ASTM D2624-00
(Test Method)Standard Test Methods for Electrical Conductivity of Aviation and Distillate Fuels
Standard Test Methods for Electrical Conductivity of Aviation and Distillate Fuels
SCOPE
1.1 These test methods cover the determination of the electrical conductivity of aviation and distillate fuels with and without a static dissipator additive. The test methods normally give a measurement of the conductivity when the fuel is uncharged, that is, electrically at rest (known as the rest conductivity).
1.2 Two test methods are available for field tests of fuel conductivity. These are: (a) portable meters for the direct measurement in tanks or the field or laboratory measurement of fuel samples, and (b) in-line meters for the continuous measurement of fuel conductivities in a fuel distribution system. In using either type of instrument, care must be taken in allowing the relaxation of residual electrical charges before measurement and in preventing fuel contamination. For specification purposes, conductivity measurements should be made with the portable meters.
1.3 The values stated in SI units are to be regarded as the standard.
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 and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see 7.1, 7.1.1, and 11.2.1.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 2624 – 00 An American National Standard
Designation: 274/99
Standard Test Methods for
Electrical Conductivity of Aviation and Distillate Fuels
This standard is issued under the fixed designation D 2624; 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 3. Terminology
1.1 These test methods cover the determination of the 3.1 Definitions:
electrical conductivity of aviation and distillate fuels with and 3.1.1 picosiemens per metre, n—the unit of electrical con-
without a static dissipator additive. The test methods normally ductivity is also called a conductivity unit (CU). A siemen is
give a measurement of the conductivity when the fuel is the SI definition of reciprocal ohm sometimes called mho.
uncharged, that is, electrically at rest (known as the rest
212 21 21
1 pS/m 5 1 3 10 V m 5 1cu 5 1 picomho/m (1)
conductivity).
3.1.2 rest conductivity, n—the reciprocal of the resistivity of
1.2 Two test methods are available for field tests of fuel
uncharged fuel in the absence of ionic depletion or polariza-
conductivity. These are: (a) portable meters for the direct
tion.
measurement in tanks or the field or laboratory measurement of
3.1.2.1 Discussion— It is the electrical conductivity at the
fuel samples, and (b) in-line meters for the continuous mea-
initial instant of current measurement after a d-c voltage is
surement of fuel conductivities in a fuel distribution system. In
impressed between electrodes.
using either type of instrument, care must be taken in allowing
the relaxation of residual electrical charges before measure-
4. Summary of Test Methods
ment and in preventing fuel contamination. For specification
4.1 A voltage is applied across two electrodes in the fuel and
purposes, conductivity measurements should be made with the
the resulting current expressed as a conductivity value. With
portable meters.
portable meters, the current measurement is made almost
1.3 The values stated in SI units are to be regarded as the
instantaneously upon application of the voltage to avoid errors
standard.
due to ion depletion. Ion depletion or polarisation is eliminated
1.4 This standard does not purport to address all of the
in dynamic monitoring systems by continuous replacement of
safety concerns, if any, associated with its use. It is the
the sample in the measuring cell. The procedure, with the
responsibility of the user of this standard to establish appro-
correct selection of electrode size and current measurement
priate safety and health practices and determine the applica-
apparatus, can be used to measure conductivities from 1 pS/m
bility of regulatory limitations prior to use. For specific
or greater. The commercially available equipment referred to in
precautionary statements, see 7.1, 7.1.1, and 11.2.1.
these methods covers a conductivity range up to 2000 pS/m
2. Referenced Documents with good precision (see Section 12), although some meters
can only read to 500 or 1000 pS/m.
2.1 ASTM Standards:
4.1.1 The EMCEE Model 1152 Meter is available with
D 4306 Practice for Aviation Fuel Sample Containers for
2 expanded ranges but the precision of the extended range meters
Tests Affected by Trace Contamination
has not been determined. If it is necessary to measure conduc-
D 4308 Test Method for Electrical Conductivity of Liquid
2 tivities below 1 pS/m, for example in the case of clay treated
Hydrocarbons by Precision Meter
fuels or refined hydrocarbon solvents, Test Method D 4308
should be used.
These test methods are under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricants and are the direct responsibility of Subcommit-
5. Significance and Use
tee D02.J on Aviation Fuels.
In the IP, these test methods are under the jurisdiction of the Standardization
5.1 The ability of a fuel to dissipate charge that has been
Committee.
generated during pumping and filtering operations is controlled
Current edition approved Jan. 10, 2000. Published March 2000. Originally
by its electrical conductivity, which depends upon its content
published as D 2624 – 67 T. Last previous edition D 2624 – 98.
Annual Book of ASTM Standards, Vol 05.02. of ion species. If the conductivity is sufficiently high, charges
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 2624
containers refer to Practice D 4306.
dissipate fast enough to prevent their accumulation and dan-
gerously high potentials in a receiving tank are avoided.
8.4 All sample containers should be thoroughly cleaned
with cleaning solvent and dried with a stream of air. Prior to
PORTABLE METER METHOD
taking the samples, all containers, including caps, should be
rinsed at least three times with the fuel under test.
6. Apparatus
8.5 Conductivity measurements should be made as soon as
6.1 Conductivity Cell and Current-Measuring Apparatus—
possible after sampling and preferably within 24 h.
Because hydrocarbon conductivities are extremely low com-
pared to aqueous solutions, special equipment that is capable of
9. Cleaning Procedures
giving an almost instantaneous response with application of
9.1 If the cell is in contact with water and the instrument is
,
3 4
voltage is needed.
switched on, an immediate offscale reading will be obtained. If
6.2 Thermometer, having a suitable range for measuring
the cell has been in contact with water, it shall be thoroughly
fuel temperature in the field. A thermometer holder should be
rinsed with cleaning solvent, preferably isopropyl alcohol, and
available so that the temperature can be directly determined for
dried with a stream of air. The meter may display a non-zero
fuel in bulk storage, rail tank cars, and trucks.
reading caused by condensation forming on the cell when the
6.3 Measuring Vessel—Any suitable cylindrical vessel ca-
meter is taken from a cool, dry environment and subjected to
pable of holding sufficient fuel to cover the electrodes of the
hot, humid conditions. This condition can be avoided by
conductivity cell. For the equipment referred to in Footnote 3,
storing the cell at a temperature 2 to 5°C in excess of the
a minimum volume of 1 L is required.
ambient temperature, when practicable.
9.2 In normal use, the probe on hand-held instruments
7. Reagents and Materials
should be cleaned with toluene or a mixture of heptane and
7.1 Cleaning Solvents—Use isopropyl alcohol if water is
isopropanol and air-dried after use, to ensure that ionic
suspected (Warning—Flammable.) followed by analytical
materials absorbed on the probe during previous tests will not
grade toluene. ( Warning—Flammable. Vapor harmful.)
contaminate the sample and give an erroneous result.
7.1.1 A mixture of 50 % volume analytical grade isopro-
panol and 50 % volume analytical grade heptane ( Warning—
10. Calibration
Flammable. Vapor harmful.) is a satisfactory substitute for
10.1 The calibration procedure will be dependent upon the
toluene.
equipment used. The procedures for the instruments listed in
Footnote 3 are described in Annex A1, Annex A2, Annex A3,
8. Sampling
and Annex A4.
8.1 Fuel conductivity measurements should be made in situ
or at the point of sampling to avoid changes during sample
11. Procedure
shipment. If it is necessary to take samples for subsequent
11.1 The specific instrument calibration procedures detailed
analysis, the following precautions should be taken:
in Annex A1, Annex A2, Annex A3, and Annex A4 are an
8.1.1 If the cell is in contact with water and the instrument
essential part of the following generalized procedures. The
is switched on, an immediate offscale reading will be obtained.
appropriate calibration steps for the instrument used should be
If the cell has been in contact with water, it shall be thoroughly
followed prior to commencing the subsequent procedures.
rinsed with cleaning solvent, preferably isopropyl alcohol, and
11.2 In Situ Field Measurement on Tanks, Tank Cars, Tank
dried with a stream of air. In hot, humid conditions, conden-
Trucks, etc.—For field measurements the conductivity meters
sation on the cell can occur, which can cause abnormally high
referred to in Footnote 3 are considered suitable. The use of
zero, calibration and sample readings. This can be avoided by
these meters in hazardous locations may be restricted by the
storing the cell at a temperature 2 to 5°C in excess of the
regulatory agency having jurisdiction. Each has an extension
maximum ambient temperature where this is practicable.
cable or can be equipped with one to lower the cell into the
8.2 The sample size should be as large as practicable, and
tank. High impedance hand held meters are susceptible to
not less than 1 L.
electrical transients caused by extension cable flexing during
8.3 The conductivity of fuels containing static dissipator
measurements. Failure to hold the apparatus steady during
additives is affected by sunlight and other strong light sources.
measurement can result in significantly poorer precision than
Samples in clear glass containers may experience significant
shown in Table 1. The following instructions apply to the
conductivity loss within 5 min of sunlight exposure. See Test
meters referenced in Footnote 3.
Method D 4306 for further discussion.
11.2.1 Check meter calibration as detailed in Annex A1,
NOTE 1—Test method results are known to be sensitive to trace
Annex A2, or Annex A4, depending on the meter used. Bond
contamination from sampling containers. For recommended sampling
the meter to the tank and lower the conductivity cell into the
tank to the desired level taking care to avoid partial immersion
3 or contact with tank water bottoms, if present. Move the
The following equipment, as listed in RR:D02-1161 and RR:D02-1476, was
conductivity cell in an up-and-down motion to remove previ-
used to develop the precision statements. Models 1150, 1151, and 1152 from Emcee
Electronics, Inc., 520 Cypress Ave., Venice FL 3429; Maihak Conductivity Indicator
ous fuel residues. (Warning—To prevent static discharge
and MLA 900 from Maihak AG, Poppenbuetteler Bogen 9b, D-22399 Hamburg
between a charged fuel and a conductive probe inserted into a
Germany. This is not an endorsement or certification by ASTM.
tank, the appropriate safety precautions of bonding and waiting
The older style Maihak Conductivity Indicator (Annex A1) and the Emcee
Model 1151 are no longer in production. for charge dissipation should be observed. For example, the
D 2624
A
TABLE 1 Precision be doubled. Conductivities less than 1 pS/m up to 20 000 pS/m can be
determined using Test Method D 4308.
Conductivity,
Repeatability Reproducibility
pS/m
12. Report
11 1
15 1 3
12.1 Report the electrical conductivity of the fuel and the
20 1 4
fuel temperature at which measurement was made. If the
30 2 6
electrical conductivity reads zero on the meter, report less than
50 3 10
70 4 13
1 pS/M.
100 5 17
200 10 32
NOTE 4—It is recognized that the electrical conductivity of a fuel varies
300 14 45
significantly with temperature and that the relationship differs for various
500 21 69
types of aviation and distillate fuel. If it is necessary to correct conduc-
700 29 92
tivity readings to a particular temperature, each laboratory would have to
1000 39 125
establish this relationship for the fuels and temperature range of interest.
1500 55 177
Refer to Appendix X2 for additional information of the effect temperature
A
The precision limits in Table 1 are applicable at room temperature; significantly
has on the electrical conductivity of fuels.
higher precision (32) may be applicable at temperatures near − 20°C.
13. Precision and Bias
American Petroleum Institute in RP 2003 recommends that a
13.1 The precision of this test method as determined by
30-min interval be allowed after pumping into a storage tank
statistical analysis of test results obtained by operator–instru-
before an operator mounts a tank to insert a sampling device.
ment pairs at a common test site is as follows. The precision
This will also ensure that the fuel is electrically at rest.)
data generated for Table 1 did not include any gasolines or
11.2.2 After flushing the cell, hold it steady and after
solvents.
activating the instrument record the highest reading after initial
NOTE 5—A precision program is being considered to develop a single
stabilization. This should occur within 3 s. On instruments with
precision statement for all portable meters.
more than one scale range, select the scale that gives the
13.1.1 Repeatability—The difference between successive
greatest sensitivity for the conductivity value being deter-
mined. Ensure that the appropriate scale multiplying factor (or measured conductivity values obtained by the same operator
with the same apparatus under constant operating conditions on
scale range) is used. Record the fuel temperature.
identical test material at the same fuel temperature would, in
11.3 Laboratory and Field Measurements on Sampled Fu-
els: the long run, in the normal and correct operation of the test
method, exceed the values in Table 1 only in one case in
11.3.1 Preparation of Containers (Metal or Glass)—Prior
to taking samples, take extreme care to ensure that all contain- twenty.
13.1.2 Reproducibility—The difference between two single
ers and measuring vessels have been thoroughly cleaned. It is
preferable that containers are laboratory cleaned prior to and independent measurements of conductivity obtained by
different operators working at the same location (13.2) on
shipment to the field for sampling (see Section 8).
11.3.2 Measurement—Rinse the conductivity cell thor- identical test material at the same fuel temperature would, in
the long run, in the normal and correct operation of the test
oughly with the fuel under test to remove fuel residues
remaining on the cell from previous tests. Transfer the fuel to method, exceed the values in Table 1 only in one case in
twenty.
the measuring vessel and record the conductivity of the fuel
using the procedure applicable to the particular apparatus. If 13.2 In 1987, a test program was carried out to investigate
reproducibility of results when samples are shipped between
one of the conductivity meters referenced in Footnote 3 is used,
follow these instructions: Rinse the cell concurrently with the laboratories. (See Appendix X1.) While repeatability values
were similar to those in Table 1, it was concluded that adequate
rinsing of the measur
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.