ASTM D2144-94
(Test Method)Standard Test Methods for Examination of Electrical Insulating Oils by Infrared Absorption
Standard Test Methods for Examination of Electrical Insulating Oils by Infrared Absorption
SCOPE
1.1 These test methods are to be used for the recording and interpretation of infrared absorption spectra of electrical insulating oils from 2.5 to 25 µm (4000 to 400 cm-1).
1.2 Two test methods are covered, a Reference Standard Test Method and a Differential Test Method.
1.3 These test methods are designed primarily for use as rapid continuity tests for identifying a shipment of oil from a supplier by comparing its spectrogram with that obtained from previous shipments, or with the sample on which approval tests were made. They also may be used for the detection of certain types of contamination in oils, and for the identification of oils in storage or service, by comparison of the spectra of the unknown and known oils. The test methods are not intended for the determination of the various constituents of an oil.
1.4 Caution--Infrared absorption is a tool of high resolving power. Conclusions as to continuity of oil quality should not be drawn until sufficient data have been accumulated so that the shipment-to-shipment variation is clearly established, for example.
1.5 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.
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Designation: D 2144 – 94
AMERICAN SOCIETY FOR TESTING AND MATERIALS
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Methods for
Examination of Electrical Insulating Oils by Infrared
1
Absorption
This standard is issued under the fixed designation D 2144; 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 E 932 Practice for Describing and Measuring Performance
3
of Dispersive Infrared Spectrophotometers
1.1 These test methods cover the recording and interpreta-
tion of infrared absorption spectra of electrical insulating oils
−1
3. Terminology
from 2.5 to 25 μm (4000 to 400 cm ).
3.1 Definitions—For definitions of terms and symbols, refer
NOTE 1—While these test methods are specific to ratio recording
to Terminology E 131.
double-beam dispersive spectrophotometers, recent developments have
made available single-beam Fourier-transform rapid scan infrared spec-
4. Summary of Test Methods
trophotometers. By computerized subtraction techniques, ratio methods
can be used. This equipment may be suitable if it complies with the
4.1 The infrared absorption spectrum may be recorded on
specifications described in Table 1.
the spectrophotometer by either of the two test methods
1.2 Two test methods are covered, a Reference Standard
outlined below. In both test methods differences in wavelength
Test Method and a Differential Test Method.
or frequency and intensity of the absorption bands are observed
1.3 These test methods are designed primarily for use as
and measured.
rapid continuity tests for identifying a shipment of oil from a
4.1.1 Reference Standard Test Method—An infrared cell
supplier by comparing its spectrogram with that obtained from
filled with the insulating oil sample is placed in the sample
previous shipments, or with the sample on which approval tests
beam of the spectrophotometer. With the shutter of the refer-
were made. They also may be used for the detection of certain
ence beam open, the infrared absorption spectrum is recorded
types of contamination in oils, and for the identification of oils
over the entire range of the instrument. The absorption spec-
in storage or service, by comparison of the spectra of the
trum of the sample oil is compared with a reference spectrum
unknown and known oils. The test methods are not intended
obtained with oil from a previous sample or the qualification
for the determination of the various constituents of an oil.
oil.
1.4 Caution—Infrared absorption is a tool of high resolving
4.1.2 Differential Test Method—Two cells having the same
power. Conclusions as to continuity of oil quality should not be
sample path length are filled, one with sample oil and the other
drawn until sufficient data have been accumulated so that the
with the reference oil. The filled cells are then placed in the
batch-to-batch variation is clearly established.
paths of the sample and reference beams, respectively, and the
1.5 This standard does not purport to address all of the
differential absorption spectrum recorded. This spectrum is
safety concerns, if any, associated with its use. It is the
then compared with the reference differential spectrum ob-
responsibility of the user of this standard to establish appro-
tained in a similar manner with the same cells filled with the
priate safety and health practices and determine the applica-
reference oil.
bility of regulatory limitations prior to use.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
5.1 The infrared spectrum of an electrical insulating oil is a
D 923 Test Method for Sampling Electrical Insulating Liq-
record of the absorption of infrared energy over a range of
2
uids
wavelengths. The spectrum indicates the general chemical
3
E 131 Terminology Relating to Molecular Spectroscopy
composition of the sample.
E 168 Practices for General Techniques of Infrared Quanti-
3 NOTE 2—The infrared spectrum of a pure chemical compound is
tative Analysis
probably the most characteristic property of that compound. However, in
the case of oils, multicomponent systems are being examined whose
1
These test methods are under the jurisdiction of ASTM Committee D-27 on
spectra are the sum total of all the spectra of the individual components.
Electrical Insulating Liquids and Gasesand are the direct responsibility of Subcom-
Because the absorption bands of the components may overlap, the
mittee D27.03on Analytical Tests.
spectrum of the oil is not as sharply defined as that for a single compound.
Current edition approved July 15, 1994. Published
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