ASTM_D_1698_-_03.pdf

Designation:D 1698 03Standard Test Method forSediments and Soluble Sludge in Service-Aged InsulatingOils1This standard is issued under the fixed designation D 1698;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.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 This standard may involve hazardous materials,opera-tions,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:D 923 Practices for Sampling Electrical Insulating Liquids2D 2440 Test Method for Oxidation Stability of MineralInsulating Oil23.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 soluble sludgeoil deterioration products or contami-nants,or both,which become insoluble upon dilution withn-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 trunnioncups,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 or1This test method is under the jurisdiction of ASTM Committee D27 onElectrical Insulating Liquids and Gases and is the direct responsibility of Subcom-mittee D27.07 on Physical Tests.Current edition approved May 10,2003.Published July 2003.Originallyapproved in 1959.Last previous edition approved in 1997 as D 1698 97.2Annual Book of ASTM Standards,Vol 10.03.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.case strong enough to eliminate danger if any breakage occurs.Calculate the speed of the rotating head by means of thefollowing equation:rpm 5 265=rcf/dwhere:rcf=relative centrifugal force,andd=diameter of swing,in.,measured between tips ofopposite tubes when in rotating position,or:d=diameter of swing cm/2.54,measured between tips ofopposite tubes when in rotating position.6.3 Electric Muffle Furnace,capable of maintaining a tem-perature of 500 6 15C.6.4 Explosion-Proof Oven,capable of maintaining a tem-perature of 105 6 3C.6.5 Filtering CrucibleG