ASTM D2945-90(2003)
(Test Method)Standard Test Method for Gas Content of Insulating Oils
Standard Test Method for Gas Content of Insulating Oils
SCOPE
1.1 This test method covers the determination of the gas content of electrical insulating oils of low and medium viscosities in the general range of 100 SUS and below at 100°F (37.8°C), and is suitable for field or laboratory use.
Note 1—For testing insulating oils with viscosities above 100 SUS, see Test Method D 831. For individual gas concentrations, see Method D 3612.
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 the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
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.
1. Scope 4. Significance and Use
1.1 This test method covers the determination of the gas 4.1 In filling electrical apparatus, it is desirable to use low
content of electrical insulating oils of low and medium gas content transformer oil in order to prevent foaming and to
viscosities in the general range of 100 SUS and below at 100°F avoid air pockets that might result in gaseous ionization. This
(37.8°C), and is suitable for field or laboratory use. procedure provides a simple method to measure the gas content
of the oil, and may be used as a factory-control test and as a
NOTE 1—For testing insulating oils with viscosities above 100 SUS, see
control or functional test in installation and maintenance work
Test Method D 831. For individual gas concentrations, see Method
by utilities.
D 3612.
1.2 This standard does not purport to address all of the
5. Apparatus
safety concerns, if any, associated with its use. It is the
5.1 Dissolved Gas Content Analyser—Fig. 1 shows the
responsibility of the user of this standard to establish appro-
assembled instrument, not drawn to scale, to permit magnifi-
priate safety and health practices and determine the applica-
cation of small details. A borosilicate glass gas buret, 100-mL
bility of regulatory limitations prior to use.
capacity, graduated in ⁄5-mL divisions, serves as a vacuum
chamber. A three-way stopcock, 120° bore with TFE-
2. Referenced Documents
fluorocarbon plug, 3 stem, 2-mm bore is fused to the buret or
2.1 ASTM Standards:
joined by a vinyl sleeve so that the joint is vacuum tight.
D 831 Test Method for Gas Content of Cable and Capacitor
5.1.1 Rubber Vacuum Tubing—About 1200 mm of 8-mm
Oils
rubber vacuum tubing is securely fastened with a 20-mm
D 3612 Test Method for Analysis of Gases Dissolved in
Hoffman pinch clamp to the lower tip of the buret, while the
Electrical Insulating Oil by Gas Chromatography
other end is secured to a 250-mL capacity leveling bulb.
D 3613 Practice for Sampling Insulating Liquids for Gas
5.1.2 Stubs 20 Gage Needle—A short section, about 40 mm
Analysis and Determination of Water Content
long, is cut and cemented to the three-way stopcock, Fig. 2.
This serves to accommodate the vinyl tubing attached to the
3. Summary of Test Method
syringe. All the glassware should be clamped to a suitable 1500
3.1 This test method consists essentially of allowing oil to
by 700 by 20-mm mounting board with rubber-covered wall-
flow into an evacuated chamber as a thin film so that the oil is
type clamps.
thoroughly exposed to the vacuum, allowing free volatilization
5.1.3 Metal Rod, 12 mm, 1500 mm long, fitted with an
of the gaseous component. The system is brought back to
adjustable leveling bulb support is fastened to the wooden
atmospheric pressure, and the evolved gases measured. From
apparatus mounting board as in 5.1.2.
the volume of oil degassed in the chamber and the volume of
5.2 Syringe Assembly (see Fig. 3)—A 50-mL Luer syringe
released gas, the percent gas content may be estimated. The
with 5-mL subdivisions or a 5-mL Luer syringe with ⁄5-mL
apparatus used produces the necessary vacuum without resort-
subdivisions is fitted with a 150-mm length of 0.8-mm inside
ing to use of a vacuum pump. This test method partially
diameter capillary vinyl tubing. An upper and lower collar of
degases the oil. The degree of degasification varies with the
plastic or metal is attached to the syringe to support the rubber
solubility of each gas in the oil.
bands required to create positive pressure in the syringe.
A20-mm Hoffman pinch clamp is used on the capillary tubing
This test method is under the jurisdiction of ASTM Committee D27 on
after sampling.
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
5.3 Oil Sampler (see Fig. 3)—A 3.2-mm tee is fitted with a
mittee D27.03 on Analytical Tests.
syringe needle stem in one arm and a short length of 6.4-mm.
Current edition approved Feb. 23, 1990. Published April 1990. Originally
Vinyl tubing is attached to the other arm. During sampling, the
published as D 2945 – 71. Last previous edition D 2945 – 84.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
tee is attached to the sampling valve and the vinyl capillary
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
tubing of the syringe assembly is attached to the needle of the
Standards volume information, refer to the standard’s Document Summary page on
tee.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
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, ⁄4 by 1 in.
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, 2.6-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
5.4 Mercury Reservoir—A 250-mL capacity leveling bulb is 6.2 An effective method is to take the sample directly from
filled with 4.5 kg (10 lb) of mercury. the pressurized line into the sampling syringe. The syringe is
maintained under slight positive pressure during the taking of
6. Sampling
the sample, during sample transfer, and during the introduction
6.1 Samples shoul
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