6-50 | Model 933S UV Analyzer
2. If the analyzer uses Measured Pressure Compensation (optional),
change it to Fixed mode so that a “f: Sample gas pressure too low”
alarm does not occur. To do this, view the Cell/Misc Parameters dialog
box and enter a value in the Default Cell Pres (pressure compensa-
tion) field that is the same as, or approximately, the Measuring Cell
pressure. Refer to “Cell/Miscellaneous (Compensation) Parameters” in
Chapter 4.
Close the sample inlet valve. Backpurge the analyzer sample system
with Zero gas for 2–3 minutes.
3. Change the Flow Control to ‘4’ (shut-in/shut-off). Click Apply (next to
Flow Control) and then click OK.
Bleed down the sample system to atmospheric pressure (check gauge).
Close the valve on the Vent Line (or cap the Vent outlet).
To avoid tearing the Membrane Filters in the Filterblock, always bleed
down the sample system pressure on the downstream (outlet) side of
the Filterblock. Pressure differentials of more than 210 KPA (30 PSI)
from the inlet side to the outlet side can tear the Filters and they will
have to be replaced.
4. Disconnect AC power to the analyzer and power down the computer
before performing maintenance on the analyzer.
5. Remove the Optical Bench from the Upper Enclosure:
While removing the Optical Bench from the Upper Enclosure, grasp
it by the upper portion of the Optical Bench to support it; do not sup-
port the assembly by its circuit boards or source lamps. Also, take care
not to damage the enclosure’s joining areas (flamepath).
a. Remove the (24) M10 screws from the Upper Enclosure door and
open it.
b. Disconnect the following wiring connectors from the Micro-Inter-
face board (see Figure 6-12 for connector locations):
• Measuring Cell RTD line from J300.
• RS-422 communication line from J104.
• Micro-Interface AC power line from J200.
• DC power line from J103.
• Optional: If your analyzer has a Cell Heater, disconnect the
Heater Cartridge wire (marked ‘N’) at J200 (Terminal 2) and
the Overtemp Switch wire (marked ‘L’) at J200 (Terminal 1).
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CAUTION
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CAUTION
Setup (tab)Cell/Misc
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