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...8 MAINTENANCE
Warning. Sodium hydroxide is extremely caustic
and must be handled with great care. Wear gloves and
eye protection.
One liter of the rinse solution is prepared as follows:
a) Dissolve 100 g of sodium hydroxide pellets, NaOH, in
approximately 600 ml of high purity water in a plastic
container. Allow the solution to cool to ambient
temperature.
b) Add to the solution 5 g di-sodium EDTA and stir to dissolve.
c) Transfer the above solution to a 1 liter measuring cylinder
and make to the mark with more high purity water. Mix well
and store in a tightly stoppered plastic container. Stored in
this container the solution is stable for many months.
8.2 Scheduled Servicing
The following servicing schedule has been produced as a
general guide only. Because the monitor is designed for a wide
range of applications, where the nature of the sample can vary
considerably, it may be necessary to amend the schedule to
suit the particular installation and sample conditions.
8.2.1 Regular Visual Checks
It is recommended that the monitor and the sampling system is
visually inspected on a regular basis to ensure the correct
functioning of the system and to check the integrity of the
readings.
a) Check for leaks particularly around the sample and drain
pipework connections.
b) Confirm sample flow by checking delivery to the constant
head unit and effluent from the drain.
c) Check liquid levels in the reagent and standard solution
containers.
d) Inspect all tubing and liquid handling components for leaks
and deterioration.
e) Check for malfunction indications on the instrument
display.
8.2.2 Five-weekly
a) Carry out the normal visual checks covered in
Section 8.2.1.
Warning. It is vital that good maintenance in this
respect is adhered to and that all leaks of potentially
aggressive chemical solutions are attended to as soon as
possible and spillages are cleaned up.
b) Discard old reagent and standard solutions, clean
containers thoroughly, and refill with fresh solutions – see
Section 8.1.
26
Caution. All unused solutions must be discarded;
the containers must be rinsed with high purity water before
refilling with the fresh solution.
c) Replace pinch tube between the cuvette and the drain
manifold. Release the tube from the pinch valve by
pressing the centre plunger and remove. Replace with new
silicon rubber tube from the spares kit. Ensure that the tube
is fully inserted into the valve to avoid any leakage of
solution from the cuvette.
d) Set the following parameters to YES using Programming
Page 2.1:
Five-Weekly System Flush
Five-Weekly Solution Replacement
Default Calibration Parameters
For single stream instruments only:
Set the color compensation frequency to OFF using
programming Page 3.3.
e) Rinse the internal pipework – see Section 8.2.4. It is
important that this procedure is carried out to ensure that
the monitor tubing is kept in a good clean condition,
essential for correct monitor operation.
Note. Before proceeding to the next step, multi-
stream users must select single stream mode as
described in Section 4.3.
f) If having not already done so energize the secondary CAL
valve (see Programming Page 2.3) and leave for
15 minutes. Adjust the reading on scale with the
switches and run the monitor for 30 to 60 minutes to
purge the old solution and assess stability.
g) If the monitor exhibits good stability, i.e. <5% of reading,
carry out a two-point BASELINE calibration – see
Programming Page 2.3.
For single stream instruments only:
h) If color compensation is required, switch to MANUAL for
manual compensation only, or to automatic timed
compensation by selecting a frequency between 1 to
24 hours using Programming Page 3.3. For general
information regarding the setting up of the color
compensation see Section 7.2.
8.2.3 Twelve-monthly
a) Service pump – see Section 8.2.6.
b) Replace all internal plumbing and pump tubing – see
Section 8.2.7.
c) Set 'Annual Service' to 'YES' – see Programming
Page 2.1.
d) Carry out the normal four-weekly schedule not already
covered in steps a) and b).
and
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