Instruction Manual
IB-106-340C Rev. 4.1
July 2004
Rosemount Analytical Inc. A Division of Emerson Process Management Troubleshooting 8-1
Hazardous Area Oxymitter 4000
SECTION 8TROUBLESHOOTING
8-1 OVERVIEW
While the Hazardous Area Oxymitter 4000
electronics provides a significant number of
diagnostic alarms to assist in troubleshooting
potential problems, it’s good to place these
alarms in perspective with respect to the
instrument’s operating principles:
a. When the Zirconium Oxide sensing cell is
heated to its setpoint [736°C (1357°F)], the
cell will generate a voltage that represents
the difference between the process O2%
and the reference O2% inside the probe
(20.95% O2 ambient air).
b. Test points, Figure 8-1, are provided to read
the raw millivolt value generated by the
ther-mocouple that controls both the cell
temperature and the raw cell signal.
c. The cell temperature at test points 3 and 4
should always be stable at approximately
29 to 30 millivolts, which represents the
736°C setpoint temperature.
37260043
1001010.01 0.10
0
50
100
150
200

Concentration O (%)

2
EMF (mV)

O Sensor Performance at 736 C

2
O
O2 % 100201510987654
EMF(mV) -34 1.0 7.25 16.1 18.4 21.1 23.8 27.2 31.2 36.0
O2 % 3 2 1 0.8 0.6 0.5 0.4 0.2 0.1 0.01
EMF(mV) 42.3 51.1 66.1 71.0 77.5 81.5 86.3 101.4 116.6 166.8
Figure 8-1. O2 Sensor mV Reading vs. % O2 at 736°C (Reference Air, 20.9% O2)
8