ASTM D3429-93(1998)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 3429 – 93 (Reapproved 1998)
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 Low-Boiling Liquids
This standard is issued under the fixed designation D 3429; 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 column by displacing it with the flowing carrier gas.
3.1.7 fractionation, n—change of composition caused by
1.1 This test method covers the determination of the solu-
change of pressure.
bilities of nonreactive gases such as nitrogen and helium in
liquids that boil below 273 K. This test method is applicable at
4. Summary of Test Method
temperatures from 77 to 300 K from subambient pressure to
4.1 A sample of test liquid A is saturated with test gas B at
6.5 MPa (65 atm). This test method does not provide for
specified temperature and pressure. A portion of the solution is
analysis of the vapor phase in equilibrium with the liquid (see
withdrawn and vaporized in an evacuated sample container at
Section 3 for a description of terms).
room temperature. The concentration of gas B in the vaporized
1.2 This test method as written describes the procedures to
sample is determined by gas chromatography. It is necessary
be followed for determination of the solubilities of helium and
that the molar concentration of the gas in the sample container
nitrogen. If suitable modifications are made to the analytical
be the same as in the liquid phase. This will be true if
measurements by gas chromatography, solubilities of other
fractionation of the sample is avoided while withdrawing it
gases such as argon, hydrogen, oxygen, etc., can be deter-
from the liquid phase, if no decomposition or polymerization
mined.
of the test liquid occurs on vaporization, and if the vapor of the
1.3 The values stated in SI units are to be regarded as the
test liquid does not react with the walls of the sample container
standard. In cases where materials, products, or equipment are
or connecting lines. It is also necessary that both the test gas
available in inch-pound units only, SI units are omitted.
and the vapor of the test liquid behave nearly ideally at 101 kPa
1.4 This standard does not purport to address all of the
(1 atm). If the above requirements are met, this test method will
safety concerns, if any, associated with its use. It is the
give estimates of solubility with an accuracy of 62%.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitations prior to use. For specific hazard
5.1 The solubility of fixed gases in liquids is an important
statements, see Note 1 and Note 3 and Annex A1.
engineering parameter in the design of hydraulic systems. It is
a measure of the amount of gas that can be released from
2. Referenced Documents
solution when a system undergoes changes in pressure and
2.1 ASTM Standards:
2 temperature. Theoretical considerations permit approximate
E 260 Practice for Packed Column Gas Chromatography
values of gas solubility to be computed with reasonable
3. Terminology accuracy. Dissolved gases are separated and quantified chro-
matographically. The test method is restricted to use with
3.1 Definitions of Terms Specific to This Standard:
low-boiling liquid samples.
3.1.1 carrier gas, n—gas used to sweep samples through the
gas chromatograph.
6. Apparatus
3.1.2 test gas, n—gas whose solubility is being determined.
6.1 Saturator and Sampler System, suitable for the tests of
3.1.3 liquid or test liquid—solvent for test gas.
low-boiling liquids and gases at various pressures and tempera-
3.1.4 vapor, n—vapor phase of test liquid.
tures, shown schematically in Fig. 1. The system comprises
3.1.5 nonreactive gas, n—gas that does not react chemically
four parts:
with the test liquid.
6.1.1 High-Pressure Test Chamber, with internal capacity of
3.1.6 elution, n—the process of removing a material ab-
approximately (1 L) such as shown in Fig. 2. The lid of the test
sorbed on the stationary phase of the gas chromatograph
chamber is equipped with three ports. The first is to contain a
thermocouple well, the second is for the addition of the test
This test method is under the jurisdiction of ASTM Committee D-2 on
liquid and pressurization of the system with the test gas, and
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
the third port is for withdrawal of the sample of solution from
D02.11on Engineering Science of High Performance Fluids and Solids.
the liquid phase by means of an eductor tube which extends to
Current edition approved Aug. 15, 1993. Published October 1993. Originally
the bottom of the chamber. The high-pressure assembly is
published as D 3429 – 75. Last previous edition D 3429 – 87.
Annual Book of ASTM Standards, Vol 14.01.
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 3429
NOTE 1—All lines and fittings 300 series stainless steel.
1. VI through V8—Stainless steel valves, metal-to-metal seat, bellows in the middle half of the scale, balance6 3 % or better), com-
sealed 14 MPa (2000 psi) rating (V8 modified, see Fig. 3) pound range from 0 to 30 in. Hg and a gage pressure from 0 to
2. T/C-1—Copper-constantan thermocouple, test liquid temperature. 103 kPa (0 to 15 psi).
3. T/C-2—Copper-constantan thermocouple, vapor cryostat temperature con- 6. Burst Disk—Select to release at 50 % higher than maximum desired system
troller. pressure
4. G-1—Bourdon gage, 4 ⁄2 or 6-in. size, Grade 3A (accuracy 60.25 % of 7. Temperature Controller—Range 77 to 300 K, accuracy 60.5 % full range
maximum reading), range 1.5 times highest desired system pressure. 8. L—Loops in stainless steel lines for flexibility.
5. G-2—Bourdon gage, 3 ⁄2 to 6-in. size, Grade A or B (accuracy 2 % or better 9. R1 and R2—Gas pressure regulators with pressure gage.
FIG. 1 Saturator Apparatus—Schematic
mounted so that an oscillating motion in a horizontal plane can nitrogen vapor cryostat can undergo temperature excursions of
be applied to it mechanically with a frequency of 1 Hz (one several degrees, the test chamber will stabilize at a temperature
cycle per second) and an amplitude of 0.02 m. Loops (pigtails) that varies by only a few tenths of a degree because of its
are formed in the connecting metal lines to the test chamber to thermal inertia. To minimize heat transfer from outside of the
avoid undue stress. apparatus and frost condensation, the top of the cryostat should
6.1.1.1 An electric motor geared down to provide a shaft be loosely covered with a lid of foamed glass or plastic, or
speed of about 60 rpm is convenient for providing the other similar insulating material.
necessary agitation. An eccentric or connecting rod from the
NOTE 1—Warning: Extremely cold. Liberates gas that can cause suf-
motor shaft to the support rod imparts an oscillating motion.
focation. Contact with skin causes burns or freezing, or both. Vapors can
Without agitation an excessive time is required for equilibrium
react violently with hot magnesium or aluminum alloys. See A1.1.
to be established.
6.1.3 Vacuum and Pressurization Manifold, required for
6.1.2 Nitrogen Vapor Cryostat, with suitable temperature
initial evacuation of the test chamber, filling the chamber with
measurement and control devices, to provide the low-
the test liquid, and pressurizing the chamber with the test gas
temperature environment for the high-pressure test chamber.
to the desired total pressure. The manifold is shown on the left
The cryostat consists of a cylindrical stainless steel Dewar or
side of Fig. 1.
other suitable insulated container not less than 0.3 m in inside
6.1.3.1 The burst disk shown in Fig. 1 shall be of the type
diameter and approximately 0.5 m in inside depth. A solenoid
capable of withstanding an external pressure of 101 kPa (1
valve is used to admit liquid nitrogen to the cryostat. The liquid
atm) when the system is evacuated.
nitrogen cools the cryostat and its contents. The liquid nitrogen
(Warning—See Note 3.) should be introduced through a 6.1.3.2 The pump used to evacuate the apparatus shall be a
diffuser, or in a fine stream behind a sheet metal baffle, so that good quality oil-filled mechanical pump capable of producing
−6
liquid does not impinge directly on the test chamber or the an ultimate vacuum of 0.1 Pa (10 atm) or better. If conden-
controller thermocouple. The latter may be attached loosely to sible vapors or reactive vapors are to be pumped, the pump
the side of the test chamber for convenience, but good thermal shall be protected by a suitable absorber or cold trap. The pump
coupling to the chamber must not be made. Although the shall run continuously for the duration of the test.
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 3429
NOTE 1—All material 300 series stainless except flange gasket. Design of perforated baffles not critical but leave 6-mm diameter holes spaced on
20-mm centers are recommended. Baffles should be spot-welded to the inside of the chamber to prevent movement. The purpose of the baffles is to
increase turbulence in the liquid and thereby increase the rate of solubility of gas in the test liquid.
NOTE 2—The conflat flange manufactured by the Varian Corp. of Palo Alto, CA, is suitable.
FIG. 2 Test Chamber Detail
6.1.4 Solution-Sampling System—This system utilizes a must be purged, otherwise the liquid and vapor in the line will
3-mm ( ⁄8-in.) outside diameter heavy-wall stainless steel not necessarily be of equilibrium composition. To reduce the
eductor tube extending nearly to the bottom of the test amount of liquid lost through purging, the sample valve (V8 in
chamber. The eductor tube end extending outside the chamber Fig. 1) should be modified to reduce liquid holdup to a
is connected to a valve just above the top of the cryostat, and minimum. The details of this modification are shown in Fig. 3.
the outlet of this valve leads to a sample cylinder or container 6.2 Gas Chromatograph, required for determination of the
of about 100-mL volume. Each time a sample is withdrawn gas concentration in the sample. It must be equipped with a gas
from the liquid phase, the eductor tube and sampling valve sampling valve. It is desirable that two different size loops be
NOTE 1—Stainless steel wire extends from the position shown in the valve to the lower end of the eductor tube. The purpose of this modification is
to reduce the volume of the valve upstream of the poppet to minimum. A valve with a blunt poppet, rather than a needle, is preferred for this service.
FIG. 3 Sampling Valve (V8) Modification
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 3429
provided so that the sample size can be adjusted depending on containing about 0.2 % and 1.0 % helium are recommended.
the concentration of test gas to be determined. Sample loops of The exact concentration should be known to 61 % of the
0.5 and 2.0 mL are recommended. The gas chromatograph absolute mole fraction of the helium concentration. Nitrogen is
system must permit easy and rapid change of carrier gas and used as the carrier gas when helium is the gas whose solubility
columns to suit a wide variety of analytical requirements. A is to be determined. Helium is used as the carrier gas when
thermal conductivity detector of the glass-coated bead type is nitrogen solubility is being determined.
recommended. The instrumentation should provide a variable
NOTE 3—Warning: Compressed gas under high pressure. Gas reduces
attenuator for the detector signal so that a wide range of fixed
oxygen available for breathing. See A1.2.
gas concentrations may be accommodated. A suitable chart
7.2 Column Materials—Because only two-component sys-
recorder, preferably equipped with integrator, should be pro-
tems are analyzed and the boiling points of the test gas and
vided. Alternatively, a digital readout may be used. A typical
liquid are relatively far apart, a relatively short column is
gas chromatograph is shown schematically in Fig. 4, and its
sufficient to provide resolution. For most test liquids, a 0.2-m
power supply is shown in Fig. 5.
column of silica gel or molecular sieve will separate the test
NOTE 2—Practice E 260 provides further description.
gas and test liquid. The column should be constructed of 6-mm
(0.25-in.) thin-walled stainless steel tubing. Certain reactive
6.3 Leak Testing—All parts of the system should be tested
test liquids, particularly the powerful oxidizers that contain
with helium for leakage at a pressure 1.5 times test operating
fluorine, may react with the stationary phase materials to
pressure and vacuum leak tested. The test should include
produce interferences. If this is the case, more elaborate
external leaks and port-to-port leaks in valves. The total system
columns must be used to afford resolution. Each combination
maximum acceptable leak rate is 0.1 std cm atm/s. A mass
of gas and liquid poses its own particular analytical problem
spectrometer leak detector is suitable for the leak rate mea-
and a certain amount of experimentation with stationary phase
surements.
materials may be required. Table 1 contains a list of materials
7. Reagents and Materials found appropriate for some typical test gas/liquid combina-
tions.
7.1 Calibration Mixtures—Gas Chromatography—For the
7.3 Gases, Compressed—High-purity helium and nitrogen,
determination of nitrogen solubility, one or more mixtures of
or other test gases, are required for saturating the test liquids.
nitrogen in helium are required for calibration of the gas
The same gases are required for carrier gases in the gas
chromatograph. Concentrations of 2 % and 10 % are recom-
chromatograph. (Warning—see Note 3.)
mended. The exact concentration of each mixture must be
accurately known to 61 % of the absolute concentration of the
8. Safety Precautions
minor constituent. Certified calibration mixtures are available
from suppliers of commercial cylinder gases. F
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