ASTM F1396-93(1999)
(Test Method)Standard Test Method for Determination of Oxygen Contribution by Gas Distribution System Components
Standard Test Method for Determination of Oxygen Contribution by Gas Distribution System Components
SCOPE
1.1 This test method covers a procedure for testing components for oxygen contribution to ultra-high purity gas distribution systems at ambient temperature. In addition, this test method allows testing of the component at elevated ambient temperatures as high as 70°C.
1.2 This test method applies to in-line components containing electronics grade materials such as those used in a semiconductor gas distribution system.
1.3 Limitations:
1.3.1 This test method is limited by the sensitivity of current instrumentation, as well as the response time of the instrumentation. This test method is not intended to be used for test components larger than 12.7-mm ( 1/2-in.) outside diameter nominal size. This test method could be applied to larger components; however, the stated volumetric flow rate may not provide adequate mixing to ensure a representative sample. Higher flow rates may improve the mixing but excessively dilute the sample.
1.3.2 This test method is written with the assumption that the operator understands the use of the apparatus at a level equivalent to six months of experience.
1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only.
1.5 This standard does not purport to address all of the safety problems, 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. Specific hazard statements are given in Section 6.
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Designation:F 1396–93 (Reapproved 1999)
Standard Test Method for
Determination of Oxygen Contribution by Gas Distribution
System Components
This standard is issued under the fixed designation F 1396; 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.
INTRODUCTION
Semiconductor clean rooms are serviced by high-purity gas distribution systems. This test method
presents a procedure that may be applied for the evaluation of one or more components considered for
use in such systems.
1. Scope 2. Terminology
1.1 This test method covers a procedure for testing compo- 2.1 Definitions:
nents for oxygen contribution to ultra-high purity gas distribu- 2.1.1 baseline—the instrument response under steady state
tion systems at ambient temperature. In addition, this test conditions.
method allows testing of the component at elevated ambient 2.1.2 glove bag—an enclosure that contains a controlled
temperatures as high as 70°C. atmosphere. A glove box could also be used for this test
1.2 This test method applies to in-line components contain- method.
ing electronics grade materials such as those used in a 2.1.3 heat trace— heating of a component, spool piece, or
semiconductor gas distribution system. teststandbyauniformandcompletewrappingoftheitemwith
1.3 Limitations: resistant heat tape.
1.3.1 Thistestmethodislimitedbythesensitivityofcurrent 2.1.4 minimum detection limit (MDL) of the instrument—
instrumentation, as well as the response time of the instrumen- the lowest instrument response detectable and readable by the
tation. This test method is not intended to be used for test instrument, and at least two times the amplitude of the noise.
components larger than 12.7-mm ( ⁄2-in.) outside diameter 2.1.5 response time—the time required for the system to
nominal size. This test method could be applied to larger reach steady state after a change in concentration.
components; however, the stated volumetric flow rate may not 2.1.6 spool piece—a null component, consisting of a
provide adequate mixing to ensure a representative sample. straightpieceofelectropolishedtubingandappropriatefittings,
Higher flow rates may improve the mixing but excessively used in place of the test component to establish the baseline.
dilute the sample. 2.1.7 standard conditions—101.3 kPa, 0.0°C (14.73 psia,
1.3.2 This test method is written with the assumption that 32°F).
the operator understands the use of the apparatus at a level 2.1.8 test component—any device being tested, such as a
equivalent to six months of experience. valve, regulator, or filter.
1.4 The values stated in SI units are to be regarded as the 2.1.9 test stand—the physical test system used to measure
standard. The inch-pound units given in parentheses are for impurity levels.
information only. 2.1.10 zero gas—a purified gas that has an impurity con-
1.5 This standard does not purport to address all of the centration below the MDL of the analytical instrument. This
safety concerns, if any, associated with its use. It is the gasistobeusedforbothinstrumentcalibrationandcomponent
responsibility of the user of this standard to establish appro- testing.
priate safety and health practices and determine the applica- 2.2 Symbols:
bility of regulatory limitations prior to use. Specific hazard 2.2.1 P —The inlet pressure measured upstream of the
statements are given in Section 6. purifier and filter in the test apparatus.
2.2.2 P —The outlet pressure measured downstream of the
analyzer in the test apparatus.
This test method is under the jurisdiction of ASTM Committee F01 on
2.2.3 ppbv—Parts per billion by volume assuming ideal gas
Electronics and is the direct responsibility of Subcommittee F01.10 on Processing
behavior, equivalent to nmole/mole (such as nL/L). The same
Environments.
Current edition approved April 15, 1993. Published June 1993. Originally as molar parts per billion (ppb).
published as F 1396 – 92. Last previous edition F 1396 – 92.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1396–93 (1999)
2.2.4 ppbw—Parts per billion by weight (such as ng/g). 4.2.1 Oxygen Analyzer—The oxygen analyzer is to be
2.2.5 ppmv—Parts per million by volume assuming ideal placed downstream of the test component. Accurate baseline
gas behavior, equivalent to µmole/mole (such as µL/L). The readings must be obtained prior to and subsequent to each of
same as molar parts per million (ppm). the tests. Excessive deviations in baseline levels (610 ppbv)
2.2.6 ppmw—Parts per million by weight (such as µg/g). before or after the tests require that all results be rejected. The
2.2.7 Q —the bypass sample flow not going through the analyzer must be capable of accurately recording changes in
analytical system. oxygen concentrations on a real time basis.
2.2.8 Q —the total sample flow through the analytical 4.2.2 Oxygen Analyzer Calibration—Zero gas shall be at an
oxygen level below the MDL of the instrument, supplied by
system.
2.2.9 Q —the flow through the spool piece or component. purifiedgas,withthepurifierincloseproximitytotheanalyzer.
s
The instrument’s internal standard, if available, is to be used
2.2.10 T —the temperature of the air discharged by the
a
analyzer’s cooling exhaust. for the span calibration.Alternatively, span gas from a cylinder
may be used.
2.2.11 T —thetemperatureofthespoolpieceorcomponent.
s
2.2.11.1 Discussion—Precautions must be taken to insure 4.3 Pressure and Flow Control—Upstream pressure is to be
controlled with a regular upstream of the test component. Flow
that the temperature measured by the thermocouple is as close
is to be controlled at a point downstream of the sampling port
as possible to that of the spool piece and test component.
and monitored at that point.Amass flow controller is preferred
Appropriate insulation and conductive shield should be used to
for maintaining the flow as described in 7.4. Sampling is to be
achieve as uniform a temperature as possible. The thermo-
performed via a tee in the line, with a section of straight tubing
couple must be in contact with the outside wall of the
before the mass flow controller. All lines must conform to
component or spool piece.
4.1.3. Inlet pressure is monitored by P .Test flow is the sum of
2.2.12 V-1, V-2—inlet and outlet valves of bypass loop,
Q and Q . Q is directly controlled, and Q is the measured
respectively.
1 2 1 2
flow through the analyzer. Refer to Fig. 1.
2.2.13 V-3, V-4—inlet and outlet valves of test loop, respec-
4.4 Bypass Loop—The design of the bypass loop is not
tively.
restrictedtoanyonedesign.Itcouldbe,forexample,a3.2-mm
( ⁄8-in) 316L stainless steel coil or a flexible tube section. This
3. Significance and Use
allows the flexibility necessary to install test components of
3.1 This test method defines a procedure for testing compo-
different lengths.
nents being considered for installation into a high-purity gas
distribution system.Application of this test method is expected
5. Hazards
to yield comparable data among components tested for pur-
5.1 It is required that the user have a working knowledge of
poses of qualification for this installation.
the respective instrumentation and that the user practice proper
handling of test components for trace oxygen analysis. Good
4. Apparatus
laboratory practices must also be understood.
4.1 Materials:
5.2 It is required that the user be familiar with proper
4.1.1 Nitrogen or Argon, clean and dry, as specified in 7.5.
component installation, and that the test components be in-
4.1.2 Spool Piece, that can be installed in place of the test
stalled on the test stand in accordance with manufacturer’s
component is required. This piece is to be a straight section of
instructions.
316Lelectropolished stainless steel tubing with no restrictions.
5.3 Do not exceed ratings (such as pressure, temperature,
The length of the spool piece shall be 200 mm.The spool piece
and flow) of component.
has the same end connections as the test component.
5.4 Gloves are to be worn for all steps.
4.1.2.1 Components With Stub Ends—Use compression fit-
5.5 Limit exposure of the instrument and test component to
tings with nylon or teflon ferrules to connect the spool piece
atmospheric contamination before and during the test.
and test component to the test loop. Keep the purged glove bag
around each component for the duration of the test. In the case 6. Calibration
of long pieces of electropolished tubing, use two glove bags,
6.1 Calibrate instruments using standard laboratory prac-
one at each end.
tices and manufacturer’s recommendations.
4.1.3 Tubing, used downstream of the test component shall
be 316L electropolished stainless steel seamless tubing. The
diameter of the sample line to the analyzer shall not be larger
than 6.4 mm ( ⁄4 in.).The length of the sample line from the tee
(installed upstream of the pressure gage P ) to the analyzer
shall not be more than 600 mm, so as to minimize the effect
(adsorption/desorption) of the sample line on the result. The
sample line shall have no more than two mechanical joints.
4.1.4 Valves, diaphragm or bellows type, capable of unim-
paired operation at 94°C (200°F). The use of all-welded,
all-metal valves is preferred.
4.2 Instrumentation: FIG. 1 Test Schematic
F 1396–93 (1999)
7. Conditioning measured by the analyzer can either be recorded continuously
by a 25 channel data logger or collected and stored in a
7.1 Ensure that adequate mixing of the test gas is attained.
computer using a data acquisition program.
7.2 Pressure—Test component at 200 kPa gage (30 psig)
measured at P .
9. Procedure (see Fig. 2)
7.3 Temperature— T is to be in the ambient temperature
s
9.1 Bake-Out—With the spool piece installed and valves
range of 18 to 26°C (64 to 78°F) and in the higher mean
V-1, V-2, V-3, and V-4 open, bake out the system (downstream
temperature range of 69 to 71°C (156 to 160°F). T must not
a
of purifier to upstream of analyzer, exclusive of the exhaust
deviate more than 6 2°C (4°F) from the time of calibration to
leg) at 94°C (200°F) until outlet oxygen concentration is stable
the termination of the test. T must either be within the range
a
below <20 ppbv. Flow of the gas is specified in 7.4. Cool to
of 18 to 26°C (64 to 78°F) or be consistent with the analytical
lower T . Close valves V-1 and V-2.
s
systems manufacturer’s specifications, whichever is more
9.2 Baseline—Flow gas through the test stand with the
stringent.
spool piece installed on the test stand. Use the flow rate as
7.4 The flow rate Q for components is 1 standard L/min
s
defined in 7.4. Flow for 30 min after the oxygen concentration
with 6 2 % tolerance.
has attained a level of <20 ppbv. Utilizing heat tape, heat the
7.5 The test gas shall be purified nitrogen or argon with a
spool piece and upstream tubing to within 80 mm of the
maximum oxygen concentration not exceeding an oxygen
upstream valve. Monitor the oxygen of the outlet and the T,as
s
concentration of 10 ppb. Gas quality must be maintained at
specified in 7.3. The time required to reach the higher T must
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flow specified in 7.4. The test gas must be passed through a
be less than or equal to 10 min. Continue testing for 30 min
filter having a pore size rating of 0.02 µm or finer. the filter
after a stable baseline is reestablished (<20 ppbv) as specified
must be compatible with the 94°C (200°F) bake-out.
in 9.1. Cool until the lower T is reached.
s
9.3 Place the spool piece, test component (in original
8. Preparation of Apparatus
bagging), and fittings into a glove bag or nitrogen tent without
8.1 A schematic drawing of a recommended test apparatus
disconnecting. Purge the glove bag with approximately five
located inside a clean laboratory is shown in Fig. 1. Deviations
glove bag volumes of inert gas. Disconnect the spool piece
from this design are acceptable as long as baseline levels
while maintaining the flow through the system. Maintain the
consistent with 4.2.1 can be maintained. Nitrogen or argon gas
spool piece in the proximity of the positive flow. Reinstall the
is purified to remove water and hydrocarbons. The base gas is
spool piece on the test stand. The entire disconnection and
then filtered by an electronics grade, high purity, point of use
reinstallation must be performed within 2 min. Maintain flow
filter (pore size rating# 0.02 µm) before it is delivered to the
through the analyzer during disconnection and installation via
test component.
thebypassloop,usingvalvesV-1,V-2,V-3,andV-4(ifV-1and
8.2 A bypass loop may be used to divert gas flow through
V-2 are open, then V-3 and V-4 will be closed). During
the test stand and the analyzer whenever the spool piece or a
disconnection, open valves V-1 and V-2 first, then close V-3
testcomponentisinstalledorremovedfromtheteststand.This
and V-4. After connection, reverse the order. Keep the purged
prevents the ambient air from contaminating the test apparatus
glove bag around each component for the duration of the test.
and the oxygen analyzer; thus, the analyzer baseline remains
In the case of long pieces of electropolished tubing, use two
the same. A glove bag is used to enclose test component lines
glove bags, one at each end.
of the test apparatus during the installation and removal of the
9.4 Initiate flow through the spool piece in accordance with
spool piece and the test piece.
8.4.MonitorT andT inaccordancewith8.3.Monitoroxygen
s a
8.3 A trace oxygen analyzer capable of detecting oxygen
until a stable baseline, in accordance with 9.2, is reestablished
concentration levels down to 2 ppb is connected to the test
(<20 ppbv). Utilizing heat tape, heat the spool piece and
stand to sample the gas flowing through the test piece. The
upstream tubing to within 80 mm of the upstream valve. Turn
purified and filtered base gas from the test stand containing <
on the current and monitor the oxygen of the outlet and the T ,
s
10 ppb oxygen is used as the zero oxygen gas source for the
in accordance with 8.3. The time required to reach the higher
analyzer.Sincetheanalyzerissensitivetothesampleflowrate,
T must be less than or equal to 10 min. Continue testing until
s
the metering valves within the analyzer should be adjusted to
a stable baseline is reestablished (<20 ppbv). Cool until the
yield the flow rates required by the specification for an inlet
lower T is reached.
s
pressure of 30 psig. The gas flow rate Q is set to 1 L/min.
s
8.4 Inlet gas pressure is controlled by a pressure regulator
and measured immediately upstr
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