ASTM D4308-21

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4308 − 13 D4308 − 21 An American National Standard
Standard Test Method for
Electrical Conductivity of Liquid Hydrocarbons by Precision
Meter
This standard is issued under the fixed designation D4308; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript 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 This test method covers and applies to the determination of the “rest” electrical conductivity of aviation fuels and other similar
low-conductivity hydrocarbon liquids in the range from 0.11 pS ⁄m to 20002000 pS pS/m ⁄m (see 3.1.2). This test method can be
used in the laboratory or in the field.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 WARNING—Mercury has been designated by many regulatory agencies as a hazardous materialsubstance that can cause
central nervous system, kidney and liver damage. serious medical issues. Mercury, or its vapor, may has been demonstrated to be
hazardous to health and corrosive to materials. Caution should be taken Use Caution when handling mercury and mercury
containing mercury-containing products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPA’s
website—http://www.epa.gov/mercury/faq.htm—for additional information. Users should be aware (SDS) for additional informa-
tion. The potential exists that selling mercury and/or mercury containing products into your state or country may be prohibited by
law.or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their
location.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For specific warning statements, see 7.1.1, 7.2, 8.3, and Annex A1.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D150 Test Methods for AC Loss Characteristics and Permittivity (Dielectric Constant) of Solid Electrical Insulation
D2624 Test Methods for Electrical Conductivity of Aviation and Distillate Fuels
D4306 Practice for Aviation Fuel Sample Containers for Tests Affected by Trace Contamination
E1 Specification for ASTM Liquid-in-Glass Thermometers
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.J0.04 on Additives and Electrical Properties.
Current edition approved June 15, 2013Jan. 1, 2021. Published July 2013March 2021. Originally approved in 1983. Last previous edition approved in 20122013 as
D4308 – 12.D4308 – 13. DOI: 10.1520/D4308-13.10.1520/D4308-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*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
D4308 − 21
3. Terminology
3.1 Definitions:
3.1.1 picosiemens per metre, n—the unit of electrical conductivity is also called a conductivity unit (CU). A siemen is the SI
definition of reciprocal ohm sometimes called mho.
212 21 21
1 pS/m5 1310 Ω m 5 1 cu 5 1 picomho/m (1)
3.1.2 rest conductivity, n—the reciprocal of the resistance of uncharged fuel in the absence of ionic depletion or polarization. It
is the electrical conductivity at the initial instant of current measurement after a dc voltage is impressed between electrodes.
4. Summary of Test Method
4.1 A sample of liquid hydrocarbon is introduced into a clean conductivity cell which is connected in series to a battery voltage
source and a sensitive dc ammeter. The conductivity, automatically calculated from the observed peak current reading dc voltage
and cell constant using Ohm’s law, appears as a digital value in either a manual or automatic mode of meter operation.
5. Significance and Use
5.1 The generation and dissipation of electrostatic charge in fuel due to handling depend largely on the ionic species present which
may be characterized by the rest or equilibrium electrical conductivity. The time for static charge to dissipate is inversely related
to conductivity. This test method can supplement Test Method D2624 which is limited to fuels containing static dissipator additive.
NOTE 1—For low-conductivity fluids below 1 pS/m in conductivity, an ac measurement technique is preferable to a dc test method for sensing the
electrical conductivity of bulk fluid. This dc test method can be used at conductivities from 0.1 to 1 pS/m if precautions are observed in cell cleaning
and sample handling. A waiting period of 15 min is required after filling the cell before measuring dc conductivities below 1 pS/m. A single-laboratory
program was conducted comparing this test method with ac Test Methods D150.
6. Apparatus
3,
6.1 Conductivity Apparatus—Components of the dc conductivity apparatus are shown in Fig. 1.
6.1.1 The conductivity cell shown in Fig. 1 consists of an inner electrode and an outer electrode separated by an insulator. The
outer electrode and cap provide a ground path and electrostatic (Faraday) shield.
6.1.2 The electrometer shown in Fig. 1 contains a battery which supplies a voltage to the cell and a bridge circuit which senses
the flow of current and converts the output signal directly into conductivity units, that is, pS/m. A pushbutton selector allows
selection of zero reading, calibration, and four range selections.
6.1.3 The cell and electrometer are connected by a triaxial cable as shown in Fig. 1.
6.2 Thermometer, general purpose type, having a range of 00 °C to 60°C60 °C (see Specification E1). Temperature measuring
devices that cover the temperature range of interest, such as an ASTM 1C thermometer, or liquid-in-glass thermometers,
thermocouples, or platinum resistance thermometers that provide equivalent or better accuracy and precision than ASTM 1C
thermometers may be used.
7. Reagents
7.1 Cleaning Solvent, The following may be used: isopropyl alcohol.
7.1.1 Toluene-Isopropyl Alcohol Mixture—(Warning—Flammable. Vapor harmful. See Annex A1.1. ) Mix two volumes of
toluene and three volumes of isopropyl alcohol both of reagent grade and distill. Discard the first 20 % and last 5 % fractions.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1241.
The sole source of supply of the apparatus, the KSLA Cell and Precision Conductivity Meter System, Emcee Model #1154, known to the committee at this time is Emcee
Electronics, Inc., 520 Cypress Ave., Venice, FL 34285.
The sole source of supply of the apparatus, Precision Conductivity Meter System, Emcee Model #1154, known to the committee at this time is Emcee Electronics, Inc.,
520 Cypress Ave., Venice, FL 34285. If you are aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will
receive careful consideration at a meeting of the responsible technical committee, which you may attend.
D4308 − 21
FIG. 1 Precision Conductivity Meter
7.2 n-Heptane—(Warning—Flammable. Harmful if inhaled. See Annex A1.2.) Prepare by percolating ASTM reference fuel grade
5,6
n-heptane through silica gel as follows:
7.2.1 Activate approximately 2000 g of 100 to 200 mesh silica gel by heating at 180°C for 24 h. Allow it to cool in a desiccator
5,7
under nitrogen or in vacuum. Soak approximately 0.5 g of glass wool for 24 h in clean n-heptane.
7.2.2 Take a tube of borosilicate glass having an inside diameter of 60 to 70 mm, a length 1500 mm, with a conically shaped lower
end provided with a glass cock. Place a perforated porcelain disk (diameter 25 mm) in the lower end of the tube and put the soaked
glass wool on top of the disk. Fill the tube with the activated silica gel while tapping to achieve homogeneous filling. The silica
gel layer will be approximately 1250 mm high. Wrap the column in black paper to exclude light.
7.2.3 Percolate n-heptane through the column at a rate of about 2 to 3 L/h. Discard the first 3 L. Never allow the column to run
dry. The silica gel charge is sufficient for the percolation of 1000 L of n-heptane, provided the conductivity of the untreated
n-heptane is below 1 pS/m.
NOTE 2—If the conductivity of the n-heptane after treatment, measured in accordance with Section 11 in a thoroughly cleaned cell, is higher than 0.1 pS/m,
the treatment should be repeated.
7.2 Hydrocarbon, for calibration. The dielectric constant must be known to 65 % at the temperature of calibration.
8. Sampling
8.1 The sample volume should be at least 0.7 L.
A standard, such as cyclohexane, with certified dielectric constant, may be obtained from the National Bureau of Standards, Washington, DC 20234.Standards and
Technology (NIST), Gaithersburg, Maryland.
D4308 − 21
8.2 Use a clean epoxy-lined can, or a new glass bottle that has been rinsed successively with hot water, distilled water, acetone,
and cleaning solvent then flush with dry nitrogen. Use only non-contaminating caps.bottle, a new polytetrafluoroethylene bottle,
or a new high density polyethylene bottle.
NOTE 2—Test method results are known to be sensitive to trace contamination from sampling containers. For recommended sampling containers refer
to Practice D4306.
NOTE 3—Bottle samples should be tested immediately, since the glass surface tends to absorb from the fuel the conductive substances that the test method
is intended to measure.
8.3 Rinse the container at least three times with portions of the hydrocarbon liquid to be sampled. (When testing diesel or aviation
turbine fuels Jet A or A-1, Warning—Combustible. Vapor harmful. See Annex A1.3A1.1.) (When testing gasoline, aviation
gasoline, or aviation turbine fuel Jet B, Warning—Extremely flammable. Harmful if inhaled. Vapors can cause flash fire. See
Annex A1.4A1.2.) If possible, fill the container, let stand, then empty and refill. Avoid taking the sample for test by pouring from
the container; pipet instead. The sample should be clean and bright when tested.
9. Preparation of Apparatus
9.1 Cleaning the Cell—The cleaning procedure to be used depends on the estimated conductivity of the sample to be tested.
9.1.1 For samples that are expected to exhibit conductivities below 1 pS/m, the KSLA cell should be completely disassembled,
the parts cleaned and the cell reassembled using protective gloves.
9.1.1.1 Dismantle the cell by removing the loose battery cap, the outer electrode electrical connector and the bottom screw-on cap.
Press the inner electrode towards the bottom of the outer electrode and remove the inner electrode TFE-fluorocarbon insulator
assembly.
9.1.1.2 Each part of the cell should be rinsed thoroughly five times with cleaning solvent followed by rinsing with treated
n-heptane. The parts should be dried with a stream of nitrogen gas.
9.1.1.3 After reassembly, the cell should be rinsed with treated n-heptane.
9.1.1.4 After cleaning, check the cleanliness of the cell by measuring the conductivity of treated n-heptane in accordance with
Section 11. The corrected value should be lower than 0.05 pS/m.
9.1.1 For samples that are expected to exhibit conductivities above 1 pS/m, the KSLAconductivity cell still assembled should be
rinsed fivethree times with cleaning solvent, followed by rinsingdrying with treatedcompressed nair.-heptane. The cell should be
dried with a stream of nitrogen gas.
9.1.1.1 After cleaning, check the cleanliness of the cell by measuring the conductivity
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