 Depress the CAL switch, the digital reading shouldindicate 1000 6 5.11.1.3 Rinse the cleaned cell three times with the sample,empty completely, then fill the outer chamber until sampleoverflows into the center receptacle. (Alternatively, the outerchamber can
41、be filled by pipet with 100 mL of sample).NOTE 7Allow static charges generated by handling the sample todissipate. If the sample is expected to have a conductivity below 1 pS/m,allow 15 min waiting time before reading.11.1.4 If the sample conductivity is known, select thecorresponding range position
42、. When the conductivity is un-known, first check the fuel on a 2000 pS/m range position, thenread in a lower scale if appropriate.11.1.5 Using the AUTO mode, depress the appropriateRANGE switch. In the AUTO mode, the reading is stabilizedafter 3 s and held on display for 9 s. Record the pS/m value.1
43、1.1.6 Repeat readings can be taken after a 1 min delay.11.1.7 Remove the cell cover and measure the temperatureof the test samples to the nearest 1C with a clean thermometer.12. Calculation12.1 If the zero error in 10.1.2 was greater than 60.01 andthe zero of the meter was not adjusted, the readings
44、 should becorrected by subtracting any positive zero error or adding anynegative zero error. For example:Sample reading (11.1.5) 1.67Uncorrected zero error (10.1.2) + 0.03Calculated reading 1.6413. Report13.1 The report is to include the following:13.1.1 The calculated conductivity of the sample in
45、pS/mafter correcting for the zero reading. Note MANUAL orAUTOmode.13.1.2 Temperature of sample.NOTE 8It is recognized that the electrical conductivity of a fuel variessignificantly with temperature and that the relationship differs for varioustypes of aviation and distillate fuel. If it is necessary
46、 to correct conduc-tivity readings to a particular temperature, each laboratory would have toestablish this relationship for the fuels and temperature range of interest.14. Precision and Bias914.1 The precision of this test method obtained by statisticalexamination of test results in the range betwe
47、en 0.1 and 2000pS/m by operator/instrument pairs at a common test site isdescribed in 14.2 and 14.3.NOTE 9The data used to determine the precision of this test methodwere obtained using the auto mode.14.2 RepeatabilityThe difference between successive testresults obtained by the same operator with t
48、he same apparatusunder constant operating conditions on identical test samples9Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D02-1170.FIG. 2 Cleaned Cell Attached to MeterD4308 104would, in the long run, in the normal and corre
49、ct operation ofthe test method, exceed the values in Fig. 3 in only one case intwenty.14.3 ReproducibilityThe difference between two singleand independent results obtained by different operators work-ing at the same location on identical test materials would, in thelong run, exceed the values in Fig. 3 only in one case in twenty.14.3.1 In the event of a dispute or concern regardingshipped sample conductivity, it is recommended that operatorscome to the bulk hydrocarbon storage site to measure conduc-tivity on freshly obtained samples according to the cite
