ASTM D1827-92(1996)e1
(Test Method)Standard Test Method for Gas Content (Nonacidic) of Insulating Liquids by Displacement with Carbon Dioxide
Standard Test Method for Gas Content (Nonacidic) of Insulating Liquids by Displacement with Carbon Dioxide
SCOPE
1.1 This test method describes the determination of the gas content of electrical insulating liquids with a viscosity of 216 cSt or less at 100°C. Any gas that is nonreactive with a strong caustic solution may be determined.
Note 1-The test method has a bias for samples containing gases other than oxygen and nitrogen in atmospheric ratios due to differential solubility effects. Gases which react with KOH such as carbon dioxide will not be measured. Unsaturated hydrocarbons such as acetylene, if present, will react with KOH to a small degree and will result in an underestimation of the total gas present.
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.
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e1
Designation: D 1827 – 92 (Reapproved 1996)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Gas Content (Nonacidic) of Insulating Liquids by
Displacement with Carbon Dioxide
This standard is issued under the fixed designation D 1827; 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—Editorial changes were made throughout in February 1997.
1. Scope 4. Summary of Test Method
1.1 This test method describes the determination of the gas 4.1 This test method consists essentially of purging dis-
content of electrical insulating liquids with a viscosity of 216 solved gases from a small liquid test specimen with pure
cSt or less at 100°C. Any gas that is nonreactive with a strong carbon dioxide gas. The dissolved gases are then carried into a
caustic solution may be determined. graduated buret (precision nitrometer) filled with a potassium
hydroxide solution for a precise measurement. The carbon
NOTE 1—The test method has a bias for samples containing gases other
dioxide is completely absorbed by the potassium hydroxide
than oxygen and nitrogen in atmospheric ratios due to differential
and the volume of other gases is measured.
solubility effects. Gases which react with KOH such as carbon dioxide
will not be measured. Unsaturated hydrocarbons such as acetylene, if
present, will react with KOH to a small degree and will result in an
5. Significance and Use
underestimation of the total gas present.
5.1 Electrical insulating liquids, in many applications, re-
1.2 This standard does not purport to address all of the
quire low gas content. This is the case with capacitors and
safety concerns, if any, associated with its use. It is the
certain types of cable, for example. This test is used as a
responsibility of the user of this standard to establish appro-
factory control test and as a control and functional test in
priate safety and health practices and determine the applica-
installation and maintenance work by utilities. This test re-
bility of regulatory limitations prior to use.
quires care in manipulation and trained, careful personnel.
2. Referenced Documents
6. Apparatus (see Fig. 1)
2.1 ASTM Standards:
6.1 Precision Nitrometer (azotometer), A, with a calibrated
D 831 Test Method for Gas Content of Cable and Capacitor
capacity of 1.5 mL and calibrated in 0.01-mL divisions.
Oils
Nitrometers shall have individual calibration correction tables
D 923 Test Method for Sampling Electrical Insulating
that give the correct volume for each 0.01-mL point on the
Liquids
scale when a 40 % aqueous potassium hydroxide solution is
D 1193 Specification of Reagent Water
used. The gas inlet shall consist of a 12/2 socket joint. The
D 3613 Test Methods of Sampling Electrical Insulating Oils
nitrometer shall be provided with a liquid leveling bulb, B,of
for Gas Analysis and Determination of Water Content
125-mL capacity. Rubber stoppers, K, with a short piece of
glass capillary tubing, should be placed in the top of the
3. Terminology
nitrometer and the leveling bulb, B, to prevent spattering of the
3.1 Definitions of Terms Specific to This Standard:
KOH solution.
3.1.1 gas content by volume—of an insulating liquid, the
6.2 Permanent Magnet and Steel Wire, The small steel wire,
volume of gas contained in a given volume of liquid. It is
suitably consisting of a ⁄8-in. (10-mm) length of paper clip,
usually expressed as a percentage at standard atmospheric
shall be placed inside the nitrometer for manipulation by the
conditions of 760 mm Hg pressure and 0°C temperature.
small external permanent magnet.
3.1.2 gas content by weight—the weight of gas contained in
6.3 Pregl-Type Micro Stopcock, C, to allow delivery of gas
a given weight of liquid, usually expressed in parts per million.
to nitrometer or venting the gas to the atmosphere. This
stopcock shall be provided with a 12/2 ball joint at the exit side
1 and a 12/2 socket joint at the inlet side.
This test method is under the jurisdiction of ASTM Committee D-27 on
6.4 Elbow Adapter, D, consisting of a 12/2 ball joint and
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
mittee D27.03on Physical Tests.
having a drawn-down tip suitable for insertion in a small hole
Current edition approved Aug. 15, 1992. Published October 1992. Originally
in the rubber stopper, E.
published as D 1827 – 61 T. Last previous edition D 1827 – 84.
6.5 Stopper, E, of oil-resistant rubber, cut to fit the sample-
Annual Book of ASTM Standards, Vol 10.03.
Annual Book of ASTM Standards, Vol 11.01. purging chamber, F, and provided with two small holes to
NOTICE:¬This¬standard¬has¬either¬been¬superseded¬and¬replaced¬by¬a¬new¬version¬or
discontinued.¬Contact¬ASTM¬International¬(www.astm.org)¬for¬the¬latest¬information.¬
D 1827
FIG. 1 Semimicro Apparatus for Determination of Gas Content of Insulating Liquids
allow tight fitting of the elbow adapter, D, and sample delivery carbon dioxide supply to control the entry of this gas to the
tube, G. apparatus.
6.6 Sample-Purging Chamber, F, with a 10-mm diameter 6.11 Low-Pressure Source of very pure carbon dioxide
fritted-glass disk, L, of medium porosity and a capacity of 15
(CO ) gas. If gas of sufficient purity is not available, one of
mL above the disk for 10-mL test specimens, or with a 25-mm the following mechanisms utilizing solid CO shall be used:
diameter fritted glass disk of medium porosity and a capacity
6.11.1 A high-pressure cylinder having an opening large
of 75 mL above the disk for 50-mL test specimens. The gas
enough to insert pieces of solid CO and capable of withstand-
inlet shall be cut straight to fit the stopper, E. A flexible heating
ing 800 to 1000 psi (5.5 to 7 MPa) pressure when the solid
tape, wrapped around the purging chamber, is necessary for
evaporates. The cylinder should be provided with a pressure-
holding constant temperature when test specimens are purged
reduction valve capable of delivering gas at a gage pressure as
at temperatures in excess of room temperature.
low as 3 to 5 psi (20 to 34 kPa). A pressure-relief valve set at
6.7 Sample Delivery Tube, G, made of a length of ⁄16-in.
about 1200 psi (8 MPa) should be included, and care should be
(1.6-mm) inside diameter stainless steel tubing, tightly inserted
exercised to limit the quantity of solid CO placed in the
into one of the holes in the stopper, E, and extending to the
cylinder due to the greater volume occupied by the gas.
fritted-glass filter. A small syringe stopcock shall be soldered to
6.11.2 A vacuum bottle that can be charged with solid CO .
permit the delivery of an accurate volume of liquid and
The bottle may be closed with a large rubber stopper fitted with
subsequent sealing of the purging chamber.
a pressure-bleed regulator, a mercury relief valve, a nichrome
6.8 Sampling Device, consisting of a calibrated glass medi-
heating element, and a gas delivery tube to the apparatus.
cal syringe fitted with a syringe stopcock for sealing of the test
6.11.3 A 12-qt (12-L) aluminum pressure cooker that can be
specimen during transfer or storage. The syringe for 10-mL test
charged with solid CO . It should be fitted with a suitable
specimens shall have a calibrated capacity of 10 mL, and for
pressure-relief device and gas delivery tube. A minimum length
50-mL test specimens, a calibrated capacity of 50 mL. It shall
of heavy-wall rubber or plastic tubing should be used in
be capable of accurately delivering a liquid volume within the
connecting the source of CO gas to the purging chamber.
accuracy required for the method.
6.9 Ball-and-Socket Clamps, size 12, for tightly securing all
Cylinders of 99.99 % minimum purity liquified carbon dioxide fitted with two
joints to prevent leakage.
stage regulator with stainless steel diaphragms have been found satisfactory.
6.10 Two-Way Stopcock, H, fitted to the inlet side of the
Cylinders of “Instrument Grade” carbon dioxide and regulators (Model No. 18-5,
purging chamber and having a 12/2 socket joint. The single-
CGA 320) may be obtained from Airco Rare and Specialty Gases, 575 Mountain A,
tube end of the stopcock shall be connected to the low-pressure Murray Hill, NJ 07974.
NOTICE:¬This¬standard¬has¬either¬been¬superseded¬and¬replaced¬by¬a¬new¬version¬or
discontinued.¬Contact¬ASTM¬International¬(www.astm.org)¬for¬the¬latest¬information.¬
D 1827
6.12 All glass shall be heat- and chemical-resistant. Capil- 9. Preparation of Apparatus
lary tubing should be used wherever possible to minimize the
9.1 Fill the bottom portion of the nitrometer, A, with
amount of purging necessary to remove air from the apparatus.
mercury to a point about 5 to 7 mm above the gas entry
6.13 An auxiliary source of vacuum, with trap, to facilitate
capillary. The mercury acts as a valve to allow the gas to
removal of spent test specimen, is optional.
bubble into the buret and also to prevent the KOH solution
from flowing into the system due to gravity. Place a ⁄8-in.
7. Reagents and Materials
(10-mm) piece of steel wire on the mercury.
7.1 Purity of Reagents—Use reagent grade chemicals in all
9.2 Open stopcock J and add KOH solution to the leveling
tests. Unless otherwise indicated, it is intended that all reagents
bulb, B, until there are 20 or 30 mm of KOH solution above the
conform to the specifications of the Committee on Analytical
stopcock, J, with the solution in the leveling bulb at the same
Reagents of the American Chemical Society, where such
level. Remove all bubbles from the nitrometer, using the steel
specifications are available. Other grades may be used, pro-
wire and magnet.
vided it is first ascertained that the reagent is of sufficiently
9.3 The system must be kept completely leak-free, since
high purity to permit its use without lessening the accuracy of
even small leaks allow diffusion of air into the apparatus and
the determ
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