1、Designation: D 3612 02 (Reapproved 2009)Standard Test Method forAnalysis of Gases Dissolved in Electrical Insulating Oil byGas Chromatography1This standard is issued under the fixed designation D 3612; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case 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 dissolv
3、ed 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 determine
4、d 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
5、to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificwarning statements see 6.1.8, 30.2.2 and 30.3.1.2. Referenced Documents2.1 ASTM Standards:D 2140 Practice for Calculating Carbon-Type Compositionof Insulating Oi
6、ls of Petroleum OriginD 2300 Test Method for Gassing of Electrical InsulatingLiquids Under Electrical Stress and Ionization (ModifiedPirelli Method)D 2779 Test Method for Estimation of Solubility of Gasesin Petroleum LiquidsD 2780 Test Method for Solubility of Fixed Gases inLiquidsD 3613 Practice fo
7、r Sampling Insulating Liquids for GasAnalysis and Determination of Water Content2D 4051 Practice for Preparation of Low-Pressure GasBlendsE 260 Practice for Packed Column Gas Chromatography2.2 IEEE Standard:C 57.104 Guide for the Interpretation of Gases Generated inOil-Immersed Transformers32.3 IEC
8、Standard:Publication No. 567 Guide for the Sampling of Gases andof Oil from Oil-Filled Electrical Equipment and for theAnalysis of Free and Dissolved Gases43. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 gas content of oil by volumein Method A, the totalvolume of gases, correc
9、ted 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 parts per million.3.1.2 headspacea volume of gas phase in contact wi
10、th 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 Method C.3.1.3 parts per million (ppm) by volume of (specific gas) in
11、oilthe volume of that gas corrected to 760 torr (101.325 kPa)and 0C, contained in 106volume of oil.3.1.4 sparging, vagitating the liquid sample using a gas tostrip other gases free.1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the
12、direct responsibility of Subcom-mittee D27.03 on Analytical Tests.Current edition approved May 15, 2009. Published June 2009. Originallyapproved in 1977. Last previous edition approved in 2002 as D 3612 02 (2009).2Withdrawn. The last approved version of this historical standard is referencedon www.a
13、stm.org.3Available from IEEE, 345 E. 47th St., New York, NY 10017.4Available from International Electrotechnical Commission (IEC), 3 rue deVaremb, Case postale 131, CH-1211, Geneva 20, Switzerland, http:/www.iec.ch1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken,
14、PA 19428-2959, United States.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 percent-age or in parts per million.4. Summa
15、ry 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 are extracted from a sampleof oil by
16、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 oil arethen equilibrated in the two p
17、hases 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 gasescontained in the loop are then in
18、troduced 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 of the headspace gases(Method C) is in
19、troduced 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 peak of the samecomponent on a reference
20、 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 decompositionproducts of varying composition which dissol
21、ve 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 ofspecific gases over time are also used to ev
22、aluate the conditionof the electric apparatus.NOTE 1Guidelines for the interpretation of gas-in-oil data are given inIEEE C 57.104.6. Apparatus6.1 Apparatus5of the type shown in Fig. 1 or Fig. 2 issuitable for use with up to 50-mL samples of oil and consistsof the following components:NOTE 2This sam
23、ple 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.NOTE 3Alternative apparatus designs
24、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 glass inlet tube, of sufficientvolum
25、e 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 Pumping System, capable of evacuating thegl
26、assware to an absolute pressure of 1 3 103torr (130 mPa)or lower.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 500-mL gas collecting flask has been
27、 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, terminated with asilicone rubber retaining
28、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 with the procedure de-scribed in Te
29、st Methods D 3613 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 important. It is alsoimportant that the qu
30、antity 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 integrity of the sample, keep the ti
31、mebetween sampling and testing as short as possible. Evaluatecontainers for maximum storage time. Samples have beenstored in syringes and metal cylinders for four weeks with noappreciable change in gas content.NOTE 4Additional sampling procedures using flexible metal cans arecurrently being studied
32、for use with Method A.METHOD AVACUUM EXTRACTION8. Method AVacuum Extraction8.1 Method A employs vacuum extraction to separate thegases from the oil. The evolved gases are compressed to5Ace Glass and Lurex Glass manufacture glass extractors. For Ace Glass, theglass apparatus conforming to Fig. 1 is P
33、art E-13099-99-99 and Fig. 2 is PartE-1400-99. Available from P.O. Box 688, 1430 Northwest Blvd., Vineland, NJ08360 or Lurex Glass, 1298 Northwest Blvd., Vineland, NJ 08360.D 3612 02 (2009)2FIG. 1 Extraction of Gas from Insulating OilFIG. 2 Extraction of Gas from Insulating OilD 3612 02 (2009)3atmos
34、pheric 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, and the volume of the collection s
35、pace, 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:Ei511 1KiVoVT2 Vo(2)where:Ei= degassing efficiency of component i,Vo= volume of oil sample,VT= t
36、otal internal volume of extraction apparatus beforeoil sample is introduced, andKi= Ostwald solubility coefficient of component i.9.4 Determine the Ostwald solubility coefficients of fixedgases in accordance with Test Method D 2780.9.5 Ostwald solubility coefficients that have been deter-mined for a
37、 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 D 2779.Component GasOstwald Solubility6(Note 5)Coefficient, Ki, 25C, 760 mm HgHydrogen 0.0558Nitrogen 0.0968Carbon monoxide 0.133Oxygen
38、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. Ostwald coefficients for mineral oi
39、ls ofdifferent density may be calculated as follows:Kicorrected!5Ki0.980 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 D 2779. Noteespecially that all of the Ostwald coefficients are changed by the same
40、factor, 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-in-oil standards of known con
41、centra-tion. The methods of preparation are outlined inAnnexA1 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 3 103torr (130 mPa) or less.(In Fig. 1, the space above the merc
42、ury 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 the air inthe connecting tubing
43、 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 the stopcocks to the vacuum pum
44、ps 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-mately 10 min. This is the vo
45、lume, Voused in the calculationin 15.4.10.6.1 If a gas bubble is 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 separat
46、ely, 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 lev
47、el of the mercury in the reference column evenwith the level in the collection tube.10.9 Measure the volume of extracted gas in the collectiontube, and correct for collection efficiency by dividing it by thevolumetric collection ratio calculated in 9.2. Correct to 760 torr6Daoust, R., Dind, J. E., M
48、organ, J., and Regis, J, “Analysis of Gas Dissolvedin Transformer Oils,” Doble Conference, 1971, Sections 6110.FIG. 3 Retaining Rubber Septum for Gas Collection TubeD 3612 02 (2009)4(101.325 kPa) and 0C. Determine the volume of oil degassedin the degassing flask. Record the gas content as a percenta
49、geof the oil by volume.10.10 Because the total concentration of gas is not extract-able from the oil, a rinse step may be required when highquantities are present. The extractor can be rinsed with oilcontaining nondetectable quantities of gases, except for thosepresent in air. The amount of rinsing needed will be dependentupon the gas concentration, type (solubility in oil), andefficiency of the extractor. To ensure that the combustible gaseshave been sufficiently removed from the extractor, the rinse oilmay be treated as a sample. Gen
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