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SEMI C59-1104 © SEMI 2002, 2004 3 9.2.4.4 Compare the average peak area of the calibration stand ard to that of the nitrogen sa mple being tested. Calcul ate the concentrat ion of hydroge n, using the formula: Sam ple Pe…
SEMI C59-1104 © SEMI 2002, 2004 2
7 Requirements
7.1 Purity and other requirements for the various
grades of nitrogen are given in Table 1.
8 Physical Constants
8.1 The physical constants of nitrogen are given in
Table 2 (for information only).
Table 2 Physical Constants of Nitrogen (for
information only)
Metric Units US Units
Molecular weight 28.013 28.013
Boiling point at 1 atm
–195.8C –320.4F
Density of gas at 21.1C
(70F) and 1 atm
1.1605 kg/m
3
0.07245 lb/ft
3
Specific gravity of gas at
21.1C and 1 atm (air = 1)
0.967 0.967
Density of liquid at boiling
point
808.8 kg/m
3
50.49 lb/ft
3
9 Analytical Procedures for Grade 4.8 Nitrogen
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
contain no more than 10% of the sample value of the
component of interest unless otherwise specified.
9.1 Carbon Monoxide and Carbon Dioxide — This
procedure is for the determination of carbon monoxide
and carbon dioxide in nitrogen using a gas
chromatograph with a flame ionization detector and
methanizer.
NOTE 3: Carrier gases should contain less than 0.1 ppm
carbon monoxide and less than 0.1 ppm hydrogen.
9.1.1 Detection Limit — 100 ppb
9.1.2 Instrument Parameters
9.1.2.1 Column: Porapak T or Q, 3 m (9.8 ft) by 3.2
mm (1/8 in) OD by 2.2 mm (0.085 in) ID stainless
steel; or Chromosorb 102, 2 m (6.6 ft) by 3.2 mm (1/8
in) OD by 2.2 mm (0.085 in) ID stainless steel; or
equivalent.
9.1.2.2 Carrier Flow: 30 mL/min helium.
9.1.2.3 Sample Volume: 0.5 to 2.0 mL.
9.1.2.4 Temperatures:
Detector
280C
Column Oven
60C
Methanizer
350C
9.1.3 Calibration Standards — 1–5 ppm carbon
monoxide, 1–5 ppm carbon dioxide, balance nitrogen.
9.1.4 Operating Procedure
9.1.4.1 Inject the calibration standard into the column
using a gas sampling valve. Record the retention times
and peak areas. Order of elution is carbon monoxide,
carbon dioxide.
9.1.4.2 Inject the sample to be tested in same manner
as the calibration standard. Record the retention times
and peak areas.
9.1.4.3 Repeat Section 9.1.4.1.
9.1.4.4 Compare the average peak area of the
calibration standard to that of the nitrogen sample being
tested. Calculate the concentrations of carbon
monoxide and carbon dioxide, using the formula:
Sample Peak Area
Concentration of Standard
Standard Peak Area
Concentration of Sample
9.1.4.5 The result may not exceed the specification in
Table 1.
9.2 Hydrogen — This procedure is for the
determination of hydrogen in nitrogen using a gas
chromatograph with a helium ionization detector.
9.2.1 Detection Limit — 500 ppb.
9.2.2 Instrument Parameters
9.2.2.1 Column — 5A molecular sieve, 1.9 m (6 ft) by
3.2 mm (1/8 in) OD by 2.2 mm (0.085 in) stainless steel
or equivalent.
9.2.2.2 Carrier Flow — 30 mL/min helium.
9.2.2.3 Sample Volume — 3.0 mL
9.2.2.4 Temperatures:
Detector
125C
Column Temperature
65C
9.2.3 Calibration Standard — 1–5 ppm hydrogen in
nitrogen.
9.2.4 Operating Procedure
9.2.4.1 Inject the calibration standard into the column
using a gas sampling valve. Record the retention time
and peak area.
9.2.4.2 Inject the sample to be tested in same manner
as the calibration standard. Record the retention time
and peak area.
9.2.4.3 Repeat Section 9.2.4.1.
SEMI C59-1104 © SEMI 2002, 2004 3
9.2.4.4 Compare the average peak area of the
calibration standard to that of the nitrogen sample being
tested. Calculate the concentration of hydrogen, using
the formula:
Sample Peak Area
Concentration of Standard
Standard Peak Area
Concentration of Sample
9.2.4.5 The result may not exceed the specification in
Table 1.
9.3 Oxygen — This procedure is for the determination
of oxygen in nitrogen using a continuous flow analyzer
using an electrochemical method.
9.3.1 Detection Limit — 100 ppb.
9.3.2 Flow Rate — Set sample flow rates in
accordance with the instrument manufacturer's
instructions.
9.3.3 Calibration Standard — 3–15 ppm oxygen in
nitrogen or in accordance with the instrument
manufacturer's instructions.
9.3.4 Operating Procedure
9.3.4.1 Do not change the sample flow setting once
established.
9.3.4.2 Introduce nitrogen sample and record oxygen
reading. The result may not exceed the specification in
Table 1.
9.4 Total Hydrocarbons — This procedure is for the
determination of total hydrocarbons in nitrogen using a
continuous flow flame ionization detector equipped
total hydrocarbon analyzer.
NOTE 4: The 0–1 range can be used provided that zero and
span gas standards in nitrogen with known levels of
hydrocarbons between 0–1 ppm are used in the calibration of
the analyzer.
NOTE 5: 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 6: The effective response of a flame ionization
detector-equipped total hydrocarbon analyzer to different
hydrocarbons can vary and must be approximated. However,
the response of the most common hydrocarbon impurities in
nitrogen can be accurately totaled and compared to methane.
9.4.1 Detection Limit — 0.1 ppm.
9.4.2 Flow Requirements
9.4.2.1 High purity, hydrocarbon-free (less than 0.1
ppm) hydrogen: 35–40 mL/min or 40% hydrogen in
either helium or nitrogen matrix at 75–80 mL/min.
9.4.2.2 Dry, hydrocarbon-free (less than 0.1 ppm) air:
350–400 mL/min.
9.4.2.3 Set sample flow rates in accordance with the
instrument manufacturer's instructions.
9.4.3 Calibration Standards
9.4.3.1 Nitrogen with known quantity of hydrocarbons
at 0.5 ppm level.
9.4.3.2 The upper level span gas not exceeding 5 times
the concentration of the specification.
9.4.4 Operating Procedure
9.4.4.1 Do not change the flow settings for hydrogen,
air and sample once established.
9.4.4.2 Introduce the nitrogen with known quantity of
hydrocarbons and, using the 0–10 ppm range, set the
needle (or output) to read the correct level using the
zero adjust knob.
9.4.4.3 Introduce the span gas standard in nitrogen and,
using the span adjust knob, set the needle (or output
reading) to match the level of hydrocarbons in the span
gas.
9.4.4.4 Introduce nitrogen sample into the analyzer and
read the quantity of hydrocarbons on the analyzer
meter. The result may not exceed the specification in
Table 1.
9.5 Water — This procedure is for the determination of
trace moisture (water) in nitrogen using a continuous
flowing piezoelectric hygrometer.
NOTE 7: The sampling system and hygrometer must be
designed to operate under the sample pressure, or the sample
pressure must be reduced (by a regulator with a diaphragm of
stainless steel or other suitable material) to accommodate the
pressure restrictions of the analytical hygrometer.
9.5.1 Detection Limit — 0.1 ppmv or 90C (130F).
9.5.2 Flow Requirements — Set the sample pressure
and flow rate in accordance with the instrument
manufacturer’s instructions.
9.5.3 Calibration Standards — Construct a calibration
curve which contains at least three points covering the
range of interest. Verify the standards employed
independently by another analytical method.
9.5.4 Operating Procedure
9.5.4.1 Obtain a continuous flow sample of gas from
the source using a clean and passivated stainless steel
line which has been purged dry after exposure to
ambient moisture.
9.5.4.2 After prepurging with a dry gas, allow the
sample gas to flow through the sampling system and the
SEMI C59-1104 © SEMI 2002, 2004 4
piezoelectric moisture hygrometer until a stable reading
is obtained.
9.5.5 Determine the moisture content of the nitrogen
sample by comparing the reading to calibration curve.
The result may not exceed the specification in Table 1.
10 Analytical Procedures for Grade 5.2
Nitrogen (See Notes 1 and 2 in Section 9)
10.1 Carbon Monoxide and Carbon Dioxide — Use
the procedure in Section 9.1 for the analysis of carbon
monoxide and carbon dioxide.
10.1.1 Hydrogen — Use the procedure in Section 9.2
for the analysis of hydrogen.
10.1.2 Oxygen — Use the procedure in Section 9.3 for
the analysis of oxygen except that the standard should
be between 1 and 5 ppm oxygen in nitrogen.
10.1.3 Total Hydrocarbons — Use procedure Section
9.4 for the determination of total hydrocarbons except
that the calibration standard should be at the 0.1 ppm
level.
10.1.4 Water — This procedure is for the
determination of moisture (water) in nitrogen using a
continuous flowing, cooled-surface condensation,
dewpoint/ frostpoint hygrometer. (See NOTE 7 in
Section 9.)
NOTE 8: The National Institute of Standards and Technology
(NIST) provides calibration services for the thermometers
used in dewpoint/frostpoint hygrometers.
NOTE 9: This method is not applicable if other constituents
in the gas will condense before water vapor, e.g., carbon
dioxide and/or oil contamination.
10.1.4.1 Detection Limit — 0.6 ppm (vol/vol) or
79C (110F).
10.1.4.2 Flow Requirements
10.1.4.2.1 Set sample flow rate and pressure in
accordance with the instrument manufacturer's
instructions.
10.1.4.2.2 Gas must flow past the chilled mirror where
optic means are provided to detect the deposit (or frost)
and to read the thermometer measuring the temperature
of the mirror.
10.1.4.3 Calibration Standard — A calibration
thermometer designed to indicate temperatures in the
79C (110F) range required.
10.1.4.4 Operating Procedure
10.1.4.4.1 Obtain a continuous flow of sample gas
from the source using a clean stainless steel (or copper)
sampling line which has been purged dry after exposure
to ambient moisture.
10.1.4.4.2 After prepurging with a dry gas, allow the
sample gas to flow through the sampling system and the
dewpoint/frostpoint hygrometer for one hour to 24
hours to allow the entire system to reach equilibrium
with regard to moisture content.
10.1.4.4.3 After equilibrium has been reached, cool
down the mirror to determine the actual
dewpoint/frostpoint of the sample gas. Follow the
manufacturer’s recommendations to create the
temperatures needed.
10.1.4.4.4 Continue to verify the dewpoint/frostpoint
for at least 30 minutes after a stable reading has been
confirmed.
10.1.4.4.5 Correct the dewpoint reading from the
measured pressure to 1 atm of pressure. The result may
not exceed the specification in Table 1.
11 Analytical Procedures for Grade 5.4
Nitrogen (See Notes 1 and 2 in Section 9)
11.1 Carbon Monoxide and Carbon Dioxide — Use
the procedure in Section 9.1 for the analysis of carbon
monoxide and carbon dioxide.
11.2 Hydrogen — Use the procedure in Section 9.2 for
the analysis of hydrogen.
11.3 Oxygen — Use the procedure in Section 9.3 for
the analysis of oxygen except that the standard should
be between 0.5 and 2.5 ppm oxygen in nitrogen.
11.4 Total Hydrocarbons
— Use procedure Section 9.4
for the determination of total hydrocarbons except that
the calibration standard should be at the 0.1 ppm level.
11.5 Water — Use procedure in Section 9.5 for the
determination of water.
12 Analytical Procedures for Grade 5.5
Nitrogen (See Notes 1 and 2 in Section 9)
12.1 Carbon Monoxide and Hydrogen — This
procedure is for the determination of carbon monoxide
and hydrogen in nitrogen using a gas chromatograph
with a reduction gas detector (See Note 3 in Section
9.1).
12.1.1 Detection Limits — 2 ppb carbon monoxide, 20
ppb hydrogen.
12.1.2 Instrument Parameters
12.1.2.1 Column — 5A molecular sieve, 0.9 m (3 ft)
by 3 mm (1/4 in) stainless steel, or equivalent.
12.1.2.2 Carrier Flow — 40 mL/min air or nitrogen.
12.1.2.3 Sample Volume — 2.0 mL.