ASTMD2440-99

Designation:D 2440-99Standard Test Method forOxidation Stability of Mineral Insulating Oil 1This standard is issued under the fixed designation D 2440;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon (e)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.ScopeCEl/IFC 61125:1992 Unused Hydrocarbon-Based Insulat-1.1 This test method determines the resistance of mineraling Liquids-Test Methods for Evaluating the Oxidationtransformer oils to oxidation under prescribed acceleratedStabilityaging conditions.Oxidation stability is measured by thepropensity of oils to fomm sludge and acid products during3.Summary of Test Methodoxidation.This test method is applicable to new oils,both3.1 A test specimen of mineral transformer oil is oxidized atuninhibited and inhibited,but is not well defi ned for used ora bath temperature of 110C,in the presence of a copperreclaimed oils.catalyst coil,by bubbling oxygen through duplicate test speci-mens for 72 and 164 h,respectively.The oil is evaluated at theNorE 1-A shorter duration oxidation test for evaluation of inhibitedend of each aging period by measuring the amount of sludgeoils is available in Test Method D2112and acid formed.The test specimen is diluted with n-heptaneNorE 2-For those interested in the measurement of volatile acidity,reference is made to the work of IEC Subcommittee 10A.2and the solution filtered to remove the sludge.The sludge isdried and weighed.The sludge-free solution is titrated at room1.2 The values stated in metric units are to be regarded astemperature with standard alcoholic base to the end pointthe standard.1.3 This standard does not purport to address all of theindicated by the color change (green-brown)of the addedp-naphthol-benzein solution.safety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-4.Signifi cance and Usepriate safety and health practices and determine the applica-4.1 The oxidation stability test of mineral transformer oils isbility of regulatory limitations prior to usea method for assessing the amount of sludge and acid products2.Referenced Documentsformed in a transformer oil when the oil is tested underprescribed conditions.Good oxidation stability is necessary in2.1 ASTM Standards:order to maximize the service life of the oil by minimizing theB 1 Specifi cation for Hard-Drawn Copper Wireformation of sludge and acid.Oils that meet the requirementsD 664 Test Method for Acid Number of Petroleum Productsspecifi ed for this test in Specifi cation D 3487 tend to minimizeby Potentiometric Titrationelectrical conduction,ensure acceptable heat transfer,andD 974 Test Method for Acid and Base Number by Col-preserve system life.There is no prove