ASTM D2780-92(1997)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 2780 – 92 (Reapproved 1997) An American National Standard
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
Solubility of Fixed Gases in Liquids
This standard is issued under the fixed designation D 2780; 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 solu- 4.1 The solubility of fixed gases in liquids is an important
bility of fixed gases in liquids. It is suitable for gases and engineering parameter in the design of hydraulic systems. It is
liquids that do not react with each other and are compatible a measure of the amount of gas which can be released from
with borosilicate glass, mercury, stainless steel, PTFE (poly- solution when a system undergoes changes in pressure and
tetrafluoroethylene), and FPM (vinylidene fluoride-hexafluoro temperature. Theoretical considerations permit approximate
propylene copolymer) under the conditions of the test. This test values of gas solubility to be computed with reasonable
method also covers the determination of the concentration of accuracy. In this test method, dissolved gases are separated
fixed gases in solutions which are not saturated with the gas. physically from a liquid and measured volumetrically. The test
1.2 This standard does not purport to address all of the method permits subsequent analysis of separated gases by any
safety concerns, if any, associated with its use. It is the appropriate method.
responsibility of the user of this standard to establish appro-
5. Apparatus
priate safety and health practices and determine the applica-
5.1 Ambient Pressure Saturator, suitable for the saturation
bility of regulatory limitations prior to use. For specific hazard
of liquids with fixed gases at various temperatures at ambient
statements see Notes 3-5, Note 7, and Note 12.
pressure is shown in Fig. 1. The system comprises four parts:
1.3 The values stated in SI units are to be regarded as the
5.1.1 Gas Supply and Pressure Regulator,
standard. The values in parentheses are for information only.
5.1.2 Gas Dispersion Element,
2. Referenced Documents
5.1.3 Heating Mantle, to fit 1000-mL separatory funnel
2.1 ASTM Standards:
(Fig. 1), and
D 831 Test Method for Gas Content of Cable and Capacitor
5.1.4 Temperature Measurement and Control Devices.
Oils
NOTE 1—In the event that it is desired to saturate a liquid with a toxic
D 2883 Test Method for Reaction Threshold Temperature of
or flammable gas, the use of this system is not recommended, unless
Liquid and Solid Materials
suitable means are provided for the collection and disposal of the escaping
D 4057 Practice for Manual Sampling of Petroleum and
gas.
Petroleum Products
5.2 Elevated Pressure Saturator, used to saturate liquids
E 260 Practice for Packed Column Gas Chromatography
with gases at pressures other than ambient. A suitable vessel,
usable at pressures up to 608 kPa (6 atm), is illustrated in Fig.
3. Summary of Test Method
2. The vessel consists of a 2.5 L stainless steel bomb with a
3.1 A specimen of the test liquid is saturated with a fixed gas
thermostatic control jacket. A valve at one end is connected to
under specified conditions of temperature and pressure. The
a pressure gage and gas supply. A valve at the other end is
saturation step may be eliminated if it is desired to determine
provided with a fitting that connects directly to the gas
the concentration of fixed gas in a liquid sample suitably
extraction apparatus.
presented for analysis. A portion of the solution of gas in liquid
5.2.1 Thermostatic Control, for jacket of saturator.
is transferred to a gas extraction apparatus in which the fixed
5.2.2 Shaker, reciprocating, horizontal.
gas is quantitatively removed from the liquid. The separated
5.2.3 Vacuum Pump, rotary.
gas is transferred to a gas buret in which its volume is
5.2.4 Transfer Line, with two male socket joint 12/2 fittings.
determined.
5.3 Gas Extraction System, as shown schematically in Fig.
3. A detailed drawing of the extraction chamber is shown in
This test method is under the jurisdiction of ASTM Committee D-2 on
Fig. 4. The apparatus provides for the separation of dissolved
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
gases from a liquid by repeatedly forcing the liquid containing
D02.11on Engineering Sciences of High Performance Fluids and Solids.
gas to pass through a narrow annular passage under reduced
Current edition approved Oct. 15, 1992. Published December 1992. Originally
published as D 2780 – 69. Last previous edition D 2780 – 86.
Annual Book of ASTM Standards, Vol 10.03.
3 5
Annual Book of ASTM Standards, Vol 05.02. The gas extraction system is similar to that described by J. H. D. Hooper, API
Annual Book of ASTM Standards, Vol 14.02. Proceedings, 1948.
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 2780
FIG. 1 Ambient Pressure Saturator
pressure. Gas removed in this manner is stored and measured the determination of the concentration of fixed gases in
in a gas buret. Provision is made for heating the extraction solutions which are not saturated with the gas, take samples in
chamber by means of a condensing vapor bath. The gas buret accordance with the procedure described in Section 3 of Test
is jacketed. Cooling water may be circulated through the jacket Method D 831.
if it is necessary to reduce the temperature of the contents of
8. Procedure A
the buret. A manometer is attached to the manifold connecting
the saturation system, gas extractor, and gas buret. Grease-free
8.1 Procedure A covers the determination of the solubility of
stopcocks and ball joints are used throughout the system (Note
fixed gases in liquids at ambient pressure.
2). All tubing and connections are 1 mm inside diameter.
8.2 Add to the ambient pressure saturator (Fig. 1) a suffi-
cient amount of the liquid to cover the gas dispersion element
NOTE 2—PTFE stopcocks are satisfactory for most purposes. However,
with at least 50 to 80 mm of liquid. Bring the cell to
for greatest precision construct the apparatus with stopcocks and joints
which are fitted with O-ring seals.
temperature equilibrium at whatever temperature is desired for
the determination.
6. Reagents and Materials
8.3 Saturate the liquid with the test gas (Warning—See
6.1 Mercury, triple-distilled, instrument-grade, sufficient
Note 4) by bubbling the gas through the liquid. Adjust the gas
amount to fill extraction apparatus, gas buret, and leveling
flow rate so that the gas stream causes thorough but not violent
bulbs.
agitation of the liquid. If saturation is to be carried out at an
elevated temperature, it may be necessary to reestablish tem-
NOTE 3—Warning: Poison can be harmful if inhaled or swallowed.
Vapor harmful, emits toxic fumes when heated. Vapor pressure at normal perature equilibrium after the start of gas flow.
room temperature exceeds threshold limit value for occupational expo-
NOTE 5—Warning: Be certain that the test gas does not react with the
sure. See A1.1.
sample under the conditions of the test. For example, oxygen may react
6.2 Compressed Gases, as required for saturating liquids to
with certain unsaturated hydrocarbons even at room temperature.
be studied.
NOTE 6—To saturate liquids at higher temperatures, it may be necessary
to preheat the saturating gas to avoid cooling the liquid. It may also be
NOTE 4—Warning: Compressed gas under high pressure. Gas reduces
necessary to provide the saturating cell with a reflux capability if it is
oxygen available for breathing. See A1.2.
desired to study volatile liquids at elevated temperatures.
7. Sampling
8.4 Attach the saturator containing the saturated liquid to
7.1 To obtain specimens for total gas solubility measure- the assembled gas extraction system (Fig. 3). Maintain tem-
ments, collect samples in accordance with Practice D 4057. For perature equilibrium of the saturator continuously in order to
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 2780
in the manner prescribed in 8.3.
NOTE 8—An excellent procedure for presentation of such samples is
given in Section 3 of Test Method D 831.
8.5.1 Lower leveling bulb H until mercury level in the gas
extraction chamber falls well below the glass umbrella F.
8.5.2 Adjust stopcock L to connect the gas extraction
chamber to the saturator through ball joint B and stopcock A.
8.5.3 Open stopcock A and permit approximately 50 mL of
the sample liquid to flow into the gas extraction chamber.
8.5.4 Close stopcock A.
8.5.5 As the liquid flows into the gas extraction chamber
some dissolved gas immediately breaks out of solution. To
transfer this gas to the buret turn stopcocks L and M so as to
connect the gas extraction chamber to the buret, raise leveling
bulb H and lower leveling bulb Q.
8.5.5.1 Care shall be taken during the gas transfer process to
avoid mercury surges, which can force the sample liquid into
manifold or gas buret P.
8.5.6 Close stopcock L. Lower leveling bulb H until the
sample liquid is drawn in a thin film through the annular space
E between the umbrella F and the wall G of the gas extraction
chamber.
8.5.7 Raise the leveling bulb H to force the liquid upward
through check valve D.
8.5.8 Repeat 8.5.6 and 8.5.7 several times, and then transfer
the liberated gas to the gas buret as described in 8.5.5.
8.5.9 Measure the volume and pressure of the gas collected
in the buret with stopcocks M and N turned to connect the buret
FIG. 2 Elevated Pressure Saturator
to the manometer R. For this measurement it is convenient to
adjust the pressure as read on manometer R in the buret to 1
prevent any change in gas content. Evacuate the system in the
atm with leveling bulb Q.
following manner:
8.5.10 Repeat 8.5.5-8.5.9 until the volume of gas collected
8.4.1 With stopcock A closed, adjust stopcocks L, M, and N
is constant.
to vent the gas extraction chamber to the atmosphere through
8.5.11 Close stopcock L and disconnect the extraction
S.
chamber from the rest of the system at ball joint C. Allow the
8.4.2 Fill the gas extraction chamber with mercury by
extraction chamber to cool if necessary.
raising leveling bulb H until mercury level reaches stopcock L.
NOTE 9—For studies of the solubility of gases in viscous liquids it m
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