1、Designation: D2878 10 (Reapproved 2016)Standard Test Method forEstimating Apparent Vapor Pressures and MolecularWeights of Lubricating Oils1This standard is issued under the fixed designation D2878; the number immediately following the designation indicates the year oforiginal adoption or, in the ca
2、se 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 a calculation procedure forconverting data obtained by Test Method
3、 D972 to apparentvapor pressures and molecular weights. It has been demon-strated to be applicable to petroleum-based and synthetic esterlubricating oils,2at temperatures of 395 K to 535 K (250 F to500 F). However, its applicability to lubricating greases hasnot been established.NOTE 1Most lubricant
4、s boil over a fairly wide temperature range, afact recognized in discussion of their vapor pressures. For example, theapparent vapor pressure over the range 0 % to 0.1 % evaporated may beas much as 100 times that over the range 4.9 % to 5.0 % evaporated.1.2 The values stated in SI units are to be re
5、garded as thestandard. In cases in which materials, products, or equipmentare available in inch-pound units only, SI units are omitted.1.3 WARNINGMercury has been designated by manyregulatory agencies as a hazardous material that can causecentral nervous system, kidney and liver damage. Mercury, ori
6、ts vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercury containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAswebsitehttp:/www.epa.gov/mercury/faq.htmfor addi-tional information. Users s
7、hould be aware that selling mercuryor mercury containing products into your state or country maybe prohibited by law.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-priat
8、e safety and health practices and determine the applica-bility or regulatory limitations prior to use. For specificwarning statements, see 6.2, 7.1, 8.2, and Annex A2.2. Referenced Documents2.1 ASTM Standards:3A240/A240M Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, an
9、d Strip for PressureVessels and for General ApplicationsD92 Test Method for Flash and Fire Points by ClevelandOpen Cup TesterD972 Test Method for Evaporation Loss of LubricatingGreases and OilsD2503 Test Method for Relative Molecular Mass (MolecularWeight) of Hydrocarbons by Thermoelectric Measure-m
10、ent of Vapor PressureD2595 Test Method for Evaporation Loss of LubricatingGreases Over Wide-Temperature RangeD2883 Test Method for Reaction Threshold Temperature ofLiquid and Solid MaterialsE659 Test Method for Autoignition Temperature of Chemi-cals3. Terminology3.1 Definitions of Terms Specific to
11、This Standard:3.1.1 apparent vapor pressure (p), nthe time-averagedvalue of the vapor pressure from the start to the end of theevaporation test.3.1.1.1 DiscussionWhile this may include some effects ofdifferences in nonideality of the vapor, heat of vaporization,surface tension, and viscosity between
12、 the m-terphenyl and thelubricating oil, these factors have been demonstrated to benegligible. Unless stated, this average shall cover the range 0 to5 6 1%.3.1.2 cell constant (k), nthe ratio of the amount ofm-terphenyl or lubricating oil carried off per unit volume of gasto that predicted by Dalton
13、s law.k 5 22.41 PW/VpM (1)where:k = call constant1This test method is under the jurisdiction of Committee D02 on PetroleumProducts, Liquid Fuels, and Lubricants and is the direct responsibility of Subcom-mittee D02.L0.07 on Engineering Sciences of High Performance Fluids and Solids(Formally D02.1100
14、).Current edition approved Jan. 1, 2016. Published February 2016. Originallyapproved in 1970. Last previous edition approved in 2010 as D2878 10. DOI:10.1520/D2878-10R16.2Coburn, J. F., “Lubricant Vapor Pressure Derived from Evaporation Loss,”Transactions, American Society of Lubricating Engineers,
15、ASLTA, Vol 12 , 1969,pp. 129134.3For 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,
16、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1P = ambient atmospheric pressure, torrW = mass of lubricant evaporated, gV = volume of gas passed through all litres at 273 K and101.3 kPa (760 torr)p = apparent vapor pressure, torrM = mole average molecular weight
17、 of lubricant vapor,g/moleT = test temperature, KIt has been empirically determined that for m-terphenyl in airk 5 0.1266 2 12.60/ T 2 273! (2)and that the cell constant is independent of the composi-tion of the lubricant.3.1.3 Test Method D972 is normally run with air, whichmay cause changes in eas
18、ily oxidized fluids. In such cases, useof common reactive gas nitrogen and recalibration to obtain aslightly different cell constant (k) is mandatory.4. Summary of Test Method4.1 The test is run at the selected temperature for a sufficienttime to give the selected amount of evaporation, which is 5 %
19、6 1 % unless otherwise specified. This evaporation rate iscompared with a standard value for pure m-terphenyl to yieldthe apparent vapor pressure and molecular weight of thelubricating oil as defined in Section 3.5. Significance and Use5.1 The vapor pressure of a substance as determined bymeasuremen
20、t of evaporation reflects a property of the bulksample. Little weight is given by the procedure to the presenceof low concentrations of volatile impurities.5.2 Vapor pressure, per se, is a thermodynamic property thatis dependent only upon composition and temperature for stablesystems. In the present
21、 method, composition changes occurduring the course of the test so that the contribution of minoramounts of volatile impurities is minimized.6. Apparatus6.1 Evaporation Cell, as described in Annex A1.6.2 Air Supply System, capable of supplying to the cell therequired flow of air free of entrained pa
22、rticles (WarningCompressed gas under high pressure. Use with extreme cautionin the presence of combustible material, since the autoignitiontemperatures of most organic compounds in air are drasticallyreduced at elevated pressures. See Annex A2.1.). A 410 mm(16 in.) length of 1 in. diameter pipe pack
23、ed with glass woolhas been found satisfactory for filtering the air.6.3 Oil Bath, as described in Annex A1.NOTE 2Other constant-temperature baths may be used if the exit airpassing over the grease sample is at the test temperature (60.5 K (1 F).6.4 Temperature Measuring DevicesResistancethermometers
24、, thermocouples, or liquid-in-glass thermometerscalibrated to accuracy within 60.5 C (61.0 F) may be used.The use of mercury-in-glass thermometers of equal accuracy ispermitted, although it is discouraged.6.5 Flowmeter4A rotameter calibrated to deliver air at arate of 2.583 g min 6 0.02 g min betwee
25、n 289 K and 302 K(60 F and 85 F) (2 L min at standard temperature andpressure). It shall be furnished with a needle valve andmounted as shown in Fig. 1.6.6 Oil Sample Cup, as described in Fig. 1 and A1.1.2.7. Calibration of Equipment7.1 It is assumed that equipment conforming to Test MethodD972 in d
26、esign and installation needs no calibration. Ifquestions arise, carry out the procedure using m-terphenyl(WarningHarmful or fatal if swallowed. See A2.2.) of goodcommercial quality. The following two points shall be deter-mined:Temperature Evaporation to Conformto Eq 2,gK F Time, h395 250 22 0.267 0
27、.027420 300 6.5 0.503 0.050If the data do not fall within the above ranges, check flowrate and temperature. If these are correct, prepare a substituteequation for k similar to Eq 2 and use it in Section 10. Whenuse of nonreactive gas is required, this calibration is necessaryas standard cell constan
28、ts are not valid for gases other than air.7.2 If the apparatus specified in Test Method D2595 is to beused, it shall be calibrated as described in 7.1.8. Procedure8.1 Weigh the clean test specimen cup and hood to thenearest 1 mg. Transfer, by means of a pipet, 10.00 g 6 0.05 gof test specimen to the
29、 cup. Assemble the cup and hood, beingcareful not to splash oil on the underside of the hood. Weighthe assembly and record the net test specimen weight to thenearest 1 mg.8.2 With cover in place, but without the hood and testspecimen cup attached, allow the evaporation cell to acquirethe temperature
30、 of the bath (controlled to 60.5 K (61 F) atwhich the test is to be made by immersing the cell in it, asshown in Fig. 1. Allow the cell to remain in the bath at least12 h before beginning the test. During this period, allow cleanair (WarningCompressed gas under high pressure. Use withextreme caution
31、 in the presence of combustible material, sincethe autoignition temperatures of most organic compounds in airare drastically reduced at elevated pressures. See Annex A2.1.)to flow through the cell at the prescribed rate, 2.583 g min 60.02 g min (2 L min at standard temperature and pressure), asindic
32、ated by the rotameter. Then remove the cover, thread andweighed hood and sample cup into place, and replace the cover.Tighten the three knurled cover-tightening screws securely toprevent air leakage under the cover. Pass clean air through thecell for the required period. (WarningDo not perform thist
33、est with air at temperatures in excess of the autoignition4The sole source of supply of the apparatus known to the committee at this timeis Flowrater meter, Fisher and Porter Co., Hatboro, PA. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters
34、. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.D2878 10 (2016)2temperature of the test specimen as determined by Test MethodE659 or Test Method D2883, or both.)8.3 At the end of the test period, remove the assembled testspe
35、cimen cup and hood from the cell, and allow to cool toroom temperature. Determine the net weight of the sample tothe nearest 1 mg.9. Determination of Molecular Weight and ApparentVapor Pressure9.1 If a value of M is already available from Test MethodD2503 or equivalent, 9.2 9.4 and 10.1 may be omitt
36、ed, eventhough this value is for the whole lubricant instead of the partvaporized, as the calculation is not very sensitive to M error.9.2 Conduct a test on the sample in accordance with theprocedure in Section 7, at 477 K (400 F). The proper test timeto evaporate 5 % (0.500 g) may be estimated from
37、 the flashpoint of the lubricant as measured by Test Method D92, fromTable 1.NOTE 3The need for a run at 477 K (400 F) is, created by lack ofexact values for the first two constants in Eq 3, Eq 4, and Eq 5 for othertemperatures.FIG. 1 Evaporation Test CellD2878 10 (2016)39.3 For synthetic and redist
38、illed petroleum oils, the varia-tion of W/t with W is not great, and the 5 % point shall beapproximated by linear interpolation of two points taken atdifferent W values. For single-distilled petroleum or unknownoils, three points shall be plotted, representing the estimatedtime and also half and twi
39、ce that time. These readings may allbe obtained on one sample by stop and start operation of theapparatus.9.4 When a single data point that does not fall within the5%6 1 % evaporated range is used (as is often justifiable onsynthetic oils) or the evaporation is measured at some otherlevel of W, this
40、 fact shall be reported in Section 11.9.5 The test for apparent vapor pressure is conducted inaccordance with Section 8 for the estimated time at the selectedtemperature. If the 5 6 1 % criterion is not met, proceed as in9.3.10. Calculations10.1 Calculation of Molecular Weight:10.1.1 Use the evapora
41、tion time, t, (in seconds) obtained in9.3 to evaporate 5 % 6 1%.10.1.2 Calculate the molecular weights of lubricants ingeneral as follows:logM 5 3.028 2 0.164log10 335 PW/t! (3)10.1.3 For lubricants of known composition, slightly greateraccuracy is obtained with special equations:10.1.3.1 For polyol
42、 esters:logM 5 3.181 2 0.207log10 335 PW/t! (4)10.1.3.2 For dibasic esters:logM 5 3.089 2 0.190log10 335 PW/t! (5)10.1.3.3 For mineral oils:logM 5 2.848 2 0.106log10 335 PW/t! (6)10.1.4 The molecular weight equations all contain thestandard value of k at 477K (400F) from Table 2. If a changegreater
43、than 63 % in this value is caused by the calibration inSection 7, adjustments shall be made in the constant 10 335 bymultiplying it by the factor (k/k).10.2 Calculation of Apparent Vapor Pressure:10.2.1 Use the molecular weight, M, as calculated in 10.1 orpredetermined in 9.1 to calculate the vapor
44、pressure as follows:p 5 672 PW/tkM (7)where k is obtained from Table 2. Use Eq 2 to extend thistable. If a special equation was required in 7.1, use it ratherthan Table 2 or Eq 2.10.2.2 For the special case of lubricants run at 477 K(400 F) for 6.5 h as required in several military aircraft engineoi
45、l specifications, with P = 760 torr:logp 5 1.164log10W! 2 1.255 (8)where 10 W = percent evaporated from a 10 g sample.10.2.3 These results may be converted to SI units by theequations:p 5 133.32p and P 5 133.32P (9)where:p = apparent vapor pressure, PaP = ambient atmospheric pressure, Pa11. Report11
46、.1 If the results are obtained in accordance with 9.1, 9.2,9.3, and 9.5, and calculated by Eq 3, they shall be reported as“Apparent Vapor Pressure=_ torr at _ _ C (_ _ F), andMolecular Weight=_.”11.2 If the results are obtained in accordance with 9.1, 9.2,9.3, and 9.5, and calculated by Eq 4, Eq 5,o
47、rEq 6, they shallbe reported as “Apparent Vapor Pressure=_torr at _ _ C(_ _ F), and Molecular Weight=_, calculated as polyolester,” “.diester,” or “.petroleum,” as appropriate.11.3 If the results are obtained as indicated in 8.2 or 9.4,they shall be reported as “Apparent Vapor Pressure=_torrat_ _ C
48、(_ _ F) and 0 to _ _ percent evaporated.” Themolecular weight shall be reported only if the test wasconducted at 477 K (400 F) or a separate test at this tempera-ture was made.12. Precision and Bias12.1 No independent precision statement can be issued atthis time. However, the statement in Test Meth
49、od D972 may beTABLE 1 Estimated Time to Evaporate 5 %, hAFlash Point Test Temperature, K (F)K F 394 (250) 422 (300) 450 (350) 477 (400) 505 (450) 533 (500)422 300 2.7 0.9 0.3 0.1 . .450 350 8.1 2.7 0.9 0.3 0.1 .477 400 24.3 8.1 2.7 0.9 0.3 0.1505 450 72.9 24.3 8.1 2.7 0.9 0.3533 500 . 72.9 24.3 8.1 2.7 0.9561 550 . . 72.9 24.3 8.1 2.7589 600 . . . 72.9 24.3 8.1AThis table may be extended by means of equation:Estimated Hours = 0.9 log10.0095(F 1.8T + 460)TABLE 2 Standard Cell ConstantsTemperatureCell Cons
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