Emerson Rosemount Oxymitter 4000, Reference Manual, Page: 164 / 198

9.3.8 Replace heater strut
Do not attempt to replace the heater strut until you have eliminated all other possibilities
for poor performance.
WARNING
The transmitter, probe tube, and flame arrestor hub can be hot (up to 572 °F [300 °C]) in
the region of the probe heater. This can cause severe burns.
Wear heat resistant gloves and clothing when removing probe.
Do not attempt to work on the probe until it has cooled to room temperature.
If you need to replace the heater strut, order a replacement heater strut. See Table 10-2 .
Procedure
1. Follow the instructions in Remove probe to remove the transmitter from the stack
or duct.
2. Remove oxygen sensing cell per Replace cell .
CAUTION
Damage to the aluminum housing can occur.
Do not force the probe housing when installing or removing it from the integral
electrical barrier/feed-through (
Figure 2-14 ).
3. Remove four screws (22, Figure 2-14 ) and washers (21) from the probe tube
assembly (23). Remove the probe tube assembly from the housing (11).
Once you have separated the probe and housing, spring tension releases, and the
heater strut assembly (32) moves up.
4. Remove strut pressure clamp (35).
5. Disconnect the heater and signal wire connectors from the mating connectors on
the heater strut assembly (32).
6. Remove tube clamps (33). Carefully pull the CAL and REF gas silicone tubes (34)
from the CAL and REF gas ports.
7. Remove gas port fittings (29) from the CAL, REF, and VENT ports.
8. Grasp the wire loop and carefully slide the heater strut assembly (32) out of the
probe tube.
See
Figure 9-6 .
Maintenance and service Reference Manual
October 2019 00809-0100-4340
164 Emerson.com/Rosemount