Rev 02, 09/21
Perma Pure LLC
• A Halma Company • [email protected] • www.permapure.com
Telephone: 7
32-244-
0010 • Toll Free: 800
-337-
3762 • Fax:
7
32-244-8140
1
001 New Hampshire Ave.,
L
akewood, NJ 08701 USA
Bypass Port Plumbing
7.1.5
PD Sample Gas Dryer
The Nafion™ polymer transfers water molecule
s from one side of the membrane to the other by a first order
kinetic reaction. This is unlike a porous membrane that depends on the physical size of molecules. Nafion™
Polymer selectivity is based on chemical reactivity, not the size of the molecule
–
therefore, not traditional
permeation. The Nafion™ polymer selectively transfers water vapors, leaving most analytes in the gas stream
untouched. The driving force for the Nafion™ polymer to transfer water molecules is the difference in humidity
levels (water vapor pressure) on either side of the
membrane. The Nafion™ polymer tries to attain equilibrium
of the partial pressure of water vapor on either side of its membrane.
PD-Series sample gas
dryers consist of a bundle of 0.030″ O.D. Nafion™
membrane tubing housed within a
single large tube shell. Sample
gas flows within the Nafion™
membrane tubing while water vapor absorbs into
the tubular membrane walls and is removed. Moisture permeating the tubing is carried away by a dry purge
gas within the shell that flows counter-current to the sample gas. The sample gas dryer purge air flow rate is
controlled by a needle valve located in the purge inlet port. The purge flow rate and vacuum level can be
monitored with the installed rotameter and vacuum gauge.
