ASTM_D_7546_-_15.pdf

Designation:D754615Standard Test Method forDetermination of Moisture in New and In-Service LubricatingOils and Additives by Relative Humidity Sensor1This standard is issued under the fixed designation D7546;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.Scope*1.1 This test method covers the quantitative determinationof water in new and in-service lubricating oils and additives inthe range of 10 mg/kg to 100 000 mg kg(0.001 wt.wt.to10%wt./wt.)using a relative humidity(RH)sensor.Methanol,acetonitrile,and other compounds are known to interfere withthis test method.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 WarningSamples tested in this test method can beflammable,explosive,and toxic.Use caution when handlingthem before and after testing.1.4 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 establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D4175 Terminology Relating to Petroleum,PetroleumProducts,and Lubricants3.Terminology3.1 For definitions of terms used in this test method,refer toTerminology D4175.4.Summary of Test Method4.1 An aliquot of sample is heated to a temperature between25 C to 200 C with 1 C resolution.The sample is maintainedat a constant temperature for the duration of the test.Dry inertgas flows over the heated sample and carries the thermallyevolved moisture past a relative humidity sensor.The sensorsignal is integrated over time to provide a measurement of totalmass of water in the sample.4.2 The sample injection may be done either by mass or byvolume.4.3 This test method utilizes anhydrous compressed gas orambient air passed through a desiccant to prevent contamina-tion from moisture present in the atmosphere.4.4 Viscous samples can be analyzed by preheating them toplace them in a more fluid state allowing them to be drawn intoa syringe,or by dissolving them in a compatible anhydroussolvent.Care should be taken to minimize time spent preheat-ing samples to prevent moisture loss.5.Significance and Use5.1 Knowledge of the water content of lubricating oils,additives,and similar products is important in the manufacture,purchase,sale,transfer,or use of such petroleum products tohelp in predicting their quality and performance characteristics.5.2 For lubricating oils,the presence of water can lead topremature corrosion and wear,an increase in the debris loadresulting in diminished lubrication and premature plugging offilters,impedance to the effect of additives,and undesirablesupport of deleterious bacterial growth.6.Interferences6.1 Methanol and acetonitrile are known to interfere withthe determination of moisture by this test method.Thesesubstances contribute to a high bias in the final results.Moregenerally,some short-chained polar molecules mimic the effectof water at the RH sensor resulting in a positive interference.Strong polar solvents,such as n-methyl-pyrrolidone,can se-verely damage the RH sensor.7.Apparatus7.1 Sample Injection Moisture Analyzer Apparatus:7.1.1 Flow Regulator,capable of maintaining the carrier gasflow rate within the manufacturers specified conditions.7.1.2 Flow Meter,capable of measuring the carrier gas flowrate within the manufacturers specified conditions.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.96.02 on Chemistry for the Evaluation of In-Service Lubricants.Current edition approved April 1,2015.Published June 2015.Originallyapproved in 2009.Last previous edition approved in 2009 as D7546 09.DOI:10.1520/D7546-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.1.3 Stainless Steel Sample Coil,for heating the sample asit is transported from the sample inlet to the sump.7.1.4 Sample Coil Heater,capable of maintaining thesample coil temperature within 1 C of the programmedtemperature between 25 C and 200 C.7.1.5 Sample Delivery System,provides programmable vari-able speed injection of the sample into the coil.7.1.6Sump,allows for collection of the sample at thebottom of the sample coil during testing and discharge of thesample to a waste container after