ASTM D2945-90(2003)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:D 2945–90(Reapproved 2003)
Standard Test Method for
Gas Content of Insulating Oils
This standard is issued under the fixed designation D 2945; 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.
e NOTE—The metric value for the inside diameter of vinyl tubing in Fig. 1 was corrected editorially in December 2003.
1. Scope apparatus used produces the necessary vacuum without resort-
ing to use of a vacuum pump. This test method partially
1.1 This test method covers the determination of the gas
degases the oil. The degree of degasification varies with the
content of electrical insulating oils of low and medium
solubility of each gas in the oil.
viscosities in the general range of 100 SUS and below at 100°F
(37.8°C), and is suitable for field or laboratory use.
4. Significance and Use
NOTE 1—Fortestinginsulatingoilswithviscositiesabove100SUS,see
4.1 In filling electrical apparatus, it is desirable to use low
Test Method D 831. For individual gas concentrations, see Method
gas content transformer oil in order to prevent foaming and to
D 3612.
avoid air pockets that might result in gaseous ionization. This
1.2 This standard does not purport to address all of the
procedureprovidesasimplemethodtomeasurethegascontent
safety concerns, if any, associated with its use. It is the
of the oil, and may be used as a factory-control test and as a
responsibility of the user of this standard to establish appro-
control or functional test in installation and maintenance work
priate safety and health practices and determine the applica-
by utilities.
bility of regulatory limitations prior to use.
5. Apparatus
2. Referenced Documents
5.1 Dissolved Gas Content Analyser—Fig. 1 shows the
2.1 ASTM Standards:
assembled instrument, not drawn to scale, to permit magnifi-
D 831 Test Method for Gas Content of Cable and Capacitor
cation of small details. A borosilicate glass gas buret, 100-mL
Oils 1
capacity, graduated in ⁄5-mL divisions, serves as a vacuum
D 3612 Test Method for Analysis of Gases Dissolved in
chamber. A three-way stopcock, 120° bore with TFE-
Electrical Insulating Oil by Gas Chromatography
fluorocarbon plug, 3 stem, 2-mm bore is fused to the buret or
D 3613 Practice for Sampling Insulating Liquids for Gas
joined by a vinyl sleeve so that the joint is vacuum tight.
Analysis and Determination of Water Content
5.1.1 Rubber Vacuum Tubing—About 1200 mm of 8-mm
rubber vacuum tubing is securely fastened with a 20-mm
3. Summary of Test Method
Hoffman pinch clamp to the lower tip of the buret, while the
3.1 This test method consists essentially of allowing oil to
other end is secured to a 250-mL capacity leveling bulb.
flow into an evacuated chamber as a thin film so that the oil is
5.1.2 Stubs 20 Gage Needle—Ashort section, about 40 mm
thoroughly exposed to the vacuum, allowing free volatilization
long, is cut and cemented to the three-way stopcock, Fig. 2.
of the gaseous component. The system is brought back to
This serves to accommodate the vinyl tubing attached to the
atmospheric pressure, and the evolved gases measured. From
syringe.Alltheglasswareshouldbeclampedtoasuitable1500
the volume of oil degassed in the chamber and the volume of
by 700 by 20-mm mounting board with rubber-covered wall-
released gas, the percent gas content may be estimated. The
type clamps.
5.1.3 Metal Rod, 12 mm, 1500 mm long, fitted with an
1 adjustable leveling bulb support is fastened to the wooden
This test method is under the jurisdiction of ASTM Committee D27 on
apparatus mounting board as in 5.1.2.
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
mittee D27.03 on Analytical Tests.
5.2 Syringe Assembly (see Fig. 3)—A 50-mL Luer syringe
Current edition approved Feb. 23, 1990. Published April 1990. Originally
with 5-mL subdivisions or a 5-mL Luer syringe with ⁄5-mL
published as D 2945 – 71. Last previous edition D 2945 – 84.
subdivisions is fitted with a 150-mm length of 0.8-mm inside
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM diameter capillary vinyl tubing. An upper and lower collar of
Standards volume information, refer to the standard’s Document Summary page on
plastic or metal is attached to the syringe to support the rubber
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D 2945–90 (2003)
1 gas buret, capacity 100 mL, graduated in ⁄5-mL divisions
1 stopcock, 120° bore with TFE fluorocarbon plug, 3 stems, 2-mm bore
1 leveling bulb, capacity 250 mL
1 beaker, capacity 250 mL
1200 mm (4 ft) vacuum rubber tubing, 8-mm ( ⁄16-in.) inside diameter
2 rubber tubing clamps, adjustable, cadmium-plated steel
2-pinch clamps, Hoffman swivel jaw, screw compressor, ⁄4 by 1 in. for vinyl tubing for 5 and 50-mL syringes
1 pinch clamp, Hoffman screw compressor for rubber tubing, ⁄4by1in.
6 clamps, wall type with wood screw to support buret, stopcock, and rod
1 leveling bulb support, adjustable, Fisher-Castaloy-R, self-locking
1 rod, diameter 12 mm ( ⁄2 in.), length 1500 mm (58 in.)
1 syringe, Luer, resistance glass, 50 mL, subdivisions 5 mL
1 syringe, Luer, resistance glass, 5 mL, subdivisions ⁄5 mL
1 1
Vinyl tubing, 1.6-mm ( ⁄16-in.) inside diameter, wall thickness 1.3 mm ( ⁄32 in.), length 150 mm (6 in.)
4.5 kg (10 lb) mercury
1 needle, 50 mm long, Stubbs gage 20
1 wooden board 1500 by 700 by 20 mm (58 by 28 by ⁄8 in.)
Components for Gas-Content Apparatus
FIG. 1 Dissolved Gas Content Analyser
FIG. 2 Detail of Needle Inlet
bands required to create positive pressure in the syringe. Vinyl tubing is attached to the other arm. During sampling, the
A20-mm Hoffman pinch clamp is used on the capillary tubing tee is attached to the sampling valve and the vinyl capillary
after sampling.
tubing of the syringe assembly is attached to the needle of the
5.3 Oil Sampler (see Fig. 3)—A 3.2-mm tee is fitted with a
tee.
syringe needle stem in one arm and a short length of 6.4-mm.
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D 2945–90 (2003)
FIG. 3 Oil Sampler
5.4 MercuryReservoir—A250-mLcapacitylevelingbulbis the (1) OFF position (A). Mount the syringe assembly on
filled
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