INFICON Composer Gas Concentration Controller - Manual (Page 71)

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Composer Operating Manual
3.1.11 Properties of Optional O-ring Materials
The use of some chemicals may preclude the use of Viton seals. KALREZ
elastomers are factory available. These materials are somewhat more
permeable than Viton, especially for small molecules.
NOTE: The high permeation rate of the optional elastomers may create some
confusion when leak checking. It is possible that an apparent leak can
occur long (approximately 30 seconds) after a specific joint has been
probed. Unless the leak detector’s response is immediate, the joint in
question is leak tight; permeation is the source of the apparent leak.
A version of the Transducer that uses metal gaskets for the primary seal is
available. Refer to
Figure 2-5 on page 2-12 .
WARNING
Perform a thorough leak check prior to connecting the
Transducer to any process gas. Many of the gasses
used for film growth are toxic at very low exposure
levels. The use of a highly sensitive helium mass
spectrometer leak detector is mandatory for safety.
Table 3-2 Permeation of gases through select elastomers
KALREZ Viton
He 2.5 1.7
H2 113 21
N2 0.05 0.031
Ar 6.1 4.1
Permeation Rate
X10
9 –
Cm
3
Cm – ( )
S Cm
2
– CmHg P ∆ – ( )
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