ASTM D4308-95(2000)e1
(Test Method)Standard Test Method for Electrical Conductivity of Liquid Hydrocarbons by Precision Meter
Standard Test Method for Electrical Conductivity of Liquid Hydrocarbons by Precision Meter
SCOPE
1.1 This test method applies to the determination of the "rest" electrical conductivity of aviation fuels and other similar low-conductivity hydrocarbon liquids in the range from 0.1 to 2000 pS/m (see 3.2). 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 the standard.
1.3 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 and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 7.1.1 and 7.2.
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An American National Standard
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Designation:D4308–95 (Reapproved 2000)
Standard Test Method for
Electrical Conductivity of Liquid Hydrocarbons by Precision
Meter
This standard is issued under the fixed designation D 4308; 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 (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.
e NOTE—Warning notes were placed in the text editorially in April 2001.
1. Scope 3.2 rest conductivity—the reciprocal of the resistance of
uncharged fuel in the absence of ionic depletion or polariza-
1.1 This test method applies to the determination of the
tion. It is the electrical conductivity at the initial instant of
“rest” electrical conductivity of aviation fuels and other similar
current measurement after a d-c voltage is impressed between
low-conductivity hydrocarbon liquids in the range from 0.1 to
electrodes.
2000 pS/m (see 3.2). This test method can be used in the
laboratory or in the field.
4. Summary of Test Method
1.2 The values stated in SI units are to be regarded as the
4.1 A sample of liquid hydrocarbon is introduced into a
standard.
clean conductivity cell which is connected in series to a battery
1.3 This standard does not purport to address all of the
voltage source and a sensitive dc ammeter. The conductivity,
safety concerns, if any, associated with its use. It is the
automatically calculated from the observed peak current read-
responsibility of the user of this standard to establish appro-
ing dc voltage and cell constant using Ohm’s law, appears as a
priate safety and health practices and determine the applica-
digital value in either a manual or automatic mode of meter
bility of regulatory limitations prior to use. For specific hazard
operation.
statements, see 7.1.1 and 7.2.
5. Significance and Use
2. Referenced Documents
5.1 The generation and dissipation of electrostatic charge in
2.1 ASTM Standards:
fuelduetohandlingdependlargelyontheionicspeciespresent
D 150 Test Methods for A-C Loss Characteristics and
which may be characterized by the rest or equilibrium electri-
Permittivity (Dielectric Constant) of Solid Electrical Insu-
2 cal conductivity. The time for static charge to dissipate is
lating Materials
inversely related to conductivity. This test method can supple-
D 2624 Test Methods for Electrical Conductivity of Avia-
3 ment Test Method D 2624 which is limited to fuels containing
tion and Distillate Fuels
static dissipator additive.
D 4306 Practice for Aviation Fuel Sample Containers for
Tests Affected by Trace Contamination
NOTE 1—For low-conductivity fluids below 1 pS/m in conductivity, an
E 1 Specification for ASTM Thermometers a-c measurement technique is preferable to a d-c test method for sensing
the electrical conductivity of bulk fluid. This d-c test method can be used
3. Terminology
at conductivities from 0.1 to 1 pS/m if precautions are observed in cell
cleaningandsamplehandling.Awaitingperiodof15minisrequiredafter
3.1 picosiemens per metre—the unit of electrical conductiv-
filling the cell before measuring d-c conductivities below 1 pS/m. A
ity is also called a conductivity unit (CU). A siemen is the SI
single-laboratoryprogramwasconductedcomparingthistestmethodwith
definition of reciprocal ohm sometimes called mho.
a-c Test Method D 150. The results are on file at ASTM Headquarters.
212 21 21
Request RR: D02-1241.
1 pS/m 5 1 3 10 V m 51cu 5 1 picomho/m (1)
6. Apparatus
This test method is under the jurisdiction of ASTM Committee D02 on 6.1 Conductivity Apparatus—Components of the dc con-
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
ductivity apparatus are shown in Fig. 1.
D02.J0 on Aviation Fuels.
Current edition approved Feb. 15, 1995. Published April 1995. Originally
published as D 4308 – 83. Last previous edition D 4308 – 89.
Annual Book of ASTM Standards, Vol 10.01.
3 6
Annual Book of ASTM Standards, Vol 05.01. The KSLA Cell and Precision Conductivity Meter System, Emcee Model
Annual Book of ASTM Standards, Vol 05.02. #1154 are available from Emcee Electronics, Inc., 520 Cypress Ave., Venice, FL
Annual Book of ASTM Standards, Vol 14.03. 34292.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D4308–95 (2000)
FIG. 1 Precision Conductivity Meter
6.1.1 The conductivity cell shown in Fig. 1 consists of an desiccator under nitrogen or in vacuum. Soak approximately
inner electrode and an outer electrode separated by an insula- 0.5 g of glass wool for 24 h in clean n-heptane.
tor. The outer electrode and cap provide a ground path and 7.2.2 Take a tube of borosilicate glass having an inside
electrostatic (Faraday) shield. diameter of 60 to 70 mm, a length 1500 mm, with a conically
6.1.2 The electrometer shown in Fig. 1 contains a battery shaped lower end provided with a glass cock. Place a perfo-
which supplies a voltage to the cell and a bridge circuit which rated porcelain disk (diameter 25 mm) in the lower end of the
senses the flow of current and converts the output signal tube and put the soaked glass wool on top of the disk. Fill the
directly into conductivity units, that is, pS/m. A pushbutton tube with the activated silica gel while tapping to achieve
selector allows selection of zero reading, calibration, and four homogeneousfilling.Thesilicagellayerwillbeapproximately
range selections. 1250 mm high. Wrap the column in black paper to exclude
6.1.3 The cell and electrometer are connected by a triaxial light.
cable as shown in Fig. 1. 7.2.3 Percolate n-heptane through the column at a rate of
6.2 Thermometer, calibrated to 0.5°C and conforming to about 2 to 3 L/h. Discard the first 3 L. Never allow the column
Specification E 1. to run dry. The silica gel charge is sufficient for the percolation
of 1000 L of n-heptane, provided the conductivity of the
7. Reagents
untreated n-heptane is below 1 pS/m.
7.1 Cleaning Solvent—The following may be used:
NOTE 2—If the conductivity of the n-heptane after treatment, measured
7.1.1 Toluene-Isopropyl Alcohol Mixture—(Warning—
in accordance with Section 11 in a thoroughly cleaned cell, is higher than
Flammable. Vapor harmful. See Annex A1.1.) Mix two vol-
0.1 pS/m, the treatment should be repeated.
umesoftolueneandthreevolumesofisopropylalcoholbothof
7.3 Hydrocarbon, for calibration. The dielectric constant
reagent grade and distill. Discard the first 20 % and last 5 %
must be known to 65 % at the temperature of calibration.
fractions.
7.2 n-Heptane—(Warning—Flammable. Harmful if in-
8. Sampling
haled. See Annex A1.2.) Prepare by percolating ASTM refer-
7 8.1 The sample volume should be at least 0.7 L.
ence fuel grade 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
A suitable product is filtering fiber Pyrex Wool. Catalogue No. 3950, supplied
by Owens-Corning Fiber Glass Corp.
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A suitable grade is available from W. R. Grace & Co., Davison Chemical A standard, such as cyclohexane, with certified dielectric constant, may be
Division, Baltimore, MD 21202 by specifying Code 923. obtained from the National Bureau of Standards, Washington, DC 20234.
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D4308–95 (2000)
cleaning.Verythoroughcleaningmayalsobeaccomplishedbyplacingthe
8.2 Use a clean epoxy-lined can, or a new glass bottle that
disassembled cell in a Soxhlet apparatus containing boiling toluene/
has been rinsed successively with hot water, distilled water,
isopropyl alcohol for several hours.
acetone, and cleaning solvent then flush with dry nitrogen. Use
NOTE 6—If testing is to be done on both low-conductivity (<1 pS/m)
only non-contaminating caps.
and high-conductivity (>1000 pS/m) samples, separate cells are recom-
NOTE 3—Test method results are known to be sensitive to trace mended.
contamination from sampling containers. For recommended sampling
containers refer to Practice D 4306. 10. Calibration and Standardization
NOTE 4—Bottle samples should be tested immediately, since the glass
10.1 Checking the Test Equipment:
surface tends to absorb from the fuel the conductive substances that the
10.1.1 Remove cell and cable from the meter.
test method is intended to measure.
10.1.2 Depress the 20-pS/m switch. The digital reading
8.3 Rinse the container several times with portions of the
should indicate 0.00 6 0.01 pS/m after 3 s. If readings
aviation turbine fuel to be sampled (JetAorA-1, (Warning—
exceed6 0.01 either adjust zero or record the zero error for
Combustible. Vapor harmful. See Annex A1.3.), Jet B
calculating final report value.
(Warning—Extremely flammable. Harmful if inhaled. Vapors
10.1.3 Depress the calibrate switch. The digital reading
can cause flash fire. See Annex A1.4). If possible fill the
should indicate 1000 6 3 pS/m.
container, let stand, then empty and refill. Avoid taking the
10.1.4 If low battery indicator is displayed during measure
sample for test by pouring from the container; pipet instead.
or calibration, the internal batteries should be replaced.
The sample should be clean and bright when tested.
10.2 Checking the Cell Constant:
10.2.1 A check on the cell constant is necessary only if the
9. Preparation of Apparatus
cell has been damaged
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