Emerson OCX 8800 Instruction Manual page 109

Instruction Manual
IM-106-880, Rev 1.0
January 2007
Cal Warning (Calibration warning)
Cal Failed (Calibration failed)
Probable Cause
Calibration gas supply low or gas connection
leaking
O cell degraded or failed
2
COe sensor degraded
Low sample gas flow in sensor housing due to
flow path plugging
Figure 8-2. Oxygen and Cell
Output
Recommended Corrective Action
Check calibration gas supplies and connections. Adjust gas pressure and flow.
Replenish low calibration gas supplies and tighten or repair loose or leaking
connections. When calibration gas supplies are adequate, recalibrate.
Check O cell impedance by reading the O2 Cell Imped value via the LOI (see
2
Figure 4-4, sheet 2), or the O2 Snsr R value via HART (see Figure 5-3, sheet 2). If cell
impedance is zero, replace O
cell housing ground fault. Repair ground fault. If cell impedance is greater than 5000
ohms and no ground fault is indicated, replace O
Flow calibration gas to the O
2
output and the calibration gas O
plotted values do not fall on the slope line shown in Figure 8-2, replace the O
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
Table continued on next page
20
10
9
8
7
6
5
4
3
2
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
-20 0
ANALYZER OUTPUT (MILLIVOLT)
cell. If cell impedance is less than 5000 ohms, check for
2
cell.
2
cell. Read the cell millivolt output. Plot the cell millivolt
concentration on the chart shown in Figure 8-2. If the
2
(23)
(73)
20 40 60 80
OCX 8800
cell.
2
100 120
8-7