ASTM D2284-95

Standard Test Method for Acidity of Sulfur Hexafluoride

SCOPE
1.1 This test method covers the determination of the acidic fluorides of sulfur hexafluoride (SF 6 ).  
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

• Status: Historical
• Publication Date: 31-Dec-1994
• Technical Committee: D27 - Electrical Insulating Liquids and Gases
• Drafting Committee: D27.06 - Chemical Test

Relations

• Replaced By: ASTM D2284-95(2002) - Standard Test Method for Acidity of Sulfur Hexafluoride (Withdrawn 2011)
• Effective Date: 15-Mar-1995

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NOTICE: This standard has either been superseded and replaced by a new version or
withdrawn.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.
Designation: D 2284 – 95
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
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Acidity of Sulfur Hexafluoride
This standard is issued under the fixed designation D 2284; 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 6. Reagents
1.1 This test method covers the determination of the acidic 6.1 Purity of Reagents—Use reagent grade chemicals in all
fluorides of sulfur hexafluoride (SF ). tests. Unless otherwise indicated, it is intended that all reagents
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1.2 This standard does not purport to address all of the shall conform to the specifications of the Committee on
safety concerns, if any, associated with its use. It is the Analytical Reagents of the American Chemical Society, where
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responsibility of the user of this standard to establish appro- such specifications are available. Other grades may be used,
priate safety and health practices and determine the applica- provided it is first ascertained that the reagent is of sufficiently
bility of regulatory limitations prior to use. high purity to permit its use without lessening the accuracy of
the determination.
2. Referenced Documents
6.2 Purity of Water—Unless otherwise indicated, references
to water shall be understood to mean reagent grade water
2.1 ASTM Standards:
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conforming to Specification D 1193.
D 1193 Specification for Reagent Water
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6.3 Phenolphthalein Indicator Solution (10 g/L)—Dissolve
D 2472 Specification for Sulfur Hexafluoride
1 g of phenolphthalein in 100 mL of ethanol (95 %).
3. Summary of Test Method
6.4 Sodium Hydroxide Solution (0.01 N)—Dissolve 0.4 6
0.01 g of sodium hydroxide (NaOH) in water and dilute to 1 L.
3.1 Acidic constituents of the sample are absorbed in
Prepare a fresh solution weekly. Standardize by titrating
slightly alkaline water containing an indicator and the excess
against a weighed amount of potassium acid phthalate.
base titrated with a standard acid solution. The resultant acidity
6.5 Sulfuric Acid (0.01 N)—Add 0.25 mL of concentrated
is expressed as equivalents of hydrofluoric acid (HF).
sulfuric acid (H SO , sp gr 1.84) to water and dilute to 1 L.
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Standardize against standard 0.01 N NaOH solution.
4. Significance and Use
4.1 Acidic fluorides are undesirable in SF used as an
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7. Sampling
electrical insulating gas in that they may contribute to corro-
7.1 Take the sample as a liquid from the cylinder to be
sion or constitute dielectric hazard.
sampled. This may be done by inverting the cylinder so that the
4.2 This test method is valid for both new and used SF .In
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outlet valve is at the bottom.
used SF , it will only measure those active species which are
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hydrolyzable.
8. Preparation of Apparatus
8.1 Place the cylinder to be sampled as suggested in Section
5. Apparatus
7 and connect a needle valve to the cylinder outlet. Connect the
5.1 Gas Washing Bottles, 500-mL capacity, two required.
inlet of one of the gas sampling bottles to the cylinder needle
5.2 Microburet, graduated to 0.01 mL.
valve and the outlet to the wet test meter. Flexible rubber or
5.3 Wet Test Meter.
plastic tubing can be used. Set the meter to zero and note the
reading.
NOTE 1—The meter is used to measure the volume of dry gas in litres
and hence the weight of SF samples. The density of sulfur hexafluoride
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9. Procedure
at 0°C and 1 atm. of pressure (STP) is 6.52 g/L. The density of sulfur
hexafluoride at 25°C and 1 atm. of pressure (normal temperature and
9.1 Boil about 600 mL of deionized water in a 1-L beaker
pressure) is 5.97 g/L. Alternatively, the sample weight may be determined
for about 5 min and cool quickly to room temperature. Add 10
by weighing the sample cylinder before and after sampling.
drops of phenolphthalein indicator solution and enough 0.01 N
NaOH solution to color the solution faintly pink. Pour half of
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This test method is under the jurisdiction of ASTM Committee D-27 on
Electrical Insulating Liquids and Gasesand is the direct responsibility of Subcom-
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mittee D27.06on Chemical Test. “Reagent Chemicals, American Chemical Society Specifications,” Am. Chemi-
Current edition approved March 15, 1995. Published May 1995. Originally cal Soc., Washington, DC. For suggestions on the testing of reagents not listed by
published as D2284 – 64T. Last previous edition D 2284 – 88. the American Chemical Society, see “Reagent Chemicals and Standards,” by Joseph
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Annual Book of ASTM Standards, Vol 11.01. Rosin, D. Van Nostrand Co., Inc., New York, NY, and the “United States
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Annual Book of
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