ASTM D5682-95(2002)
(Test Method)Standard Test Methods for Electrical Resistivity of Liquid Paint and Related Materials
Standard Test Methods for Electrical Resistivity of Liquid Paint and Related Materials
SIGNIFICANCE AND USE
These tests are suitable for testing paints adjusted for compatibility with various electrostatic spray coating applications, and by their use, spray performance can be optimized.
SCOPE
1.1 These test methods cover the determination of specific resistance (resistivity) of liquid paints, solvents, and other fluids in the range of 0.6 to 2640 M-cm.
1.2 Test Method A describes a procedure for making resistance tests with a commonly used paint application test assembly (Fig 1).
1.3 Test Method B describes a procedure for making resistance tests with a conductivity meter (Fig 2).
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.
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Designation:D5682–95(Reapproved2002)
Standard Test Methods for
Electrical Resistivity of Liquid Paint and Related Materials
This standard is issued under the fixed designation D 5682; 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.
1. Scope
1.1 These test methods cover the determination of specific
resistance (resistivity) of liquid paints, solvents, and other
fluids in the range of 0.6 to 2640 MV-cm.
1.2 Test Method A describes a procedure for making resis-
tance tests with a commonly used paint application test
assembly (Fig. 1).
1.3 Test Method B describes a procedure for making resis-
tance tests with a conductivity meter (Fig. 2).
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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
FIG. 1 Paint Application Test Assembly
2. Terminology
2.1 Definitions:
3. Summary of Test Methods
2.1.1 specific resistance (resistivity)—The ratio of the d-c
3.1 Test Methods A and B measure direct current through
potentialgradientinvoltspercentimeterparallelingthecurrent
concentric cylinder electrodes immersed in a liquid paint
flow within the specimen to the current density in amperes per
specimen.
square centimeter at a given instant of time and under
prescribed conditions.
4. Significance and Use
2.1.1.1 Discussion—This is numerically equal to the resis-
4.1 These tests are suitable for testing paints adjusted for
tancebetweenoppositefacesofacentimetercubeoftheliquid.
compatibility with various electrostatic spray coating applica-
The units are ohm centimeters (or megohm centimeters).
tions, and by their use, spray performance can be optimized.
2.2 Definitions of Terms Specific to This Standard:
2.2.1 kilohms (KV)—resistance value equal to 1000 V
5. Interferences
(10 ).
5.1 Contamination of the specimen is the most likely cause
2.2.2 megohms (MV)—resistance value equal to 1 000 000
of error. Very small amounts of water, acids, or polar solvents
V (10 ).
will lower the resistance of high resistivity solvents and paints.
2.2.3 ohm-centimeters (or megohm-centimeters)—unit of
5.2 High humidity is not known to interfere with the test
specific resistance (resistivity).
itself but can lead to water pickup by the specimen. For
repeatable results, tests should be made under the same
atmospheric conditions and specimens should be stored and
These test methods are under the jurisdiction of ASTM Committee D01 on
Paint and Related Coatings, Materials, and Applications and is the direct responsi- handled so as to keep water pickup to a minimum.
bility of Subcommittee D01.24 on Physical Properties of Liquid Paints and Paint
5.3 Resistivity varies with temperature. A standard test
Materials.
temperature of 25°C is recommended. Other temperatures are
Current edition approved March 15, 1995. Published May 1995.
possible on agreement between the producer and the user.
Paint application test assembly such as the Ransburg 70408-00 Tester or
equivalent may be obtained from ITW Ransburg Electrostatic Systems, P.O. Box
5.4 Electrification time must be the same for every test due
913, Toledo, OH 43697-0913.
to ion migrations that cause current flow to decrease with time.
Conductivity meter such as the Byk-Gardner LC2 conductivity meter, Model
Variations with time of electrification can result in appreciable
1722/1710 or equivalent may be obtained from Byk-Gardner, Inc., 2435 Linden
Lane, Silver Spring, MD 20910. variation in the test results.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D5682
TEST METHOD A
8. Standardization
8.1 For maximum accuracy, the probe should be standard-
ized to determine the exact cell constant. For routine measure-
ments a cell constant (K) of 132 may be used (see Appendix
X1).
8.2 The electronic-resistance measuring assembly may be
checked by use of a standard-resistance decade box ( ⁄2 %
accuracy or better).
9. Procedure
9.1 Prior to tests, make sure that the probe is thoroughly
cleaned (see Section 9.2).
9.2 Insert the paint test probe into the jack in the lower right
side of the meter case.
9.3 Set the scale select switch (top center) to the Scale B
position.
9.4 Move the mode select switch (top right) to the Zero
Adjust position and rotate the zero adjust knob (top left) until
the dial indicator needle centers on the adjust position (far
right).Maximumaccuracywillberealizedwiththemeterlying
flat, meter face up.
NOTE 1—If the needle will not adjust to zero, replace the battery.
9.5 Move the mode select switch to the Paint Test position.
9.6 Immerse the probe vertically into a well-mixed, visually
uniform specimen of the subject material until the holes at the
bottom of the slots in the probe sleeve are submerged.
FIG. 2 Conductivity Meter
Caution—Do NOT immerse the probe past the top of
sleeve.
9.7 Read the paint resistance from Scale B. If the reading is
5.5 Equipment outlined in Test Methods A and B apply
less than 0.5 on the B scale, move the scale select switch to the
differenttestvoltages(45Vand15V,respectively).Becauseof
ScaleAposition, repeat 9.4, then read the paint resistance from
this, some variation in results may be expected.
Scale A.
9.8 Read the scale value at 10 s after immersion in the test
6. Apparatus
sample. Ignore any slow drift that may occur after this time.
9.9 To convert the megohms reading on the tester to
6.1 Paint Application Test Assembly —designed to provide
resistivity in megohm-centimeters, multiply by constant “K”
measurement of the electrical resistance of paint formulations
found in 8.1 or 132.
for all electrostatic applications.To provide greater accuracy in
9.10 Clean the probe thoroughly. Allow the apparatus and
measuring low resistance paints, the meter is equipped with
specimen to stand for 1 h (keep lids on specimens tightly
dual range selection. Range “A” is .005 to 1 MV, Range “B”
closed to prevent loss of volatiles). Repeat the measurement,
is .05 to 20 MV.
making certain to remix the specimen.
9.11 Report the result as the mean value of the two
7. Reagents and
...
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