ASTM D1827-92(2002)
(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
SIGNIFICANCE AND USE
Electrical insulating liquids, in many applications, require low gas content. This is the case with capacitors and certain types of cable, for example. This test is used as a factory control test and as a control and functional test in installation and maintenance work by utilities. This test requires care in manipulation and trained, careful personnel.
FIG. 1 Semimicro Apparatus for Determination of Gas Content of Insulating Liquids
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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Designation:D 1827–92(Reapproved 2002)
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 gas content by weight—theweightofgascontainedin
agivenweightofliquid,usuallyexpressedinpartspermillion.
1.1 This test method describes the determination of the gas
content of electrical insulating liquids with a viscosity of 216
4. Summary of Test Method
cSt or less at 100°C.Any gas that is nonreactive with a strong
4.1 This test method consists essentially of purging dis-
caustic solution may be determined.
solved gases from a small liquid test specimen with pure
NOTE 1—Thetestmethodhasabiasforsamplescontaininggasesother
carbon dioxide gas.The dissolved gases are then carried into a
than oxygen and nitrogen in atmospheric ratios due to differential
graduated buret (precision nitrometer) filled with a potassium
solubility effects. Gases which react with KOH such as carbon dioxide
hydroxide solution for a precise measurement. The carbon
will not be measured. Unsaturated hydrocarbons such as acetylene, if
dioxide is completely absorbed by the potassium hydroxide
present, will react with KOH to a small degree and will result in an
and the volume of other gases is measured.
underestimation of the total gas present.
1.2 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 Electrical insulating liquids, in many applications, re-
responsibility of the user of this standard to establish appro-
quire low gas content. This is the case with capacitors and
priate safety and health practices and determine the applica-
certain types of cable, for example. This test is used as a
bility of regulatory limitations prior to use.
factory control test and as a control and functional test in
installation and maintenance work by utilities. This test re-
2. Referenced Documents
quires care in manipulation and trained, careful personnel.
2.1 ASTM Standards:
D 831 Test Method for Gas Content of Cable and Capacitor
6. Apparatus (see Fig. 1)
Oils
6.1 Precision Nitrometer (azotometer), A, with a calibrated
D 923 Practices for Sampling Electrical Insulating Liquids
capacity of 1.5 mL and calibrated in 0.01-mL divisions.
D 1193 Specification of Reagent Water
Nitrometers shall have individual calibration correction tables
D3613 PracticeforInsulatingLiquidsforGasAnalysisand
that give the correct volume for each 0.01-mL point on the
Determination of Water Content
scale when a 40% aqueous potassium hydroxide solution is
used. The gas inlet shall consist of a 12/2 socket joint. The
3. Terminology
nitrometer shall be provided with a liquid leveling bulb, B,of
3.1 Definitions of Terms Specific to This Standard:
125-mL capacity. Rubber stoppers, K, with a short piece of
3.1.1 gas content by volume—of an insulating liquid, the
glass capillary tubing, should be placed in the top of the
volume of gas contained in a given volume of liquid. It is
nitrometerandthelevelingbulb, B,topreventspatteringofthe
usually expressed as a percentage at standard atmospheric
KOH solution.
conditions of 760 mm Hg pressure and 0°C temperature.
6.2 Permanent Magnet and Steel Wire,Thesmallsteelwire,
suitably consisting of a ⁄8-in. (10-mm) length of paper clip,
1 shall be placed inside the nitrometer for manipulation by the
This test method is under the jurisdiction of ASTM Committee D27 on
small external permanent magnet.
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
mittee D27.03on Physical Tests.
6.3 Pregl-Type Micro Stopcock, C, to allow delivery of gas
Current edition approved Aug. 15, 1992. Published October 1992. Originally
to nitrometer or venting the gas to the atmosphere. This
published as D1827–61T. Last previous edition D1827–84.
stopcockshallbeprovidedwitha12/2balljointattheexitside
Annual Book of ASTM Standards, Vol 10.03.
Annual Book of ASTM Standards, Vol 11.01. and a 12/2 socket joint at the inlet side.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 1827–92 (2002)
FIG. 1 Semimicro Apparatus for Determination of Gas Content of Insulating Liquids
6.4 Elbow Adapter, D, consisting of a 12/2 ball joint and 6.9 Ball-and-Socket Clamps,size12,fortightlysecuringall
having a drawn-down tip suitable for insertion in a small hole joints to prevent leakage.
in the rubber stopper, E. 6.10 Two-Way Stopcock, H, fitted to the inlet side of the
6.5 Stopper, E, of oil-resistant rubber, cut to fit the sample- purging chamber and having a 12/2 socket joint. The single-
purging chamber, F, and provided with two small holes to tubeendofthestopcockshallbeconnectedtothelow-pressure
allowtightfittingoftheelbowadapter, D,andsampledelivery 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
mLabove the disk for 10-mLtest 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-
inletshallbecutstraighttofitthestopper, E.Aflexibleheating 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).Apressure-relief valve set at
6.7 Sample Delivery Tube, G, made of a length of ⁄16-in. about1200psi(8MPa)shouldbeincluded,andcareshouldbe
(1.6-mm)insidediameterstainlesssteeltubing,tightlyinserted 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-glassfilter.Asmallsyringestopcockshallbesolderedto 6.11.2 Avacuum bottle that can be charged with solid CO .
permit the delivery of an accurate volume of liquid and Thebottlemaybeclosedwithalargerubberstopperfittedwith
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
specimenduringtransferorstorage.Thesyringefor10-mLtest
Cylinders of 99.99% minimum purity liquified carbon dioxide fitted with two
specimens shall have a calibrated capacity of 10 mL, and for
stage regulator with stainless steel diaphragms have been found satisfactory.
50-mL test specimens, a calibrated capacity of 50 mL. It shall
Cylinders of “Instrument Grade” carbon dioxide and regulators (Model No. 18-5,
be capable of accurately delivering a liquid volume within the
CGA 320) may be obtained from BOC Gases Customer Service Center, 100
accuracy required for the method. Corporate Drive, Lebanon, NJ 08833.
D 1827–92 (2002)
6.11.3 A12-qt(12-L)aluminumpressurecookerthatcanbe for obtaining samples in the field. This sample container has
charged with solid CO . It should be fitted with a suitable been found satisfactory for storing oil samples with a low gas
pressure-reliefdeviceandgasdeliverytube.Aminimumlength content for a week or more. Transfer the test specimen to the
of heavy-wall rubber or plastic tubing should be used in sample delivery tube of the measuring apparatus with a
connecting the source of CO gas to the purging chamber. syringe.
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
amountofpurgingnecessarytoremoveairfromtheapparatus.
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
7. Reagents and Materials
from flowing into the system due to gravity. Place a ⁄8-in.
(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.Unlessotherwiseindicated,itisintendedthatallreagents
bulb, B,untilthereare20or30mmofKOHsolutionabovethe
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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