Appendix A: Miscellaneous Options; Asymmetric Cycle - Ametek 5000 Instrument Manual

Asymmetric Cycle 5000 Moisture Analyzer
This option minimizes effects of dirty sample streams on detector life. The basic manual describes
the standard version. This addendum covers the differences between the standard and asymmetric
cycle options versions.
Function

Asymmetric Cycle

Cycle (Gas flow 0.5 min wet sample/9.5 min dry reference
through the
moisture cell)
Reference gas 3A molecular sieve dryer, plus activated
conditioning charcoal contaminant trap (recommended)
The primary causes of 5000 sensitivity loss is contaminant buildup on the crystal detector in the moisture
cell. Anything done to minimize detector exposure to the contaminant or to remove the contaminant
from the crystal will improve service life. The asymmetric cycle option minimizes exposure to a dirty
sample and removes volatile contaminants from the crystal.
The exposure reduction is obvious (see comparison above). The standard cycle detector is exposed to
the sample for 5 minutes out of each 10, whereas the asymmetric cycle detector is exposed for only 0.5
minute out of 10, resulting in a 90 percent time reduction in exposure to contaminants, assuming that
the reference gas is clean. The reference gas can be cleaned either by using a separate known clean gas
or by removing the contaminants from that portion of the sample gas used as a reference. The latter
is the method most often used and is done by placing an activated charcoal contaminant trap ahead
of the reference gas dryer.
MISCELLANEOUS OPTIONS
Standard
0.5 min wet sample/0.5 min dry
reference
3A molecular sieve dryer
Options A-1