ASTM D3612-02(2017)
(Test Method)Standard Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography
Standard Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography
SIGNIFICANCE AND USE
5.1 Oil and oil-immersed electrical insulation materials may decompose under the influence of thermal and electrical stresses, and in doing so, generate gaseous decomposition products of varying composition which dissolve in the oil. The nature and amount of the individual component gases that may be recovered and analyzed may be indicative of the type and degree of the abnormality responsible for the gas generation. The rate of gas generation and changes in concentration of specific gases over time are also used to evaluate the condition of the electric apparatus.
Note 1: Guidelines for the interpretation of gas-in-oil data are given in IEEE C57.104.
SCOPE
1.1 This test method covers three procedures for extraction and measurement of gases dissolved in electrical insulating oil having a viscosity of 20 cSt (100 SUS) or less at 40°C (104°F), and the identification and determination of the individual component gases extracted. Other methods have been used to perform this analysis.
1.2 The individual component gases that may be identified and determined include:
Hydrogen—H2
Oxygen—O2
Nitrogen—N2
Carbon monoxide—CO
Carbon dioxide—CO2
Methane—CH4
Ethane—C2H6
Ethylene—C2H4
Acetylene—C2H2
Propane—C3H8
Propylene—C3H6
1.3 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 warning statements see 6.1.8, 30.2.2 and 30.3.1.
1.4 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
Relations
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: D3612 − 02 (Reapproved 2017)
Standard Test Method for
Analysis of Gases Dissolved in Electrical Insulating Oil by
Gas Chromatography
This standard is issued under the fixed designation D3612; 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.
1. Scope D2140Practice for Calculating Carbon-Type Composition
of Insulating Oils of Petroleum Origin
1.1 This test method covers three procedures for extraction
D2300Test Method for Gassing of Electrical Insulating
and measurement of gases dissolved in electrical insulating oil
Liquids Under Electrical Stress and Ionization (Modified
havingaviscosityof20cSt(100SUS)orlessat40°C(104°F),
Pirelli Method)
and the identification and determination of the individual
D2779Test Method for Estimation of Solubility of Gases in
component gases extracted. Other methods have been used to
Petroleum Liquids
perform this analysis.
D2780TestMethodforSolubilityofFixedGasesinLiquids
1.2 The individual component gases that may be identified 3
(Withdrawn 2010)
and determined include:
D3613Practice for Sampling Insulating Liquids for Gas
Hydrogen—H
2 AnalysisandDeterminationofWaterContent(Withdrawn
Oxygen—O 3
2007)
Nitrogen—N
D4051PracticeforPreparationofLow-PressureGasBlends
Carbon monoxide—CO
Carbon dioxide—CO
2 E260Practice for Packed Column Gas Chromatography
Methane—CH
2.2 IEEE Standard:
Ethane—C H
2 6
Ethylene—C H C57.104 GuidefortheInterpretationofGasesGeneratedin
2 4
Acetylene—C H
2 2
Oil-Immersed Transformers
Propane—C H
3 8
2.3 IEC Standard:
Propylene—C H
3 6
PublicationNo.567GuidefortheSamplingofGasesandof
1.3 This standard does not purport to address all of the
Oil from Oil-Filled Electrical Equipment and for the
safety concerns, if any, associated with its use. It is the
Analysis of Free and Dissolved Gases
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use.
3.1 Definitions of Terms Specific to This Standard:
For specific warning statements see 6.1.8, 30.2.2 and 30.3.1.
3.1.1 gas content of oil by volume—in Method A, the total
1.4 This international standard was developed in accor-
volume of gases, corrected to 760 torr (101.325 kPa) and 0°C,
dance with internationally recognized principles on standard-
contained in a given volume of oil, expressed as a percentage.
ization established in the Decision on Principles for the
In Methods B and C, the sum of the individual gas concentra-
Development of International Standards, Guides and Recom-
tionscorrectedto760torr(101.325kPa)and0°C,expressedin
mendations issued by the World Trade Organization Technical
percent or parts per million.
Barriers to Trade (TBT) Committee.
3.1.2 headspace—a volume of gas phase in contact with a
2. Referenced Documents
volumeofoilinaclosedvessel.Thevesselisaheadspacevial
2.1 ASTM Standards: of 20-mL nominal capacity.
3.1.2.1 Discussion—Other vessel volumes may also be
used, but the analytical performance may be somewhat differ-
This test method is under the jurisdiction of ASTM Committee D27 on
ent than that specified in Method C.
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
mittee D27.03 on Analytical Tests.
Current edition approved Nov. 15, 2017. Published December 2017. Originally
approved in 1977. Last previous edition approved in 2009 as D3612–02 (2009). The last approved version of this historical standard is referenced on
DOI: 10.1520/D3612-02R17. www.astm.org.
2 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from IEEE, 345 E. 47th St., New York, NY 10017.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Available from International Electrotechnical Commission (IEC), 3 rue de
Standards volume information, refer to the standard’s Document Summary page on Varembé, Case postale 131, CH-1211, Geneva 20, Switzerland, http://www.iec.ch.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3612 − 02 (2017)
3.1.3 parts per million (ppm) by volume of (specific gas) in 6. Apparatus
oil—thevolumeofthatgascorrectedto760torr(101.325kPa) 6
6.1 Apparatus of the type shown in Fig. 1 or Fig. 2 is
and 0°C, contained in 10 volume of oil.
suitable for use with up to 50-mL samples of oil and consists
3.1.4 sparging, v—agitatingtheliquidsampleusingagasto of the following components:
strip other gases free.
NOTE2—Thissamplesizehasbeenfoundtobesufficientformostoils.
However, oil that has had only limited exposure to air may contain much
3.1.5 volume concentration of (specific gas) in the gas
smalleramountsofnitrogenandoxygen.Fortheseoilsitmaybedesirable
sample—the volume of the specific gas contained in a given
to increase the size of the sample and the extraction apparatus.
volumeofthegassampleatthesametemperatureandpressure
NOTE 3—Alternative apparatus designs including the use of a Toepler
(as the measured total volume), expressed either as a percent-
pump have also been found successful.
age or in parts per million.
6.1.1 Polytetrafluoroethylene (PTFE) Tubing, narrow-bore,
terminatedwithaLuer-Lockfittedglasssyringe,andleadingto
4. Summary of Test Method
a solid plug, three-way, high-vacuum stopcock.
4.1 MethodA—Dissolvedgasesareextractedfromasample 6.1.2 Degassing Flask, with a glass inlet tube, of sufficient
of oil by introduction of the oil sample into a pre-evacuated volume to contain up to 50 mL of oil below the inlet tube,
capable of being evacuated through a vacuum pump, contain-
known volume. The evolved gases are compressed to atmo-
spheric pressure and the total volume measured. ing a PTFE-coated magnetic spin bar, and mounted on a
magnetic stirrer.
4.2 Method B—Dissolvedgasesareextractedfromasample
6.1.3 Means of Measuring Absolute Pressure within the
of oil by sparging the oil with the carrier gas on a stripper
apparatus.
column containing a high surface area bead.
6.1.4 Vacuum Pumping System, capable of evacuating the
−3
4.3 Method C—MethodCconsistsofbringinganoilsample
glasswaretoanabsolutepressureof1×10 torr(130mPa)or
in contact with a gas phase (headspace) in a closed vessel
lower.
purgedwithargon.Thedissolvedgasescontainedintheoilare
6.1.5 Vacuum Glassware, sufficiently large compared to the
then equilibrated in the two phases in contact under controlled
volume of the oil sample, so that virtually complete degassing
conditions (in accordance with Henry’s law). At equilibrium,
isobtainedandthatthevolumetriccollectionratioisaslargeas
the headspace is overpressurized with argon and then the
possible. A 500-mL gas collecting flask has been found
content of a loop is filled by the depressurization of the
suitable.
headspaceagainsttheambientatmosphericpressure.Thegases
6.1.6 High-Vacuum Valves or Stopcocks, employing the
contained in the loop are then introduced into a gas chromato-
minimum necessary amounts of high-vacuum stopcock grease
graph.
are used throughout the apparatus.
6.1.7 Gas Collection Tube, calibrated in 0.01-mLdivisions,
4.4 Theremaybesomedifferencesinthelimitsofdetection
capable of containing up to 5 mL of gas, terminated with a
and precision and bias between Methods A, B, and C for
silicone rubber retaining septum. A suitable arrangement is
various gases.
shown in Fig. 3.
4.5 Aportionoftheextractedgases(MethodA)orallofthe
6.1.8 Reservoir of Mercury, sufficient to fill the collection
extractedgases(MethodB)oraportionoftheheadspacegases
flask and collection tube. (Warning—Mercury vapor is ex-
(Method C) is introduced into a gas chromatograph. Calibra-
tremely toxic. Appropriate precautions should be taken.)
tioncurvesareusedinMethodCtoestablishtheconcentration
of each species. The composition of the sample is calculated 7. Sampling
from its chromatogram by comparing the area of the peak of
7.1 Obtain samples in accordance with the procedure de-
each component with the area of the peak of the same
scribed in Test Methods D3613 for sampling with syringetype
component on a reference chromatogram made on a standard
devices or rigid metal cylinders. The use of rigid metal
mixture of known composition.
cylinders is not recommended for use with Method B.
7.2 The procurement of representative samples without loss
5. Significance and Use
ofdissolvedgasesorexposuretoairisveryimportant.Itisalso
5.1 Oilandoil-immersedelectricalinsulationmaterialsmay
important that the quantity and composition of dissolved gases
decompose under the influence of thermal and electrical
remain unchanged during transport to the laboratory. Avoid
stresses, and in doing so, generate gaseous decomposition
prolonged exposure to light by immediately placing drawn
products of varying composition which dissolve in the oil.The
samples into light-proof containers and retaining them there
natureandamountoftheindividualcomponentgasesthatmay
until the start of testing.
be recovered and analyzed may be indicative of the type and
7.2.1 To maintain the integrity of the sample, keep the time
degree of the abnormality responsible for the gas generation.
between sampling and testing as short as possible. Evaluate
The rate of gas generation and changes in concentration of
specific gases over time are also used to evaluate the condition
of the electric apparatus. Ace Glass and Lurex Glass manufacture glass extractors. For Ace Glass, the
glass apparatus conforming to Fig. 1 is Part E-13099-99-99 and Fig. 2 is Part
NOTE1—Guidelinesfortheinterpretationofgas-in-oildataaregivenin E-1400-99. Available from P.O. Box 688, 1430 Northwest Blvd., Vineland, NJ
IEEE C57.104. 08360 or Lurex Glass, 1298 Northwest Blvd., Vineland, NJ 08360.
D3612 − 02 (2017)
FIG. 1 Extraction of Gas from Insulating Oil
FIG. 2 Extraction of Gas from Insulating Oil
D3612 − 02 (2017)
9.5 Ostwald solubility coefficients that have been deter-
mined for a number of gases in one specific electrical insulat-
ing oil at 25°C are shown as follows.Values for gases in other
oils may be estimated by reference to Test Method D2779.
Ostwald Solubility (Note 5)
Component Gas
Coefficient, K , 25°C, 760 mm Hg
i
Hydrogen 0.0558
Nitrogen 0.0968
Carbon monoxide 0.133
Oxygen 0.179
Methane 0.438
Carbon dioxide 1.17
Acetylene 1.22
Ethylene 1.76
Ethane 2.59
Propane 11.0
NOTE 5—The Ostwald coefficient values shown in this table are correct
onlyforthespecificmineraloilhavingadensityat15.5°Cof0.855g/cm
usedintheoriginaldetermination.Ostwaldcoefficientsformineraloilsof
different density may be calculated as follows:
FIG. 3 Retaining Rubber Septum for Gas Collection Tube
0.980 2density
K ~corrected! 5 K (3)
i i
0.130
where, density =density of the oil of interest, g/cm at 15.5°C (60°F).
containers for maximum storage time. Samples have been
This equation is derived from the equation in Test Method D2779. Note
stored in syringes and metal cylinders for four weeks with no
especially that all of the Ostwald coefficients are changed by the same
factor, meaning that though the absolute solubilities of each of the gases
appreciable change in gas content.
will change if a different oil is used, the ratio of the solubility of one gas
NOTE 4—Additional sampling procedures using flexible metal cans are
to another gas will remain constant.
currently being studied for use with Method A.
9.6 A procedure to check the extraction efficiency requires
the use of prepared gas-in-oil standards of known concentra-
METHOD A—VACUUM EXTRACTION
tion.ThemethodsofpreparationareoutlinedinAnnexA1and
8. Method A—Vacuum Extraction
Annex A2.
8.1 Method A employs vacuum extraction to separate the
10. Procedure
gases from the oil. The evolved gases are compressed to
atmospheric pressure and the total volume measured. The
10.1 Lower the mercury level from the collection flask.
gases are then analyzed by gas chromatography.
10.2 Evacuate the system of collection flask and degassing
−3
flasktoanabsolutepressureof1×10 torr(130mPa)orless.
9. Preparation of Apparatus
(In Fig. 1, the space above the mercury in the reservoir must
9.1 Check the apparatus carefully for vacuum tightness of
also be evacuated.)
all joints and stopcocks.
10.3 Connect the oil sample syringe by the PTFE tubing to
9.2 Measure the total volume of the extraction apparatus,
the three-way stopcock leading to the degassing flask.
V , and the volume of the collection space, V , and calculate
T c
10.4 Flush a small quantity of oil from the syringe through
the ratio as the volumetric collection ratio:
thetubingandstopcocktowaste,makingsurethatalltheairin
V
c
the connecting tubing is displaced by oil.
(1)
V 2 V
T o
10.4.1 Any gas bubbles present in the syringe should be
retained during this flushing operation. This may be accom-
where V =the volume of oil to be added.
o
plished by inverting the syringe so that the bubble remains at
9.3 Calculate the degassing efficiencies for each individual
the plunger end of the syringe during the flushing operation.
component gas as follows:
10.5 Close the stopcocks to the vacuum pumps and then
slowly open the three-way stopcock to allow oil and any gas
E 5 (2)
i
K V
i o
bubbles that may be present from the sample syringe to enter
V 2 V
T o
the degassing flask.
where:
10.6 Allow the desired amount of oil to enter the degassing
E = degassing efficiency of component i,
flask and operate the magnetic stirrer vigorously for approxi-
i
V = volume of oil sample,
o mately 10 min. This is the volume, V used in the calculation
o
V = totalinternalvolumeofextractionapparatusbeforeoil
T in 15.4.
sample is introduced, and
K = Ostwald solubility coefficient of component i.
i
9.4 Determine the Ostwald solubility coefficients of fixed
Daoust, R., Dind, J. E., Morgan, J., and Regis, J, “Analysis of Gas Dissolved
gases in accordance with Test Method D2780. in Transformer Oils,” Doble Conference, 1971, Sections 6–110.
D3612 − 02 (2017)
10.6.1 If a gas bubble is present in the syringe, either 11.5 Awiderangeofchromatographicconditionshavebeen
analyze the total content of the syringe including the bubble; successfullyemployed.Bothargonandheliumhavebeenused
or, if the gas bubble is large, and it is suspected that the as carrier ga
...
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