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SEMI C3.23-1000 © SEMI 1984, 2004 4 4.6.2 Flow Requirements 4.6.2.1 H igh purity, hydrocar bon-free (less than 0.1 ppm) hydr ogen, 35–4 0 mL/min or 40% hydro gen in either helium or nitrogen at 75–80 m L/min. 4.6.2.2 Dry…
SEMI C3.23-1000 © SEMI 1984, 2004 3
4.4 Krypton and Nitrogen — This procedure is for the
determination of krypton and nitrogen using a gas
chromatograph with a thermal conductivity detector.
4.4.1 Detection Limits — 3 ppm (mole/mole) krypton,
3 ppm (mole/mole) nitrogen
4.4.2 Instrument Parameter
4.4.2.1 Column: 3.6 m (12 ft) by 3.2 mm (1/8 in)
stainless steel tubing packed with molecular sieve 5A,
60/80 mesh, washed to remove fines and activated at
300°C for 24 hours or equivalent.
4.4.2.2 Carrier Flow: 45 mL/min helium.
4.4.2.3 Sample Volume: 25 mL.
4.4.2.4 Temperatures:
Detector 40°C
Column 25°C
4.4.3 Calibration Standards — 5–15 ppm (mole/
mole) krypton, 15–5 ppm (mole/mole) nitrogen,
balance helium.
4.4.4 Operating Procedure
4.4.4.1 With the valve in Position A, load the sample
loop. Switch the valve to Position B to inject the sample
into the column and allow the oxygen to pass through
the column to vent. Switch valve to Position A to allow
the krypton and nitrogen to be carried to the detector.
Record the peak areas and retention times.
4.4.4.2 Inject the sample to be tested in the same
manner as 4.4.4.1. Record the retention times and peak
areas.
4.4.4.3 Repeat 4.4.4.1.
4.4.4.4 Calculate the concentrations of krypton and
nitrogen using the formula below. The result may not
exceed the specification in Section 2 of this standard.
Sample of
ionConcentrat
Standard of
ionConcentrat
AreaPeak Standard
AreaPeak Sample
4.5 Nitrous Oxide — This procedure is for the
determination of nitrous oxide using dual beam optical
non-dispersive infrared spectrophotometry.
4.5.1 Detection Limit — 0.05 ppm (mole/mole)
4.5.2 Instrument Parameters
4.5.2.1 Detector: “Luft” type or equivalent
4.5.2.2 10" Infrared Gas Cell or gas cell with
equivalent sensitivity
4.5.2.3 Sample Cell Pressure: 200 psig for full scale
range 0–5 ppm nitrous oxide or appropriate pressure as
recommended by the cell manufacturer.
4.5.2.4 Sample Flowrate: 500 cc/minute or as
recommended by the instrument manufacturer
4.5.2.5 Wavelength: 4.5 micrometers (4500 nm)
4.5.2.6 Wavenumber: 2222 cm
-1
4.5.3 Calibration Standard: 5 ppm (mole/mole) nitrous
oxide, balance oxygen.
4.5.4 Operating Procedure — (See Notes 5 and 6)
4.5.4.1 Open the zero gas (prepurified nitrogen or
certified pure oxygen, independently measured to be
less than 0.1 ppm N
2
O) cylinder valve. Open valve V1,
close valves V2 and V3. Flow the gas through the
system and adjust the back pressure regulator to 200
psig as shown on gauge G. Adjust the flowrate on the
flowmeter to 1000 cc/minute by adjusting valve Vl.
After a constant readout is observed, adjust the zero
control knob of the analyzer to set the absorbance
output to read zero.
4.5.4.2 Open the calibration gas standard cylinder
valve. Close Vl and V2, and open valve V3. Flow the
calibration gas through the system and adjust the back
pressure regulator to 200 psig. Adjust the flowrate on
the flowmeter to 1000 cc/minute. After a constant
readout is observed, record the absorbance of the
calibration standard, if the instrument indicates
absorbance directly. If the instrument indicates
concentration, adjust the span control to read the
concentration of nitrous oxide in the calibration gas.
4.5.4.3 Introduce the oxygen sample into the analyzer
by closing valves Vl and V3, opening Valve V4 and
slowly opening valve V2 until the flowrate on the
flowmeter is 1000 cc/minute. Adjust the back pressure
regulator to 200 psig. Read the absorbance of the
sample and calculate the quantity of nitrous oxide,
using the formula below. If the instrument indicates
concentration, record the concentration. The result may
not exceed the specification in Section 2 of this
standard.
Sample of
ionConcentrat
Standard of
ionConcentrat
Standard of Absorbance Measured
Sample of Absorbance Measured
4.6 Total Hydrocarbons — This procedure is for the
determination of total hydrocarbons in oxygen using a
continuous flow flame ionization detector-equipped
total hydrocarbon analyzer. (See Notes 7, 8.)
4.6.1 Detection Limit — 0.1 ppm (mole/mole)
SEMI C3.23-1000 © SEMI 1984, 2004 4
4.6.2 Flow Requirements
4.6.2.1 High purity, hydrocarbon-free (less than 0.1
ppm) hydrogen, 35–40 mL/min or 40% hydrogen in
either helium or nitrogen at 75–80 mL/min.
4.6.2.2 Dry, hydrocarbon-free (less than 0.1 ppm) air,
350 mL–400 mL/min.
4.6.2.3 Set sample flow rate in accordance with the
instrument manufacturer’s instructions.
4.6.3 Calibration Standards
4.6.3.1 Zero oxygen with a known quantity of
hydrocarbons of approximately 0.1 ppm.
4.6.3.2 Upper level balance oxygen span gas of not
more than five times the concentration specified in
Section 2 of this Standard.
4.6.4 Operating Procedure
4.6.4.1 Do not change initial flow settings for
hydrogen, air and sample once established.
4.6.4.2 Introduce the zero oxygen with a known
quantity of hydrocarbons and, using the 0–1 ppm range,
set the output to read the correct level, using the zero
adjust knob.
4.6.4.3 Introduce the span gas standard in oxygen and,
using the span adjust knob, set the output to the level in
the span gas.
4.6.4.4 Introduce the oxygen sample into the analyzer
and read the quantity of hydrocarbons on the analyzer.
The result may not exceed the specification in Section 2
of this standard.
4.7 Water — This procedure is for the determination
of trace moisture (water) in oxygen using a continuous
flowing, cooled-surface condensation, dewpoint/frost-
point hygrometer. (See Note 9.)
4.7.1 Detection Limit — 0.6 ppm (vol/vol) at -79°C (-
100°F)
4.7.2 Flow Requirements
4.7.2.1 Set sample flow rate and pressure in
accordance with the instrument manufacturer’s
instructions.
4.7.3 Calibration Standard — A calibration ther-
mometer designed to indicate temperatures in the -79°C
(100°F) range is required.
4.7.4 Operating Procedure
4.7.4.1 An appropriately cleaned stainless steel or
copper sampling line must be used. If it has been
exposed to ambient moisture, it must be purged with
dry gas prior to use.
4.7.4.2 Flow the sample gas through the hygrometer
until the sampling system and instrument have reached
equilibrium with the gas.
4.7.4.3 After equilibrium has been reached, cool the
mirror of the hygrometer, as specified by its
manufacturer, to determine the dewpoint/frostpoint of
the sample gas.
4.7.4.4 Verify the dewpoint/frostpoint reading for at
least 30 minutes after it becomes stable.
4.7.4.5 Correct the dewpoint/frostpoint reading to 1
atm pressure. Convert it to ppm (vol/vol) using an
appropriate table. The result may not exceed the
specification in Section 2 of this standard.
4.8 Notes
Note 1: Introduce the calibration standard as many
times as necessary to achieve the desired precision.
Note 2: All gases used in the analysis of the sample
should not contain more than 10% of the specified
value of the component of interest, unless otherwise
stated.
Note 3: A flow restrictor should be installed on the vent
from port 8 to match the pressure drop of the detector.
Note 4: A flow controller is required on each carrier
inlet.
Note 5: An example of an operating procedure is
outlined below for the sample system shown in Figure
1. This procedure is appropriate only when the infrared
gas cell is designed to withstand the 200 psig sample
pressure.
Note 6: Operating procedures for other non-dispersive
infrared analyzers vary depending on manufacturer.
Refer to individual instrument vendor instructions in
each case.
Note 7: As the flow rate and heat capacity of the matrix
gas affect the instrument output, the zero and span gas
matrices must coincide with that of the sample gas.
Note 8: The effective response of a flame ionization
detector-equipped total hydrocarbon analyzer can vary
among different hydrocarbons and must be
approximated. However, the response of the most
common hydrocarbon impurities can be accurately
totaled and compared to methane.
Note 9: The sampling system and hygrometer must be
designed to operate at the sample pressure, or the
sample pressure must be reduced by a regulator with a
diaphragm of stainless steel or other suitable material.
SEMI C3.23-1000 © SEMI 1984, 2004 5
Figure 1
Figure 2