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8.2.4 Rinsing Internal Pipework
Important Note.
• It cannot be stressed strongly enough that the five-
weekly chemical rinse with the NaOH rinse solution is
vitally important. It is also very effective at reducing
calibration problems, drift and signal noise. Any
evidence of white precipitate in the mixer or reaction coil
must be removed with the rinse solution.
• If the routine rinse procedure has not been carried out
on a regular basis as scheduled, or the liquid handling
section is in poor condition, run the cleaning solution
through the monitor for several hours.
Carry out the following procedure on a five-weekly basis:
a) Remove the secondary standard tube from the solution
container and immerse in the ammonia/detergent rinse
solution.
b) Energize the secondary cal. valve (see Section 6,
Programming Page 2.2) and allow the rinse solution to run
through the monitor for about 30 minutes.
c) Remove the secondary solution tube from the rinse
solution, wash it well with high purity water and return it to
the secondary calibration solution.
d) Carry out a calibration of the monitor as described in
Section 8.2.2, starting at step f).
In some applications deposits may accumulate in the pipework
which are unaffected by the alkaline ammonia wash solution.
In this case an acid cleaner, e.g. the reagent solution, may be
more effective and can be introduced in a similar manner to
that described in this section.
8.2.5 Consumable Spares Kit – see Section 10
This kit includes all the components which are recommended
for annual replacement (refer to the details in the spares kit).
This annual refurbishment ensures a high level of reliability
from the monitor for many years. The kit should be re-ordered
when used so that all the items are available throughout the
following years operation.
The kit contains:
•
one set of pump tubing,
•
one set of pump capstans,
•
a syringe for checking free flow though valved and
tubing and for clearing blockages,
•
a complete set of plumbing tubing, and
•
sundry items – 'O' rings, tube connectors, pump tube
bungs, and sample filters.
8.2.6 Peristaltic Pump – Fig. 8.1
It is recommended that the pump tubing and pump capstans,
supplied in the Consumable Spares Kit, are replaced after one
year of operation. Carry out the procedure shown in Fig.8.1.
8.2.7 Replacement of Plumbing Tubing – Fig. 8.2
All the following items are included in the Consumable Spares
Kit.
Caution. It is essential that the correct tube,
which was chosen with great care, is fitted in each
position. Failure to do this could upset the performance of
the monitor or result in solution leakages around
connections due to chemical attack.
a) Remove each section of the sample and reagent plumbing
tubing in turn and replace with new tubing of the same
length.
b) Remove drain tubing, and replace with new tubing of the
same length.
c) It is recommended that the sample and drain tubing to and
from the monitor is inspected and replaced if the condition
of the tubing is poor or shows evidence of any build-up of
solids.
8.3 Shutdown Procedure
The monitor can be left with the pump switch off for up to
24 hours without any detrimental effects. However, for longer
periods it must be shutdown correctly to prevent chemical
precipitation
in
the
pipework
maintenance and recommissioning.
Perform the following Shutdown sequence:
a) Close the sample valve up-stream of the monitor.
b) Rinse the internal pipework – see Section 8.2.4. It is
important to flush the reagent bottle tube; so these
need to be immersed in the rinse solution also.
c) Repeat the process with high purity water to flush out the
ammonia.
d) Switch off the monitor.
e) Remove the platen from the peristaltic pump and release
the tube from the pinch valve.
f) Empty reagent and standard containers and rinse with high
purity water.
8 MAINTENANCE...
resulting
in
extensive
27
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