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8. SOUND ATTENUATION
If noise level must be limited, it should be specified
in terms of a sound pressure level at a given
distance from the generator enclosure. Then the
enclosure must be designed to attenuate the noise
generated inside the enclosure to produce the
required level outside. Don't attempt to make this
noise level unnecessarily low, because the means of
achieving it may be costly.
Use of resilient mounts for the generating set plus
normal techniques for controlling exhaust, intake
and radiator fan noise should reduce generating set
noise to an acceptable level for many installations.
If the remaining noise level is still too high, acoustic
treatment of either the room or the generating set is
necessary. Sound barriers can be erected around
the generating set, or the walls of the generator
room can be sound insulated, or the generating set
can be enclosed in a specially developed sound
insulated enclosure. See figure 8.1.
In most cases it is necessary that the air intake and
air discharge openings will have to be fitted with
sound attenuators. If it is desired to protect
operating personnel from direct exposure to
generating set noise, the instruments and control
station may be located in a separate sound-
insulated control room.
9. ENGINE COOLING
Some diesel engines are air cooled but the majority
are cooled by circulating a liquid coolant through
the oil cooler if one is fitted and through passages
in the engine block and head. Hot coolant emerging
from the engine is cooled and recirculated through
the engine. Cooling devices are commonly coolant-
to-air (radiator) or coolant-to-raw water (heat
exchanger) types.
In the most common generating set installation, the
engine coolant is cooled in a set-mounted radiator
with air blown through the radiator core by an
engine driven fan. Some installations use a remotely
mounted radiator, cooled by an electric motor-
driven fan. Where there is a continuously available
supply of clean, cool raw water, a heat exchanger
may be used instead of a radiator; the engine
coolant circulates through the heat exchanger and
is cooled by the raw water supply.
An important advantage of a radiator cooling
system is that it is self-contained. If a storm or
accident disrupted the utility power source, it might
also disrupt the water supply and disable any
generating set whose supply of raw water
depended upon a utility.
Whether the radiator is mounted on the generating
set or mounted remotely, accessibility for servicing
the cooling system is important. For proper
maintenance, the radiator fill cap, the cooling
system drain cocks, the fan belt tension adjustment
must all be accessible to the operator.
9.1 Set Mounted Radiator
A set-mounted radiator is mounted on the
generating set base in front of the engine. See
figure 9.1. An engine-driven fan blows air through
the radiator core, cooling the liquid engine coolant
flowing through the radiator.
FIG 8.1 TYPICAL SOUND ATTENUATED INSTALLATION