ASTM D2112-00
(Test Method)Standard Test Method for Oxidation Stability of Inhibited Mineral Insulating Oil by Pressure Vessel
Standard Test Method for Oxidation Stability of Inhibited Mineral Insulating Oil by Pressure Vessel
SCOPE
1.1 This test method is intended as a rapid method for the evaluation of the oxidation stability of new mineral insulating oils containing a synthetic oxidation inhibitor. This test is considered of value in checking the oxidation stability of new mineral insulating oils containing 2,6-ditertiary-butyl para-cresol or 2,6-ditertiary-butyl phenol, or both, in order to control the continuity of this property from shipment to shipment. The applicability of this procedure for use with inhibited insulating oils of more than 12 cSt at 40°C (approximately 65 SUS at 100°F) has not been established.
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Note 1—A modification of this test method which uses the same procedure and apparatus but a higher (150°C) bath temperature has been published as Test Method D2272.
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Designation: D 2112 – 00
Standard Test Method for
Oxidation Stability of Inhibited Mineral Insulating Oil by
Pressure Vessel
This standard is issued under the fixed designation D 2112; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method is intended as a rapid method for the
evaluation of the oxidation stability of new mineral insulating
oils containing a synthetic oxidation inhibitor. This test is
considered of value in checking the oxidation stability of new
mineral insulating oils containing 2,6-ditertiary-butyl para-
cresol or 2,6-ditertiary-butyl phenol, or both, in order to control
the continuity of this property from shipment to shipment. The
applicability of this procedure for use with inhibited mineral
insulating oils of more than 12 cSt at 40°C (approximately 65
SUS at 100°F) has not been established.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility of whoever uses this standard to consult and
establish appropriate safety and health practices and deter-
mine the applicability of regulatory limitations prior to use.
FIG. 1 Rotating Bomb Oxidation Test Apparatus
NOTE 1—A modification of this test method, which uses the same
procedure and apparatus but a higher (150°C) bath temperature, has been
ence of water, at a bath temperature of 140°C. The time for an
published as Test Method D 2272.
oil to react with a given volume of oxygen is measured;
completion of the test is indicated by a specific drop in
2. Referenced Documents
pressure.
2.1 ASTM Standards:
B 1 Specification for Hard-Drawn Copper Wire
4. Signifance and Use
D 2272 Test Method for Oxidation Stability of Steam
4.1 This is a control test of oxidation stability of new,
Turbine Oils by Rotating Bomb
inhibited mineral insulating oils for determining the induction
E 1 Specification for ASTM Thermometers
period of oxidation inhibitors under prescribed accelerated
aging conditions. There is no proven correlation between oil
3. Summary of Test Method
performance in this test and performance in service. However,
3.1 The test specimen is agitated by rotating axially at 100
the test method may be used to check the continuity of
rpm at an angle of 30° from the horizontal, under an initial
oxidation stability of production oils.
oxygen pressure of 90 psi (620 kPa), in a stainless steel or
copper vessel (for rapid temperature equilibrium), with a glass
5. Apparatus
test specimen container and copper catalyst coil, in the pres-
5.1 Oxidation Vessel— Glass test specimen container with
cover and catalyst coil, pressure gage, thermometer, test bath,
and accessories as described in Annex A1. The assembled
This test method is under the jurisdiction of ASTM Committee D-27 on
apparatus is shown in Fig. 1, and its design shown schemati-
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
cally in Fig. 2.
mittee D27.06 on Chemical Test.
Current edition approved April 10, 2000. Published June 2000. Originally
published as D 2112 – 62 T. Last previous edition D 2112 – 95.
6. Reagents and Materials
Annual Book of ASTM Standards, Vol 02.03.
3 6.1 Purity of Reagents—Use reagent grade chemicals in all
Annual Book of ASTM Standards, Vol 05.01.
Annual Book of ASTM Standards, Vol 14.03. tests. Unless otherwise indicated, all reagents shall conform to
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D2112
FIG. 2 Schematic Drawing of Rotary Vessel
the specifications of the Committee on Analytical Reagents of 48 mm and stretched to a height of 40 to 42 mm. Clean the coil
the American Chemical Society, where such specifications are thoroughly with chloroform or acetone and allow it to air-dry.
available. Immediately after air drying, insert the coil with a twisting
6.2 Hydrochloric Acid, 10 vol %. motion into the glass test specimen container. Handle the coil
6.3 Silicon Carbide Abrasive Cloth, 100-grit with cloth only with clean tongs to avoid contamination. Weigh the coil
backing. and the container to the nearest 0.1 g and record the weight.
6.4 Chloroform, cp. or Acetone, cp. Prepare a new coil for each test specimen.
6.5 2-Propanol, 99 vol %, refined.
8.2 Alternative Method of Catalyst Preparation—Wind ap-
6.6 Liquid Detergent.
proximately3mof copper wire into a coil of the dimensions
6.7 Oxygen, 99.5 %, with pressure regulation above 90 psi
specified in 8.1, and add to the glass container. Weigh the coil
(620 kPa). (Warning—Oxygen vigorously accelerates com- and container to the nearest 0.1 g and record the weight. Wash
bustion).
the coil by filling the container above the level of the coil with
6.8 Potassium Hydroxide, Alcohol Solution (1 mass %)— 10 % hydrochloric acid by volume for 30 s. Discard the acid
Dissolve 7.93 g of potassium hydroxide (KOH) pellets in 1 L
and rinse the coils three times with tap water followed by three
of 99 % refined 2-propanol. times with distilled water. Reweigh the coil and container and
6.9 Silicone Stopcock Grease.
determine by difference the water retained in the system. The
6.10 Wire Catalyst— AWG No. 14 (0.0641-in. (1.628-mm) coils are now ready for use. This procedure has been found to
diameter) electrolytic copper wire 99.9 % purity, conforming
be acceptable for treatment of commercially available, pre-
to Specification B 1. Soft-drawn copper wire of an equivalent
packaged, preformed coils that meet the requirement described
grade may also be used.
in this test method. Use a new coil for each test specimen.
8.3 Cleaning of Vessel— Wash the vessel body, lid, and
7. Hazards
inside of vessel stem with hot detergent solution and with
7.1 Consult Material Safety Data Sheets for all materials
water. Rinse inside of stem with 2–propanol and blow dry with
used in this test method.
clean dry air. An alternative cleaning solution is the use of a
50/50 volumetric blend of methanol and acetone; it has been
8. Preparation of Apparatus
found to be effective in cleaning sludge from the vessel. If the
8.1 Catalyst Preparation—Immediately before use, polish
vessel body, lid, or inside of stem smells sour after simple
the copper wire with silicon carbide abrasive cloth and wipe
cleaning, wash with alcoholic KOH solution and repeat as
free from abrasives with a clean dry cloth. Wind approximately
before (see Note 2).
3 m of the wire into a coil having an outside diameter of 44 to
NOTE 2—Insufficient cleaning of the vessel may adversely affect test
results.
Reagent Chemicals, American Chemical Society Specifications, American
9. Procedure
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
9.1 Charging—Weigh 50 6 0.5 g of oil sample into the
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
container, add 5 mL of distilled water, and cover with a 2-in.
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. (51-mm) watch glass or a 2 ⁄4-in. (57.2-mm) PTFE disk with
D2112
one or four holes and retaining spring. If rinse water is present vessels are inserted. Maintain the test temperature within 6
in the container, compensate for it by using less added water 0.1°C (see Note 6).
based on the water retention determined in 8.3. Add 5 mL of
NOTE 5—The time for the bath to reach the operating temperature after
distilled water to the vessel and slide the test specimen
insertion of the vessels may differ for different apparatus assemblies and
container and cover lid into the vessel body (see Note 3). Apply
should be observed for each unit. The objective is to find a set of
a thin coating of silicone stopcock grease to the O-ring bomb
conditions that does not permit a drop of more than 2°C after insertion of
the vessels and allows the vessel pressure to reach a plateau within 15 min
seal located in the gasket groove of the vessel lid to provide
as shown in Curve A of Fig. 3.
lubrication, and insert the lid into the vessel body. Place the
NOTE 6—Maintaining the correct temperature within the specification
vessel cap over the vessel stem, and tighten by hand. Cover the
limits of 60.1°C during the entire test run is the most important single
threads of the gage-nipple with a thin coating of stopcock
factor ensuring good repeatability and reproducibility of test results.
grease or TFE-fluorocarbon, or both, and screw the gage into
9.3 Keep the bombs completely submerged and maintain
the top-center tap of the vessel stem. Flush the vessel twice
rotation continuously and uniformly throughout the test. A
with oxygen supplied to the vessel at 90 psi (620 kPa) and
standard rotational speed of 100 6 5 rpm is required; any
release to the atmosphere. Adjust the regulating valve on the
appreciable variations in this speed could cause erratic results.
oxygen supply tank to 90 psi at a room temperature of 25°C
If a dial gage is used, take readings every 5 min.
(77°F). For each 2.8°C (5.1°F) above or below this tempera-
9.4 The test is complete after the pressure drops more than
ture, add or subtract 1
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