Note: Descriptions are shown in the official language in which they were submitted.
~l~U8~08
This invention relates to a sterile air module
that includes a high efficiency particule air filter and
a blower for discharging air under pressure through the
blower. More particularly this invention relates to a
sterile air room module for a clean room that has a fresh
air inlet, room air inlets, a filtered air outlet, a high
efficiency particulate air filter in the outlet and a blower
for drawing air through the inlets and discharging air to
pass through the filter and the outlet.
In the prior art it is old to provide a filter sys-
tem for a clean room that includes a housing having a single
air inlet, and an outlet, a high efficiency particulate air
filter in the outlet, and a blower in the housing for draw-
ing air in through the inlet and discharging air through the
filter to pass through the outlet; for example see my U.S.
Patent, Patent No. 3,828,530. Further it is old to provide
clean rooms, free from particulate matter and suitable for
medical research, surgery theaters, patient care rooms, and
sophisticated industrial processes by circulating HEPA fil-
tered air downwardly from ceiling to floor or across from
wall to wall, in each case carrying return room air through
ducts external to ~e room back to blowers and HEPA filters
for recyling. However, such prior art filter systems do not
provide for both recirculating room air and discharging fresh
air into the room. In order to provide a sterile air module
that filters both recycled room air and fresh air, this in-
vention has been made.
An object of this invention is to provide new and
novel means for recycling room air and fresh air and filter
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the air before discharge into the room to result in an air
quality that meets Federal Standard 209b. Another object
of this invention is to provide new and novel means for
selectively controlling the amount of fresh makeup air dis-
charged into a room and independently selectively control-
ling the rate of recycling air in the room with both the
fresh air and recycled air being HEPA filtered before being
discharged into the room.
The invention will now be described with reference
to the accompanying drawings in which
Figure l is a somewhat schematic showing of the
apparatus of this invention mounted in a room for recycling
room air and discharging fresh air into the room;
Figure 2 is a horizontal cross sectional view of
the sterile air recycling module of this invention, said view
being generally taken along the line and in the direction of
the arrows 2-2 of Figure 3:
Figure 3 is a transverse vertical cross sectional view
generally taken along the line and in the direction of arrows
3-3 of Figure 2; and
Figure 4 is a fragmentary view of the wall of the
module that has the fresh air opening therein.
Referring now to the drawings, there is schemati-
cally shown a room having a ceiling 10, a floor 12 and side
walls 11 and 13. The sterile air recycling module of this
invention, generally designated 15, is mounted by the ceiling
to extend therethrough, the module including opposite side
walls 16 and 17, opposite end walls 18, a front or bottom wall
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l9, and a top or rear wall2~. The bottom wall l9 includes
a perimetric flange portion l9d that defines an opening l9b
in which an air diffuser panel l9a is mounted. The panel
l9a has a plurality of air diffuser passageways l9c extend-
ing therethrough for discharging air vertically downwardly
into the room interior.
Mounted in the housing interior is a high effici-
ency particulate air (HEPA) filter F that includes a filter
frame 21 and filter material 22. The filter F has at least
a 75 percent efficiency for the removal of 0.3 micron par-
ticles as determined by the standard D.O.P. Test of the Army
Chemical Corps and preferably provides 99.9 percent removal
of all aerosol particulate contaminants 0.3 microns or larger,
as defined by government specifications TID-7023, High Effi-
ciency Particulate Air Filter Units.
Plenum chamber side walls 25, end walls 26, and top
wall 27 are joined together to in conjunction with the filter
F define an air tight supply pressure plenum chamber 24 in
fluid communication with the filter material 22. The plenum
chamber top wall 27 is provided with an inlet opening 28, a
flexible duct 29 being connected to the plenum chamber top
wall for placing the inlet opening 28 in fluid communication
with the outlet 30 of the blower B. The blower is mounted
within the housing by a suitable blower mount 32 which may
be mounted by one of end walls 18. The blower has an inlet
31 that opens within the housing and preferably is of an
adjustable speed type for selectively varying the volume
of air discharged thereby per unit of time.
The filter F, the supply pressure plenum 25-27,
the duct 29, and the blower B are connected to one another
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and mounted in the housing to in conjunction with the hous-
ing walls defining a negative pressure plenum chamber 47 to
which the blower inlet 31 opens. Thus, when the blower is
operating, air in the negative pressure plenum chamber 47
is drawn through the inlet 31 to flow through the duct 29
and the supply pressure plenum chamber 24 to the filter F
and then therethrough to be discharged through the diffuser
panel openings l9C. Accordingly, when the blower is oper-
ating, the air that is discharged through the diffuser panel
openings (both room air and fresh air) first flows through
the filter to be filtered thereby.
For supplying fresh air to the negative pressure
plenum 47, the housing top wall 20 is provided with an inlet
opening 34, a duct 35 that provides fresh air to the inlet
34 being connected to a suitable conditioned air source 50,
for example, rough filtered, heated or cooled, humidified or
dehumidified air system that is usually installed in a build-
ing or plant for air ventilation purposes and usuallyp~o-
vides air under pressure. The air flow from source 50 to
the negative pressure plenum chamber 47 is controlled by a
suitable valving component, for example a damper 36 mounted
in the duct 35 (or may be a damper, not shown, mounted by
wall 20 for partially or completely closing opening 34).
Each of the side walls 16 and 17 is provided with
a plurality of grill inlet openings 41 that open to the
room interior. Mounted within each grill opening is a grill
frame 43 on which there is provided a movable grill 42 for
adjustably controlling the volume of the air flow through
the grill opening. The grill members 42, 43 may be of any
suitable conventional construction. For example, each grill
42 may be provided with a knob 56 for moving grill 42 be-
tween a position to partially close the opening defined by
grill frame 43 and a closed position to prevent air inflow
through the respective opening 41. The grill openings open
to the negative pressure plenum 47 and are located more re-
mote from the housing top wall 20 than the flanges 45 that
are joined to the walls 16-18 for mounting the module on the
ceiling.
A suitable door (not shown) may be provided in one
of the housing walls 16, 17, 18, 20 or the diffuser panel
mounted in a manner to permit changing the filter F and do-
ing maintenance work on the blower.
A conventional room outflow grill 60, preferably ad-
justable, is provided in one of the room walls. The outflow
grill 60 is in fluid communication with an exhaust duct 61
that discharges the exhaust air at a suitable location. The
grill 60 permits an outflow of air from the room R that is
equal to the inflow of fresh air from duct 35.
In using the apparatus of this invention, the damper
36 is adjusted so that the fresh air inflow is compatible
with the number of people in the room and the heating or
cooling load. The fresh air inflow results in air in the
room exhausting through exhaust duct 61 whereby there is a
reduction in objectionable odors in the room. The recycled
air flow CFM is selected to provide a room air change rate
that removes contaminants to meet the air quality cleanness
desired. The recycled room air, for example 15 air filtered
room air changes per hour, is controlled by the inflow grill
members 42, 43 while the total air flow (discharged through
the diffuser panel) is controlled by adjusting the blower
speed. Accordingly, with the blower operating, air from the
room interior is drawn through the grilled openings 41 into
the plenum chamber 47 while air from duct 35 passes through
the inlet 34 into said plenum chamber 47. Air in the p'enum
chamber 47 is drawn into the blower inlet 31 ~d discharged
under pressure through duct 29 to the pressure plenum 24
whereupon it passes through the filter F and thence through
the diffuser panel to flow downwardly generally as indicated
by arrows 52. Assuming the unit 15 is generally in the cen~
tral part ~ the room and there is only one such unit in the
room, as the air flows downwardly it will diffuse and spread
out as indicated by arrows 53, 54 toward the vertical room
walls and thence upwardly and inwardly toward the grilled
openings 41 such as indicated in Figure 1.
With the apparatus of this invention, the air flow
can be controlled so as to provide the desired amount of .
fresh make-up air flowing into the room with independent
control of the recirculated air within the room, via room
air change rate. Further, if necessary more than one of
the modules 15 may be mounted in, for example, in the ceil-
ing of a large room and connected to the source 50 in a
manner previously indicated if one such module does not
have the capacity to maintain an air quality of a desired
cleanliness.
Even though the invention has been described with
reference to the unit 15 being mounted in the ceiling, it
is to be understood that it may be mounted in one of the
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vertical walls of the room to discharge toward the opposite
vertical wall. For example wall lO could be considered one
side wall and wall 12 an opposite side wall while wall 20 of
the housing would be a vertical rear wall rather than the
top wall thereof.
