TM 5-6115-593-34
NAVFAC P-8-631-34
TO-35C2-3-463-2
17-30. In most installations, intake and exhaust louvers
are used. Figures 17-6 through 17-9 illustrate a variety
of louver installations which may be used. The use of
louvers requires the opening area to be increased by a
factor of 1/4 to 1/2 times that of an unobstructed
opening. Where possible, the inlet duct should be on
the shaded side of the building. Care should be taken to
provide adequate unobstructed space outside the outlet
to
prevent
development
of
back
pressure
and
consequent limiting of outlet air flow. Where possible,
the outlet duct should not be exposed to strong
prevailing winds, since wind may cancel fan effect and
impair cooling. A duct should be installed between the
radiator and the outlet vent to prevent recirculation of air
passed through the radiator, as its effectiveness as a
heat exchanger would be diminished. The duct should
be installed between the radiator and outlet vent with as
few bends as possible.
Figure 17-6. Fixed Louvers for Air Inlet
17-31. All units can be fitted with radiator duct flanges.
If bends are required, they should be in the form of
gradual sweeps to allow an air flow against minimum
restriction. Increase duct size 1/4 to 1/2 to compensate
for bends. Exhaust duct static pressure should be
essentially zero. If a duct is not used, the outlet vent
should be twice the area of the radiator and the unit
should be mounted as close as possible to the outlet
vent.
Figure 17-7. Thermostatically Controlled Louvers
17-32. Intake and exhaust ventilation shutters are used
to prevent entry of cold air, which would reduce the
ambient temperature of the area in which the unit is
located causing difficulty in engine starting. Shutters
also exclude entry of rain, snow, and insects into the
building.
Figure 17-8. Exhaust Fan Operated Louvers
17-10
