COSA Xentaur Xentaur XPDM - Manual (Page 7)

page 4
A note about dry-storage
The dry-storage consist of a stainless steel container filled with desiccant. The elec-
tropolished stainless steel sensor guard slides between the dry-storage and the sample
cell through a spring energized PTFE seal, assuring maximum possible gas tightness
and minimum gas transport between the two chambers when the sensor is moved. When
in dry-storage, the sensor guard is separated from the desiccant by a stainless steel wire
mesh with a thickness of 127µ (0.005”) and a mesh size of 100µ. This keeps the distance
between the sensor and the desiccant to a minimum, which is critical for fast and low dry-
downs, while protecting the sensor from contamination with desiccant particles.
The factory supplied desiccant provides dry-storage dewpoints as low as -80°C when
fresh. When the sensor is pushed into dry-storage it will take some time to dry down
completely and reach equilibrium with the dewpoint in the dry-storage. The dry-down
time to equilibrium depends on how wet the sensor was before it was returned to dry-
storage, and in case that it was completely wet, how long it had remained in wet condi-
tion.
To take full advantage of the dry-storage, make sure, that the dry-storage dewpoint is
below the expected dewpoint of the sample gas by periodically checking the indicated
dewpoint after the sensor has remained in dry-storage for an extended period of time, for
example over night. Replace the desiccant cartridge, if the dry-storage dewpoint is much
higher than -80°C and above your expected sample dewpoints.