| Application and Design Information (cont.)
|
Double Stud Offset
Wall with Interwoven Insulation |
Ductwork turning vanes typically improve pressure drop and degrade acoustical
performance. High quality construction and installation
of the turning vanes reduce the acoustic penalty.
Recommended Maximum Air
Velocities
The maximum recommended velocity
for the discharge air duct is 2000 ft/min. The maximum
recommended velocity for the return air duct is 1000 ft/min. Limit air velocities
below these operating points to minimize the risk of
flow turbulence that causes regenerated noise.
The use of round duct and static regain allows maximum discharge air velocities
up to 4000 to 5000 ft/min. Round duct also provides
substantial attenuation of low frequency noise. However, the potential for flow regenerated
noise increases dramatically. Therefore the quality of
installation of the ductwork greatly affects the acoustic results of the installed
system.
Equipment Room Construction
Options
The preferred equipment room wall construction is concrete block. If this is not
feasible then a double stud offset wall is suggested.
This removes physical contact that would transmit sound through the equipment
room wall to the occupied space.
The space between the studs should be interwoven with fiberglass insulation.
Two layers of Sheetrock should be used on each side of
the wall.
Workmanship details are critical to acoustic performance. All wall and floor penetrations by the ductwork, water
piping, and equipment room access doors should be
sealed with a flexible material such as caulk and/or
gasketing to stop noise and air leaks. Small air leaks can occur at a crack in the wall or with improper fit at a corner in
the equipment room. These small leaks can result in a
substantial acoustical leak into the occupied space.
The equipment room door should be located away from acoustically sensitive areas
like conference rooms. The door should swing out of
the equipment room, if possible, so that the low pressure in the equipment room
pulls the door in to help maintain a tight seal. Refer
also to section Il. EQUIPMENT ROOM LAYOUT LOCATION FOR MAXIMUM USABLE
FLOOR SPACE for other door orientation considerations.
Equipment Options
The factory installed flexible horizontal discharge allows multiple duct
outlets with multiple factory designed and tested
outlet options. This minimizes the risk of acoustic
and/or pressure drop problems by avoiding complex transitions close to the fan
discharge. |
