Emerson Rosemount OCX 8800 - COe purge; zero feature

3.7.3 Configuring the calibration tolerance feature with the
LOI
Complete the following steps to configure the calibration tolerance feature with the LOI.
1. Use the Z pattern to enter the LOI menu tree.
2. From the SYSTEM menu, select Calib Setup.
3. From the Calib Setup menu, select the following:
• O2 Tol Check: Select Yes to enable the calibration tolerance feature for the
oxygen calibration.
• Comb Tol Check: Select Yes to enable the calibration tolerance feature for the
combustibles calibration.
3.8 COe purge / zero feature
This feature provides a way to periodically flood the COe sensor with air to perform two
functions:
1. Provide additional oxygen to burn off any combustible residue from the COe sensor
2. Allow for optional adjustment of the COe calibration constant.
If the transmitter is configured to update the COe calibration constant, only the constant is
updated. The COe calibration slope is not affected. To update both the constant and slope,
a full calibration must take place.
The feature uses the calibration solenoid that is used for high O
2
test gas and COe zero gas.
For the feature to work properly, instrument air is used as the high O
2
test gas. This also
requires the high O
2
test gas value to be set at 20.95%.
As an option, a two way valve may be installed to switch the high O2 test gas between the
normal calibration gas and instrument air. This allows the transmitter to use a specified
calibration gas for calibration, then instrument air for the COe zero feature. Switching
between the two gases must be manually coordinated between scheduled calibrations
and COe zero events.
When the COe zero feature is used, special pneumatic connections are required. See
Section for details.
The COe feature is only valid if the transmitter is supplied with calibration solenoids and
the solenoids have been activated.
A transmitter shipped from the factory must be configured before the COe zero feature
can be implemented. This same process must be performed any time a replacement card
stack is installed.
Configuration and startup
Reference Manual 53