with piping and wiring in place, it is simple to install
and may be placed wherever there is a clearance of 2
feet for the intake end and a space of 10 feet or more in
front of the fan. The discharge end must not face the
prevailing wind and should not be directed into a
traffic area because drift loss may be objectionable.
In some situations, an indoor location for the
cooling tower may be desirable. An induced draft
tower of the counterflow or cross-flow design is
generally selected for indoor installation. Two
connections to the outside are usually requiredone
for drawing outdoor air into the tower and the other for
discharging it back to the outside. A centrifugal blower
is often necessary for this application to overcome the
static pressure of the ductwork. Many options are
possible as to the point of air entrance and air
discharge. This flexibility is often important in
designing an indoor installation. Primary water
breakup is by pressure spray and fill of various types.
The induced draft cooling tower for indoor
installation is a completely assembled packaged unit
but is so designed that it can be partially disassembled
to permit passage through limited entrances. Indoor
installations of cooling towers are becoming more
popular. External space restrictions, architectural
compatibility, convenience for observation and
maintenance all combine to favor an indoor location.
The installation cost is somewhat higher than an
Packaged towers are available in
capacities to serve the cooling requirements of
refrigeration plants in the 5- to 75-ton range.
A forced draft cooling tower uses a fan to force air
into the tower. In the usual installation, the fan shaft is
in a horizontal plane. The air is forced horizontally
through the fill and upward to be discharged out of the
top of the tower.
Underflow cooling towers are an improved design
of the forced draft tower that retains all the advantages
of the efficient parallel-flow design. Air is forced into
the center of the tower at the bottom. The air is then
turned horizontally (both right and left) through fill
chambers and is discharged vertically at both ends. By
forcing the air to flow upward and outward through the
fill and leave at the ends, operating noise is baffled and
a desirable reduction of sound level is achieved. All
sides of the underflow tower are smoothly encased
with no louver openings. This blends with modern
architecture and eliminates the necessity of masonry
walls or other screening devices oftentimes necessary
to conceal cooling towers of other types.
Redwood has been the standard construction
material for cooling towers for many years. Though
cypress, as well as treated fir and pine, has been used
occasionally, these materials have not enjoyed a wide
application. Casings are constructed of laminated
waterproof plywood. Such casings, as well as other
noncorrosive materials at critical points, are essential
in areas having a highly corrosive atmosphere. Nails,
bolts, and nuts of copper or aluminum are almost
standard practice for cooling tower construction.
Cooling towers of metal coated with plastic or
bituminous materials that have air intake louvers and
fill made of redwood have met with only limited
success. The limited success is primarily because of
the high maintenance cost as compared to wood
Packaged towers with metal sides and wood fill are
reasonably common. Some manufacturers have used
sheet aluminum for siding for limited periods of time.
Plastic slats have been used for fill material but have
not proved satisfactory in all cases.
Fire ordinances of a large city may require that no
wood be used in construction of cooling towers. With
steel or some other fireproof casing and without fill, a
cooling tower will comply with the most restrictive
Recently, cooling towers have been linked to the
s p r e a d o f L e g i o n n a i r e ' s d i s e a s e . S e v e r a l
precautionary measures are recommended to help
eliminate this problem. These include placing of
cooling towers downwind and use of chloride
compounds as disinfectants on a monthly maintenance
Water treatment is an important part of the
operation of a cooling tower. The evaporation of water
from a cooling tower leaves some solids behind.
Recirculation of the water in the condenser cooling
tower circuit, and the accompanying evaporation,
causes the concentration of solids to increase. This
concentration must be controlled or scale and
corrosion will result.