1、Designation: D7546 15Standard 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. Scope*1.1 This test method covers the quantitative determinationof water in new and in-s
3、ervice 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.
4、 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
5、 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 Lubrican
6、ts3. 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
7、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
8、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 c
9、ompatible 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
10、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 o
11、f 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 mole
12、cules 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 r
13、ate 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 respo
14、nsibility 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
15、 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 Har
16、bor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States17.1.3 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
17、between 25 C and 200 C.7.1.5 Sample Delivery System, provides programmable vari-able speed injection of the sample into the coil.7.1.6 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
18、.1.7 Manifold, which provides: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 Mic
19、rocontroller, which provides: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
20、precision for weighingsample.7.2 Headspace Vial Moisture Analyzer Apparatus:7.2.1 Flow Regulator, capable of maintaining the carrier gasflow rate within the manufacturers specified conditions.7.2.2 Flow Meter, capable of measuring the carrier gas flowrate within the manufacturers specified condition
21、s.7.2.3 Sample Heating Chamber, capable of maintaining thesample chamber temperature within 1 C of the programmedtemperature between 25 C and 200 C.7.2.4 Sample Delivery System, transports vial into sampleheating chamber.7.2.5 Manifold, which provides:7.2.5.1 A thermally stable port for mounting and
22、 operationof the relative humidity sensor7.2.5.2 Inlet and outlet ports for the carrier gas.7.2.6 Relative Humidity (RH) Sensor, a capacitive sensingelement that measures the relative humidity of the carrier gas.7.2.7 Microcontroller, which provides:7.2.7.1 Capability of integrating and converting t
23、he RHsensor signal.7.2.7.2 Capability of controlling the temperature of thesample heating chamber, and the sensor manifold.7.2.7.3 Capability of controlling the speed of the sampledelivery system.7.2.8 Balance, external, with 1 mg precision for weighingsample.8. Reagents and Materials8.1 Carrier Gas
24、, any dry inert gas including, but not limitedto, dry air, nitrogen, helium, or argon.8.2 Water, deionized.8.3 For Sample Injection Moisture Analyzer:8.3.1 Traceable Syringe, traceable at the desired total massof water, typically 500 g (0.5 L).8.3.2 Glass or Plastic Syringe, 1 mL or 5 mL capacity.8.
25、3.3 Needle, 18 gauge or 22 gauge.8.4 For Headspace Vial Moisture Analyzer:8.4.1 Traceable 1 L microcapillary, traceable at the desiredtotal mass of water, typically 1000 g (1.0 L).9. Sampling9.1 Laboratory sample shall be thoroughly homogeneousbefore drawing a test specimen.9.2 Sample Injection Mois
26、ture AnalyzerSelect test speci-men size as indicated in Table 1 based on the expected waterconcentration.9.3 Headspace Vial Moisture AnalyzerSelect test speci-men size as indicated in Table 2 based on the expected waterconcentration.10. Preparation of Apparatus10.1 Establish carrier gas flow to the
27、analyzer by eitheropening 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 Sample Injection Moisture Analyzer:11.1.1 To ensure the integrity of the test results, the RHsensor shall be ver
28、ified and calibrated using a traceablesyringe. Alternatively, the RH sensor may be verified using atraceable standard solution of water in a compatible solvent.Other suitable instrument calibration methods and standardsmay be used as specified by the instrument manufacturer.NOTE 1Examples of suitabl
29、e water standards include water inpropylene carbonate or water in xylenes.11.1.2 Perform the coil heater calibration in accordancewith the manufacturers instructions. After calibration, the coilshall verifiably maintain an arbitrary set temperature from25 C to 200 C within 61 C. Coil heater calibrat
30、ion shouldbe performed at least once annually.11.1.3 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 g to 525 gwater detected.1
31、1.1.3.1 If the RH sensor verification is not within theacceptable range:TABLE 1 Suggested Injection Volume Based on Expected WaterContentExpected Water Concentration,(% m/m)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 1D7546 15211.1.3.2 Perform at
32、 least five injections using the procedureoutlined in 11.1.3. If the coefficient of variation between thefive injections is 2 %, use the mean result of the fiveinjections to perform a single-point recalibration of the instru-ment.11.1.3.3 Repeat step 11.1.3 to verify RH sensor calibration.11.1.3.4 I
33、f results are not within acceptable range, contactthe analyzer manufacturer.11.2 Headspace Vial Moisture Analyzer:11.2.1 To ensure the integrity of the test results, the RHsensor shall be verified and calibrated using a traceablesyringe. Alternatively, the RH sensor may be verified using atraceable
34、standard solution of water in a compatible solvent.Other suitable instrument calibration methods and standardsmay be used as a specified by the instrument manufacturer.11.2.2 Perform the heating chamber calibration in accor-dance with the manufacturers instructions. After calibration,the sample heat
35、ing chamber shall verifiably maintain an settemperature from 25 C to 275 C within 61 C. Heatingchamber calibration should be performed at least once annu-ally.11.2.3 To perform the RH sensor verification, set the instru-ment to calibration/verification mode and inject 1.0 L waterdirectly into the se
36、nsor chamber of the instrument using thecalibrated syringe. Acceptable results are 950 g to 1050 gwater detected.11.2.3.1 If the RH sensor verification is not within accept-able range:11.2.3.2 Perform at least five injections using the procedureoutlined in 11.1.3. If the coefficient of variation bet
37、ween thefive injections is 2 %, use the mean result of the fiveinjections to perform a single-point recalibration of the instru-ment.11.2.3.3 Repeat step 11.1.3 to verify RH sensor calibration.11.2.3.4 If results are not within acceptable range, contactthe analyzer manufacturer.12. Procedure A (Syri
38、nge Injection Method)12.1 Sample Analysis:12.1.1 Program the analyzer with appropriate test condi-tions.12.1.2 Flush clean syringe and 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 2
39、Suggested test specimen sizes are listed in Table 1.12.1.5 Place syringe with test specimen back onto balanceand reweigh.12.1.6 Record 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 p
40、rompts 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.13. Procedure B (Headspace Vial Method)13.1 Sample Analysis:13.1.1 Program the analyzer with appropriate test condi-tions.13.1.2 Flush clean syringe and needle 2 to 5
41、times with thematerial to be tested.13.1.3 Place empty sample vial (with septum/cap) on thebalance, and tare it.13.1.4 Pour/inject desired amount of sample into the samplevial.NOTE 3Suggested test specimen sizes are listed in Table 2.13.1.5 Place sample vial with test specimen back ontobalance and r
42、eweigh.13.1.6 Record the sample mass.13.1.7 Load the sample vial with the test specimen in thetesting portion of the analyzer.13.1.8 Begin the program and follow the instrument pro-vided prompts for starting analysis.13.1.9 Record result displayed at the end of the test.13.1.10 Repeat to 13.1.4 to 1
43、3.1.9 for subsequent tests.14. Calculation or Interpretation of Results14.1 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, m
44、L.14.2 If results are displayed as percent of water present andconversion to mg/kg is desired, calculate as follows:mg/kg 5 water %! 3104(2)14.3 No further calculation or interpretation is necessary.15. Report15.1 Report the water concentration to the nearest wholemg/kg the nearest 0.01 mass %, the
45、nearest whole L/mL, orthe nearest 0.01 volume %.16. Precision and Bias316.1 Precision and bias statements will be established fol-lowing completion of the round robin analyses in accordancewith ASTM requirements.3Supporting data have been filed at ASTM International Headquarters and maybe obtained b
46、y requesting Research Report: RR:D02-1674.TABLE 2 Suggested Sample Mass Based on Expected WaterContentExpected Water Concentration,(% m/m)Sample Volume, gLess than 0.02 1.000.02 to 0.025 1.000.025 to 0.035 0.500.035 to 0.050 0.25Greater than 0.05 0.10D7546 15317. Keywords17.1 additives; lubricating
47、oils; moisture determination;relative humidity sensorSUMMARY OF CHANGESSubcommittee D02.96 has identified the location of selected changes to this standard since the last issue(D7546 09) that may impact the use of this standard. (Approved April 1, 2015.)(1) Updated test method to include headspace s
48、ample vialmethod (Procedure B).ASTM 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, and the riskof i
49、nfringement 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 revision 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 co
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