ASTM D1533-20

Standard Test Method for Water in Insulating Liquids by Coulometric Karl Fischer Titration

SIGNIFICANCE AND USE
4.1 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.  
4.2 This test is 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 μg 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 standard. No other units of measurement are included in this 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements see 8.1 and A2.1.  
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2020
• ICS: 29.040.10 - Insulating oils
• Technical Committee: D27 - Electrical Insulating Liquids and Gases
• Drafting Committee: D27.06 - Chemical Test

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1533 − 20
Standard Test Method for
Water in Insulating Liquids by Coulometric Karl Fischer
1
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.
1. Scope 3. Summary of Test Method
3.1 This test method is based on the reduction of iodine
1.1 This test method covers the measurement of water
containing reagent according to the traditional Karl Fischer
present in insulating liquids by coulometric Karl Fischer
3
reaction. The proposed reaction mechanism is as follows:
titration.Thistestmethodisusedcommonlyfortestspecimens
below 100 % relative saturation of water in oil. The coulomet-
SO 1CH OH1RN 5 @RNH#SO CH (1)
2 3 3 3
ric test method is known for its high degree of sensitivity
H O1I 1 RNH SO CH 12RN 5 RNH SO CH 12 RNH I
@ # @ # @ #
2 2 3 3 4 3
(typically 10 µg H O). This test method requires the use of
2
equipment specifically designed for coulometric titration.
RN 5 Base
~ !
1.2 This test method recommends the use of commercially
The endpoint is determined amperometrically with a plati-
available coulometric Karl Fischer titrators and reagents.
num electrode that senses a sharp change in cell resistance
when the iodine has reacted with all of the water in the test
1.3 The values stated in SI units are to be regarded as
specimen.
standard. No other units of measurement are included in this
standard. 3.2 The coulometric Karl Fischer test method requires the
use of an automatic titrator with commercially available
1.4 This standard does not purport to address all of the
reagents. Karl Fischer instruments regenerate iodine coulo-
safety concerns, if any, associated with its use. It is the
metrically from the iodide in the Karl Fischer reagent. The test
responsibility of the user of this standard to establish appro-
specimen is injected into a titration cell where the iodine
priate safety, health, and environmental practices and deter-
consumed by the reaction with water is electrolytically regen-
mine the applicability of regulatory limitations prior to use.
erated by anodic oxidation of iodide. The completion of the
For specific precautionary statements see 8.1 and A2.1.
reaction is detected with a platinum sensing electrode. The
1.5 This international standard was developed in accor-
coulombs of electricity required to generate the necessary
dance with internationally recognized principles on standard-
amount of iodine then is converted into the amount of water
ization established in the Decision on Principles for the
present in the test specimen by use of the Faraday equation.
Development of International Standards, Guides and Recom-
3.3 Titration Cell—The coulometric titration cell consists of
mendations issued by the World Trade Organization Technical
either a sealed vessel containing both an anode and cathode
Barriers to Trade (TBT) Committee.
which are separated by a diaphragm or a sealed vessel
containing an anode and cathode which are not separated by a
2. Referenced Documents
diaphragm. In both cells the anode compartment contains a
2
solution consisting of sulfur dioxide, iodide, and an amine in a
2.1 ASTM Standards:
solvent containing methanol/chloroform or methanol/longer
D923 Practices for Sampling Electrical Insulating Liquids
chain alcohol. In the cell with a diaphragm the cathode
compartment contains similar reagents optimized for cathodic
reduction.
1
This test method is under the jurisdiction of ASTM Committee D27 on
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
4. Significance and Use
mittee D27.06 on Chemical Test.
Current edition approved Nov. 1, 2020. Published November 2020. Originally
4.1 Electrical characteristics of an insulating liquid may be
approved in 1958. Last previous edition approved in 2012 as D1533 – 12. DOI:
affected deleteriously by excessive water content.Ahigh water
10.1520/D1533-20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
3
Standards volume information, refer to the standard’s Document Summary page on Scholz, E., “Karl-Fischer Titration,” Springer-Verlag, Berlin, Heidelberg, New
the ASTM website. York, Tokyo, 1984, 140 pp.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ------------------
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D1533 − 12 D1533 − 20
Standard Test Method for
Water in Insulating Liquids by Coulometric Karl Fischer
1
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.
1. 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 μg H O). This test method requires the use of equipment specifically designed for
2
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 standard. No other units of measurement are included in this 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 practicesafety, health, and environmental practices and
determine the applicability of regulatory limitations prior to use. For specific precautionary statements see 8.1 and A2.1.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
D923 Practices for Sampling Electrical Insulating Liquids
2.2 IEC Standard:
IEC 60814: Insulating Liquids—Oil-Impregnated Paper and Pressboard—Determination of Water by Automatic Coulometric
3
Karl Fischer Titration
3. Summary of Test Method
3.1 This test method is based on the reduction of iodine containing reagent according to the traditional Karl Fischer reaction. The
3
proposed reaction mechanism is as follows:
1
This test method is under the jurisdiction of ASTM Committee D27 on Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcommittee D27.06
on Chemical Test.
Current edition approved Dec. 1, 2012Nov. 1, 2020. Published December 2012November 2020. Originally approved in 1958. Last previous edition approved in 20052012
as D1533 – 00D1533 – 12.(2005). DOI: 10.1520/D1533-12.10.1520/D1533-20.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Scholz, E., “Karl-Fischer Titration,” Springer-Verlag, Berlin, Heidelberg, New York, Tokyo, 1984, 140 pp.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
D1533 − 20
SO 1CH OH1RN 5 RNH SO CH (1)
@ #
2 3 3 3
H O1I 1@RNH#SO CH 12RN 5 @RNH#SO CH 12@RNH#I
2 2 3 3 4 3
~RN 5 Base!
The endpoint is determined amperometrically with a platinum electrode that senses a sharp change in cell resistance when the
iodine has reacted with all of the water in the test specimen.
3.2 The coulometric Karl Fischer test method requires the use of an automatic titrator with commercially available reagents. Karl
Fischer instruments regenerate iodine coulometrically from the iodide in the Karl Fischer reagent. The test specimen is injected
into a titration cell where the iodine consumed by the reaction with water is electrolytically regenerated by anodic oxidation of
iodide. The completion of the reaction is detected with a platinum sensing electrode. The coulombs of electricity required to
generate the necessary amount of iodine then is converted into the amount of water present in the test specimen by use of the
Faraday equation.
3.3 Titration Cell—The coulometric titration cell consists of either a sealed vessel containing both an anode and cathode which
are separated by a diaphragm or a sealed vessel containing an anode and cathode which are not separated by a diaphragm. In both
cells the anode compartment contains a solution consisting of
...