ASTM D971-12
(Test Method)Standard Test Method for Interfacial Tension of Oil Against Water by the Ring Method
Standard Test Method for Interfacial Tension of Oil Against Water by the Ring Method
SIGNIFICANCE AND USE
4.1 Interfacial tension measurements on electrical insulating oils provide a sensitive means of detecting small amounts of soluble polar contaminants and products of oxidation. A high value for new mineral insulating oil indicates the absence of most undesirable polar contaminants. The test is frequently applied to service-aged oils as an indication of the degree of deterioration.
SCOPE
1.1 This test method covers the measurement of the interfacial tension between mineral oil and water, under non-equilibrium conditions.
1.2 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: D971 − 12
Standard Test Method for
1
Interfacial Tension of Oil Against Water by the Ring Method
This standard is issued under the fixed designation D971; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber 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 U.S. Department of Defense.
1. Scope 4. Significance and Use
1.1 This test method covers the measurement of the inter-
4.1 Interfacialtensionmeasurementsonelectricalinsulating
facial tension between mineral oil and water, under non-
oils provide a sensitive means of detecting small amounts of
equilibrium conditions.
soluble polar contaminants and products of oxidation. A high
value for new mineral insulating oil indicates the absence of
1.2 This standard does not purport to address all of the
most undesirable polar contaminants. The test is frequently
safety concerns, if any, associated with its use. It is the
applied to service-aged oils as an indication of the degree of
responsibility of the user of this standard to establish appro-
deterioration.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
5. Apparatus (Figs. 1 and 2)
2. Referenced Documents 4
5.1 Tensiometer —Force measurement on the tensiometer
2
2.1 ASTM Standards: maybemadeusingatorsionwire,loadcell,oranyothermeans
D117Guide for Sampling, Test Methods, and Specifications of linearly determining tension in the range of 0 to 100 mN/m.
for Electrical Insulating Oils of Petroleum Origin
5.1.1 Horizontal platform to hold the sample container
D923Practices for Sampling Electrical Insulating Liquids
should be capable of movement upward or downward using a
D2285Test Method for Interfacial Tension of Electrical mechanical screw, lever mechanism, electronic drive, or any
Insulating Oils of Petroleum OriginAgainst Water by the
other means of precisely changing vertical position of the
3
Drop-Weight Method (Withdrawn 2008) sample.
5.2 Rings made of platinum or platinum-iridium alloy may
3. Summary of Test Method
beused.Theringshouldbeweldedintoacontinuouscircleand
3.1 InterfacialTensionisdeterminedbymeasuringtheforce
attached to at least two parallel stirrups. Circumference of the
necessary to detach a planar ring of platinum wire from the
ring should be minimum 40 mm and diameter of the ring wire
surface of the liquid of higher surface tension, that is, upward
shouldbeabout0.3mm.Ratiooftheringmajorradius(R)and
from the water-oil interface. To calculate the interfacial
the wire radius (r) should be known (R/r) to at least three
tension, the force so measured is corrected by an empirically
significant figures. Stirrups should be at least 25 mm long.
determined factor which depends upon the force applied, the
5.2.1 The ring may be suspended from or rigidly fixed into
densities of both oil and water, and the dimensions of the ring.
the tensiometer force measuring system.
Measurements are made under rigidly standardized nonequi-
5.3 Sample Container—Glass beaker or clear cylindrical
librium conditions in which the measurement is completed
container having a minimum diameter of 45 mm.
within 60 s after formation of the interface.
6. Reagents
1
This test method is under the jurisdiction of ASTM Committee D27 on 6.1 Purity of Reagents—Reagent grade chemicals shall be
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
used in the test.
mittee D27.07 on Physical Test.
Current edition approved May 1, 2012. Published May 2012. Originally
6.2 Purity of Water—Unless otherwise indicated, references
approved in 1948 as D971–48 T. Last previous edition approved in 2004 as
towatershallbeunderstoodtomeandistilledwaterorwaterof
D971–99a(2004). DOI: 10.1520/D0971-12.
equal purity.
2
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
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
The last approved version of this historical standard is referenced on Tensiometers that use the Du Nouy principle for measuring interfacial and
www.astm.org. surface tension should be used.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D971 − 12
thoroughly with tap and then distilled water. Dry the glass
vessel if not for immediate use.
7.2 The ring should be cleaned by immersing it in a small
container of xylene, hexane or another suitable hydrocarbon
solvent for a
...
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: D971 − 99a (Reapproved 2004) D971 − 12
Standard Test Method for
1
Interfacial Tension of Oil Against Water by the Ring Method
This standard is issued under the fixed designation D971; 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.
1. Scope
1.1 This test method covers the measurement of the interfacial tension between mineral oil and water, under non-equilibrium
conditions.
1.2 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.
2. Referenced Documents
2
2.1 ASTM Standards:
D117 Guide for Sampling, Test Methods, and Specifications for Electrical Insulating Oils of Petroleum Origin
D923 Practices for Sampling Electrical Insulating Liquids
D2285 Test Method for Interfacial Tension of Electrical Insulating Oils of Petroleum Origin Against Water by the Drop-Weight
3
Method (Withdrawn 2008)
3. Summary of Test Method
3.1 Interfacial Tension is determined by measuring the force necessary to detach a planar ring of platinum wire from the surface
of the liquid of higher surface tension, that is, upward from the water-oil interface. To calculate the interfacial tension, the force
so measured is corrected by an empirically determined factor which depends upon the force applied, the densities of both oil and
water, and the dimensions of the ring. Measurements are made under rigidly standardized nonequilibrium conditions in which the
measurement is completed within 60 s after formation of the interface.
4. Significance and Use
4.1 Interfacial tension measurements on electrical insulating oils provide a sensitive means of detecting small amounts of
soluble polar contaminants and products of oxidation. A high value for new mineral insulating oil indicates the absence of most
undesirable polar contaminants. The test is frequently applied to service-aged oils as an indication of the degree of deterioration.
Figs. 1 and 2)
5. Apparatus (
4
5.1 Tensiometer —Force measurement on the tensiometer may be made using a torsion wire, load cell, or any other means of
linearly determining tension in the range of 0 to 100 mN/m.
5.1.1 Horizontal platform to hold the sample container should be capable of movement upward or downward using a mechanical
screw, lever mechanism, electronic drive, or any other means of precisely changing vertical position of the sample.
5.2 Rings made of platinum or platinum-iridium alloy may be used. The ring should be welded into a continuous circle and
attached to at least two parallel stirrups. Circumference of the ring should be minimum 40 mm and diameter of the ring wire should
be about 0.3 mm. Ratio of the ring major radius (R) and the wire radius (r) should be known (R/r) to at least three significant
figures. Stirrups should be at least 25 mm long.
1
This test method is under the jurisdiction of ASTM Committee D27 on Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcommittee D27.07
on Physical Test.
Current edition approved Oct. 1, 2004May 1, 2012. Published November 2004May 2012. Originally approved in 1948 as D971 – 48 T. Last previous edition approved
in 19992004 as D971 – 99a.D971 – 99a(2004). DOI: 10.1520/D0971-99AR04.10.1520/D0971-12.
2
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
4
Tensiometers that use the Du Nouy principle for measuring interfacial and surface tension should be used.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
---------------------- Page: 1 ----------------------
D971 − 12
FIG. 1 Interfacial Tensiometer
FIG. 2 Top View of Interfacial Tensiometer
5.2.1 The ring may be suspended from or rigidly fixed into the tensiometer force measuring system.
5.3 Sample Container—Glass beaker or clear cylindric
...
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