ASTM D1533-00(2005)
(Test Method)Standard Test Method for Water in Insulating Liquids by Coulometric Karl Fischer Titration
Standard Test Method for Water in Insulating Liquids by Coulometric Karl Fischer Titration
SIGNIFICANCE AND USE
Electrical characteristics of an insulating liquid may be affected deleteriously by excessive water content. A high water content may make a dielectric liquid unsuitable for some electrical applications due to deterioration of properties such as the dielectric breakdown voltage.
These tests are suitable for use in acceptance specifications, in control of processing, and in evaluating the condition of dielectric liquids in service.
SCOPE
1.1 This test method covers the measurement of water present in insulating liquids by coulometric Karl Fischer titration. This test method is used commonly for test specimens below 100 % relative saturation of water in oil. The coulometric test method is known for its high degree of sensitivity (typically 10 g H2O). This test method requires the use of equipment specifically designed for coulometric titration.
1.2 This test method recommends the use of commercially available coulometric Karl Fischer titrators and reagents.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 practice and determine the applicability of regulatory limitations prior to use. For specific precautionary statements see and .
General Information
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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
Designation: D1533 − 00(Reapproved 2005)
Standard Test Method for
Water in Insulating Liquids by Coulometric Karl Fischer
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Titration
This standard is issued under the fixed designation D1533; 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.
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1. Scope lometric Karl Fischer Titration
1.1 This test method covers the measurement of water
3. Summary of Test Method
present in insulating liquids by coulometric Karl Fischer
3.1 This test method is based on the reduction of iodine
titration.Thistestmethodisusedcommonlyfortestspecimens
containing reagent according to the traditional Karl Fischer
below 100 % relative saturation of water in oil. The coulomet-
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reaction. The proposed reaction mechanism is as follows:
ric test method is known for its high degree of sensitivity
(typically 10 µg H O). This test method requires the use of SO 1CH OH1RN 5 @RNH#SO CH (1)
2 2 3 3 3
equipment specifically designed for coulometric titration.
H O1I 1@RNH#SO CH 12RN 5 @RNH#SO CH 12@RNH#I
2 2 3 3 4 3
1.2 This test method recommends the use of commercially
available coulometric Karl Fischer titrators and reagents.
RN 5 Base
~ !
1.3 The values stated in SI units are to be regarded as
The endpoint is determined amperometrically with a plati-
standard. No other units of measurement are included in this
num electrode that senses a sharp change in cell resistance
standard.
when the iodine has reacted with all of the water in the test
1.4 This standard does not purport to address all of the specimen.
safety concerns, if any, associated with its use. It is the
3.2 The coulometric Karl Fischer test method requires the
responsibility of the user of this standard to establish appro-
use of an automatic titrator with commercially available
priate safety and health practice and determine the applica-
reagents. Karl Fischer instruments regenerate iodine coulo-
bility of regulatory limitations prior to use. For specific
metrically from the iodide in the Karl Fischer reagent. The test
precautionary statements see 8.1 and A2.1.
specimen is injected into a titration cell where the iodine
consumed by the reaction with water is electrolytically regen-
2. Referenced Documents
erated by anodic oxidation of iodide. The completion of the
2
2.1 ASTM Standards:
reaction is detected with a platinum sensing electrode. The
D923 Practices for Sampling Electrical Insulating Liquids
coulombs of electricity required to generate the necessary
D3613 Practice for Sampling Insulating Liquids for Gas
amount of iodine then is converted into the amount of water
AnalysisandDeterminationofWaterContent(Withdrawn
present in the test specimen by use of the Faraday equation.
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2007)
3.3 Titration Cell—The coulometric titration cell consists of
2.2 IEC Standard:
either a sealed vessel containing both an anode and cathode
IEC 60814: Insulating Liquids—Oil-Impregnated Paper and
which are separated by a diaphragm or a sealed vessel
Pressboard—Determination of Water by Automatic Cou-
containing an anode and cathode which are not separated by a
diaphragm. In both cells the anode compartment contains a
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This test method is under the jurisdiction of ASTM Committee D27 on solution consisting of sulfur dioxide, iodide, and an amine in a
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
solvent containing methanol/chloroform or methanol/longer
mittee D27.06 on Chemical Test.
chain alcohol. In the cell with a diaphragm the cathode
Current edition approved Oct. 1, 2005. Published November 2005. Originally
compartment contains similar reagents optimized for cathodic
approved in 1958. Last previous edition approved in 2000 as D1533 – 00. DOI:
10.1520/D1533-00R05.
reduction.
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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
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Standards volume information, refer to the standard’s Document Summary page on American National Standards Institute, 11 West 42nd Street, New York, NY
the ASTM website. 10036–8002.
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The last approved version of this historical standard is referenced on Scholz, E., “Karl-Fischer Titration,” Springer-Verlag, Berlin, Heidelberg, New
www.astm.org. York, Tokyo, 1984, 140 pp.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D1533 − 00 (2005)
4. Significance and Use reaction to take place. It may consist of two platinum meshes
or w
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