felisa FE-390 Instructivo De Operación página 9

12
SCALE REMOVAL.
Soft scale may be removed with a stiff bristle brush, after cleaning all
particles should be flushed out with water.
Hard scale may be removed by using a 10% solution of inhibited HCl, this
acid solution is available commercially or may be prepared using 20 parts
of water and 6 parts 30% HCl. When using the acid solution, do not allow
the acid remain in contact with the parts for more than 20 minutes. Flush
with water thoroughly, a 5% sodium bicarbonate solution may be used to
remove any acid left on the parts.
If desired a 10% sulfamic o acetic acid solution may be used instead of
HCl. Under no circumstances should any acid cleaner be allowed to come
in contact with tinned surfaces. Always wear protective clothing and eye
shield when handling acid.
Organic scale may be formed with a dark brown or black color from
organic impurities present in the feed water. This type of scale can be
removed with a strong detergent solution, should be allowed to be in
contact with the scale for 24 hours, rinse off the parts with water after
cleaning.
CAUTION.
Do not add the acid cleaning solution rapidly because if any bicarbonate
scale is present, gas will be released in considerable amount, left the
solution remain in the parts for 15 to 20 minutes, then drain, repeat if
necessary until scale is removed. Wash the parts thoroughly after using the
acid cleaning solution, do not use the acid cleaning solution on any tinned
part of the Still.
BIOLOGICAL CLEANING.
Biological cleaning is used on the parts that come in contact with the
distillate (such as, the distilled water side of the condenser, or the distilling
water transmission tube), to remove any biological contamination, immerse
the part in a 1% formaldehyde solution over night, do not rinse the part with
water after cleaning (avoid splashing the solution on open cuts).
After the Still reassembled and operating, reduce the cooling water
throttling valve until steams issues from the condenser vent at least 12
inches. Operate the Still in this manner for 30 to 60 minutes, ventilate the
room during this operation.
13
CLEANING FREQUENCY.
The frequency of cleaning will depend upon the purity in the water being
used, for example, the evaporator should require infrequent cleaning if it is
fed with pretreated water; however, the cooling water side of the
condenser will have to be cleaned at more frequent intervals due to the fact
that raw water is flowing through it and it will scale up sooner. The Still
should be inspected at frequents intervals, until cleaning intervals are
determined.
DISASSEMBLE, INSPECT AND CLEAN.
Shut off and drain the Still. Shut off the water supply. Remove the
condenser (2) from the Still, inspect the cooling water side of the condenser
for scale and clean as required., if required, clean the distilled water side as
described under "Biological Cleaning". Remove the heating gasket (13)
and the baffle (14), now the interior of the evaporator is visible, inspect the
interior for scale and remove as required. Disassemble the constant level
device (6), inspect the level device, the drain line and the drain valve, clean
as required. Reassemble the Still, assembly is essentially the reverse of
disassembly, connect the water, waste and distillate lines. Start the Still as
described under "initial Startup".
Lower the cooling water flow rate with the valve(23) until steam issue from
the condenser vent 12 inches approx. Operate in this manner for 30 to 60
minutes to sterilize and clean the Still.
TEST FOR CONDENSER LEAKS.
Visual test for leaks. A simple test for condenser leaks may be performed
as follow: Shut off the Still heat supply. Let the cooling water flow through
the condenser until the condenser is cool. Note if there is a flow, even in
drop quantities from the distillate outlet, if there is a continuous flow, it is
possible that there is a leak from the cooling water side to the distillate side,
if this is the case, the condenser must be replaced.
Pressure test for leaks. If a more positive test is required proceed as follow:
Remove the condenser from the Still. Remove the cooling water discharge
tube (10), plug the discharge connection in the condenser with a plug or
stopper. Attach a hose to the cooling water inlet connection and apply
about 5 psi air pressure to the condenser. Submerge the entire condenser in
a tank of water. If any air bubbles come from the condenser, replacement is
necessary.