Putting Into Service - AERMEC TRA Manuel Technique

Preliminary controls
Before putting the cooling system
previously filled with water into
operation, carry out the following
operations and checks:
1) turn the fan and check that it turns in
the right direction for the air to enter
from the lower vents and escape from
the cylindrical opening at the top.
If this is not the case, stop the fan, then
change the rotation direction of the
motor by inverting the position of two
of the three phases.
The fans' rotation direction must
therefore be checked each time repairs
or maintenance is conducted on the
electrical motors and their commands.
Make sure that the shield grille is
properly fixed to the fan support
ring and that there are no abnormal
vibrations on the machine as a whole.
2) set the water circulation pumps in
motion and check:
- the jet from the nozzles that must
be pointing vertically downwards
with the cone well open and that
the intensity is the same for all the
nozzles.
- the jets together that must fully and
evenly cover the surface of the filling
material so as to produce a uniform
rain falling on the lower part of the
pack.
- the tightness of the flange joints,
threaded joints and gaskets
- the pressure, in water column meters
indicated by the hydrometer in
glycerine. Remember that this value
must necessarily correspond with
what is shown on the identification
plate on the machine: otherwise, it
signifies that the water flow rate in the
system is different from the flow rate
for which the evaporation tower was
dimensioned.
3) operate the fan and the water

Putting into service

recirculation pump together and
carefully check the input current of
the relative motors and check that the
values measured do not exceed those
on the relevant rating plates.
exercise
Operating conditions
The normal usage conditions of the
cooling towers are the following:
- maximum pressure of supply water
0.5 bar (5 metres of the water
column)
- maximum inlet water temperature
55 °C (standard versions)
75 °C (ATT version)
Topping up with river water
When river water is used for topping
up cooling towers, in addition to the
problems of acidity and hardness
normally connected with topping up
water wherever it comes from, great
attention must be paid to making sure
that there are no suspended solids that
might also be large in size,as well as
being lime, sand and clay.
In this case, it is as well to install a
suitable filtering system with a screen
upstream to trap the larger particles.
Topping up with salt water
Given that fibreglass parts do not suffer
minimally from the presence of salts
in the water, there might however be
problems with the metal elements
because salt water causes a chemical
reaction especially on galvanised
parts when there even tiny flaws in the
protective zinc layer.
You are therefore advised, in this
particular to choose the stainless-steel
version of the evaporation tower or the
version with all the metal parts made of
AISI 304/AISI 316 stainless steel.
Winter running:
In areas where the winter ambient
temperature falls below 0°C, there is
the possibility of ice forming in or on the
components of the towers and the area
immediately around them.
The parts and the areas most subject to
freezing and the formation of ice are:
- the water collection tanks
- the water delivery and recovery piping
as well as that of the secondary
circuits
- the fans
- occasionally the air around the tower
In general, when the tower is functioning
normally even during the winter season
there is no danger of freezing. It is
however possible that with external
temperatures lower than -2°C / -3°C,
ice might form even when the system is
stopped for quite short periods.
Formation of ice in the tanks
Ice begins to form from the surface of
the water then the process extends to the
entire mass of water in the tank; as the
phenomenon proceeds and the mass of
ice increases the speed of its formation
slows down. .
To remedy this problem it is possible
to install one or more electrical heaters
with an appropriately calculated
capacity and controlled by a regulation
thermostat which guarantee a water
temperature of between +3°C and 5°C
throughout the tank or, if the tank is very
big, an area of it that is sufficient for
ensuring that at least the volume of water
necessary for starting up the system is in
liquid form. A supplementary tank in
a closed or underground room can be
used. In this way the cooled water from
the tower can flow into it freely in such
a way that the collection basin of the
tower is always empty.
N.B.:
The thermostat supplied together with
the electrical heating element acts
exclusively on the basis of the water
in the tank and not on the basis of the
heat produced by the element itself. .
If there is no water, however, the heating
element that has come on anyway could
cause irreparable damage. : you are
therefore advised to fit a minimum level
switch to protect the electrical element
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