ASTM D942-02(2007)
(Test Method)Standard Test Method for Oxidation Stability of Lubricating Greases by the Oxygen Pressure Vessel Method
Standard Test Method for Oxidation Stability of Lubricating Greases by the Oxygen Pressure Vessel Method
SIGNIFICANCE AND USE
This test method measures the net change in pressure resulting from consumption of oxygen by oxidation and gain in pressure due to formation of volatile oxidation by-products. This test method may be used for quality control to indicate batch-to-batch uniformity. It predicts neither the stability of greases under dynamic service conditions, nor the stability of greases stored in containers for long periods, nor the stability of films of greases on bearings and motor-parts. It should not be used to estimate the relative oxidation resistance of different grease types.
SCOPE
1.1 This test method determines resistance of lubricating greases to oxidation when stored statically in an oxygen atmosphere in a sealed system at an elevated temperature under conditions of test.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements see Sections 6 and 7.
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Standards Content (Sample)
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Designation: D942 − 02(Reapproved 2007)
Designation: 142/85 (92)
Standard Test Method for
Oxidation Stability of Lubricating Greases by the Oxygen
Pressure Vessel Method
This standard is issued under the fixed designation D942; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* 2.2 Other Standards:
IP Specification for Standard IP Thermometers
1.1 This test method determines resistance of lubricating
BS 970:1983Part I, Section S
greases to oxidation when stored statically in an oxygen
atmosphereinasealedsystematanelevatedtemperatureunder
3. Summary of Test Method
conditions of test.
3.1 The sample of grease is oxidized in a pressure vessel
1.2 The values stated in SI units are to be regarded as
heated to 99°C (210°F) and filled with oxygen at 110 psi (758
standard. No other units of measurement are included in this
kPa).Pressureisobservedandrecordedatstatedintervals.The
standard.
degree of oxidation after a given period of time is determined
1.2.1 Exception—Pressure measurement appears in psi with
by the corresponding decrease in oxygen pressure.
kPa provided in parentheses for information only.
1.2.2 Exception—In Fig.A1.1, all dimensions are in inches,
NOTE 1—The pressure vessel has been referred to as “a bomb” in
with millimetres provided in parentheses for information only.
previous issues of this test method.
1.3 This standard does not purport to address all of the
NOTE 2—The accepted unit of pressure is the pascal (Pa) for ASTM
safety concerns, if any, associated with its use. It is the methods and will be parenthetically included after the conventional
pound-force per square inch (psi) value. The Institute of Petroleum uses
responsibility of the user of this standard to establish appro-
the bar as a pressure measurement. Conversion of units may be obtained
priate safety and health practices and determine the applica-
as follows:
bility of regulatory limitations prior to use. For specific hazard
To convert from pound-force per square inch (psi) to pascal (Pa)
statements see Sections 6 and 7.
multiply by 6.894757×10 .
To convert from pound-force per square inch (psi) to bar multiply by
2. Referenced Documents
0.06894757.
To convert from bar to pascal (Pa) multiply by 10 .
2.1 ASTM Standards:
A240/A240MSpecification for Chromium and Chromium-
4. Significance and Use
Nickel Stainless Steel Plate, Sheet, and Strip for Pressure
Vessels and for General Applications 4.1 This test method measures the net change in pressure
D525Test Method for Oxidation Stability of Gasoline (In-
resultingfromconsumptionofoxygenbyoxidationandgainin
duction Period Method)
pressure due to formation of volatile oxidation by-products.
E1Specification for ASTM Liquid-in-Glass Thermometers
This test method may be used for quality control to indicate
batch-to-batch uniformity. It predicts neither the stability of
greases under dynamic service conditions, nor the stability of
This test method is under the jurisdiction of ASTM Committee D02 on
greases stored in containers for long periods, nor the stability
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.09.0E on Oxidation of Greases.
of films of greases on bearings and motor-parts. It should not
In the IP, this test method is under the jurisdiction of the Standardization
beusedtoestimatetherelativeoxidationresistanceofdifferent
Committee. This test method has been approved by the sponsoring committee and
grease types.
acceptedbythecooperatingsocietiesinaccordancewiththeestablishedprocedures.
Current edition approved May 1, 2007. Published June 2007. Originally
approved in 1947. Last previous edition approved in 2002 as D942–02. DOI:
10.1520/D0942-02R07.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM U.K., http://www.energyinst.org.uk.
Standards volume information, refer to the standard’s Document Summary page on Available from British Standards Institute (BSI), 389 Chiswick High Rd.,
the ASTM website. London W4 4AL, U.K., http://www.bsi-global.com.
*A Summary of Changes section appears at the end of this standard
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D942 − 02 (2007)
5. Apparatus Use with adequate ventilation. Do not take internally.) For this
comparison, visual appearance and mass loss on heating the
5.1 Oxidation Pressure Vessel, Sample Dish, Dish Holder,
glassware under test conditions may be used. Detergent clean-
Pressure Gage and Oil Bath as described in detail in the
ing avoids the potential hazards and inconveniences related to
Annex.
handling corrosive chromic acid solutions; this procedure
NOTE 3—Other constant-temperature baths may be used if they are
remains the reference cleaning practice and as such may
equivalent in heat capacity and thermal gradient characteristics to the oil
function as an alternate to the preferred procedure, cleaning
bath described in the Annex and can be shown to maintain the pressure
with detergent solutions.
vessel at the prescribed test temperature.
5.2 Thermometer, having a range as shown below and
7. Preparation of Apparatus
conforming to the requirements as prescribed in Specification
7.1 Clean the sample dishes from all contamination from
E1 or in the Specifications for IP Standard Thermometers:
previous runs and from dust settling from the air by washing
Thermometer Number
them with n-heptane and then with a cleaning solution. Follow
Temperature Range ASTM IP
95 to 103°C 22C 24C
the final cleaning operation by a thorough tap water rinse, a
204 to 218°F 22F 24F
distilled water rinse, and drying in an oven. Handle the clean
dishes only with forceps. (Warning—Handle in well-
6. Material
ventilated area, preferably in a hood. Keep away from heat,
6.1 Oxygen, of not less than 99.5% purity.
sparks, and open flame. Keep container closed when not in
6.2 (Warning—Since oxygen vigorously accelerates use.) (Warning—See 6.3, and avoid skin contact, which may
cause severe burns.)
combustion, observe the following procedures: (1) Keep oil
and grease away from oxygen at high pressure. Keep oil and
7.2 If lacquer is found after a run, clean the inside of the
grease away from all regulators, gages and control equipment.
oxidation pressure vessel and the metal supports for the
(2) Use oxygen only with equipment conditioned for oxygen
pressure vessel dishes by immersing in an appropriate solvent
service by careful cleaning to remove oil and grease from area
capable of removing the lacquer, such as gum solvent as
in contact with high pressure oxygen. (3) Keep combustibles
specified in Test Method D525, and scrubbing with a bristle
away from oxygen and eliminate ignition sources. (4) Keep
brush followed by drying. Scrub further with water and a fine
surfaces clean to prevent ignition or explosion, or both, upon
scouring powder until all the lacquer deposits are removed.
contact with high pressure oxygen. (5) Always use a pressure
Follow the scouring operation by a thorough tap water rinse, a
regulator to deliver oxygen. Release regulator tension before
distilled water rinse, and drying in an oven. Handle the clean
opening oxygen cylinder. (6) All equipment used must be
metal supports only with forceps.
suitable and recommended for oxygen service. (7) Never
attempttotransferoxygenfromcylinderinwhichitisreceived
8. Procedure
to any other cylinder prior to use. (8) Do not drop oxygen
8.1 Filleachofthefivedisheswith4.00 60.01gofgrease.
cylinders.(9)Keepcylindervalveclosedwhennotinuse.(10)
Distribute the samples in the dishes in a uniform layer with a
Stand away from valve when opening cylinder. (11)Donot
smooth level upper surface. Place the filled dishes on the five
breathe or use technical grade oxygen for inhalation purposes.
bottom shelves of the holder, leaving the top shelf to act as a
(12) See Compressed Gas Association Booklets G-4 and
5 cover to prevent condensing volatile products from dropping
G-4-1 for details of safe practice in the use of oxygen.)
into the grease samples. When assembling the pressure vessel,
6.3 n-Heptane—(Warning—Flammable. Harmful if in-
place a small ball of glass wool in the bottom of the stem.
haled. Keep away from heat, sparks, and open flame. Keep
8.2 Place the dish holder in the pressure vessel with a
container closed. Use with adequate ventilation.Avoid breath-
sealing gasket in place, and close the pressure vessel by
ing vapor or spray mist. Avoid prolonged or repeated contact
tightening the bolts slowly and uniformly. Clear the air from
with skin.)
the pressure vessel by introducing oxygen slowly until a
6.4 Cleaning Solution, capable of satisfactorily cleaning the
pressureof100psi(689kPa)isattained,thenallowtheoxygen
glassware used in the test. The criterion for satisfactory
to escape slowly; repeat four times. Bring the oxygen pressure
cleaningshallbeamatchingofthequalityofthatobtainedwith
to a value as shown in the following table:
chromic acid cleaning solutions (fresh chromic acid, 6-h
Room Temperature Pressure
soaking period, rinsing with distilled water and drying) or
°C °F psi kPa
some other equivalently strong oxidizing non-chromium con- 17 to 20 62 to 68 85 586
20 to 23 68 to 74 86 593
taining acid cleaning solutions on used sample dishes.
23 to 27 74 to 80 87 600
(Warning—Causes severe b
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