1、Designation: D 2624 07aDesignation: 274/99An American National StandardStandard Test Methods forElectrical Conductivity of Aviation and Distillate Fuels1This standard is issued under the fixed designation D 2624; the number immediately following the designation indicates the year oforiginal adoption
2、 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. Scop
3、e*1.1 These test methods cover the determination of theelectrical conductivity of aviation and distillate fuels with andwithout a static dissipator additive. The test methods normallygive a measurement of the conductivity when the fuel isuncharged, that is, electrically at rest (known as the restcon
4、ductivity).1.2 Two test methods are available for field tests of fuelconductivity. These are: (1) portable meters for the directmeasurement in tanks or the field or laboratory measurement offuel samples, and (2) in-line meters for the continuous mea-surement of fuel conductivities in a fuel distribu
5、tion system. Inusing portable meters, care must be taken in allowing therelaxation of residual electrical charges before measurementand in preventing fuel contamination.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 Thi
6、s 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 to use. For specificprecautio
7、nary statements, see 7.1, 7.1.1, and 11.2.1.2. Referenced Documents2.1 ASTM Standards:2D 4306 Practice for Aviation Fuel Sample Containers forTests Affected by Trace ContaminationD 4308 Test Method for Electrical Conductivity of LiquidHydrocarbons by Precision Meter3. Terminology3.1 Definitions:3.1.
8、1 picosiemens per metre, nthe unit of electrical con-ductivity is also called a conductivity unit (CU). A siemen isthe SI definition of reciprocal ohm sometimes called mho.1 pS/m 5 1 3 10212V21m215 1cu5 1 picomho/m (1)3.1.2 rest conductivity, nthe reciprocal of the resistivity ofuncharged fuel in th
9、e absence of ionic depletion or polariza-tion.3.1.2.1 DiscussionIt is the electrical conductivity at theinitial instant of current measurement after a dc voltage isimpressed between electrodes, or a measure of the averagecurrent when an alternating current (ac) voltage is impressed.4. Summary of Tes
10、t Methods4.1 Avoltage is applied across two electrodes in the fuel andthe resulting current expressed as a conductivity value. Withportable meters, the current measurement is made almostinstantaneously upon application of the voltage to avoid errorsdue to ion depletion. Ion depletion or polarization
11、 is eliminatedin dynamic monitoring systems by continuous replacement ofthe sample in the measuring cell, or by the use of an alternatingvoltage. The procedure, with the correct selection of electrodesize and current measurement apparatus, can be used tomeasure conductivities from 1 pS/m or greater.
12、 The commer-cially available equipment referred to in these methods coversa conductivity range up to 2000 pS/m with good precision (seeSection 12), although some meters can only read to 500 or1000 pS/m.1These test methods are under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubr
13、icants and are the direct responsibility of Subcommit-tee D02.J0.04 on Additives and Electrical Properties.In the IP, these test methods are under the jurisdiction of the StandardizationCommittee.Current edition approved Dec. 1, 2007. Published January 2008. Originallyapproved in 1967. Last previous
14、 edition approved in 2007 as D 262407.2For 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 Summary of Changes
15、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.4.1.1 The EMCEE Model 1152 Meter is available withexpanded ranges but the precision of the extended range metershas not been determined. If it
16、 is necessary to measure conduc-tivities below 1 pS/m, for example in the case of clay treatedfuels or refined hydrocarbon solvents, Test Method D 4308should be used.5. Significance and Use5.1 The ability of a fuel to dissipate charge that has beengenerated during pumping and filtering operations is
17、 controlledby its electrical conductivity, which depends upon its contentof ion species. If the conductivity is sufficiently high, chargesdissipate fast enough to prevent their accumulation and dan-gerously high potentials in a receiving tank are avoided.PORTABLE METER METHOD6. Apparatus6.1 Conducti
18、vity Cell and Current-Measuring ApparatusBecause hydrocarbon conductivities are extremely low com-pared to aqueous solutions, special equipment that is capable ofgiving an almost instantaneous response with application ofvoltage is needed.3,46.2 Thermometer, having a suitable range for measuringfuel
19、 temperature in the field. A thermometer holder should beavailable so that the temperature can be directly determined forfuel in bulk storage, rail tank cars, and trucks.NOTE 1The Emcee Model 1153 measures and stores the sampletemperature during the test cycle.6.3 Measuring VesselAny suitable vessel
20、 capable of hold-ing sufficient fuel to cover the electrodes of the conductivitycell.37. Reagents and Materials7.1 Cleaning SolventsUse isopropyl alcohol (WarningFlammable) if water is suspected followed by analytical gradetoluene (WarningFlammable. Vapor harmful).7.1.1 A mixture of 50 % volume anal
21、ytical grade isopro-panol and 50 % volume analytical grade heptane (WarningFlammable. Vapor harmful) is a satisfactory substitute fortoluene.8. Sampling8.1 Fuel conductivity measurements should be made in situor at the point of sampling to avoid changes during sampleshipment. If it is necessary to t
22、ake samples for subsequentanalysis, the following precautions should be taken:8.1.1 If the cell is in contact with water and the instrumentis switched on, an immediate offscale reading will be obtained.If the cell has been in contact with water, it shall be thoroughlyrinsed with cleaning solvent, pr
23、eferably isopropyl alcohol, anddried with a stream of air. In hot, humid conditions, conden-sation on the cell can occur, which can cause abnormally highzero, calibration and sample readings. This can be avoided bystoring the cell at a temperature 2 to 5C in excess of themaximum ambient temperature
24、where this is practicable.8.2 The sample size should be as large as practicable (see6.3).8.3 The conductivity of fuels containing static dissipatoradditives is affected by sunlight and other strong light sources.Samples in clear glass containers can experience significantconductivity loss within 5 m
25、in of sunlight exposure. SeePractice D 4306 for further discussion.NOTE 2Test method results are known to be sensitive to tracecontamination from sampling containers. For recommended samplingcontainers refer to Practice D 4306.8.4 Prior to taking the samples, all sample containers,including caps, sh
26、all be rinsed at least three times with the fuelunder test. Used containers should be thoroughly cleaned withcleaning solvent, if necessary, in accordance with D 4306,paragraph 6.6, and air dried.8.5 Conductivity measurements should be made as soon aspossible after sampling and preferably within 24
27、h.9. Cleaning Procedures9.1 If the cell is in contact with water and the instrument isswitched on, an immediate offscale reading will be obtained. Ifthe cell has been in contact with water, it shall be thoroughlyrinsed with cleaning solvent, preferably isopropyl alcohol, anddried with a stream of ai
28、r. The meter may display a non-zeroreading caused by condensation forming on the cell when themeter is taken from a cool, dry environment and subjected tohot, humid conditions. This condition can be avoided bystoring the cell at a temperature 2 to 5C in excess of theambient temperature, when practic
29、able.9.2 In normal use, the probe on handheld instrumentsshould be cleaned with toluene or a mixture of heptane andisopropanol and air-dried after use, to ensure that ionicmaterials absorbed on the probe during previous tests will notcontaminate the sample and give an erroneous result.10. Calibratio
30、n10.1 The calibration procedure will be dependent upon theequipment used. The procedures for the instruments listed inFootnote 3 are described in Annex A1-Annex A5.11. Procedure11.1 The specific instrument calibration procedures detailedin Annex A1-Annex A5 are an essential part of the followinggene
31、ralized procedures. The appropriate calibration steps forthe instrument used should be followed prior to commencingthe subsequent procedures.11.2 In Situ Field Measurement on Tanks, Tank Cars, TankTrucks, etc.For field measurements the conductivity metersreferred to in Footnote 3 are considered suit
32、able. The use of3The following equipment, as listed in RR:D02-1161, RR:D02-1476, andRR:D021575, was used to develop the precision statements. Models 1150, 1151,1152, and 1153 from Emcee Electronics, Inc., 520 Cypress Ave., Venice FL 3429;Maihak Conductivity Indicator and MLA 900 from Maihak AG, Popp
33、enbuettelerBogen 9b, D-22399 Hamburg Germany. This is not an endorsement or certificationby ASTM. If you are aware of alternative suppliers, please provide this informationto ASTM International Headquarters. Your comments will receive careful consid-eration at a meeting of the responsible technical
34、committee,1which you may attend.4The older style Maihak Conductivity Indicator (Annex A1) and the EmceeModel 1151 are no longer in production.D 2624 07a2these meters in hazardous locations may be restricted by theregulatory agency having jurisdiction. Each has an extensioncable or can be equipped wi
35、th one to lower the cell into thetank. High impedance hand held meters are susceptible toelectrical transients caused by extension cable flexing duringmeasurements. Failure to hold the apparatus steady duringmeasurement can result in significantly poorer precision thanshown in Table 1. The following
36、 instructions apply to themeters referenced in Footnote 3.11.2.1 Check meter calibration as detailed in Annex A1,Annex A2, Annex A4,orAnnex A5, depending on the meterused. Bond the meter to the tank and lower the conductivitycell into the tank to the desired level taking care to avoid partialimmersi
37、on or contact with tank water bottoms, if present.Move the conductivity cell in an up-and-down motion toremove previous fuel residues. (WarningTo prevent staticdischarge between a charged fuel and a conductive probeinserted into a tank, the appropriate safety precautions ofbonding and waiting for ch
38、arge dissipation should be observed.For example, the American Petroleum Institute in RP 2003recommends that a 30-min interval be allowed after pumpinginto a storage tank before an operator mounts a tank to inserta sampling device. This will also ensure that the fuel iselectrically at rest.)11.2.2 Af
39、ter flushing the cell, hold it steady and afteractivating the instrument record the highest reading after initialstabilization.This should occur within 3 s. On instruments withmore than one scale range, select the scale that gives thegreatest sensitivity for the conductivity value being deter-mined.
40、 Ensure that the appropriate scale multiplying factor (orscale range) is used. Record the fuel temperature.NOTE 3The Emcee Model 1153 automatically measures and recordsthe reading at 3 s.11.3 Laboratory and Field Measurements on Sampled Fu-els:11.3.1 Preparation of Containers (Metal or Glass)Priorto
41、 taking samples, take extreme care to ensure that all contain-ers and measuring vessels have been thoroughly cleaned. It ispreferable that containers are laboratory cleaned prior toshipment to the field for sampling (see Section 8).11.3.2 MeasurementRinse the conductivity cell thor-oughly with the f
42、uel under test to remove fuel residuesremaining on the cell from previous tests. Transfer the fuel tothe measuring vessel and record the conductivity of the fuelusing the procedure applicable to the particular apparatus. Ifone of the conductivity meters referenced in Footnote 3 is used,follow these
43、instructions: Rinse the cell concurrently with therinsing of the measuring vessel. Then transfer the sample to betested to the clean, rinsed measuring vessel. Check metercalibration as detailed in Annex A1, Annex A2,orAnnex A5,depending on the meter used. Fully immerse the conductivitycell into the
44、test fuel and measure the conductivity followingthe procedure in 11.2.2 and the appropriate Annex. Record thefuel temperature.NOTE 4In order to avoid erroneous readings, it is important to ensurethat the bottom of the conductivity cell does not touch the samplecontainer. This is applicable to all co
45、ntainers, whatever the material ofconstruction.NOTE 5When using an analog meter, measurements exceeding therange of the meter are obvious. With the Emcee Model 1152 Digital Meterand the Maihak MLA 900 Meter, measurements exceeding the range ofthe meter are indicated by a single digit “1” in the left
46、 side of the displaywhere 1000s are shown. A qualitative conductivity estimate (for whichprecision has not been established) can be made by inserting the probe inthe sample to the first set of holes closest to the tip, which are at the midpoint of the sensing portion of the probe. Since the displaye
47、d conductivityis inversely proportional to the depth of immersion, the value displayed,if any, should be doubled. Conductivities less than 1 pS/m up to 20 000pS/m can be determined using Test Method D 4308. When using theEmcee Model 1153 Digital Meter, measurements exceeding the range ofthe meter “O
48、VER” will be displayed.12. Report12.1 Report the electrical conductivity of the fuel and thefuel temperature at which measurement was made. If theelectrical conductivity reads zero on the meter, report less than1 pS/m.NOTE 6It is recognized that the electrical conductivity of a fuel variessignifican
49、tly with temperature and that the relationship differs for varioustypes of aviation and distillate fuel. If it is necessary to correct conduc-tivity readings to a particular temperature, each laboratory would have toestablish this relationship for the fuels and temperature range of interest.Refer toAppendix X2 for additional information of the effect temperaturehas on the electrical conductivity of fuels.13. Precision and Bias513.1 The precision of this test method as determined bystatistical analysis of test results obtained by operatorinstru-ment pairs at a c
