MIL-HDBK-1191
23.4.5
Noise Control Within Mechanical Equipment Rooms.
23.4.5.1
Introduction. Mechanical equipment rooms are noisy environments.
In conditions where exposure duration in excess of 85 dBA occurs for more
than 8 hours (or higher noise levels are exceed for shorter periods of time),
noise mitigation procedures may be required to meet federal noise exposure
guidelines (e.g., OSHA regulations) and to reduce the possibility of hearing
damage; permissible exposure limitations for lower noise levels are indicated
below.
When designing equipment rooms which will be regularly occupied by
maintenance personnel (as opposed to rooms requiring only periodic maintenance
visits), designers shall consider attenuation features necessary to control
noise level.
Exposure Duration per
sound
day, day in hours
level in
dBA
8
85
6
87
4
90
3
92
2
95
1
97
1
100
105
and less
100 (max)
23.4.6
Vibration Isolation.
23.4.6.1
Introduction. Structure-borne sound is produced by a noise
source, such as vibrating or rotating machinery, which transmits energy
directly into to and through the structure. This noise is often transmitted
to far-removed locations in a building and is re-radiated by wall and floor
construction as airborne noise. All vibrating equipment in a medical facility
should be resiliently isolated on vibration isolation systems to reduce the
transmission of structure-borne noise, according to manufacturers'
recommendations and guide specifications.
23.4.6.2
Equipment location. The effectiveness of vibration isolators
depends upon the degree of flexibility of the supporting structural system,
and it always preferable to provide resilient support from a stiff and rigid
base. Because of its high degree of stiffness, the grade slab of any building
is the preferred location for major generating and prime moving equipment.
All mechanical equipment installed above grade should be located as close as
possible over a column, load-bearing wall, or other stiff structural member.
23.4.6.3
Static deflection. The effectiveness of any vibration isolation
system is determined by its static deflection (that is, deflection under
load). The design of the proper static deflection is determined by the speed
and horsepower of the equipment being isolated, as well as by the location of
the equipment within the building and the stiffness of the supporting
structure. The determination of the static deflections for specific pieces of
mechanical equipment will be made using the tables in section V of TM 5-0805-
4, or as recommended by the equipment manufacturer to meet specified vibration
transmission limitations.
23.4.6.4
Flanking transmission. Flanking transmission of vibration energy
from mechanical equipment should be minimized. All connections to vibrating
equipment should be through flexible connectors, conduits, piping, or hose.
All piping in mechanical equipment spaces connected to vibrating equipment
should be supported by resilient ceiling hangers or floor-mounted resilient
supports. Penetrations through equipment room walls and ceilings should be
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