Refurbishing The Hydrazine Sensor Assembly; Hydrazine Sensor Removal; Dismantling And Cleaning - ABB Navigator 550 Operating Instructions Manual

Navigator 500
Hydrazine analyzer

8.4 Refurbishing the hydrazine sensor assembly

Warning. The reagent used in the wet-section is extremely
caustic and must be handled with great care. Gloves,
protective clothing and eye protection must be worn
throughout this procedure.
Note. Before removing the hydrazine sensor assembly,
either:

close the sample isolating valve upstream of the
wet-section and leave the constant-head unit to drain
or

pinch off the sample inlet line from the constant-head
unit to the hydrazine sensor assembly.

8.4.1 Hydrazine sensor removal

Referring to Fig. 8.4:
1. Disconnect the hydrazine
B
temperature sensor
2. Pull the hydrazine sensor assembly
D
clip on the sub-panel.
3. Holding the sensor over a suitable container, pull the inlet
E
tube off inlet nipple
into the container.
Place the end of the inlet tube in the container.
B Blue
C
E
Fig. 8.4 Hydrazine sensor removal
58
A
sensor (red)
(blue) electrical connectors.
C
out of its mounting
and let the tube and sensor drain
Red
A
D

8.4.2 Dismantling and cleaning

Referring to Fig. 8.5:
1. Remove the 2 x 10-32 UNF blanking plugs
2. Hold outer sleeve
assembly up from the inlet nipple
sensor from outer sleeve.
Warning. The gel in the hydrazine sensor assembly
contains silver oxide and sodium hydroxide. The gel is
caustic and stains skin and clothing. Wear gloves,
protective clothing and eye protection.
3. Wash all components thoroughly with high-purity water to
remove all traces of gel.
4. Unscrew knurled nut
platinum electrode, taking care not to damage the
electrode or the electrical connection.
5. Insert the brush supplied in the sensor kit into the bore of
the ceramic tube, rotate gently and withdraw. Immerse the
and
platinum anode in a test tube containing 50 % nitric acid
for a few minutes until clean.
Warning. Nitric acid must be handled with great care.
Wear gloves, protective clothing and eye protection.
6. If the silver cathode is tarnished or blackened, dip a cotton
wool bud in 50% nitric acid and rub over the wire to
restore it to a matt silver finish. Rinse thoroughly with high
purity water.
7. Soak the ceramic tube for one hour in 2% sodium
hydroxide solution and rinse with high purity water.
C
Fig. 8.5 Hydrazine sensor dismantling
C
and carefully push the sensor
D
E
and withdraw sleeve
E
F
O-ring
B
D
OI/AHM550–EN Rev. A
A B
and .
end to remove
F
and the
A