Figure 5.2
Figure 5.3
Multiple Blower Placement
The use of more than one blower can dramatically increase airflow (volume)
and reduce the time necessary to complete a ventilation operation.
For standard entrance openings (that is, door openings of three feet by six and one-half feet), maximum
effectiveness is achieved by placing two blowers "in-line" with each other. As in (F
igure 5.2)
, blower A is
positioned about two feet from the entrance opening. This ensures that all of the pressurized air from the
blower enters the building, yet allows sufficient room for personnel to enter and exit the building. Blower B is
then positioned behind blower A. The proper location for blower B is determined by the distance necessary
to cover the entrance opening with pressurized air. Blower B covers the entrance opening with pressurized air
and increases the capacity of blower A by approximately ten percent.
For standard entrance openings, multiple blowers in a parallel (side-by-side) configuration are less effective
than multiple blowers in an in-line configuration. However, for large entrance openings, multiple blowers in a
parallel configuration
(Figure 5.3)
should be used due to their combined ability to cover the larger opening
with pressurized air. The size of the opening dictates the numbers of blowers necessary to cover the opening
with combined cones of pressurized air.
Remember that some openings (such as loading-
dock doors) can be reduced in size by partially
closing the door to reduce the size of the entrance
opening that must be covered by pressurized air.
Depending on the number of blowers that are
available, large areas may be effectively ventilated
by using a combination of parallel (proper
coverage of the opening) and in-line (increased
volume) blowers.
Areas or locations that do not have openings that
can be used as exhaust openings (storage rooms,
offices, enclosed work areas, etc.) can be
effectively ventilated by using multiple blowers as
depicted below.
Use a blower to provide a flow of air past the
opening. This blower can be located outside the building to provide pressurized air to the interior of the
building and past the area to be ventilated. The blower should be placed in the bottom portion of the
opening and will provide pressurized air that will create positive pressure within the area to be ventilated and
force the contaminants out of the upper portion of the entrance opening. The air flowing past the entrance
opening will force the exhausting contaminants to follow its direction to the exterior of the building.
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