1、Designation: D7546 09Standard 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
2、, 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 quantitative determinationof water in new and in-se
3、rvice lubricating oils and additives inthe range of 10 to 100 000 mg/kg (0.001 to 10% wt./wt.) usinga relative humidity (RH) sensor. Methanol, acetonitrile, andother compounds are known to interfere with this test method.1.2 The values stated in SI units are to be regarded asstandard. No other units
4、 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 the
5、responsibility 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. Terminolog
6、y3.1 For definitions of terms used in this test method, refer toTerminology D4175.4. Summary of Test Method4.1 An aliquot of sample is injected onto a heated stainlesssteel coil. The temperature of the coil is programmable in 1Cincrements from 25C to 200C. The coil is maintained at aconstant tempera
7、ture for the duration of the test. As the sampletravels down the coil, an opposing dry inert gas carries thethermally evolved moisture past a relative humidity sensor.The sensor signal is integrated over time to provide a measure-ment of total mass of water in the sample.4.2 The sample injection may
8、 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 the
9、m 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
10、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 an
11、d 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 fi
12、nal 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 Moisture Analyzer,3an apparatus that consists of:1This
13、 test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.96.02 on Chemistry for the Evaluation of In-Service Lubricants.Current edition approved Oct. 1, 2009. Published November 2009. DOI:10.1520/D7546-09.2Fo
14、r 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.3The sole source of supply of the apparatus known to the committ
15、ee at this timeis Arizona Instrument, 3375 N Delaware St., Chandler, AZ 85225. If you are awareof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you m
16、ay attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 flow
17、rate within the manufacturers specified conditions.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 1C of the programmed tem-perature between 25C and 200C
18、.7.1.5 Sample Delivery System, provides programmable vari-able speed injection of the sample into the coil.7.1.6 Sump, allows for collection of the sample at thebottom of the sample coil during testing and discharge of thesample to a waste container after testing is completed.7.1.7 Manifold, which p
19、rovides:7.1.7.1 A thermally stable port for mounting and operationof the relative humidity sensor.7.1.7.2 Inlet and outlet ports for the carrier gas.7.1.8 Relative Humidity (RH) Sensor, a capacitive sensingelement that measures the relative humidity of the carrier gas.7.1.9 Microcontroller, which pr
20、ovides:7.1.9.1 Capability of integrating and converting the RHsensor signal.7.1.9.2 Capability of controlling the temperature of the coilheater, and the sensor manifold.7.1.9.3 Capability of controlling the speed of the sampledelivery system.7.1.10 Balance, external, with 1 mg precision for weighing
21、sample.8. Reagents and Materials8.1 Traceable4Syringe, traceable at the desired total mass ofwater, typically 500 g (0.5 L).8.2 Glass or Plastic Syringe, 1 or 5 mL capacity.8.3 Needle, 18- or 22-gauge.8.4 Water, deionized.8.5 Carrier Gas, any dry inert gas including, but not limitedto, dry air, nitr
22、ogen, helium, or argon.9. Sampling9.1 Laboratory sample shall be thoroughly homogeneousbefore drawing a test specimen.9.2 Select test specimen size as indicated in Table 1 basedon the expected water concentration.10. Preparation of Apparatus10.1 Establish carrier gas flow to the analyzer by eitherop
23、ening the source regulator or turning on the dry air generator.10.2 Turn on analyzer and allow equilibration for at least 15min.11. Calibration and Standardization11.1 To ensure the integrity of the test results, the RH sensorshall be verified and calibrated using a traceable syringe.Alternatively,
24、the RH sensor may be verified using a traceablestandard solution of water in a compatible solvent. Othersuitable instrument calibration methods and standards may beused as specified by the instrument manufacturer.NOTE 1Examples of suitable water standards include water in propy-lene carbonate or wat
25、er in xylenes.11.2 Perform the coil heater calibration in accordance withthe manufacturers instructions. After calibration, the coil shallverifiably maintain an arbitrary set temperature from 25 to200C within 61C. Coil heater calibration should be per-formed at least once annually.11.2.1 If the resu
26、lts are not within the acceptable range,contact the analyzer manufacturer.11.3 To perform the RH sensor verification, set the instru-ment to calibration/verification mode and inject 0.5 L waterdirectly into the sensor chamber of the instrument using thecalibrated syringe. Acceptable results are 475
27、to 525 g waterdetected.11.3.1 If the RH sensor verification is not within acceptablerange:11.3.2 Perform at least five injections using the procedureoutlined in 11.3. If the coefficient of variation between the fiveinjections is 2%, use the mean result of the five injections toperform a single-point
28、 recalibration of the instrument.11.3.3 Repeat step 11.3 to verify RH sensor calibration.11.3.4 If results are not within acceptable range, contact theanalyzer manufacturer.12. Procedure12.1 Sample Analysis:12.1.1 Program the analyzer with appropriate test condi-tions.12.1.2 Flush clean syringe and
29、needle 2 to 5 times with thematerial to be tested.12.1.3 Place empty syringe on the balance, and tare it.12.1.4 Draw desired amount of sample into the syringe.NOTE 2Suggested test specimen sizes are listed in Table 1.12.1.5 Place syringe with test specimen back onto balanceand reweigh.12.1.6 Record
30、the sample weight.12.1.7 Load the syringe with the test specimen in the testingportion of the analyzer.12.1.8 Begin the program and follow the instrument pro-vided prompts for starting analysis.12.1.9 Record result displayed at the end of the test.12.1.10 Repeat 12.1.4-12.1.9 for subsequent tests.4T
31、raceable to national or international standards like NIST, ISO, etc., as definedin Terminology D4175.TABLE 1 Suggested Injection Volume Based on Expected WaterContentExpected Water Concentration, % Sample Volume, mLLess than 0.02 50.02 to 0.025 40.025 to 0.035 30.035 to 0.050 2Greater than 0.05 1D75
32、46 09213. Calculation or Interpretation of Results13.1 Calculate the water concentration in mass or volume %of the sample as follows:water, mass % 5R1043Wor (1)volume % 5R1043Vwhere:R = total water result for test specimen, g,W = sample weight, g, andV = volume of sample used, mL.13.2 If results are
33、 displayed as percent of water present andconversion to mg/kg is desired, calculate as follows:mg/kg 5 water %!3104(2)13.3 No further calculation or interpretation is necessary.14. Report14.1 Report the water concentration to the nearest wholemg/kg the nearest 0.01 mass %, the nearest whole L/mL, or
34、the nearest 0.01 volume %.15. Precision and Bias515.1 Precision and bias statements will be established fol-lowing completion of the round robin analyses in accordancewith ASTM requirements. See Table 2 for information onrepeatability of this test method.16. Keywords16.1 additives; lubricating oils;
35、 moisture determination;relative humidity sensorASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights,
36、 and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for rev
37、ision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you
38、 shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be
39、obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D02-1674.TAB
40、LE 2 Repeatability Limits for Instrument Utilizing RelativeHumidity SensorNOTERepeatability data based on 30 tests per material/single operator/two instrumentsMaterial = Hydraulic FluidSample Size = 4 mLTest Temperature = 120CSyringe Speed = 5.0 minEnding Criteria = Rate = 0.10 g/sMean = 0.0277% (wt./wt.)Standard Deviation = 0.0017Repeatability Limit (2.77 *S.D.) = 0.0046Material = Turbine OilSample Size = 5 mLTest Temperature = 120CSyringe Speed = 5.0 minEnding Criteria = Rate = 0.10 g/sMean = 0.0015% (wt./wt.)Standard Deviation = 0.0002Repeatability Limit (2.77 *S.D.) = 0.0007D7546 093
