AAF International PRU - Manual (Page 6)

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2.2 Recirculation System: The recirculation system is intended to
draw air from a defined space, clean the air, and then return the
cleaned air to the space. The system is supplied when contaminants
are generated within the space or infiltrate from outside the space. It is
normally provided to protect personnel, equipment (particularly
electronic equipment), or product. A typical schematic of the
recirculation system operation is shown in Figure 2.
2.3 Pressurization System: The pressurization system is intended to
pressurize a space by drawing air from outside the space, cleaning the
air, and then discharging the cleaned air to the space. The system is
supplied when contaminants are generated from outside the space. All
leakage will be from the higher pressure space within the room to the
lower pressure surrounding environment. This prevents outside
contaminants from entering the space. An optional arrangement allows
some in-room recirculation to take place. This system is normally
provided to protect personnel, equipment (particularly electronic
equipment), or product. A typical schematic of the pressurization system
operation is shown in Figure 3.
3.0 Installation Instructions
Consult the product drawing(s) submitted on this order before proceeding.
3.1 Space Requirements: A minimum of 36" clear space must be
available at the access side of the Recirculation Unit to perform
routine maintenance. Additional space may be required for inlet and
outlet ductwork.
3.2 Foundations, Supports, and Anchoring: The foundation and/or
supports must be designed to be adequate to support the filter system
operating weight, and any seismic, live or other loads (if any), with a
sufficient factor of safety as determined to comply with the
requirements of all applicable governing codes, standards, and laws.
Ensure that the foundation or support surface is level and smooth
before proceeding. The filter system is designed for operation in
indoor locations. The equipment is not specifically designed to resist
and operate under unusual dynamic loading situations such as
earthquake conditions. If the equipment is required to function in such
circumstances, special precautions may be required to ensure that the
equipment will remain intact, anchored, and functioning. If this
situation applies, consult with a qualified professional engineer before
installing the equipment.
RU
Filter
System
Fan
Outlet
Inlet
Contaminated
Air
Recirculated
Air
Clean Air
Enclosed Room
PRU
Filter
System
Fan
Outlet
Clean Air
*Pressurized Space
Air Leakage at
Windows, Doors and
Other Penetrations
will be Outwards
from the Room
Enclosed Room
Optional Inlet Damper and Dampered
In-room Inlet may be Supplied to
Allow some Recirculation of Air
Inlet Air
from Outside
of the Room
Duct
Figure 2 - Recirculation System Using the PRU
Figure 3 - Pressurization System Using the PRU
Fan section access panel
Safety grille
Fan
Typical fan section with access panel removed.