IB-106-340
6-14
NOTE
To determine if the diffusion element needs
to be replaced, refer to paragraph 6-2.
c.
If equipped with the optional ceramic diffusion
assembly, remove and discard the setscrews and
remove the vee deflector (Figure 6-10). Use span-
ner wrenches from the probe disassembly kit
(Table 8-1), to turn the hub free from the retainer.
Inspect the diffusion element. If damaged, replace
the element.
d.
Loosen the four socket head cap screws from the
cell and flange assembly and remove the assembly
and the corrugated seal. The cell flange has a
notch that may be used to gently pry the flange
away from the probe. Note that the contact pad
inside of the probe will sometimes fuse to the oxy-
gen sensing cell. If the cell is fused to the contact
pad, push the cell assembly back into the probe
(against spring pressure) and quickly twist the cell
assembly. The cell and contact pad should sepa-
rate. If the contact pad stays fused to the cell, a
new contact/thermocouple assembly must be in-
stalled. Disconnect the cell and the thermocouple
wires at the probe electronics and withdraw the
cell with the wires still attached.
e.
Remove entire electronics per paragraph 6-5a,
steps 2 through 6.
f.
If the contact assembly is damaged, replace the
strut or the contact pad. Instructions for replacing
the contact pad are in the cell replacement kit.
g.
Remove and discard the corrugated seal. Clean
the mating faces of the probe tube and retainer.
Remove burrs and raised surfaces with a block of
wood and crocus cloth. Clean the threads on the
retainer and hub.
h.
Rub a small amount of anti-seize compound on
both sides of the new corrugated seal.
i.
Assemble the cell and flange assembly, corrugated
seal, and probe tube. Make sure the calibration
tube lines up with the calibration gas passage in
each component. Apply a small amount of anti-
seize compound to the screw threads and use the
screws to secure assembly. Torque to
35 in-lbs (4 N·m).
j.
Install the entire electronics per paragraph
6-5a, steps 7 through 13.
k.
Apply anti-seize compound to the threads of the
cell assembly, hub, and setscrews. Reinstall the
hub on the cell assembly. Using pin spanner
wrenches, torque to 10 ft-lbs (14 N·m). If appli-
cable, reinstall the vee deflector, orienting apex
toward gas flow. Secure with the setscrews and
anti-seize compound. Torque to 25 in-lbs
(2.8 N·m).
l.
On systems equipped with an abrasive shield,
install the dust seal gaskets, with joints 180° apart.
m. Reinstall the probe and gasket on the stack flange.
n.
Follow the instructions in paragraph 6-4a2 to
install the Oxymitter 4000 into the stack or duct. If
installing an Oxymitter 4000/SPS 4000 assembly,
follow the instructions in paragraph 6-4b2. If there
is an abrasive shield in the stack, make sure the
dust seal gaskets are in place as they enter the 15°
reducing cone.
o.
Turn on power and monitor thermocouple output.
It should stabilize at 29.3+0.2 mV. Set reference
air flow at 2 scfh (56.6 l/hr). After the Oxymitter
4000 stabilizes, calibrate the unit. If new compo-
nents have been installed, repeat calibration after
24 hours of operation.
OPTIONAL CERAMIC
DIFFUSION ELEMENT
VEE
DEFLECTOR
HUB
SPANNER
WRENCH
SETSCREW
RETAINER
CEMENT
PORT
CEMENT
FILLET
22220029
Figure 6-10. Ceramic Diffusion Element Replacement
Summary of Contents for Oxymitter 4000
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