To calculate the required CFM to filter the air in a room that is 15 feet wide by 40 feet long with an
8-foot ceiling, plug in the size of the room in the formulas for either 3 or 4 air changes per hour (ACH)
As the filters become loaded, the eective cfm will drop slightly, so be sure you have a little more capacity
than the minimum.
Air Purifiers may be required to circulate and filter the air within one or more of the contaminated areas to
be collect contaminates as they are released into the air, as well as making certain there are no “dead spots”
in the contained area where there could be a contaminate buildup.
be unthinkable to start the work without a temporary
barrier of plastic sheeting to prevent the dust from
covering the occupants and the oice equipment. If
the dust was potentially toxic and the particles were
too small to be seen by the naked eye, even more
protection for both the workers and the adjacent
occupants would be required. This is the basic
reason, it is necessary to filter the air in the work area,
and to put that contaminated area in a “Negative
Pressure” condition.
The size and number of machines depends on the
volume of the space being cleaned as well as how
many Air Changes per Hour (ACH) are required by
local regulation. As a starting point, calculate the
square footage of the room or rooms, multiply by the
ceiling height. It is generally recommended to have
3 to 4 air changes per hour in occupied areas. To
convert this requirement to a Cubic Feet per Minute
(CFM) spec for the Air Purifier, multiply the Volume of
the work area by 4 (or 3) changes/Hour then divide by
60 Minutes/Hour.
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