ASTM D4496-87(1998)e1
(Test Method)Standard Test Method for D-C Resistance or Conductance of Moderately Conductive Materials
Standard Test Method for D-C Resistance or Conductance of Moderately Conductive Materials
SCOPE
1.1 This test method covers the determination of the measurement of electrical resistance or conductance of materials that are generally categorized as moderately conductive and are neither good electrical insulators nor good conductors.
1.2 This test method applies to all materials that exhibit volume resistivity in the range of 1 to 10 [omega]-cm or surface resistivity in the range of 10 to 10 [omega] (per square).
1.3 This test method is designed for measurements at standard conditions of 23°C and 50% relative humidity, but its principles of operation can be applied to specimens measured at lower or higher temperatures and relative humidities.
1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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. Specific precautionary statements are given in 8.3.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
An American National Standard
e1
Designation: D 4496 – 87 (Reapproved 1998)
Standard Test Method for
D-C Resistance or Conductance of Moderately Conductive
Materials
This standard is issued under the fixed designation D 4496; 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.
e NOTE—The adjunct number was editorially corrected to ADJD4496 in September 1999.
1. Scope 3. Terminology
1.1 This test method covers the determination of the mea- 3.1 Definitions:
surement of electrical resistance or conductance of materials 3.1.1 moderately conductive—a solid material having vol-
that are generally categorized as moderately conductive and are ume resistivity between 1 and 10 V·cm.
neither good electrical insulators nor good conductors. 3.1.2 For definitions of other terms used in this standard,
1.2 This test method applies to all materials that exhibit refer to Terminology D 1711.
volume resistivity in the range of 1 to 10 V-cm or surface 3.2 Description of Term Specific to This Standard:
3 7
resistivity in the range of 10 to 10 V (per square). 3.2.1 steady state—for the purpose of this test method,
1.3 This test method is designed for measurements at steady-state is attained if any rate of change in the observed
standard conditions of 23°C and 50 % relative humidity, but its resistance (or conductance) averages less than 0.25 %/s.
principles of operation can be applied to specimens measured
4. Summary of Test Method
at lower or higher temperatures and relative humidities.
4.1 Specimens of material are conditioned in prescribed
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the environments and subjected to direct-voltage stress. Resistance
or conductance is measured and used with the dimensional
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- aspects of the specimen to compute a resistivity of the material.
The apparatus and techniques used in this test method are in
bility of regulatory limitations prior to use. Specific precau-
tionary statements are given in 8.3. accordance with the general principles set forth in Test Meth-
ods D 257.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
D 257 Test Methods for D-C Resistance or Conductance of 5.1 This test method is useful for the comparison of mate-
rials, as a quality control test, and may be used for specification
Insulating Materials
D 374 Test Methods for Thickness of Solid Electrical Insu- purposes.
5.2 This test method is useful in the selection and use of
lation
D 618 Practice for Conditioning Plastics and Electrical materials in wires, cables, bushings, high-voltage rotating
machinery, and other electrical apparatus in which shielding or
Insulating Materials for Testing
D 991 Test Method for Rubber Property Volume Resistivity the distribution of voltage stress may be of value.
5.3 Commercially available “moderately conductive” mate-
of Electrically Conductive and Antistatic Products
D 1711 Terminology Relating to Electrical Insulation rials frequently are comprised of both conductive and resistive
components (that is, cellulose fibers with colloidal carbon
black particles attached to portions of the surfaces of those
This test method is under the jurisdiction of ASTM Committee D-9 on
fibers, or discrete conductive particles adhered to the surfaces
Electrical and Electronic Insulating Materials and is the direct responsibility of
of electrical insulating polymers). Such commercially available
Subcommittee D09.12 on Electrical Tests.
materials are often manufactured in a manner that may result in
Current edition approved Oct. 30, 1987. Published December 1987. Originally
published as D 4496 – 85. Last previous edition D 4496 – 85.
anisotropy with respect to electrical conduction. Hence, the
Annual Book of ASTM Standards, Vol 10.01.
significance of tests using this test method may depend upon
Annual Book of ASTM Standards, Vol 08.01.
4 the orientation of the specimen tested to the electric field and
Annual Book of ASTM Standards, Vol 09.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
e1
D 4496 – 87 (1998)
FIG. 1 Cell For Volume Resistivity 1-in. Electrode (Mercury)
the relationship between this orientation and the orientation of 6.3 Test cells, that have been found to be satisfactory are
the material in the electrical apparatus which uses these depicted in Fig. 1, Fig. 2, and Fig. 3.
materials.
NOTE 1—Conductive paint may provide suitable electrodes on speci-
mens of certain materials and testing such specimens may not require test
6. Apparatus
cell assemblies as shown in Fig. 1, Fig. 2, and Fig. 3 (see Annex A1 for
6.1 The apparatus shall conform to the general requirements
additional information).
set forth in Test Methods D 257.
6.2 Voltage Device—Capable of limiting the magnitude of
Drawings suitable for construction of test cells are available from ASTM
the direct voltage applied to the specimen. (See Appendix X1
Headquarters, 100 Barr Harbor Drive, West Conshohocken, PA 19428. Request
for discussion of voltage stress and specimen heating.) adjunct No. ADJD4496.
A—Mass for applying contact force between current electrodes and the specimen (300 N/m times the specimen width in metres) (Note 1).
B—Mass for applying contact force between potential electrodes and the specimen (60 N/m times specimen width in metres) (Note 2).
C—The specimen.
D—Current electrodes.
E—Potential electrodes.
F—Distance between the current and potential electrodes (20 mm minimum).
G—Distance between potential electrodes depends on specimen size.
H—Width of current electrode, 5 to 8 mm (0.2 to 0.3 in.).
X—Electrical insulating material (10 V·cm minimum resistivity).
Note 1—For a specimen 150 mm (6 in.) wide, mass is approximately 4.5 kg (10 lb).
Note 2—For a specimen 150 mm (6 in.) wide, mass is approximately 0.9 kg (2 lb).
Note 3—Fig. 2 is taken from Test Method D 991.
The electrode assembly (Fig. 2) shall consist of a rigid base made from an electrical insulating material having a resistivity greater than 10 ohm-cm (for example, hard
rubber, polyethylene, polystyrene, etc.) to which a pair of potential electrodes are fastened in such a manner that the four electrodes are parallel and their top surfaces
are in the same horizontal plane. Another pair of current electrodes identical with the first pair shall be fastened to a second piece of insulating material so that they can
be superimposed on the specimen directly above the first pair. The current electrodes shall have a length at least 10 mm (0.4 in.) greater than the specimen width, a width
between 5 and 8 mm (0.2 and 0.3 in.), and a height uniform with 0.05 mm (0.002 in.) between 10 and 15 mm (0.4 and 0.6 in.). The potential electrodes shall have a length
and height equal to the current electrodes, and shall be tapered to an edge having a radius of 0.5 mm (0.02 in.) maximum at the top surface. The distance between the
potential electrodes shall be not less than 10 mm (0.4 in.) nor more than 66 mm (2.6 in.) and shall be known within+2%.The current electrodes shall be equidistant outside
the potential electrodes by at least 20 mm (0.8 in.). The electrodes shall be made from a corrosion-resistant metal such as brass, nickel, stainless steel, etc. Insulation
resistance between electrodes shall be greater than 1 TV.
FIG. 2 Electrode Assembly
e1
D 4496 – 87 (1998)
undue heating of the test specimen. See Appendix X1 for
discussion of time effects of voltage stress and specimen
heating.
8.2 Do not apply to the test specimen a power input
exceeding 1 W. For very conductive materials it may be
necessary to increase the size of a specimen or to decrease the
test voltage by one or more orders of magnitude below 500 V
in order to avoid overheating of the specimen.
8.3 Test a minimum of five specimens from each sample in
each of the principal directions of anisotropy. Use caution in
handling the specimens to avoid contaminating the surfaces.
8.4 Place the specimen in the test cell or attach the leads to
the painted-on electrodes. If mercury electrodes are used, take
special care in handling the mercury.
8.4.1 Warning—Mercury metal-vapor poisoning has long
been recognized as a hazard in the industry. The maximum
exposure limits are set by the American Conference of Gov-
FIG. 3 CELL For Surface Resistance Assembly Photo ernmental Industrial Hygienists. The concentration of mercury
vapor over spills from broken thermometers, barometers, or
other instruments using mercury can easily exceed these
exposure limits. Mercury, being a liquid and quite heavy, will
7. Specimen Preparation and Selection
disintergrate into small droplets and seep into cracks and
7.1 Take specimens from a sample of material that has been
crevices in the floor. The use of a commercially available
obtained in a random manner. Take care to protect the sample
emergency spill kit is recommended whenever a spill occurs.
and the specimens from any contamination which will affect
The increased area of exposure adds significantly to the
the results of the resistance or conductance tests. Such con-
mercury vapor concentration in the air. Mercury vapor concen-
tamination can include salts or moisture from human hands,
tration is easil
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.