Emerson Rosemount OCX 8800 Reference Manual page 212

Troubleshooting
Table 8-1: Troubleshooting
O2 Constant error (Constant not between -20 mV and +20
mV)
Cal Warning (Calibration warning)
Cal Failed (Calibration failed)
Probable cause
COe sensor degraded
• COe slope error (slope not between 200 ppm/Ohm and
4500 ppm/Ohm)
• COe constant error (constant not between -100 Ohms
and +100 Ohms)
Low sample gas flow in sensor housing due to flow path
plugging
Calibration gas concentration incorrect or gas bottle emp-
ty
202
(continued)
Flow calibration gas to the O
output. Plot the cell millivolt output and the calibration gas
O concentration on the chart shown in
2
plotted values do not fall on the slope line shown in
Figure 8-2, replace the O cell.
2
Figure 8-2: Oxygen and cell output
Recommended corrective action
Replace COe sensor or increase warning level (SYSTEM,
CALIB SETUP, COe Slope Warn via HART).
Check the following portions of the flow path for plugging:
• Blowback filter
• In-situ filter
• Eductor outlet path
O Tol Error (not within 10% of configured O
2
COe Tol Error (not within 30% of configured CO test gas)
cell. Read the cell millivolt
2
Figure 8-2. If the
test gas)
2
OCX 8800