ASTM D4308-95(2000)
(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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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
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Designation: D 4308 – 95 (Reapproved 2000) An American National Standard
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.
1. Scope current measurement after a d-c voltage is impressed between
electrodes.
1.1 This test method applies to the determination of the
“rest” electrical conductivity of aviation fuels and other similar
4. Summary of Test Method
low-conductivity hydrocarbon liquids in the range from 0.1 to
4.1 A sample of liquid hydrocarbon is introduced into a
2000 pS/m (see 3.2). This test method can be used in the
clean conductivity cell which is connected in series to a battery
laboratory or in the field.
voltage source and a sensitive dc ammeter. The conductivity,
1.2 The values stated in SI units are to be regarded as the
automatically calculated from the observed peak current read-
standard.
ing dc voltage and cell constant using Ohm’s law, appears as a
1.3 This standard does not purport to address all of the
digital value in either a manual or automatic mode of meter
safety concerns, if any, associated with its use. It is the
operation.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitations prior to use. For specific hazard
5.1 The generation and dissipation of electrostatic charge in
statements, see Notes 2-4.
fuel due to handling depend largely on the ionic species present
2. Referenced Documents which may be characterized by the rest or equilibrium electri-
cal conductivity. The time for static charge to dissipate is
2.1 ASTM Standards:
inversely related to conductivity. This test method can supple-
D 150 Test Methods for A-C Loss Characteristics and
ment Test Method D 2624 which is limited to fuels containing
Permittivity (Dielectric Constant) of Solid Electrical Insu-
static dissipator additive.
lating Materials
D 2624 Test Methods for Electrical Conductivity of Avia-
NOTE 1—For low-conductivity fluids below 1 pS/m in conductivity, an
tion and Distillate Fuels 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
D 4306 Practice for Aviation Fuel Sample Containers for
at conductivities from 0.1 to 1 pS/m if precautions are observed in cell
Tests Affected by Trace Contamination
cleaning and sample handling. A waiting period of 15 min is required after
E 1 Specification for ASTM Thermometers
filling the cell before measuring d-c conductivities below 1 pS/m. A
single-laboratory program was conducted comparing this test method with
3. Terminology
a-c Test Method D 150. The results are on file at ASTM Headquarters.
3.1 picosiemens per metre—the unit of electrical conductiv-
Request RR: D02-1241.
ity is also called a conductivity unit (CU). A siemen is the SI
6. Apparatus
definition of reciprocal ohm sometimes called mho.
6.1 Conductivity Apparatus—Components of the dc con-
212 21 21
1 pS/m 5 1 3 10 V m 5 1cu 5 1 picomho/m (1)
ductivity apparatus are shown in Fig. 1.
3.2 rest conductivity—the reciprocal of the resistance of
6.1.1 The conductivity cell shown in Fig. 1 consists of an
uncharged fuel in the absence of ionic depletion or polariza-
inner electrode and an outer electrode separated by an insula-
tion. It is the electrical conductivity at the initial instant of
tor. 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
This test method is under the jurisdiction of ASTM Committee D-2 on
which supplies a voltage to the cell and a bridge circuit which
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
senses the flow of current and converts the output signal
D02.J on Aviation Fuels.
Current edition approved Feb. 15, 1995. Published April 1995. Originally
published as D 4308 – 83. Last previous edition D 4308 – 89.
2 5
Annual Book of ASTM Standards, Vol 10.01. 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, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 4308
FIG. 1 Precision Conductivity Meter
directly into conductivity units, that is, pS/m. A pushbutton shaped lower end provided with a glass cock. Place a perfo-
selector allows selection of zero reading, calibration, and four rated porcelain disk (diameter 25 mm) in the lower end of the
range selections. tube and put the soaked glass wool on top of the disk. Fill the
6.1.3 The cell and electrometer are connected by a triaxial tube with the activated silica gel while tapping to achieve
cable as shown in Fig. 1. homogeneous filling. The silica gel layer will be approximately
6.2 Thermometer, calibrated to 0.5°C and conforming to 1250 mm high. Wrap the column in black paper to exclude
Specification E 1. light.
7.2.3 Percolate n-heptane through the column at a rate of
7. Reagents
about 2 to 3 L/h. Discard the first 3 L. Never allow the column
7.1 Cleaning Solvent—The following may be used:
to run dry. The silica gel charge is sufficient for the percolation
7.1.1 Toluene-Isopropyl Alcohol Mixture—(Warning—See
of 1000 L of n-heptane, provided the conductivity of the
Note 2) Mix two volumes of toluene and three volumes of
untreated n-heptane is below 1 pS/m.
isopropyl alcohol both of reagent grade and distill. Discard the
NOTE 4—If the conductivity of the n-heptane after treatment, measured
first 20 % and last 5 % fractions.
in accordance with Section 11 in a thoroughly cleaned cell, is higher than
0.1 pS/m, the treatment should be repeated.
NOTE 2—Warning: Flammable. Vapor harmful. See Annex A1.1.
7.3 Hydrocarbon, for calibration. The dielectric constant
7.2 n-Heptane—(Warning—See Note 4) Prepare by perco-
must be known to 65 % at the temperature of calibration.
lating ASTM reference fuel grade n-heptane through silica gel
as follows:
8. Sampling
NOTE 3—Warning: Flammable. Harmful if inhaled. See Annex A1.3.
8.1 The sample volume should be at least 0.7 L.
7.2.1 Activate approximately 2000 g of 100 to 200 mesh
8.2 Use a clean epoxy-lined can, or a new glass bottle that
silica gel by heating at 180°C for 24 h. Allow it to cool in a
has been rinsed successively with hot water, distilled water,
desiccator under nitrogen or in vacuum. Soak approximately
acetone, and cleaning solvent then flush with dry nitrogen. Use
0.5 g of glass wool for 24 h in clean n-heptane.
only non-contaminating caps.
7.2.2 Take a tube of borosilicate glass having an inside
NOTE 5—Test method results are known to be sensitive to trace
diameter of 60 to 70 mm, a length 1500 mm, with a conically
contamination from sampling containers. For recommended sampling
containers refer to Practice D 4306.
A suitable grade is available from W. R. Grace & Co., Davison Chemical
Division, Baltimore, MD 21202 by specifying Code 923.
7 8
A suitable product is filtering fiber Pyrex Wool. Catalogue No. 3950, supplied A standard, such as cyclohexane, with certified dielectric constant, may be
by Owens-Corning Fiber Glass Corp. obtained from the National Bureau of Standards, Washington, DC 20234.
D 4308
NOTE 6—Bottle samples should be tested immediately, since the glass
10. Calibration and Standardization
surface tends to absorb from the fuel the conductive substances that the
10.1 Checking the Test Equipment:
test method is intended to measure.
10.1.1 Remove cell and cable from the meter.
8.3 Rinse the container several times with portions of the
10.1.2 Depress the 20-pS/m switch. The digital reading
aviation turbine fuel to be sampled (Jet A or A-1, (Warning—
should indicate 0.00 6 0.01 pS/m after 3 s. If readings
See Note 8), Jet B (Warning—See Note 9)). If possible fill the
exceed6 0.01 either adjust zero or record the zero error for
container, let stand, then empty and refill. Avoid taking the
calculating final report value.
sample for test by pouring from the container; pipet instead.
10.1.3 Depress the calibrate switch. The digital reading
The sample should be clean and bright when tested.
should indicate 1000 6 3 pS/m.
10.1.4 If low battery indicator is displayed during measure
NOTE 7—Warning: Combustible. Vapor harmful. See Annex A1.4.
or calibration, the internal batteries should be replaced.
NOTE 8—Warning: Extremely flammable. Harmful if inhaled. Vapors
10.2 Checking the Cell Constant:
can cause flash fire. See Annex A1.5 .
10.2.1 A check on the cell constant is necessary only if the
9. Preparation of Apparatus
cell has been damaged. Two capacitance measurements are
required with a precision a-c bridge. Make a rigid two-terminal
9.1 Cleaning the Cell—The cleaning procedure to be used
connection between the cell assembly and the bridge. Measure
depends on the estimated conductivity of the sample to be
the total capacitance, C (picofarad) of the empty assembly.
...
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