1、Designation: D4308 13 An 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 ca
2、se 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 U.S. Department of Defense.1. Scope*1.1 Thi
3、s test 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 3.1.2). This test method can be used inthe laboratory or in the field.1.2 The values stated in SI
4、units are 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 an
5、d corrosive 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/
6、or mercury 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 d
7、etermine 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 Permit-tivity (Dielectric Constant) of Solid Electrical InsulationD2624 T
8、est Methods for Electrical Conductivity of Aviationand Distillate FuelsD4306 Practice for Aviation Fuel Sample Containers forTests Affected by Trace ContaminationE1 Specification for ASTM Liquid-in-Glass Thermometers3. Terminology3.1 Definitions:3.1.1 picosiemens per metre, nthe unit of electrical c
9、on-ductivity is also called a conductivity unit (CU). A siemen isthe SI definition of reciprocal ohm sometimes called mho.1 pS/m 5 1 31021221m215 1cu5 1 picomho/m (1)3.1.2 rest conductivity, nthe reciprocal of the resistance ofuncharged fuel in the absence of ionic depletion or polariza-tion. It is
10、the electrical conductivity at the 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 d
11、c ammeter. The conductivity,automatically 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
12、 infuel due to handling depend largely 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
13、 containingstatic dissipator additive.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
14、are observed in cellcleaning and sample handling.Awaiting period of 15 min is required after1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.J0.04 on Additives and Electrical Prope
15、rties.Current edition approved June 15, 2013. Published July 2013. Originallyapproved in 1983. Last previous edition approved in 2012 as D4308 12. DOI:10.1520/D4308-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
16、 Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1filling the ce
17、ll before measuring dc conductivities 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 cons
18、ists of aninner electrode and an outer 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
19、current and converts the output signaldirectly 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 typ
20、e, having a range of 0to 60C (see Specification E1). Temperature measuring devicesthat cover the temperature range of interest, such as an ASTM1C thermometer, or liquid-in-glass thermometers,thermocouples, or platinum resistance thermometers that pro-vide equivalent or better accuracy and precision
21、than ASTM1C thermometers may be used.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 twovolumes of toluene and three volumes of isopropyl alcoholboth of reagent grade and distill. Discard the fi
22、rst 20 % and last5 % fractions.7.2 n-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 c
23、ool in adesiccator under nitrogen or 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 porc
24、elain disk (diameter 25 mm) in the lower end of thetube and put the soaked glass wool on top of the disk. Fill the3Supporting 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 apparatus, the KSLA Cel
25、l 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 comments will receive car
26、eful 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 shouldbe clean and bright when tested.9. Preparation of Apparatus9.1 Cleaning the CellTh
27、e 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 completelydisassembled, the parts cleaned and the cell reassembled usingprotective gloves.9.1.1.1 Dismantl
28、e 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 cell should be rinsed thoro
29、ughly 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 bymeasuring the conductivity of
30、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 withtreated n-heptane. The
31、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:9.2.1 Pipets used to transf
32、er 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 is, more than 1000 pS/m,
33、 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 (1000 pS/m) samples, separate
34、 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 zero or record the zero err
35、or 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 :10.2.1 A check on the cell
36、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 disturbing the connecti
37、on, 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 CS2 CE!/k 2 1! (2)wher
38、e:k = dielectric constant of the hydrocarbon at testtemperatures.10.2.3 Calculate the cell constant as follows:8A standard, such as cyclohexane, with certified dielectric constant, may beobtained from the National Bureau of Standards, Washington, DC 20234.D4308 133K 5 8.854/CA(3)10.2.4 The cell cons
39、tant 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 the same value recorded
40、 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 be filled by pipet with
41、 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. When the conductivity
42、 isunknown, first check the fuel on a 2000 pS/m range position,then read 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.11.1.6 Repeat readings can
43、 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 should becorrected by su
44、btracting 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 pS/mafter correcting for
45、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 to correct conduc-tivity
46、 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 between 0.1 and 2000pS/m by op
47、erator/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 the same apparatusunder co
48、nstant 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 134would, in the long run, in the normal and correct operation ofthe test m
49、ethod, 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 citedprocedure. This ensure
