ASTM D3429-93(2007)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D3429 – 93 (Reapproved 2007)
Standard Test Method for
Solubility of Fixed Gases in Low-Boiling Liquids
This standard is issued under the fixed designation D3429; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.5 nonreactive gas, n—gasthatdoesnotreactchemically
with the test liquid.
1.1 This test method covers the determination of the solu-
3.1.6 elution, n—the process of removing a material ab-
bilities of nonreactive gases such as nitrogen and helium in
sorbed on the stationary phase of the gas chromatograph
liquids that boil below 273 K.This test method is applicable at
column by displacing it with the flowing carrier gas.
temperatures from 77 to 300 K from subambient pressure to
3.1.7 fractionation, n—change of composition caused by
6.5 MPa (65 atm). This test method does not provide for
change of pressure.
analysis of the vapor phase in equilibrium with the liquid (see
Section 3 for a description of terms).
4. Summary of Test Method
1.2 This test method as written describes the procedures to
4.1 Asample of test liquid A is saturated with test gas B at
be followed for determination of the solubilities of helium and
specified temperature and pressure.Aportion of the solution is
nitrogen. If suitable modifications are made to the analytical
withdrawn and vaporized in an evacuated sample container at
measurements by gas chromatography, solubilities of other
room temperature.The concentration of gas B in the vaporized
gases such as argon, hydrogen, oxygen, etc., can be deter-
sample is determined by gas chromatography. It is necessary
mined.
that the molar concentration of the gas in the sample container
1.3 The values stated in SI units are to be regarded as the
be the same as in the liquid phase. This will be true if
standard. In cases where materials, products, or equipment are
fractionation of the sample is avoided while withdrawing it
available in inch-pound units only, SI units are omitted.
from the liquid phase, if no decomposition or polymerization
1.4 This standard does not purport to address all of the
ofthetestliquidoccursonvaporization,andifthevaporofthe
safety concerns, if any, associated with its use. It is the
testliquiddoesnotreactwiththewallsofthesamplecontainer
responsibility of the user of this standard to establish appro-
or connecting lines. It is also necessary that both the test gas
priate safety and health practices and determine the applica-
andthevaporofthetestliquidbehavenearlyideallyat101kPa
bility of regulatory limitations prior to use. For specific hazard
(1atm).Iftheaboverequirementsaremet,thistestmethodwill
statements, see 6.1.2 and 7.1 and Annex A1.
give estimates of solubility with an accuracy of 62%.
2. Referenced Documents
5. Significance and Use
2.1 ASTM Standards:
5.1 The solubility of fixed gases in liquids is an important
E260 Practice for Packed Column Gas Chromatography
engineering parameter in the design of hydraulic systems. It is
3. Terminology a measure of the amount of gas that can be released from
solution when a system undergoes changes in pressure and
3.1 Definitions of Terms Specific to This Standard:
temperature. Theoretical considerations permit approximate
3.1.1 carriergas,n—gasusedtosweepsamplesthroughthe
values of gas solubility to be computed with reasonable
gas chromatograph.
accuracy. Dissolved gases are separated and quantified chro-
3.1.2 test gas, n—gas whose solubility is being determined.
matographically. The test method is restricted to use with
3.1.3 liquid or test liquid—solvent for test gas.
low-boiling liquid samples.
3.1.4 vapor, n—vapor phase of test liquid.
6. Apparatus
This test method is under the jurisdiction of ASTM Committee D02 on
6.1 Saturator and Sampler System, suitable for the tests of
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
low-boilingliquidsandgasesatvariouspressuresandtempera-
D02.L0.07 on Engineering Sciences of High Performance Fluids and Solids.
tures, shown schematically in Fig. 1. The system comprises
Current edition approved May 1, 2007. Published June 2007. Originally
´1
approved in 1975. Last previous edition approved in 2002 as D3429–93 (2002) .
four parts:
DOI: 10.1520/D3429-93R07.
6.1.1 High-Pressure Test Chamber,withinternalcapacityof
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approximately(1L)suchasshowninFig.2.Thelidofthetest
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
chamber is equipped with three ports. The first is to contain a
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.
D3429 – 93 (2007)
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, balance 6 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
thermocouple well, the second is for the addition of the test or in a fine stream behind a sheet metal baffle, so that liquid
liquid and pressurization of the system with the test gas, and does not impinge directly on the test chamber or the controller
the third port is for withdrawal of the sample of solution from thermocouple.Thelattermaybeattachedlooselytothesideof
the liquid phase by means of an eductor tube which extends to thetestchamberforconvenience,butgoodthermalcouplingto
the bottom of the chamber. The high-pressure assembly is the chamber must not be made. Although the nitrogen vapor
mountedsothatanoscillatingmotioninahorizontalplanecan cryostat can undergo temperature excursions of several de-
be applied to it mechanically with a frequency of 1 Hz (one grees, the test chamber will stabilize at a temperature that
cycle per second) and an amplitude of 0.02 m. Loops (pigtails) varies by only a few tenths of a degree because of its thermal
are formed in the connecting metal lines to the test chamber to inertia.Tominimizeheattransferfromoutsideoftheapparatus
avoid undue stress. and frost condensation, the top of the cryostat should be
6.1.1.1 An electric motor geared down to provide a shaft loosely covered with a lid of foamed glass or plastic, or other
speed of about 60 rpm is convenient for providing the similar insulating material. (Warning—Extremely cold. Lib-
necessary agitation. An eccentric or connecting rod from the erates gas that can cause suffocation. Contact with skin causes
motor shaft to the support rod imparts an oscillating motion. burns or freezing, or both. Vapors can react violently with hot
Without agitation an excessive time is required for equilibrium 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.Asolenoid capable of withstanding an external pressure of 101 kPa (1
valveisusedtoadmitliquidnitrogentothecryostat.Theliquid atm) when the system is evacuated.
nitrogencoolsthecryostatanditscontents.Theliquidnitrogen 6.1.3.2 The pump used to evacuate the apparatus shall be a
(Warning—See 7.1.) should be introduced through a diffuser, good quality oil-filled mechanical pump capable of producing
D3429 – 93 (2007)
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
an ultimate vacuum of 0.1 Pa (10 atm) or better. If conden- columns to suit a wide variety of analytical requirements. A
sible vapors or reactive vapors are to be pumped, the pump thermal conductivity detector of the glass-coated bead type is
shallbeprotectedbyasuitableabsorberorcoldtrap.Thepump
recommended. The instrumentation should provide a variable
shall run continuously for the duration of the test. attenuator for the detector signal so that a wide range of fixed
6.1.4 Solution-Sampling System—This system utilizes a
gas concentrations may be accommodated. A suitable chart
3-mm ( ⁄8-in.) outside diameter heavy-wall stainless steel
recorder, preferably equipped with integrator, should be pro-
eductor tube extending nearly to the bottom of the test
vided. Alternatively, a digital readout may be used. A typical
chamber. The eductor tube end extending outside the chamber
gas chromatograph is shown schematically in Fig. 4, and its
is connected to a valve just above the top of the cryostat, and
power supply is shown in Fig. 5.
the outlet of this valve leads to a sample cylinder or container
NOTE 1—Practice E260 provides further description.
of about 100-mL volume. Each time a sample is withdrawn
from the liquid phase, the eductor tube and sampling valve
6.3 Leak Testing—All parts of the system should be tested
must be purged, otherwise the liquid and vapor in the line will
with helium for leakage at a pressure 1.5 times test operating
not necessarily be of equilibrium composition. To reduce the
pressure and vacuum leak tested. The test should include
amount of liquid lost through purging, the sample valve (V8 in
externalleaksandport-to-portleaksinvalves.Thetotalsystem
Fig. 1) should be modified to reduce liquid holdup to a
maximum acceptable leak rate is 0.1 std cm atm/s. A mass
minimum.The details of this modification are shown in Fig. 3.
spectrometer leak detector is suitable for the leak rate mea-
6.2 Gas Chromatograph, required for determination of the
surements.
gasconcentrationinthesample.Itmustbeequippedwithagas
sampling valve. It is desirable that two different size loops be
7. Reagents and Materials
provided so that the sample size can be adjusted depending on
theconcentrationoftestgastobedetermined.Sampleloopsof 7.1 Calibration Mixtures—Gas Chromatography—For the
determination of nitrogen solubility, one or more mixtures of
0.5 and 2.0 mL are recommended. The gas chromatograph
system must permit easy and rapid change of carrier gas and nitrogen in helium are required for calibration of the gas
D3429 – 93 (2007)
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
FIG. 4 Gas Chromatograph Schematic
chromatograph. Concentrations of 2% and 10% are recom- sufficient to provide resolution. For most test liquids, a 0.2-m
mended. The exact concentration of each mixture must be column of silica gel or molecular sieve will separate the test
accuratelyknownto 61%oftheabsoluteconcentrationofthe gasandtestliquid.Thecolumnshouldbeconstructedof6-mm
minor constituent. Certified calibration mixtures are available (0.25-in.) thin-walled stainless steel tubing. Certain reactive
from suppliers of commercial cylinder gases. For the determi- test liquids, particularly the powerful oxidizers that contain
nation of helium solubilities, mixtures of helium in nitrogen fluorine, may react with the stationary phase materials to
containing about 0.2% and 1.0% helium are recommended. produce interferences. If this is the case, more elaborate
The exact concentration should be known to 61% of the columns must be used to afford resolution. Each combination
absolutemolefractionoftheheliumconcentration.Nitrogenis of gas and liquid poses its own particular analytical problem
used as the carrier gas when helium is the gas whose solubility and a certain amount of experimentation with stationary phase
is to be determined. Helium is used as the carrier gas when materials may be required. Table 1 contains a list of materials
nitrogen solubility is being determined. (Warning— found appropriate for some typical test gas/liquid combina-
Compressed gas under high pressure. Gas reduces oxygen tions.
available for breathing. See A1.2.) 7.3 Gases, Compressed—High-purity helium and nitrogen,
7.2 Column Materials—Because only two-component sys- or other test gases, are required for saturating the test liquids.
tems are analyzed and the boiling points of the test gas and The same gases are required for carrier gases in the gas
liquid are relatively far apart, a relatively short column is chromatograph. (Warning—see 7.1.)
D3429 – 93 (2007)
FIG. 5 Power Supply Schematic
TABLE 1 Typical Stationary Phase Materials for Chromatograph Columns
Test Gas/Liquid System Carrier Gas Column Description Remarks
A
N /diborane He 2 m molecular sieve Hydrogen, produced by reaction of diborane with moisture in
column, produces initial downscale peak followed by N peak.
He/fluorine N
He/FLOX
...