1、Designation: D942 02 (Reapproved 2007)D942 15Designation: 142/85 (92)Standard Test Method forOxidation Stability of Lubricating Greases by the OxygenPressure Vessel Method1This standard is issued under the fixed designation D942; the number immediately following the designation indicates the year of
2、original 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.This standard has been approved for use by agencies of the U.S. Departm
3、ent of Defense.1. Scope*1.1 This test method determines resistance of lubricating greases to oxidation when stored statically in an oxygen atmospherein a sealed system at an elevated temperature under conditions of test.1.2 The values stated in SI units are to be regarded as standard. No other units
4、 of measurement are included in this standard.1.2.1 ExceptionPressure measurement appears in psi with kPa provided in parentheses for information only.1.2.2 ExceptionIn Fig. A1.1, all dimensions are in inches, with millimetres provided in parentheses for information only.1.3 This standard does not p
5、urport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazard statements see Sections
6、6 and 7.2. Referenced Documents2.1 ASTM Standards:2A240/A240M Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels andfor General ApplicationsD525 Test Method for Oxidation Stability of Gasoline (Induction Period Method)E1 Specification for ASTM
7、 Liquid-in-Glass Thermometers2.2 Other Standards:IP Specification for Standard IP Thermometers3BS 970:1983 Part I, Section S43. Summary of Test Method3.1 The sample of grease is oxidized in a pressure vessel heated to 99C (210F)99 C (210 F) and filled with oxygen at 110psi (758 kPa). 110 psi (758 kP
8、a). Pressure is observed and recorded at stated intervals. The degree of oxidation after a given periodof time is determined by the corresponding decrease in oxygen pressure.NOTE 1The pressure vessel has been referred to as “a bomb” in previous issues of this test method.NOTE 2The accepted unit of p
9、ressure is the pascal (Pa) for ASTM methods and will be parenthetically included after the conventional pound-forceper square inch (psi) value. The Energy Institute of Petroleum uses the bar as a pressure measurement. Conversion of units may be obtained as follows:To convert from pound-force per squ
10、are inch (psi) to pascal (Pa) multiply by 6.894757 103.To convert from pound-force per square inch (psi) to bar multiply by 0.06894757.To convert from bar to pascal (Pa) multiply by 105.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubrica
11、nts and is the direct responsibility of SubcommitteeD02.09.0E on Oxidation of Greases.In the IP, this test method is under the jurisdiction of the Standardization Committee. This test method has been approved by the sponsoring committee and accepted bythe cooperating societies in accordance with the
12、 established procedures.Current edition approved May 1, 2007April 1, 2015. Published June 2007June 2015. Originally approved in 1947. Last previous edition approved in 20022007 asD942 02.D942 02 (2007). DOI: 10.1520/D0942-02R07.10.1520/D0942-15.2 For referencedASTM standards, visit theASTM website,
13、www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR, U.K., http:/www.energyinst.org.uk.4 Availa
14、ble from British Standards Institute (BSI), 389 Chiswick High Rd., London W4 4AL, U.K., http:/www.bsi-.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technic
15、ally possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this st
16、andardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 This test method measures the net change in pressure resulting from consumption of oxygen by oxidation and gain inpressure due to formation of volatile o
17、xidation by-products. This test method may be used for quality control to indicatebatch-to-batch uniformity. It predicts neither the stability of greases under dynamic service conditions, nor the stability of greasesstored in containers for long periods, nor the stability of films of greases on bear
18、ings and motor-parts. It should not be used toestimate the relative oxidation resistance of different grease types.5. Apparatus5.1 Oxidation Pressure Vessel, Sample Dish, Dish Holder, Pressure Gage and Oil Bath as described in detail in the Annex.NOTE 3Other constant-temperature baths may be used if
19、 they are equivalent in heat capacity and thermal gradient characteristics to the oil bathdescribed in the Annex and can be shown to maintain the pressure vessel at the prescribed test temperature.5.2 Thermometer, having a range as shown below and conforming to the requirements as prescribed in Spec
20、ification E1 or inthe Specifications for IP Standard Thermometers:Thermometer NumberTemperature Range ASTM IP95 to 103C 22C 24C95 C to 103 C 22C 24C204 to 218F 22F 24F204 F to 218 F 22F 24F6. Material6.1 Oxygen, of not less than 99.5 % purity.6.2 (WarningSince oxygen vigorously accelerates combustio
21、n, observe the following procedures: (1) Keep oil and greaseaway from oxygen at high pressure. Keep oil and grease away from all regulators, gages and control equipment. (2) Use oxygenonly with equipment conditioned for oxygen service by careful cleaning to remove oil and grease from area in contact
22、 with highpressure oxygen. (3) Keep combustibles away from oxygen and eliminate ignition sources. (4) Keep surfaces clean to preventignition or explosion, or both, upon contact with high pressure oxygen. (5) Always use a pressure regulator to deliver oxygen.Release regulator tension before opening o
23、xygen cylinder. (6) All equipment used must be suitable and recommended for oxygenservice. (7) Never attempt to transfer oxygen from cylinder in which it is received to any other cylinder prior to use. (8) Do notdrop oxygen cylinders. (9) Keep cylinder valve closed when not in use. (10) Stand away f
24、rom valve when opening cylinder. (11)Do not breathe or use technical grade oxygen for inhalation purposes. (12) See Compressed Gas Association Booklets G-4 andG-4-15 for details of safe practice in the use of oxygen.)6.3 n-Heptane(WarningFlammable. Harmful if inhaled. Keep away from heat, sparks, an
25、d open flame. Keep containerclosed. Use with adequate ventilation. Avoid breathing vapor or spray mist. Avoid prolonged or repeated contact with skin.)6.4 Cleaning Solution, capable of satisfactorily cleaning the glassware used in the test. The criterion for satisfactory cleaningshall be a matching
26、of the quality of that obtained with chromic acid cleaning solutions (fresh chromic acid, 6-h6 h soaking period,rinsing with distilled water and drying) or some other equivalently strong oxidizing non-chromium containing acid cleaningsolutions on used sample dishes. (WarningCauses severe burns.Areco
27、gnized carcinogen. Strong oxidizer; contact with organicmaterial may cause fire. Hygroscopic.) (WarningDo not get in eyes, on skin, or on clothing.Avoid breathing vapor or mist. Keepcontainer closed. Use with adequate ventilation. Do not take internally.) For this comparison, visual appearance and m
28、ass loss onheating the glassware under test conditions may be used. Detergent cleaning avoids the potential hazards and inconveniencesrelated to handling corrosive chromic acid solutions; this procedure remains the reference cleaning practice and as such mayfunction as an alternate to the preferred
29、procedure, cleaning with detergent solutions.7. Preparation of Apparatus7.1 Clean the sample dishes from all contamination from previous runs and from dust settling from the air by washing themwith n-heptane and then with a cleaning solution. Follow the final cleaning operation by a thorough tap wat
30、er rinse, a distilled waterrinse, and drying in an oven. Handle the clean dishes only with forceps. (WarningHandle in well-ventilated area, preferably ina hood. Keep away from heat, sparks, and open flame. Keep container closed when not in use.) (WarningSee 6.3, and avoidskin contact, which may caus
31、e severe burns.)7.2 If lacquer is found after a run, clean the inside of the oxidation pressure vessel and the metal supports for the pressure vesseldishes by immersing in an appropriate solvent capable of removing the lacquer, such as gum solvent as specified in Test MethodD525, and scrubbing with
32、a bristle brush followed by drying. Scrub further with water and a fine scouring powder until all thelacquer deposits are removed. Follow the scouring operation by a thorough tap water rinse, a distilled water rinse, and drying inan oven. Handle the clean metal supports only with forceps.5 Available
33、 from Compressed Gas Association (CGA), 4221 Walney Rd., 5th Floor, Chantilly, VA 20151-2923, http:/.D942 1528. Procedure8.1 Fill each of the five dishes with 4.004.00 g 6 0.01 g 0.01 g of grease. Distribute the samples in the dishes in a uniform layerwith a smooth level upper surface. Place the fil
34、led dishes on the five bottom shelves of the holder, leaving the top shelf to act asa cover to prevent condensing volatile products from dropping into the grease samples. When assembling the pressure vessel, placea small ball of glass wool in the bottom of the stem.8.2 Place the dish holder in the p
35、ressure vessel with a sealing gasket in place, and close the pressure vessel by tightening thebolts slowly and uniformly. Clear the air from the pressure vessel by introducing oxygen slowly until a pressure of 100 psi (689kPa) 100 psi (689 kPa) is attained, then allow the oxygen to escape slowly; re
36、peat four times. Bring the oxygen pressure to a valueas shown in the following table:Room Temperature PressureC F psi kPa17 to 20 62 to 68 85 58620 to 23 68 to 74 86 59323 to 27 74 to 80 87 60027 to 30 80 to 86 88 60730 to 33 86 to 92 89 61433 to 37 92 to 98 90 62137 to 40 98 to 104 91 627Allow the
37、pressure vessel to stand overnight to make sure there are no leaks.NOTE 4It has been found that pressure readings as shown above will result in a pressure reading of 110 6 2 psi (758 6 14 kPa) 110 psi 6 2 psi(758 kPa 6 14 kPa) when the pressure vessel is placed in the bath in the following step, 8.3
38、, and consequently no release of oxygen will be required inmost cases.This minimizes the chance of a leak developing at the valve after the overnight check for leaks has shown the pressure vessel to be satisfactory.8.3 Place the pressure vessel in the oil bath maintained at a temperature of 9999 C 6
39、 0.5C (2100.5 C (210 F 61.0F).1.0 F). As the pressure rises, if needed, intermittently release oxygen from the pressure vessel until a constant pressure of110 6 2 psi (758 6 14 kPa) 110 psi 6 2 psi (758 kPa 6 14 kPa) is obtained and maintained for at least 2 h. A gradual drop inpressure indicates a
40、continuous leak in the pressure vessel. Observe and record the pressure at least every 24 h. In case a leakdevelops, do not report the results but repeat the test.8.4 Start timing at the moment of immersion of the pressure vessel in the oil bath, and continue the oxidation for the time periodspecifi
41、ed.NOTE 5Specifications are usually given in terms of pressure drop in pounds per square inch, or kilopascals at one or more time intervals, for instance,after 100, 200 h, 100 h, 200 h, and so forth.9. Report9.1 Report the average of duplicate determinations as pressure drop in pounds per square inc
42、h, or kilopascals for the specifiedtest time, or times in hours, according to Test Method D942.10. Precision and Bias10.1 The precision of this test method as determined by statistical examination of interlaboratory results is as follows:10.1.1 RepeatabilityThe difference between two test results, o
43、btained by the same operator with the same apparatus underconstant operating conditions on identical test material would, in the long run, in the normal and correct operation of the testmethod, exceed the following values only in one case in twenty:Mean Pressure Drop, psi (kPa) Repeatability0 to 5 (
44、34.5) 2 (13.8)Over 5 to 10 (34.5 to 68.9) 3 (20.7)Over 10 to 20 (68.9 to 138) 6 (41.4)Over 20 to 55 (138 to 379) 10 (68.9)10.1.2 ReproducibilityThe difference between two single and independent results obtained by different operators working indifferent laboratories on identical test material would,
45、 in the long run, in the normal and correct operation of the test method,exceed the following values only in one case in twenty:Mean Pressure Drop, psi (kPa) Reproducibility0 to 5 (34.5) 3 (20.7)Over 5 to 10 (34.5 to 68.9) 5 (34.5)Over 10 to 20 (68.9 to 138) 8 (55.2)Over 20 to 55 (138 to 379) 20 (13
46、8)NOTE 6These precision values apply only to that portion of the data for which oxygen is absorbed at a rate approximately proportional to time (forexample, the induction period). The end of the induction period is evidenced by a rapid acceleration in the rate of oxygen absorption in a short timeint
47、erval.10.2 The following information on the precision of this test method has been developed by the Energy Institute of Petroleum(London). The precision of this test method as determined by statistical examination of interlaboratory results is as follows:D942 15310.2.1 RepeatabilityThe difference be
48、tween two test results, obtained by the same operator with the same apparatus underconstant operating conditions on identical test material would, in the long run, in the normal and correct operation of the testmethod, exceed the following values only in one case in twenty:Mean PressureDrop, psig Re
49、peatabilityMean PressureDrop, kPa Repeatability0 to 2 1 0 53 to 6 2 5 to 20 107 to 10 3 25 to 40 1511 to 14 4 45 to 60 2015 to 18 5 65 to 85 2519 to 20 6 90 to 105 30110 to 125 35130 to 140 4010.2.2 ReproducibilityThe difference between two single and independent results obtained by different operators working indifferent laboratories on identical test material would, in the long run, in the normal and correct operation of the test method,exceed the following values only in one case in twenty:Mean PressureDrop,
