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SEMI C3.37-07 01 © SEMI 1989 , 2001 1 SEMI C3.37-0701 SPECIFICA TION FOR HEX A FLUOROETHANE (C 2 F 6 ), 99.97% QUAL ITY This specif ication was technic ally approved by the Global Ga ses Committee and is the direct respo…
SEMI C3.20-92 © SEMI 1982, 19993
4.5.4.2 Introduce the zero helium 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.
4.5.4.3 Introduce the span gas standard in helium and,
using the span adjust knob, set the needle (or output
reading) to match the level of hydrocarbons in the span
gas.
4.5.4.4 Introduce helium 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.
4.6 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
contain not more than 10% of the specified value of the
component of interest unless otherwise specified.
NOTE 3: 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.
NOTE 4: The 0-1 range may be used provided that zero and
span gas standards in helium 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 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
helium can be accurately totaled and compared to methane.
NOTICE: These standards do not purport to address
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appropriate safety and health practices and determine
the applicability of regulatory limitations prior to use.
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mentioned herein. These standards are subject to
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SEMI C3.37-0701 © SEMI 1989, 20011
SEMI C3.37-0701
SPECIFICATION FOR HEXAFLUOROETHANE (C
2
F
6
), 99.97% QUALITY
This specification was technically approved by the Global Gases Committee and is the direct responsibility of
the North American Gases Committee. Current edition approved by the North American Regional Standards
Committee on April 30, 2001. Initially available at www.semi.org May 2001; to be published July 2001.
Originally published in 1989; previously published in 1993.
1 Description
1.1 Hexafluoroethane is one of the most stable of all
organic compounds. It is inert, colorless,
nonflammable, odorless and tasteless.
2 Specifications
QUALITY: 99.97%
Impurities
Maximum Impurities
Acceptable (ppm)*
Carbon Dioxide (CO
2
)1
Carbon Monoxide (CO) 1
Nitrogen (N
2
) 100
Other Halogenated Hydrocarbons
(CF
3
Cl, CF
3
H, CF
2
HCl, C
2
F
5
Cl)
50
Oxygen (O
2
)25
Water (H
2
O) (v/v) 40
TOTAL LISTED IMPURITIES 217
*An analysis of significant figures has not been considered. The
number of significant figures will be based on analytical accuracy and
the precision of the provided procedure.
3 Chemical Specification
Total Acidity 0.1 ppmw max.
4 Physical Constants (for in formation only)
Metric Units US Units
Molecular weight 138.01 138.01
Boiling point at 1 atm -78.2°C -108.8°F
Density of gas at 24°C
(75°F) and 1 atm
5.734 kg/m
3
0.357 lb/ft
3
Specific gravity of gas
at 24°C and 1 atm
4.823 4.823
Density of liquid at -
80.0°C
1611 kg/m
3
100.6 lb/ft
3
5 Analytical Procedures (Se e Notes 1, 2, 3,
and Figure 1)
5.1 Oxygen, Nitrogen, Carbon Monoxide, and Carbon
Dioxide — This procedure is for the determination of
oxygen, nitrogen, carbon monoxide, and carbon dioxide
in hexafluoroethane using a gas chromatograph with an
ultrasonic detector.
5.1.1 Detection Limit — 0.5 ppm (mol/mol) for each
impurity.
5.1.2 Instrument Parameters
5.1.2.1 Columns:
Column 1: Haysep D, 100/120 mesh, 4.6 m (15 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 2: Porapak QS, 100/120 mesh, 2.1 m (7 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 3: Porapak QS, 100/120 mesh, 3.6 m (2 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 4: Haysep D, 100/120 mesh, 4.6 m (15 ft) by 3.2
mm (1/8 in) OD ss, or equivalent.
Column 5: Molecular Sieve 13×, 45/60 menh, 2.1 m (7 ft)
by 3.2 mm (1/8 in) OD ss, or equivalent.
5.1.2.2 Carrier Flow: 16 mL/min helium
5.1.2.3 Sample Volume: 1.0 and 2.0 mL
5.1.2.4 Temperatures:
Detector 120°C
Column 1, 2 and 5 50°C
Column 3 and 4 90°C
Valve 90°C
5.1.2.5 Time Table — Determine the times for valve
switching and signal changes, and enter into the run
table.
An example run table follows:
Valve
On Off
10.01*
29.20*
3 0.01 12.00
* Valve left on until end of run.
5.1.3 Calibration Standard — 1–5 ppm (mol/mol)
each carbon dioxide, nitrogen, oxygen and carbon
monoxide, balance helium.
5.1.4 Operating Procedure
5.1.4.1 Inject a sample of the calibration standard into
the column using a gas sampling valve. Record
retention times and peak areas. The approximate
retention times are: oxygen 11.1 minutes, nitrogen 11.6
SEMI C3.37-0701 © SEMI 1989, 2001 2
minutes, carbon monoxide 14.5 minutes and carbon
dioxide 15.9 minutes.
5.1.4.2 Analyze the hexafluoroethane sample to be
tested in the same manner as in 5.1.4.1
5.1.4.3 Repeat 5.1.4.1.
5.1.4.4 Calculate the concentration of oxygen,
nitrogen, carbon monoxide and carbon dioxide in the
sample, using the formula below. The result may not
exceed specification in Section 2 of this Standard.
Sample Pea
k
Are
a
Standard Peak Are
a
×
Concentratio
n
of Standar
d
=
Concentratio
n
of Sam
p
le
5.2 Halogenated Hydrocarbons — This procedure is
for the determination of halogenated hydrocarbons in
hexafluoroethane using a gas chromatograph with a
flame ionization detector.
5.2.1
Detection Limit — 0.5 ppm (mol/mol).
5.2.2 Instrument Parameters
5.2.2.1 Column: 1% SP-1000 on Carbopak B, 60/80
mesh, 7.3 m (24 ft) by 3.2 mm (1/8 in) OD ss, or
equivalent.
5.2.2.2
Carrier Flow: 40 mL/min helium
5.2.2.3 Support Gases: Set the flow rates as specified
by the instrument manufacturer.
5.2.2.4 Sample Volume: 2.0 mL
5.2.2.5 Temperatures:
Detector 250°C
Initial Oven 35°C
Pre-Program Hold 7 min
Temperature Rise 10°C/min
Final Oven 150°C
5.2.3 Calibration Standard — 5 ppm (mol/mol) each
CF
3
H, C
2
F
6
, CF
3
Cl, CF
2
HCl, C
2
F5Cl balance helium.
5.2.4 Operating Procedure
5.2.4.1 Inject a sample of the calibration standard into
the column using a gas sampling valve. Record
retention times and peak areas. The order of elution is
CF
3
H, C
2
F
6
, CF
3
Cl, CF
2
HCl, C
2
F
5
Cl.
5.2.4.2 Analyze the hexafluoroethane sample to be
tested in the same manner as in 5.2.4.1.
5.2.4.3 Repeat 5.2.4.1.
5.2.4.4 Calculate the concentration of each impurity in
the sample using the formula below. Total the amounts
of chlorofluorocarbons and hydrofluorocarbons. The
result may not exceed the specification in Section 2 of
this Standard.
Sample Pea
k
Are
a
Standard Peak Are
a
×
Concentratio
n
of Standar
d
=
Concentratio
n
of Sam
p
le
5.3 Water (See Note 4) — This procedure is for the
determination of trace moisture (water) in
hexafluoroethane, using a continuous flowing
electrolytic hygrometer.
5.3.1
Detection Limit — 1.0 ppm (ppmw). This is
equivalent to a frostpoint of -76°C (-105°F).
5.3.2 Sample Pressure and Flow — Set in accordance
with instrument manufacturer's instructions.
5.3.3
Operation Check — The instrument should be
checked periodically for correct operation. A gas
containing a known amount of moisture should be
passed through the instrument. Agreement between the
hygrometer and the standard should be within their
relative accuracies.
5.3.4
Operating Procedure
5.3.4.1 Obtain a continuous flow sample of the
hexafluoroethane source, using a clean, electropolished
or passivated (see Note 5) stainless steel line which has
been purged dry after exposure to ambient moisture.
5.3.4.2
After purging with a dry gas, allow the sample
gas to flow through the sampling system and
hygrometer until a stable reading is obtained. The
reading may not exceed specification in Section 2 of
this Standard.
5.4
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: Samples of hexafluoroethane should be equilibrated
at no less than 22°C (72°F) for at least 24 hours prior to
analysis to ensure that the material, whose critical temperature
is 20°C (68°F), is single phase.
NOTE 4: 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 stainless steel
diaphragm) to accommodate the pressure restrictions of the
hygrometer.
NOTE 5: A passivation procedure is described in Metals
Handbook, Eighth Edition, Volume 2, ASM International,
Metals Park, Ohio.