Dynalab A4000D - Manuel (Page 18)

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– the Reservoir pressure switch is
fitted to the distillate collection
vessel.
– the dummy shorting plug has
been removed from it’s socket
and replaced with the lead from
the WCK/N.
3 Switch on the electricity supply –
the green indicator light will
illuminate.
4 Press the ON/OFF switch to the ON
position – the switch will illuminate.
5 Recheck that the CLEAN switch is
in the CLEAN position and
illuminated.
6 Turn on the mains water supply
and using the needle valve on the
side of the cabinet, adjust the flow
rate to approximately 1 Litre/Min.
for A4000 and 2 Litres/Min. for
A8000 and A4000D. Ensure that
the mains water flows to drain
without any restriction.
7 Turn on the supply of deionised or
pre-treated water. Observe that
deionised water enters the boiler
via the float system of the WCK/N.
8 Allow deionised water to flow into
the boiler until the heating
element(s) is covered by
approximately 10mm. At this level
the flow of deionised water into
the boiler should be automatically
cut off by the WCK/N float system.
9 Switch off the CLEAN button by
pressing it for a second time – the
switch light goes out.
The heater(s) will start to warm up
and eventually run at a red glow. (If
heater fails to glow, check that the
flow of mains water is adequate).
10 Allow distillation to commence and
observe that the WCK/N float
system allows fresh deionised water
to enter the boiler and maintain a
satisfactory operating level.
If the deionised supply fails then
the WCK/N will switch off the
heater until it is restored.
11 Replace the perspex viewing
screen.
When any of the Aquatron stills have
been used to produce distilled water
directly from a mains water supply, there
will inevitably be a build-up of scale in
the boiler and on the heating element(s).
To obtain optimum performance from
the still the scale should be r emoved on
a regular basis. The time span between
cleaning depends entirely upon the
hardness of the water supply. In very
hard water areas it may be necessary to
clean the still once a week, wher eas in
soft water areas several weeks may
elapse before cleaning is necessary.
It should not, of course, be necessary to
de-scale the second stage boiler on the
A4000D or when the stills have been
operated from a de-ioniser.
Cleaning the still involves the use of
concentrated hydrochloric acid. As a
safety precaution protective clothing,
gloves, mask and goggles should be
worn during cleaning.
Note:
The cabinet and perspex screen should
be cleaned using a dilute detergent
solution only.
It is possible to descale the Aquatr on
Water Still without dismantling the
glassware by following these instructions
in conjunction with Control of
Substances Hazardous to Health
regulations (COSHH) 1988.
Method
1 Push the CLEAN switch to the
CLEAN position – the switch
illuminates.
2 Observe that the heating element/s
has switched off. Allow boiling to
stop and water to cool.
3 Push ON/OFF switch to OFF
position.
4 Remove perspex screen.
5 Open the Rotaflo stopcock on the
level control WL48, allow the boiler
to empty to 3 /
4
’s of its full capacity,
and close stopcock.
6 Carefully add about 100ml. of
concentrated hydrochloric acid into
the glass funnel of the WL48.
7 Push the ON/OFF switch to the ON
position, the boiler will refill to its
operating level.
8 Push the ON/OFF switch to the OFF
position
.
9 Allow the chemical reaction within
the boiler to continue until all the
deposits have been removed.
Note – if scale has built up above
the operating level, the boiler may
be completely filled by either lifting
the drain pipe or restricting the
flow of water to drain. This
operation must be carefully
controlled so that the boiler does
not over-fill and cause water to be
forced over the funnel top.
10 Open Rotaflo stopcock and allow
contents of the boiler to drain
completely.
Note:
If the acid added to the boiler has
not been completely neutralised,
the liquid flowing to drain may be
strongly acid. Necessary safety
precautions should be observed
around the drain position, and any
effluent control procedures
followed.
11 Close Rotaflo stopcock.
12 Push ON/OFF switch to ON position
and allow boiler to fill with water.
Again the boiler may be completely
filled by following procedure
detailed in step 8.
13 Push ON/OFF switch to OFF
position.
14 Drain the boiler by opening the
Rotaflo stopcock..
15 Repeat steps 11-14 two or three
times until the boiler has been
thoroughly flushed through.
16 The still is re-started by finishing
the cleaning cycle at step 12, and
then pushing the CLEAN switch to
the OFF position. (Switch is not
illuminated).
Before collecting the distillate the
still should be allowed to run for
about 10 minutes with the distillate
running to drain, this will ensure
that any residual acid is removed.
Note:
The amount of acid required will
depend upon the degree of scaling.
If after performing the cleaning
cycle deposits are left in the boiler,
it may be necessary to repeat the
cleaning cycle using a fresh
quantity of acid.
The benefits gained from regular
cleaning cannot be over
emphasised.
Cleaning
A4000, A8000,
A4000D