ASTM_D_1698_-_03_2008.pdf

Designation:D169803(Reapproved 2008)Standard Test Method forSediments and Soluble Sludge in Service-Aged InsulatingOils1This standard is issued under the fixed designation D1698;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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of sedimentand soluble sludge in service-aged insulating oils of petroleumorigin.Also,provision is made for determining organic andinorganic content of the sediment.The method is intendedprimarily for oils of comparatively low viscosity;for example5.7 to 13.0 cSt(mm2/s)at 40C(104F).Suitability for highviscosity oils have not been determined.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard may involve hazardous materials,operations,and equipment.This standard does not purport toaddress all of the safety concerns,if any,associated with itsuse.It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D923 Practices for Sampling Electrical Insulating LiquidsD2440 Test Method for Oxidation Stability of MineralInsulating Oil3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 inorganic sedimentthat portion of the total sedimentwhich remains after ignition at 500C.3.1.2 organic sedimentthat portion of the total sedimentwhich is lost during ignition at 500C.3.1.3 sedimentany solid substance or substances that areinsoluble in the oil under test at ordinary room temperatures,and that can be separated by centrifuging under certainprescribed conditions.3.1.4 solublesludgeoildeteriorationproductsorcontaminants,or both,which become insoluble upon dilutionwith n-pentane under prescribed conditions.4.Summary of Test Method4.1 A sample portion is centrifuged to separate sedimentfrom the oil.The upper,sediment-free portion is decanted andretained for determination of soluble sludge.The sediment isdislodged and filtered through a filtering crucible.After dryingand weighing to obtain total sediment the crucible is ignited at500C and reweighed.Loss in weight is organic and theremainder is inorganic content of sediment.Soluble sludge isdetermined on the sediment-free portion by dilution withn-pentane to precipitate n-pentane insolubles,and filtrationthrough a filtering crucible or 0.45 m filter membrane.5.Significance and Use5.1 Sediment in insulating oil may deposit on transformerparts and interfere with heat transfer and may choke oil ducts;thus hindering oil circulation and heat dissipation.Inorganicsediment usually indicates contamination of some type andorganic sediment indicates either deterioration of the oil orcontamination.5.2 Soluble sludge indicates deterioration of the oil,pres-ence of contaminants,or both.It serves as a warning thatformation of sediment may be imminent.5.3 The determination of sediment and soluble sludge in aused insulating oil assists in deciding whether the oil maycontinue to be used in its existing condition or should bereplaced,reclaimed,or reconditioned.6.Apparatus6.1 Centrifuge Tube,30-mL capacity,preferably with roundor elliptical bottom to facilitate removal of sediment.Pear-shaped tubes are not recommended.6.2 Centrifuge,capable of whirling two or more filledcentrifuge tubes at a speed which can be controlled to give arelative centrifugal force(rcf)between 600 and 700 at the tipsof the tubes.The revolving head,trunnion rings,and trunnion1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-mittee D27.07 on Physical Test.Current edition approved May 1,2008.Published June 2008.Originallyapproved in 1959.Last previous edition approved in 2003 as D1698 03.DOI:10.1520/D1698-03R08.2For 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 website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesNOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest information1cups,including the rubber cushion,shall be soundly con-structed to withstand the maximum centrifugal force capable ofbeing delivered by the power source.The trunnion cups andcushions shall firmly support the tubes when the centrifuge isin motion.The centrifuge shall be enclosed by a metal shield orcase strong enough to eliminate danger if any breakage occu