ASTM D5770-02(2007)
(Test Method)Standard Test Method for Semiquantitative Micro Determination of Acid Number of Lubricating Oils During Oxidation Testing
Standard Test Method for Semiquantitative Micro Determination of Acid Number of Lubricating Oils During Oxidation Testing
SIGNIFICANCE AND USE
This test method provides a semiquantitative estimate of the acid number of lubricating oils obtained from laboratory oxidation tests using smaller amounts of sample than Test Methods D 974, D 664, or D 3339. It has specific application in Test Method D 943 and in Test Method D 4871. This test method, therefore, provides a means of monitoring the relative oxidation of lubricating oils by measuring changes in acid number, at different time intervals and under various oxidizing test conditions.
Since this test method is semiquantitative, each laboratory shall develop its own criteria for each oxidation test method for determining when to switch from this semiquantitative test method to a more precise test method for acid number.
SCOPE
1.1 This test method is a semiquantitative micro method intended for monitoring the changes in acidic constituents occurring in lubricating oils during oxidation testing, when the acid number of such oils falls within the range from 0.02 to 1.0 mg of potassium hydroxide per gram of sample. It is applicable to such oils as turbine oils, hydraulic oils, and other circulating oils. Note 1 - This test method is a micro version of Test Method D 974 and it produces results similar to that method.
1.2 This test method is designed for use where sample size is limited. It shall not be used as a replacement for higher precision methods such as Test Methods D 974 or D 664. It shall not be used to monitor oils in-service.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D5770–02 (Reapproved 2007)
Standard Test Method for
Semiquantitative Micro Determination of Acid Number of
Lubricating Oils During Oxidation Testing
This standard is issued under the fixed designation D5770; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D3339 Test Method for Acid Number of Petroleum Prod-
ucts by Semi-Micro Color Indicator Titration
1.1 This test method is a semiquantitative micro method
D4871 Guide for Universal Oxidation/Thermal Stability
intended for monitoring the changes in acidic constituents
Test Apparatus
occurring in lubricating oils during oxidation testing, when the
acid number of such oils falls within the range from 0.02 to 1.0
3. Terminology
mgofpotassiumhydroxidepergramofsample.Itisapplicable
3.1 Definitions:
to such oils as turbine oils, hydraulic oils, and other circulating
3.1.1 acid number, n—the quantity of base, expressed in
oils.
milligrams of potassium hydroxide per gram of sample, that is
NOTE 1—This test method is a micro version of Test Method D974 and
required to titrate a sample dissolved in a specified solvent to
it produces results similar to that method.
a specified endpoint.
1.2 This test method is designed for use where sample size
3.1.1.1 Discussion—In this test method, the acid number is
is limited. It shall not be used as a replacement for higher
calculated from the number of drops required to produce a
precisionmethodssuchasTestMethodsD974orD664.Itshall
change in solution color from blue-green to orange, compared
not be used to monitor oils in-service.
to the number of drops required to produce an identical color
1.3 The values stated in SI units are to be regarded as the
change using a reference standard. Because this is a direct
standard. The values given in parentheses are for information
comparison method, the acid number value can be reported in
only.
milligrams of potassium hydroxide per gram of sample.
1.4 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.1 A2.0-mLportion of the titration solution is titrated with
priate safety and health practices and determine the applica-
a sample using a dropping pipet. The number of drops of
bility of regulatory limitations prior to use. sample required to turn the blue-green titration solution to a
persistent orange color is noted.
2. Referenced Documents
4.2 A second 2.0-mL portion of the titration solution is
2.1 ASTM Standards:
titrated with an acid number reference solution of known acid
D664 Test Method forAcid Number of Petroleum Products
number. The number of drops of the reference solution
by Potentiometric Titration
required to turn the blue-green titration solution to a persistent
D943 Test Method for Oxidation Characteristics of Inhib-
orange color is noted.
ited Mineral Oils
4.3 The estimated acid number of the sample is calculated
D974 Test Method for Acid and Base Number by Color-
using the acid number of the reference solution and the ratio of
Indicator Titration
the number of drops of the reference solution required to effect
the color change to the number of drops of the sample required
for the same change.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee 5. Significance and Use
D02.06 on Analysis of Lubricants.
5.1 Thistestmethodprovidesasemiquantitativeestimateof
Current edition approved May 1, 2007. Published June 2007. Originally
the acid number of lubricating oils obtained from laboratory
approved in 1995. Last previous edition approved in 2002 as D5770 – 02. DOI:
10.1520/D5770-02R07.
oxidation tests using smaller amounts of sample than Test
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Methods D974, D664,or D3339. It has specific application in
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Test Method D943 and in Test Method D4871. This test
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. method, therefore, provides a means of monitoring the relative
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D5770–02 (2007)
oxidation of lubricating oils by measuring changes in acid 7.6 Propanol-2-ol (Isopropyl Alcohol)—(Warning—
number, at different time intervals and under various oxidizing Flammable.) (Warning—It has been reported that, unless
test conditions. inhibitedagainstit,peroxidescanforminpropanol-2-oland,as
5.2 Since this test method is semiquantitative, each labora- the storage vessel or equipment such as a dispensing bottle
tory shall develop its own criteria for each oxidation test becomeemptyandapproachdryness,anexplosivemixturecan
method for determining when to switch from this semiquanti- occur.)
tative test method to a more precise test method for acid 7.7 Titration Solution—Mix 350 mL of toluene, 350 mL of
number. propanol-2-ol, and 7 mL of the p-naphtholbenzein solution in
a 1-L plastic bottle.Add 15 mL of 0.1 M potassium hydroxide
6. Apparatus
alcoholic solution and mix well. (Warning—Flammable. Va-
por harmful. Corrosive.)
6.1 Glass Beakers, 10-mL capacity, or glass vials, 4 or 6
dram.
NOTE 3—The strength of the titration solution depletes with time and
6.2 Glass Syringe,2-5mLcapacity.A5-mLinterchangeable
should be periodically replaced. Up to one month has been found to be
syringe with a 20 gage, 12 cm needle is satisfactory. satisfactory.
6.3 Dropping Pipet, glass with rubber bulb, capable of
7.8 Toluene—(Warning—Flammable. Vapor harmful.)
delivering 35 to 40 drops of oil.
8. Procedure
7. Reagents
8.1 Sampling—Withdraw the minimal amoun
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