Emerson OCX 8800 ANALYZER OUTPUT (, OXYGEN CONCENTRATION (%), MILLIVOLT )

Instruction Manual
IM-106-880, Rev 1.0
January 2007
8-7
OCX 8800
Figure 8-2. Oxygen and Cell
Output
Cal Warning (Calibration warning)
Cal Failed (Calibration failed)
Probable Cause Recommended Corrective Action
Calibration gas supply low or gas connection
leaking
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.
O2 cell degraded or failed Check O2 cell impedance by reading the O2 Cell Imped value via the LOI (see
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 O2 cell. If cell impedance is less than 5000 ohms, check for
cell housing ground fault. Repair ground fault. If cell impedance is greater than 5000
ohms and no ground fault is indicated, replace O2 cell.
Flow calibration gas to the O2 cell. Read the cell millivolt output. Plot the cell millivolt
output and the calibration gas O2 concentration on the chart shown in Figure 8-2. If the
plotted values do not fall on the slope line shown in Figure 8-2, replace the O2 cell.
COe sensor degraded Replace COe sensor or increase warning level (SYSTEM, CALIB SETUP, COe Slope
Warn via HART.)
Low sample gas flow in sensor housing due to
flow path plugging
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
8
9
7
5
0.8
0.9
0.7
0.5 0.6
0.4
0.3
0.2
0.1
6
4
3
2
1
-20 0 20 40 60 80 100 120
ANALYZER OUTPUT
(
MILLIVOLT
)
(23)
(73)
37390051
OXYGEN CONCENTRATION (%)