SPX Cooling Technologies CoolingTower Marley MCW - Manual (Page 16)

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3. As cold air enters the tower, it causes the falling water to be drawn
inward. Thus, under fan operation, the lower periphery of the tower
structure remain partly dry, seeing only random splashing from within
the tower—plus normal atmospheric moisture from the entering air.
Such lightly wetted areas are most subject to freezing.
Although ice is unlikely to cause structural damage, it may build up
sufficiently to restrict the free flow of air. This will have the effect of
reducing the tower’s thermal performance efficiency. When excessive
ice forms, stop the fan for a few minutes. With the fan off, the action
of the spray system will cause a slight downward movement of air
through the fill and deice the fill.
intermittent Wintertime Operation:
If periods of shutdown (nights, weekends, etc.) occur during freezing
weather, measures must be taken to prevent the water in the cold water
basin—and all exposed pipework—from freezing. Several methods are
used to combat this, including automatic basin heater systems available
from Marley.
Unless some means of freeze prevention is incorporated into your
system, the tower basin and exposed pipework should be drained at
the beginning of each wintertime shutdown period.
If tower basin is drained, verify that all basin heaters have been shut
off either by automatic cutoff or disconnect switch.
It is recommended that you discuss your freeze prevention options with
your local Marley sales representative.
Water Treatment and Blowdown
Maintaining Water Quality:
The steel used in MCW towers has been galvanized with a heavy zinc
coating averaging 2.0 mils in thickness. The MCW stainless steel option
is even more corrosion resistant than galvanized steel in certain environ-
ments. Other materials used (PVC fill, drift eliminators, and louvers, etc.)
are selected to offer maximum service life in a “normal” cooling tower
environment, defined as follows:
Operation
Caution
Warning