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2150EX Area Velocity Flow Module
Section 5 Maintenance
5-8
5.4 Desiccant
The 2150EX System devices use desiccant to protect the internal
components from moisture damage. In the 2150EX, a desiccant
cartridge is used to dry the reference air for the sensor. This pre-
vents moisture from plugging the reference line, which would
cause the sensor to report erroneous level readings. The car-
tridge is filled with indicating silica gel, which is blue or yellow
when dry. As the desiccant becomes saturated, the color changes
from blue to pink, or from yellow to green. Replace the desiccant
before the entire length of the cartridge turns pink or green.
The 2191EX battery module uses desiccant bags to keep the
interior of the case dry. The bags are located inside the battery
caps. Attached to the inside face of each cap is a humidity indi-
cator. Humidity indicators have regions that display 20, 30, and
40 percent humidity levels. Ideally, each region should be com-
pletely blue. As the desiccant becomes saturated, the humidity
levels will increase and the regions turn pink. When the 40
percent region begins to turn pink, the components are no longer
adequately protected and the desiccant must be replaced.
5.4.1 Replacing the
Desiccant: AV Module
The desiccant is contained in a cartridge located on the left side
of the 2150EX. To remove the cartridge, unscrew the collar and
slide the cartridge out of the 2150EX. The opaque tube reveals
the silica gel desiccant inside.
CAUTION
To prevent static electricity, do not replace silica in potentially
explosive atmospheres. Empty and fill the desiccant cartridge
in a safe area.
To replace the silica gel desiccant:
1. Hold the cartridge upright with the collar at the top.
2. As shown to the left, push the collar off the cartridge.
3. Empty the saturated silica gel beads or granules.
4. Fill the tube with new (P/N 099-0011-03) or reactivated
(see section 5.4.3) silica gel desiccant.
5. Press the collar onto the tube.
6. Slide the cartridge into the 2150EX Module. Tighten the
collar to seal the cartridge in place.
5.4.2 Replacing the
Desiccant: Battery
Module
A bag of desiccant is located inside each of the battery caps
behind a retaining plate. To replace the desiccant:
1. Loosen the two mounting screws that secure the metal
retaining plate.
Battery Module
20
30
40
Humidity Indicator
Collar
Cartridge