Emerson Rosemount OCX8800A - Page 263

Do not attempt to replace the O
2
cell until all other possibilities for poor
performance have been considered. If cell replacement is needed, order the O
2
cell replacement kit (refer to Replacement parts).
The O
2
cell replacement cell contains an O
2
cell and flange assembly, gaskets,
socket head cap, screws, and anti-seize compound. The items are carefully
packaged to preserve precise surface finishes.
Do not remove items from the package until you are ready to use them.
Procedure
1. Remove the four Allen cap screws (M, Figure 10-14) from the O
2
cell (L).
Remove the O
2
cell.
The cell flange has a notch that may be used to gently pry the flange away
from the heater tube (I).
Note
The pad on the end of the contact/thermocouple assembly (A) will
sometimes fuse to the O
2
cell (L).
2. If the O
2
cell is fused to the contact pad, push the O
2
cell back into the
heater tube (against spring pressure) and quickly twist the O
2
cell.
The cell and contact pad should separate. If the contact pad stays fused to
the cell, you will need to install a new contact/thermocouple assembly (A).
3. Remove and discard the gasket (J). Clean the mating surface of the heater
tube (I). Remove burrs and raised surfaces with a block of wood and a
crocus cloth.
CAUTION
Equipment damage
The ceramic rod in this assembly is fragile.
Use care when handling the contact and thermocouple assembly.
4. Remove screws (B), lockwashers (C), return wire (D), and heater strut
assembly (E).
5. If replacing contact and thermocouple assembly (A), use a pencil to mark
the location of the spring clip (H) before removing. Squeeze tabs on the
spring clip to remove. Retain the spring clip and spring (G); replace if
damaged.
6. While carefully handling the new contact and thermocouple assembly (A),
lay the old assembly next to the new one. Transfer match marks to the new
assembly.
7. Carefully guide the new contact and thermocouple assembly (A) through
the strut bracket (F), spring (G), and spring clip (H) until the spring clip
reaches the pencil mark.
Manual Maintenance and service
00809-0500-4880 December 2022
Rosemount OCX8800A 263