ASTM D3277-95(2001)e1
(Test Method)Standard Test Methods for Moisture Content of Oil-Impregnated Cellulosic Insulation (Withdrawn 2010)
Standard Test Methods for Moisture Content of Oil-Impregnated Cellulosic Insulation (Withdrawn 2010)
SIGNIFICANCE AND USE
Moisture has an adverse effect on the dielectric strength, dielectric loss, dc resistivity, and aging characteristics of oil-impregnated cellulosic insulating materials.
When cellulosic insulation such as paper and pressboard are impregnated with and immersed in oil, there is an interchange of moisture between the cellulose and oil until they attain equilibrium with respect to their relative saturations with moisture.
Considerable care should be taken in using these test methods to measure the water content of dry (0.5 %) paper and board. Contamination of material by water from the surroundings during sampling and handling may be both rapid and significant in the case of dry test specimens. This is an even greater concern with cellulose insulation prior to oil impregnation.
SCOPE
1.1 These test methods cover the determination of the weight percent of water in new or aged, oil-impregnated electrical insulation. These test methods depend on solvent extraction of the water at room temperature. The range from 0.1 to 7.0% water has been explored.
1.2 There are four test methods, A, B, C, and D. Methods A and B for thin paper and dense materials, respectively, are manual methods for solvent extraction of water from the specimens. Titration is used to determine the amount of water. Method C uses automatic titration to determine the amount of water. Method D is a direct automated method for extraction and detection of the water.
1.3 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.
WITHDRAWN RATIONALE
These test methods cover the determination of the weight percent of water in new or aged, oil-impregnated electrical insulation. These test methods depend on solvent extraction of the water at room temperature. The range from 0.1 to 7.0 % water has been explored.
Formerly under the jurisdiction of Committee D27 on Electrical Insulating Liquids and Gases and the direct responsibility of Subcommittee D27.06 on Chemical Test, these test methods were withdrawn in January 2010 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
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Designation: D3277 – 95 (Reapproved 2001)
Standard Test Methods for
Moisture Content of Oil-Impregnated Cellulosic Insulation
This standard is issued under the fixed designation D3277; 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 (´) indicates an editorial change since the last revision or reapproval.
´ NOTE—Editorial changes were made in April 2001.
1. Scope 4. Significance and Use
1.1 These test methods cover the determination of the 4.1 Moisture has an adverse effect on the dielectric strength,
weight percent of water in new or aged, oil-impregnated dielectric loss, dc resistivity, and aging characteristics of
electrical insulation. These test methods depend on solvent oil-impregnated cellulosic insulating materials.
extraction of the water at room temperature. The range from 4.2 When cellulosic insulation such as paper and pressboard
0.1 to 7.0 % water has been explored. are impregnated with and immersed in oil, there is an inter-
1.2 There are four test methods,A, B, C, and D. MethodsA change of moisture between the cellulose and oil until they
and B for thin paper and dense materials, respectively, are attain equilibrium with respect to their relative saturations with
manual methods for solvent extraction of water from the moisture.
specimens. Titration is used to determine the amount of water. 4.3 Considerable care should be taken in using these test
Method C uses automatic titration to determine the amount of methods to measure the water content of dry (<0.5 %) paper
water. Method D is a direct automated method for extraction and board. Contamination of material by water from the
and detection of the water. surroundings during sampling and handling may be both rapid
1.3 This standard does not purport to address all of the andsignificantinthecaseofdrytestspecimens.Thisisaneven
safety concerns, if any, associated with its use. It is the greater concern with cellulose insulation prior to oil impreg-
responsibility of the user of this standard to establish appro- nation.
priate safety and health practices and determine the applica-
5. Apparatus
bility of regulatory limitations prior to use.
5.1 Karl Fischer Electrometric Titration Apparatus.
2. Referenced Documents
5.2 Magnetic Stirrer and TFE-Fluorocarbon Coated Stir-
2.1 ASTM Standards: ring Bars.
D1533 Test Method for Water in Insulating Liquids by 5.3 Erlenmeyer Flasks, glass-stoppered, 250-mL.
Coulometric Karl Fischer Titration 5.4 Graduate, glass, 100-mL.
5.5 Büchner Funnel, small porcelain.
3. Summary of Test Methods
5.6 Micro-Syringe, total capacity 0.2 mL, 0.01-mL divi-
3.1 These test methods depend on solvent extraction of the
sions.
moisture at room temperature and Karl Fischer titration (see 5.7 Blender, industrial type.
Test Methods D1533). For paper insulation 0.010 in. (0.25 5.8 Syringe, 10 mL, ground glass.
mm) thick and less, extraction is accomplished by stirring the
5.9 Drying Oven,1106 5°C.
solvent with small pieces of insulation. In the special case of 5.10 Laboratory Desiccator.
dense, thick sections, such as pressboard, the extraction rate is
5.11 Analytical Balance.
increased by delaminating thick sections and pulping the
6. Reagents
sample in a blender.
6.1 Karl Fischer Reagent—Commercially available stabi-
lized solution, diluted from approximately 5 mg of water per 1
These test methods are under the jurisdiction of ASTM Committee D27 on
mL to 2.5 to 3.0 mg of water per 1 mL by adding absolute
Electrical Insulating Liquids and Gases and are the direct responsibility of
acetone-free methanol (MethodsAand B). For Methods C and
Subcommittee D27.06 on Chemical Test.
Current edition approved June 15, 1995. Published August 1995. Originally
D, prepare commercially available solutions for use in auto-
published as D3277 – 73. Last previous edition D3277 – 94. DOI: 10.1520/D3277-
matic titrators in accordance with the manufacturer’s instruc-
95R01E01.
tions.
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
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D3277 – 95 (2001)
6.2 Titration Solvent—Mix 2 volumes of acetone-free 8.3 Weigh the syringe and its contents to the nearest 0.1 mg
methanol and 1 volume of dry chloroform. Keep the solution on an analytical balance.
tightly capped to prevent moisture absorption from the atmo-
8.4 Deliver from 0.03 to 0.05 mL of water into the neutral-
sphere.
ized solvent.
6.3 Purity of Reagents—Use reagent grade chemicals in all
8.5 Reweigh the syringe to determine the exact weight of
tests. Unless otherwise indicated, it is intended that all reagents
water added to the neutralized titration solvent.
shall conform to the Committee on Analytical Reagents of the
8.6 Reneutralize the solution by titrating with the Karl
American Chemical Society, where such specifications are
Fischer reagent.
available. Other grades may be used, provided that it is first
8.7 Calculate the water equivalent of the Karl Fischer
ascertained that the reagent is of sufficiently high purity to
reagent (grams of water per millilitre of Karl Fischer reagent)
permit its use without lessening the accuracy of the determi-
bydividingtheweightofwateradded,ingrams,bythevolume
nation.
inmillilitresofKarlFischerreagentrequiredfortitrationofthe
6.4 Methanol, acetone-free with no more than 0.001 %
added water.
acetone.
9. Procedure
7. Sampling
9.1 Test MethodA(0.010 in. (0.254 mm) or Thinner Paper):
7.1 The sampling procedure is not defined since it would be
9.1.1 Proceed in accordance with 8.1.
different for different apparatus, whether the samples were new
9.1.2 Dry the solvent containing more than 50 ppm of water
or aged. Sample storage may also vary depending upon
by weight, which may be achieved by numerous techniques.
expected water content and time between sampling and testing.
Onetechniqueistopassthesolventthrougha30by1 ⁄2-in.(76
The assumption is made that the sample is representative of the
by4-cm)columncontaining3Amolecularsievedriedat250°C
condition the analyst is attempting to assess.
under vacuum for at least 4 h. Purging with dry nitrogen
7.1.1 Dried cellulose absorbs moisture at an extremely fast
instead of using a vacuum and the use of other temperatures
rate. Precautions such as using polyethylene gloves for han-
can also achieve properly prepared molecular sieve material.
dling sample materials, and flushing the sample bottles with
Regardless of the test method used, test the dried solvent using
nitrogen during sampling have been found to be good prac-
a Karl Fischer apparatus to verify that the water content is less
tices, especially when testing for low levels of moisture in
than 50 ppm by weight. Store the dried solvent under nitrogen.
cellulose. Drying the sample bottle may cause a slight negative
9.1.3 Add 100 mL of titration solvent to each of two
bias, but this would be expected to be much smaller than the
Erlenmeyer flasks which have previously been pre-dried for a
positive bias that would occur if moist air were left in a sample
minimum of 4 h at 125°C. Place a dry TFE-fluorocarbon
container. Other practices, such as placing the paper immedi-
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coated stirring bar (about 1 ⁄2 in. (38 m) long by ⁄16 in. (8 mm)
ately into a bottle containing the oil from the apparatus from
in diameter) in each flask.
which it was taken, leaving little or no air space and a high
9.1.4 To one flask, add 2 to3gof paper sample to be
solid to liquid weight ratio, have been found to preserve the
1 1
analyzed,cutintostrips ⁄2by1 ⁄2in.(13by38mm)orsmaller.
water content. The time element during which the paper
9.1.5 Insert a stopper in each flask and agitate contents for
sample is exposed to ambient conditions must be minimized
40 to 50 min.
and kept under several minutes when low (<1 %) water
9.1.6 Decant the solvent from the flask containing the paper
contents are expected.Another method of preservation that has
strips into the titration chamber of the Karl Fischer apparatus
been used is to wrap large sections of paper in plastic wrap
and titrate.
followed by a layer of foil wrap.
9.1.7 Place the paper strips in a weighing dish, dry for at
least 4 h at 110°C, cool to room temperature in a desiccator,
8. Standardization of Reagent by Distilled Water (Test
andweigh.Thisweight,minusthetare,isthespecimenweight.
Methods A and B)
9.1.8 Repeat 9.1.6 for the flask that did not contain any
8.1 Add about 100 mL of solvent (chloroform-methanol) to
paper. This is the blank.
the clean titration flask. Turn on the indicating circuit and
9.1.9 Determine percent weight of water in the paper as
magnetic stirrer and adjust the potentiometer to maximum
follows:
deflection. (Check the battery every day.) Then add the Karl
Fischer reagent in large amounts to neutralize the water present
Water, wt % 5 [~@1.03 V 2 V #F! 3 100]/W (1)
2 1
in the solvent. At first the needle will deflect due to local
where:
concentrations of the unreacted reagent about the electrodes,
1.03 = correction factor for the loss of solvent during this
but will fall back to near the original position.As the end point
analytical procedure due to adsorption of solvent
isreached,theneedlewillfallbackmoreandmoreslowlyafter
into the paper,
each addition of Karl Fischer reagent. The end point is reached
V = Karl Fischer reagent required for titration of the
when, after addition of a single drop of reagent, the needle
solvent from the flask containing the paper strips,
remains at rest near the position of maximum deflection for 30
mL,
s.
V = Karl Fischer reagent required for titration of the
8.2 Partially fill a small-volume syringe (such as a Gilmont
solvent from the flask containing no paper, mL,
micrometer syringe of 0.2-mL capacity) with distilled water.
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