1、Designation: D2112 15Standard Test Method forOxidation Stability of Inhibited Mineral Insulating Oil byPressure Vessel1This standard is issued under the fixed designation D2112; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This test method covers a
3、nd is intended as a rapidmethod for the evaluation of the oxidation stability of newmineral insulating oils containing a synthetic oxidation inhibi-tor. This test is considered of value in checking the oxidationstability of new mineral insulating oils containing 2,6-ditertiary-butyl para-cresol or 2
4、,6-ditertiary-butyl phenol, orboth, in order to control the continuity of this property fromshipment to shipment. The applicability of this procedure foruse with inhibited mineral insulating oils of more than 12 cStat 40C (approximately 65 SUS at 100F) has not beenestablished.1.2 The values stated i
5、n SI units are to be regarded asstandard except where there is no direct equivalent for hard-ware designed on the inch-pound unit basis.1.3 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 es
6、tablish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. (See warning in6.7.)2. Referenced Documents2.1 ASTM Standards:2B1 Specification for Hard-Drawn Copper WireE1 Specification for ASTM Liquid-in-Glass Thermometers3. Summary of Test
7、 Method3.1 The test specimen is agitated by rotating axially at 100r/min at an angle of 30 from the horizontal, under an initialoxygen pressure of 620 kPa (90 psi), in a stainless steel orcopper vessel (for rapid temperature equilibrium), with a glasstest specimen container and copper catalyst coil,
8、 in the pres-ence of water, at a bath temperature of 140C. The time for anoil to react with a given volume of oxygen is measured;completion of the test is indicated by a specific drop inpressure.4. Significance and Use4.1 This is a control test of oxidation stability of new,inhibited mineral insulat
9、ing oils for determining the inductionperiod of oxidation inhibitors under prescribed acceleratedaging conditions. There is no proven correlation between oilperformance in this test and performance in service. However,the test method may be used to check the continuity ofoxidation stability of produ
10、ction oils.5. Apparatus5.1 Oxidation VesselGlass test specimen container withcover and catalyst coil, pressure gauge, thermometer, test bath,and accessories as described in Annex A1. The assembledapparatus is shown in Fig. 1, and its design shown schemati-cally in Fig. 2.6. Reagents and Materials6.1
11、 Purity of ReagentsUse reagent grade chemicals in alltests. Unless otherwise indicated, all reagents shall conform tothe specifications of the Committee on Analytical Reagents ofthe American Chemical Society, where such specifications areavailable.36.2 Hydrochloric Acid, 10 vol %.6.3 Silicon Carbide
12、 Abrasive Cloth, 100-grit with clothbacking.6.4 Acetone, ACS grade.1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.06 on Chemical Test.Current edition approved Nov. 15, 2015. Published F
13、ebruary 2015. Originallyapproved in 1962. Last previous edition approved in 2007 as D211201a(2007).DOI: 10.1520/D2112-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refe
14、r to the standards Document Summary page onthe ASTM website.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH
15、 Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.5 2-Propanol, 99 vol %, refined.6.6 Liqui
16、d Detergent.6.7 Oxygen, 99.5 %, with pressure regulation above 620 kPa(90 psi). (Warning Oxygen vigorously accelerates combus-tion).6.8 Potassium Hydroxide, Alcohol Solution (1 mass %)Dissolve 7.93 g of potassium hydroxide (KOH) pellets in 1 Lof 99 % refined 2-propanol.6.9 Silicone Stopcock Grease.6
17、.10 Wire Catalyst AWG No. 14 (approximately1.628-mm diameter) electrolytic copper wire 99.9 % purity,conforming to Specification B1. Soft-drawn copper wire of anequivalent grade may also be used.7. Hazards7.1 Consult Safety Data Sheets for all materials used in thistest method.8. Preparation of Appa
18、ratus8.1 Catalyst PreparationImmediately before use, polishthe copper wire with silicon carbide abrasive cloth and wipefree from abrasives with a clean dry cloth. Wind approximately3 m of the wire into a coil having an outside diameter of 44 to48 mm and stretched to a height of 40 to 42 mm. Clean th
19、e coilthoroughly with acetone and allow it to air-dry. Immediatelyafter air drying, insert the coil with a twisting motion into theglass test specimen container. Handle the coil only with cleantongs to avoid contamination. Weigh the coil and the containerto the nearest 0.1 g and record the weight. P
20、repare a new coilfor each test specimen.8.2 Alternative Method of Catalyst PreparationWind ap-proximately3mofcopper wire into a coil of the dimensionsspecified in 8.1, and add to the glass container. Weigh the coiland container to the nearest 0.1 g and record the weight. Washthe coil by filling the
21、container above the level of the coil with10 % hydrochloric acid by volume for 30 s. Discard the acidand rinse the coils three times with tap water followed by threetimes with distilled water. Reweigh the coil and container anddetermine by difference the water retained in the system. Thecoils are no
22、w ready for use. This procedure has been found tobe acceptable for treatment of commercially available,prepackaged, preformed coils that meet the requirement de-scribed in this test method. Use a new coil for each testspecimen.8.3 Cleaning of Vessel Wash the vessel body, lid, andinside of vessel ste
23、m with hot detergent solution and withwater. Rinse inside of stem with 2propanol and blow dry withclean dry air. An alternative cleaning solution is the use of a50/50 volumetric blend of methanol and acetone; it has beenfound to be effective in cleaning sludge from the vessel. If thevessel body, lid
24、, or inside of stem smells sour after simplecleaning, wash with alcoholic KOH solution and repeat asbefore (see Note 1).NOTE 1Insufficient cleaning of the vessel may adversely affect testresults.9. Procedure9.1 ChargingWeigh 50 6 0.5 g of oil sample into thecontainer, add 5 mL of distilled water, an
25、d cover with a 51-mm(2-in.) watch glass or a 57.2-mm (214-in.) PTFE disk with oneor four holes and retaining spring. If rinse water is present inthe container, compensate for it by using less added waterbased on the water retention determined in 8.2.Add5mLofdistilled water to the vessel and slide th
26、e test specimencontainer and cover lid into the vessel body (see Note 2).Applya thin coating of silicone stopcock grease to the O-ring vesselseal located in the gasket groove of the vessel lid to providelubrication, and insert the lid into the vessel body. Place thevessel cap over the vessel stem, a
27、nd tighten by hand. Cover thethreads of the gauge-nipple with a thin coating of stopcockgrease or TFE-fluorocarbon, or both, and screw the gauge intothe top-center tap of the vessel stem. A pressure transducer canalso be used. Flush the vessel twice with oxygen supplied tothe vessel at 620 kPa (90 p
28、si) and release to the atmosphere.Adjust the regulating valve on the oxygen supply tank to 620kPa (90 psi) at a room temperature of 25C. For each 2.8Cabove or below this temperature, add or subtract 7 kPa (1 psi)unit to attain the required initial pressure. Fill the vessel to thisrequired pressure a
29、nd close the inlet valve securely by hand. Ifdesired, test the vessel for leaks by immersion in water (seeNote 3). Prepare a duplicate test specimen in exactly the sameway.NOTE 2The water between the vessel well and the test specimencontainer aids heat transfer.NOTE 3If the vessel was immersed in wa
30、ter to check for leaks, dry theoutside of the wet vessel by any convenient means such as an air blast ora towel. Such drying is advisable to prevent subsequent introduction offree water into the hot oil bath, which would cause sputtering.9.2 OxidationBring the heating bath to the test tempera-ture o
31、f 140C while the stirrer is in operation. Insert the vesselsinto the rotating carriages and note the time. If an auxiliaryheater is used, keep it on for the first 5 min of the run and thenturn it off (see Note 4). Allow the bath temperature to level outat the test temperature; this must occur within
32、 10 min after thevessels are inserted. Maintain the test temperature within60.1C (see Note 5).FIG. 1 Rotating Vessel Oxidation Test ApparatusD2112 152NOTE 4The time for the bath to reach the operating temperature afterinsertion of the vessels may differ for different apparatus assemblies andshould b
33、e observed for each unit. The objective is to find a set ofconditions that does not permit a drop of more than 2C after insertion ofthe vessels and allows the vessel pressure to reach a plateau within 15 minas shown in Curve A of Fig. 3.NOTE 5Maintaining the correct temperature within the specificat
34、ionlimits of 60.1C during the entire test run is the most important singlefactor ensuring good repeatability and reproducibility of test results.9.3 Keep the vessels completely submerged and maintainrotation continuously and uniformly throughout the test. Astandard rotational speed of 100 6 5 r/min
35、is required; anyappreciable variations in this speed could cause erratic results.If a dial gauge is used, take readings every 5 min.9.4 The test is complete after the pressure drops more than172 kPa (25 psi) below the maximum pressure. The 172-kPaFIG. 2 Schematic Drawing of Rotary VesselFIG. 3 Press
36、ure Versus Time Plot of Two Rotary Vessel Oxidation Test RunsD2112 153(25-psi) pressure drop usually, but not always, coincides withan induction-type “period of rapid pressure drop.” When itdoes not, the operator should question whether a valid experi-ment has been produced (Note 6).NOTE 6A typical
37、experiment is shown in Fig. 3 as Curve A. Themaximum pressure expected to be reached within 30 min; a pressureplateau is established and an induction-type pressure drop is observed.Curve B, in which there is a gradual decrease in pressure before theinduction break is recorded, is more difficult to e
38、valuate. The gradualdecrease in pressure could be due to a vessel leak; however, somesynthetic fluids will generate this type of curve. If a leak is suspected,repeat the test in a different vessel. If the same type of curve is derivedwhen the test is repeated, the experiment is likely valid.9.5 Afte
39、r termination of the test, remove the vessels fromthe oil bath, dip briefly into and swirl around in a bath of lightmineral oil or detergent and water to wash off the adhering bathoil. Rinse off the vessels with hot water, then immerse in coldwater to bring them quickly to room temperature. Allow th
40、evessel to fully cool before bleeding off excess oxygen pressureand opening the vessel (Note 7).NOTE 7A hazardous situation can arise when excess oxygen is bledoff immediately upon removal of the vessel from the bath since it may beaccompanied by hot oil and steam. (See 6.7).10. Interpretation of Re
41、sults10.1 Observe a plot of the recorded pressure versus time andestablish the plateau pressure (see Note 6).Also record the timeat the point on the falling part of the curve where the pressureis 172 kPa (25 psi) less than the established plateau pressure.Plateau pressures in duplicate tests should
42、not differ by morethan 35 kPa (5 psi).10.2 The vessel life of the test specimen is the time inminutes from the start of the test to a 172-kPa (25-psi) pressuredrop from the level of the established plateau.11. Report11.1 Report test method used.11.2 Report the time as the average of two duplicatedet
43、erminations and the difference of the individual determina-tions. The recipient of the report can then be reassured that thedetermination is not suspect, as specified in 12.1.12. Precision and Bias12.1 The following criteria should be used for judging theacceptability of results (95 % probability):1
44、2.1.1 RepeatabilityDuplicate determinations by the sameoperator should not be considered suspect unless they differ bymore than 23 min. If the two results differ by more than thespecified value, another set of duplicate tests should beperformed.12.1.2 ReproducibilityResults submitted by each of twol
45、aboratories based on the average of two determinations in eachlaboratory should not be considered suspect unless they differby more than 43 min.12.2 No justifiable statement can be made on the bias of theprocedure in this test method since there is no acceptedreference material suitable for determin
46、ing oxidation stability.13. Keywords13.1 electrical; inhibitor; insulating oil; mineral oil; oxida-tion stability; pressure vessel; rotating vessel ; transformer oilANNEX(Mandatory Information)A1. ROTATING VESSEL OXIDATION TEST APPARATUSA1.1 Oxidation VesselA1.1.1 Construct the oxidation vessel, wit
47、h lid, cap, andstem, as shown in Fig. A1.1.A1.1.2 Machine the vessel body and lid from a 76-mm(3-in.) solid copper rod for maximum rate of heat transfer. Givethe interior surface a smooth finish to facilitate cleaning.Heavily chrome plate the vessel body and lid.Alternatively, thevessel body and cap
48、 may be constructed of 18-8 or 321S12/321S20 Part 1 (BSI) stainless steel to ensure a proper rate ofheat transfer.A1.1.3 Construct the vessel stem of stainless steel, equippedwith an inside diameter of 6.35 mm (14 in.) and equip with a14-in. needle valve.A1.1.4 Make the vessel cap (or closure ring)
49、of plated steel.A1.1.5 The vessel shall withstand a working pressure of 3.4MPa (500 psi) at 150C.A1.1.6 O-ring gaskets, TFE-fluorocarbon resin reinforcedsilicone, 50.8 mm (2 in.) in inside diameter by 60.3 mm (238in.) in outside diameter, or alternatively Buna-N gaskets withthe same dimensions.A1.2 Glass Sample ContainerA1.2.1 Construct the glass test specimen container, 175-mLcapacity, with copper catalyst coil, of borosilicate glass asshown in Fig. A1.2.A1.2.2 Cover the top of the test specimen container with a50.8-mm (2-in.) diameter watch glas
