1、Designation: D3612 02 (Reapproved 2017)Standard Test Method forAnalysis of Gases Dissolved in Electrical Insulating Oil byGas Chromatography1This standard is issued under the fixed designation D3612; the number immediately following the designation indicates the year oforiginal adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers three procedures for extractionand measurement of gases dissolved
3、 in electrical insulating oilhaving a viscosity of 20 cSt (100 SUS) or less at 40C (104F),and the identification and determination of the individualcomponent gases extracted. Other methods have been used toperform this analysis.1.2 The individual component gases that may be identifiedand determined
4、include:HydrogenH2OxygenO2NitrogenN2Carbon monoxideCOCarbon dioxideCO2MethaneCH4EthaneC2H6EthyleneC2H4AcetyleneC2H2PropaneC3H8PropyleneC3H61.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to
5、 establish appro-priate safety, health, and environmental practices and deter-mine 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 accor-dance with internationally recognized princi
6、ples on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D2140 Practice for Calculating Ca
7、rbon-Type Compositionof Insulating Oils of Petroleum OriginD2300 Test Method for Gassing of Electrical InsulatingLiquids Under Electrical Stress and Ionization (ModifiedPirelli Method)D2779 Test Method for Estimation of Solubility of Gases inPetroleum LiquidsD2780 Test Method for Solubility of Fixed
8、 Gases in Liquids(Withdrawn 2010)3D3613 Practice for Sampling Insulating Liquids for GasAnalysis and Determination of Water Content (Withdrawn2007)3D4051 Practice for Preparation of Low-Pressure Gas BlendsE260 Practice for Packed Column Gas Chromatography2.2 IEEE Standard:C 57.104 Guide for the Inte
9、rpretation of Gases Generated inOil-Immersed Transformers42.3 IEC Standard:Publication No. 567 Guide for the Sampling of Gases and ofOil from Oil-Filled Electrical Equipment and for theAnalysis of Free and Dissolved Gases53. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 gas con
10、tent of oil by volumein Method A, the totalvolume of gases, corrected to 760 torr (101.325 kPa) and 0C,contained in a given volume of oil, expressed as a percentage.In Methods B and C, the sum of the individual gas concentra-tions corrected to 760 torr (101.325 kPa) and 0C, expressed inpercent or pa
11、rts per million.3.1.2 headspacea volume of gas phase in contact with avolume of oil in a closed vessel. The vessel is a headspace vialof 20-mL nominal capacity.3.1.2.1 DiscussionOther vessel volumes may also beused, but the analytical performance may be somewhat differ-ent than that specified in Met
12、hod C.1This test method is under the jurisdiction of ASTM Committee D27 onElectrical 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. Originallyapproved in 1977. Last previous edi
13、tion approved in 2009 as D3612 02 (2009).DOI: 10.1520/D3612-02R17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM web
14、site.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from IEEE, 345 E. 47th St., New York, NY 10017.5Available from International Electrotechnical Commission (IEC), 3 rue deVaremb, Case postale 131, CH-1211, Geneva 20, Switzerland, http:/www.iec.chCopyr
15、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of Internatio
16、nal Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.1.3 parts per million (ppm) by volume of (specific gas) inoilthe volume of that gas corrected to 760 torr (101.325 kPa)and 0C, contained in 106volume of oil.3.1.4 sparging,
17、 vagitating the liquid sample using a gas tostrip other gases free.3.1.5 volume concentration of (specific gas) in the gassamplethe volume of the specific gas contained in a givenvolume of the gas sample at the same temperature and pressure(as the measured total volume), expressed either as a percen
18、t-age or in parts per million.4. Summary of Test Method4.1 Method ADissolved gases are extracted from a sampleof oil by introduction of the oil sample into a pre-evacuatedknown volume. The evolved gases are compressed to atmo-spheric pressure and the total volume measured.4.2 Method BDissolved gases
19、 are extracted from a sampleof oil by sparging the oil with the carrier gas on a strippercolumn containing a high surface area bead.4.3 Method CMethod C consists of bringing an oil samplein contact with a gas phase (headspace) in a closed vesselpurged with argon. The dissolved gases contained in the
20、 oil arethen equilibrated in the two phases in contact under controlledconditions (in accordance with Henrys law). At equilibrium,the headspace is overpressurized with argon and then thecontent of a loop is filled by the depressurization of theheadspace against the ambient atmospheric pressure. The
21、gasescontained in the loop are then introduced into a gas chromato-graph.4.4 There may be some differences in the limits of detectionand precision and bias between Methods A, B, and C forvarious gases.4.5 Aportion of the extracted gases (MethodA) or all of theextracted gases (Method B) or a portion
22、of the headspace gases(Method C) is introduced into a gas chromatograph. Calibra-tion curves are used in Method C to establish the concentrationof each species. The composition of the sample is calculatedfrom its chromatogram by comparing the area of the peak ofeach component with the area of the pe
23、ak of the samecomponent on a reference chromatogram made on a standardmixture of known composition.5. Significance and Use5.1 Oil and oil-immersed electrical insulation materials maydecompose under the influence of thermal and electricalstresses, and in doing so, generate gaseous decompositionproduc
24、ts of varying composition which dissolve in the oil. Thenature and amount of the individual component gases that maybe recovered and analyzed may be indicative of the type anddegree of the abnormality responsible for the gas generation.The rate of gas generation and changes in concentration ofspecif
25、ic gases over time are also used to evaluate the conditionof the electric apparatus.NOTE 1Guidelines for the interpretation of gas-in-oil data are given inIEEE C57.104.6. Apparatus6.1 Apparatus6of the type shown in Fig. 1 or Fig. 2 issuitable for use with up to 50-mL samples of oil and consistsof th
26、e following components:NOTE 2This sample size has been found to be sufficient for most oils.However, oil that has had only limited exposure to air may contain muchsmaller amounts of nitrogen and oxygen. For these oils it may be desirableto increase the size of the sample and the extraction apparatus
27、.NOTE 3Alternative apparatus designs including the use of a Toeplerpump have also been found successful.6.1.1 Polytetrafluoroethylene (PTFE) Tubing, narrow-bore,terminated with a Luer-Lock fitted glass syringe, and leading toa solid plug, three-way, high-vacuum stopcock.6.1.2 Degassing Flask, with a
28、 glass inlet tube, of sufficientvolume to contain up to 50 mL of oil below the inlet tube,capable of being evacuated through a vacuum pump, contain-ing a PTFE-coated magnetic spin bar, and mounted on amagnetic stirrer.6.1.3 Means of Measuring Absolute Pressure within theapparatus.6.1.4 Vacuum Pumpin
29、g System, capable of evacuating theglassware to an absolute pressure of 1 103torr (130 mPa) orlower.6.1.5 Vacuum Glassware, sufficiently large compared to thevolume of the oil sample, so that virtually complete degassingis obtained and that the volumetric collection ratio is as large aspossible. A 5
30、00-mL gas collecting flask has been foundsuitable.6.1.6 High-Vacuum Valves or Stopcocks, employing theminimum necessary amounts of high-vacuum stopcock greaseare used throughout the apparatus.6.1.7 Gas Collection Tube, calibrated in 0.01-mL divisions,capable of containing up to 5 mL of gas, terminat
31、ed with asilicone rubber retaining septum. A suitable arrangement isshown in Fig. 3.6.1.8 Reservoir of Mercury, sufficient to fill the collectionflask and collection tube. (WarningMercury vapor is ex-tremely toxic. Appropriate precautions should be taken.)7. Sampling7.1 Obtain samples in accordance
32、with the procedure de-scribed in Test Methods D3613 for sampling with syringetypedevices or rigid metal cylinders. The use of rigid metalcylinders is not recommended for use with Method B.7.2 The procurement of representative samples without lossof dissolved gases or exposure to air is very importan
33、t. It is alsoimportant that the quantity and composition of dissolved gasesremain unchanged during transport to the laboratory. Avoidprolonged exposure to light by immediately placing drawnsamples into light-proof containers and retaining them thereuntil the start of testing.7.2.1 To maintain the in
34、tegrity of the sample, keep the timebetween sampling and testing as short as possible. Evaluate6Ace Glass and Lurex Glass manufacture glass extractors. For Ace Glass, theglass apparatus conforming to Fig. 1 is Part E-13099-99-99 and Fig. 2 is PartE-1400-99. Available from P.O. Box 688, 1430 Northwes
35、t Blvd., Vineland, NJ08360 or Lurex Glass, 1298 Northwest Blvd., Vineland, NJ 08360.D3612 02 (2017)2FIG. 1 Extraction of Gas from Insulating OilFIG. 2 Extraction of Gas from Insulating OilD3612 02 (2017)3containers for maximum storage time. Samples have beenstored in syringes and metal cylinders for
36、 four weeks with noappreciable change in gas content.NOTE 4Additional sampling procedures using flexible metal cans arecurrently being studied for use with Method A.METHOD AVACUUM EXTRACTION8. Method AVacuum Extraction8.1 Method A employs vacuum extraction to separate thegases from the oil. The evol
37、ved gases are compressed toatmospheric pressure and the total volume measured. Thegases are then analyzed by gas chromatography.9. Preparation of Apparatus9.1 Check the apparatus carefully for vacuum tightness ofall joints and stopcocks.9.2 Measure the total volume of the extraction apparatus,VT, an
38、d the volume of the collection space, Vc, and calculatethe ratio as the volumetric collection ratio:VcVT2 Vo(1)where Vo= the volume of oil to be added.9.3 Calculate the degassing efficiencies for each individualcomponent gas as follows:Ei5111KiVoVT2 Vo(2)where:Ei= degassing efficiency of component i
39、,Vo= volume of oil sample,VT= total internal volume of extraction apparatus before oilsample is introduced, andKi= Ostwald solubility coefficient of component i.9.4 Determine the Ostwald solubility coefficients of fixedgases in accordance with Test Method D2780.9.5 Ostwald solubility coefficients th
40、at have been deter-mined for a number of gases in one specific electrical insulat-ing oil at 25C are shown as follows. Values for gases in otheroils may be estimated by reference to Test Method D2779.Component GasOstwald Solubility7(Note 5)Coefficient, Ki, 25C, 760 mm HgHydrogen 0.0558Nitrogen 0.096
41、8Carbon monoxide 0.133Oxygen 0.179Methane 0.438Carbon dioxide 1.17Acetylene 1.22Ethylene 1.76Ethane 2.59Propane 11.0NOTE 5The Ostwald coefficient values shown in this table are correctonly for the specific mineral oil having a density at 15.5C of 0.855 g/cm3used in the original determination. Ostwal
42、d coefficients for mineral oils ofdifferent density may be calculated as follows:Kicorrected! 5 Ki0.980 2 density0.130(3)where, density = density of the oil of interest, g/cm3at 15.5C (60F).This equation is derived from the equation in Test Method D2779. Noteespecially that all of the Ostwald coeffi
43、cients are changed by the samefactor, meaning that though the absolute solubilities of each of the gaseswill change if a different oil is used, the ratio of the solubility of one gasto another gas will remain constant.9.6 A procedure to check the extraction efficiency requiresthe use of prepared gas
44、-in-oil standards of known concentra-tion. The methods of preparation are outlined in AnnexA1 andAnnex A2.10. Procedure10.1 Lower the mercury level from the collection flask.10.2 Evacuate the system of collection flask and degassingflask to an absolute pressure of 1 103torr (130 mPa) or less.(In Fig
45、. 1, the space above the mercury in the reservoir mustalso be evacuated.)10.3 Connect the oil sample syringe by the PTFE tubing tothe three-way stopcock leading to the degassing flask.10.4 Flush a small quantity of oil from the syringe throughthe tubing and stopcock to waste, making sure that all th
46、e air inthe connecting tubing is displaced by oil.10.4.1 Any gas bubbles present in the syringe should beretained during this flushing operation. This may be accom-plished by inverting the syringe so that the bubble remains atthe plunger end of the syringe during the flushing operation.10.5 Close th
47、e stopcocks to the vacuum pumps and thenslowly open the three-way stopcock to allow oil and any gasbubbles that may be present from the sample syringe to enterthe degassing flask.10.6 Allow the desired amount of oil to enter the degassingflask and operate the magnetic stirrer vigorously for approxi-
48、mately 10 min. This is the volume, Voused in the calculationin 15.4.7Daoust, R., Dind, J. E., Morgan, J., and Regis, J, “Analysis of Gas Dissolvedin Transformer Oils,” Doble Conference, 1971, Sections 6110.FIG. 3 Retaining Rubber Septum for Gas Collection TubeD3612 02 (2017)410.6.1 If a gas bubble i
49、s present in the syringe, eitheranalyze the total content of the syringe including the bubble;or, if the gas bubble is large, and it is suspected that theconcentration of dissolved gases is high, measure and analyzethe gas bubble separately, extract an aliquot of the oil sample,and correct as applicable.10.7 Close the stopcock isolating the collection flask, andallow mercury to flow into the collection flask.10.8 Open the stopcock to the reference column and bymeans of the hand pump (Fig. 1) or leveling bottle (Fig. 2)bring the le
