ASTM D4308-95(2010)
(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
SIGNIFICANCE AND USE
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.
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 0.1 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 standard. No other units of measurement are included in this 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 warning statements, see 7.1.1, 7.2, and 8.3.
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An American National Standard
Designation:D4308–95 (Reapproved 2010)
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 Department of Defense.
212 21 21
1. Scope
1 pS/m 5 1 3 10 V m 51cu 5 1 picomho/m (1)
1.1 Thistestmethodcoversandappliestothedetermination
3.2 rest conductivity—the reciprocal of the resistance of
of the “rest” electrical conductivity of aviation fuels and other
uncharged fuel in the absence of ionic depletion or polariza-
similarlow-conductivityhydrocarbonliquidsintherangefrom
tion. It is the electrical conductivity at the initial instant of
0.1 to 2000 pS/m (see 3.2).This test method can be used in the
current measurement after a d-c voltage is impressed between
laboratory or in the field.
electrodes.
1.2 The values stated in SI units are to be regarded as
4. Summary of Test Method
standard. No other units of measurement are included in this
standard.
4.1 A sample of liquid hydrocarbon is introduced into a
1.3 This standard does not purport to address all of the
cleanconductivitycellwhichisconnectedinseriestoabattery
safety concerns, if any, associated with its use. It is the
voltage source and a sensitive dc ammeter. The conductivity,
responsibility of the user of this standard to establish appro-
automatically calculated from the observed peak current read-
priate safety and health practices and determine the applica-
ing dc voltage and cell constant using Ohm’s law, appears as a
bility of regulatory limitations prior to use. For specific
digital value in either a manual or automatic mode of meter
warning statements, see 7.1.1, 7.2, and 8.3.
operation.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards: 5.1 The generation and dissipation of electrostatic charge in
D150 Test Methods for AC Loss Characteristics and Per-
fuelduetohandlingdependlargelyontheionicspeciespresent
mittivity (Dielectric Constant) of Solid Electrical Insula-
which may be characterized by the rest or equilibrium electri-
tion
cal conductivity. The time for static charge to dissipate is
D2624 TestMethodsforElectricalConductivityofAviation
inversely related to conductivity. This test method can supple-
and Distillate Fuels
ment Test Method D2624 which is limited to fuels containing
D4306 Practice for Aviation Fuel Sample Containers for
static dissipator additive.
Tests Affected by Trace Contamination
NOTE 1—For low-conductivity fluids below 1 pS/m in conductivity, an
E1 Specification for ASTM Liquid-in-Glass Thermometers
acmeasurementtechniqueispreferabletoadctestmethodforsensingthe
electrical conductivity of bulk fluid. This dc test method can be used at
3. Terminology
conductivities from 0.1 to 1 pS/m if precautions are observed in cell
3.1 picosiemens per metre—the unit of electrical conductiv-
cleaningandsamplehandling.Awaitingperiodof15minisrequiredafter
filling the cell before measuring dc 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.
ac Test Methods D150.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.J0.04 on Additives and Electrical Properties.
Current edition approved Feb. 15, 2010. Published March 2010. Originally
approved in 1983. Last previous edition approved in 2005 as D4308–95 (2005).
DOI: 10.1520/D4308-95R10.
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 Supporting data have been filed at ASTM International Headquarters and may
the ASTM website. be obtained by requesting Research Report RR:D02-1241.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4308–95 (2010)
FIG. 1 Precision Conductivity Meter
6. Apparatus umesoftolueneandthreevolumesofisopropylalcoholbothof
reagent grade and distill. Discard the first 20 % and last 5 %
6.1 Conductivity Apparatus—Components of the dc con-
4,5
fractions.
ductivity apparatus are shown in Fig. 1.
7.2 n-Heptane—(Warning—Flammable. Harmful if in-
6.1.1 The conductivity cell shown in Fig. 1 consists of an
haled. See Annex A1.2.) Prepare by percolating ASTM refer-
inner electrode and an outer electrode separated by an insula-
,
5 6
ence fuel grade n-heptane through silica gel as follows:
tor. The outer electrode and cap provide a ground path and
7.2.1 Activate approximately 2000 g of 100 to 200 mesh
electrostatic (Faraday) shield.
silica gel by heating at 180°C for 24 h. Allow it to cool in a
6.1.2 The electrometer shown in Fig. 1 contains a battery
desiccator under nitrogen or in vacuum. Soak approximately
which supplies a voltage to the cell and a bridge circuit which
,
5 7
0.5 g of glass wool for 24 h in clean n-heptane.
senses the flow of current and converts the output signal
7.2.2 Take a tube of borosilicate glass having an inside
directly into conductivity units, that is, pS/m. A pushbutton
diameter of 60 to 70 mm, a length 1500 mm, with a conically
selector allows selection of zero reading, calibration, and four
shaped lower end provided with a glass cock. Place a perfo-
range selections.
rated porcelain disk (diameter 25 mm) in the lower end of the
6.1.3 The cell and electrometer are connected by a triaxial
tube and put the soaked glass wool on top of the disk. Fill the
cable as shown in Fig. 1.
tube with the activated silica gel while tapping to achieve
6.2 Thermometer, calibrated to 0.5°C and conforming to
homogeneousfilling.Thesilicagellayerwillbeapproximately
Specification E1.
1250 mm high. Wrap the column in black paper to exclude
light.
7. Reagents
7.2.3 Percolate n-heptane through the column at a rate of
7.1 Cleaning Solvent, The following may be used:
about 2 to 3 L/h. Discard the first 3 L. Never allow the column
7.1.1 Toluene-Isopropyl Alcohol Mixture—(Warning—
to run dry.The silica gel charge is sufficient for the percolation
Flammable. Vapor harmful. See Annex A1.1.) Mix two vol-
of 1000 L of n-heptane, provided the conductivity of the
untreated n-heptane is below 1 pS/m.
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 The sole source of supply known to the committee at this time is Code 923,
time is Emcee Electronics, Inc., 520 Cypress Ave., Venice, FL 34285. from W. R. Grace & Co., Davison Chemical Division, Baltimore, MD 21202.
5 7
If you are aware of alternative suppliers, please provide this information to The sole source of supply of the apparatus, filtering fiber Pyrex Wool.
ASTM International Headquarters. Your comments will receive careful consider- Catalogue No. 3950, known to the committee at this time is Owens-Corning Fiber
ation at a meeting of the responsible technical committee, which you may attend. Glass Corp., Toledo, OH.
D4308–95 (2010)
NOTE 2—If the conductivity of the n-heptane after treatment, measured
9.1.2.1 After cleaning, check the cleanliness of the cell by
in accordance with Section 11 in a thoroughly cleaned cell, is higher than
measuring the conductivity of treated n-heptane in accordance
0.1 pS/m, the treatment should be repeated.
with Section 11. The corrected value should be lower than 0.1
7.3 Hydrocarbon, for calibration. The dielectric constant
pS/m.
must be known to 65 % at the temperature of calibration. 9.2 Cleaning of Auxiliary Equipment:
9.2.1 Pipets used to transfer samples should be rinsed inside
8. Sampling
and outside with cleaning solvent using a non-contaminating
8.1 The sample volume should be at least 0.7 L. squeeze bottle, then blown dry with clean, dry nitrogen.
8.2 Use a clean epoxy-lined can, or a new glass bottle that
Thermometers should be similarly rinsed and maintained.
has been rinsed successively with hot water, distilled water,
NOTE 5—If a cell has been used to test samples of high-conductivity,
acetone, and cleaning solvent then flush with dry nitrogen. Use
that is, more than 1000 pS/m, it should be disassembled for thorough
only non-contaminating caps.
cleaning.Verythoroughcleaningmayalsobeaccomplishedbyplacingthe
disassembled cell in a Soxhlet apparatus containing boiling toluene/
NOTE 3—Test method results are known to be sensitive to trace
isopropyl alcohol for several hours.
contamination from sampling containers. For recommended sampling
NOTE 6—If testing is to be done on both low-conductivity (<1 pS/m)
containers refer to Practice D4306.
and high-conductivity (>1000 pS/m) samples, separate cells are recom-
NOTE 4—Bottle samples should be tested immediately, since the glass
mended.
surface tends to absorb from the fuel the conductive substances that the
test method is intended to measure.
10. Calibration and Standardization
8.3 Rinse the container several times with portions of the
10.1 Checking the Test Equipment:
aviation turbine fuel to be sampled (JetAorA-1, (Warning—
10.1.1 Remove cell and cable from the meter.
Combustible. Vapor harmful. See Annex A1.3.), Jet B
10.1.2 Depress the 20-pS/m switch. The digital reading
(Warning—Extremely flammable. Harmful if inhaled. Vapors
should indicate 0.00 6 0.01 pS/m after 3 s. If reading
...
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