Instruction Manual

IM-106-880, Rev 1.0 January 2007

OCX 8800

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

Check the following portions of the flow path for plugging:

flow path plugging

blowback filter

 

in-situ filter

 

eductor outlet path

 

 

 

Table continued on next page

Figure 8-2. Oxygen and Cell

Output

OXYGEN CONCENTRATION (%)

20

(23)

10

9

8

7

6

5

4

3

2

(73)

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

-20

0

20

40

60

80

100

120

ANALYZER OUTPUT (MILLIVOLT)

37390051

8-7

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Image 109
Emerson OCX 8800 instruction manual Oxygen Concentration %