6 MAINTENANCE
9070
6.2-2 BI-MONTHLY
9
Replace the bottle of Buffer solution.
9
Do not allow the level of solution to fall below about three-quarters
full.
9
On low, ambient temperature, the solution may require replacement
more frequently.
6.2-3 QUARTERLY
9
Check the condition of all plastic tubing; replace as required.
9
Refurbish the sensor.
6.2-4 REFURBISHING
THE
SENSOR
9
Close the valve upstream of the monitor and allow the constant head
unit to drain.
9
Pull the hydrazine sensor out of its mounting clips on the sample
panel. Disconnect the electrical leads at the plug and socket.
9
Pull off the sample inlet “J” tube and let the tube and sensor cell drain.
9
Carefully pull the sensor apart, and wash the components thoroughly
to remove all traces of gel.
9
Withdraw the platinum electrode, taking care not to damage the
electrode or the electrical connection. Insert the brush supplied with
the sensor kit into the bore of the ceramic tube. Rotate it gently and
withdraw the brush. Immerse the platinum anode in a test tube
containing the 25% nitric acid cleaning solution for a few minutes.
Caution
: Do not let the acid cleaning solution touch the rubber plug.
9
If the silver cathode is tarnished or blackened, dip a cotton wool bud in
50% nitric acid and run this over the wire to restore it to a matte silver
finish. Rinse thoroughly with high purity water.
9
Assemble the sensor and fill with gel as follows:
9
Place the plastic plunger into position and cut off the blocked portion of
the syringe tip.
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