Note: Descriptions are shown in the official language in which they were submitted.
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lOB1027
This lnvention relates to apparatus for gener-
a~ing a clean air zone, for example in an operating
theatre, în a pharmaceutical "clean room" where
drugs or chemicals are being prepared or processed,
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or in an electronics "clean room" wherein ~ilectronic
, ; components are assembled.
~ Many installations ~or this purpose are hnown
`.~ which rely on a downwardly flowing stream of clean
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~s air to sweep a desired clean area and discourage or
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;~ lO pre~ent contamination approaching the working area.
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One known installation provides for a whole room to
have ilir supplied through its ceiling and with-
~`~ drawn at the base of the room. However this needs
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;i to be încorporated at the design stage of the build-
` ing, and is very expensive. Other known installa-
tions have downward clean air flows enclosed in
~! solid walls or walls of high speed air ta so-
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` called "air-curta~n"). Unfortunately the solid
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~ walls heavily restrict access to the working area
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and the approach or workers via doors enables co~-
-tamination to enter. The air-curtain has the dis-
ij; advantage that when broken it actively encourages
i~; the entrainment of contamination into the slower-
~ moving air inside it, and can also "stir up" con-
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- tamination from the floor. Both these latter ln-
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stallations also have the disadvantage that the
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clean area generated is only of the same or smaller
area than the air supply apparatus, and thus if a
large clean area is needed a correspondingly larger,
and thus more expensive apparatus is required. Many
known installations are also not re-circulatory,
which although it does not impair the efficiency of
the apparatus, means that the input to the supply
apparatus is substantially of ambient "dirty" air.
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This has the effect that the usual filters in the
air supply apparatus have to cope with a constant
flow of "dirty" air and msut be cleaned at rela~-
ively frequent intervalss
An object of the present invention is to provide
an improved apparatus for generating a clean air
zone, wherein sQme or all of the above disadvan- ;
tages are obviated or minimised.
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~ The apparatus is conveniently in the form of a
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canopy having a common plenum chamber or a plur-
ality of plenum chambers supplying the delivery
means which can befof dif~erent permeabilities to `~
provide the different air speeds.
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Distribution of the in~ts about the periphery
of the apparatus has the effect of creating a clean
zone which extends a considerableedistance outside
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the area of the apparatus itself. This is in con-
tradistinction to known apparatus, wherein inlets
have been provided at floor level or at one side
only. The inlets must be distri~uted so that a
generally symmetrical air flow is generated beneath
and around -the apparatus.
.
The present invention provides appratus for
~'~ generating a cl~an air zone wherein inlets to the
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~; apparatus are distributed about the apparatus.
The invention further provides apparatus for
generating a clean air zone, comprîsing: air del-
, ivery means ~or delivering a flow o~ clean air to
`; the zone; air supply means for supplying air to
`~ the air delivery means; cleansing means for clean-
ing the air and inlets to the supply means distri-
~; buted around the apparatus.
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The invention still ~urther provides apparatus `~
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for generating a clean air zone comprising: a
housing and air delivery means; cleansing means
and air supply means in the housing, and inlets to
, ~ the air supply means distributed around the periphery
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; of the housing. `
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~, The invention will be described further, by way
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of e~ample, with reference to the accompanying draw-
ings, wherein:- -
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;` Fig. 1 is a transverse cross-sectional
schematic view of a preferred apparatus of the
invention, the cross-section taken on the line
I-I of Fig. 2.
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Fig. 2 is an inverted plan view of the appar- `
atus of the invention.
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- Fig. 3 is a gramentary perspective cut-away
view of one module forming part of the apparatus
of the invention, pa~ts having been ~mitted for
` 10 clarity.
Fig. 4 is an enlarged fragmentary cross-section
;~ on the line IV-IV of Pig. 2, showing details of the
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~- fan
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A preferred embodiment of apparatus 10 con-
forming to the invention is suitable for attach-
ment to the ceiling of an oparating theatre to pro-
vide a clean air zone around a patient undergoing
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-~ surgery, or to the ceiling of a pharmaceutical or
electronics clean room to provide a clean air zone
around a machine or a manufacturing process. In-
stead of being ceiling mounted, the apparatus could
;~, be wall-mounted, or mounted on a wheeled frame to -
i render it mobile and to enable -tit to be moved fromg
say, one machine to another.
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'` The apparatus 10 is in the form of a unit con-
~, structed from four modules 11, one of which is
~`; shown in detail in Fig. 3. Each uni-t thus has
~: four air supply means constituted by fans 12, and
three air delivery means (Fig. 2) constituted by
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areas of diffuser plates 1~ of the modules.
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. A central one of the air delivery means is in
the form of a square panel 14 of relatively high
permeability ~i.e. it has more and/or larger aper~
tures than the other air delivery means) and in
- use delivers air at a line~r velocity from 90-130
f.p.m. Cpreferably 110 f.p.m.). A second of the
air delivery means is in the form of a panel 15
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~` surrounding ~anel 14 and so perforated as to del-
iver air at a linear velocity of 60-90 f.p.m.
, (preferably 75 f.p.m.). A third of the air del-
ivery means in the form of a panel 16 surrounding
~! panel 15 and so perfora-ted as to deliver air at a
linear velocity of 20-60 f.p.m. (preferably 40 f.p.m.).
It must be noted, however, that whilst the veloc-
ities of the flows from the delivery means can
" vary, there must always exist a differential be-
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, tween adjacent flows of at least 5 f.p.m. and pref-
,~ erably over 20 f.p.m.
As has been previously mentioned, the apparatus
,` 10 is in the f~rm of a unit constructed from four
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modu~es~ll. Referring now to F~g. 3, each module 11
is made o~ sheet metal and has a generally square top
`;i plate 17, an L-shaped base plate 18 and a rectangular
~` perforated diffuser plate 13. Plate 13 has three
distînct areas of different permeability (indicated
by the variable cross-hatching at 19, 20, 21 in Fig, 2)
to achieve the aforesaid different flow velocities.
`~ Each plate 13 is hinged at 22 ~Fig. 1) to facilitate
:` ~ servicing and cleaning.
The module 11 has closed inner adjacent side walls
~;, - 23, 24 and side walls 25, 26 each having an elong~te in-
let window 27. Parallel to these latter walls and
along the inner edges of the L-shaped base pla-te extend
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internal walls 28 and 29 which help to define an inner
compartment of the module and fan inlet chambers 30
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;-I and 31. Each inlet window is closed by a hinged panel
~` 32 (Figs, 1 and 2) carrying a pre-filter pad 33 for
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`~ removing coarse contaminants ~rom incoming air.
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The inner compartment of module 11 has a shallow
~,, 20 sheet metal tray 34 therein which has apertures 35 and
;,; which supports filter pads 36. Below the tray 34 and
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;- above the plate 13 is a plenum chamber 37 and above the
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pads 36 and below top plate 13 is an intake chamber 38
to whieh air is supplied by fan 12 (Fig. 4). The fan
12 has been omitted from Fig. 3 for clarity.
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Turning now to Fig. 4, it will be seen that
each fan 12 is a conventional radial flow fan having
two axial inlets 39 and 40 and a tangential outlet
41 which discharges into intake chamber 38. The
inlets 39 and 40 face and take air from fan inlet
chambers 30 and 31. The rotor and integral electric
motor of the fan have not been illustrated as they form
, no part of the present invention,
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From the arrows in Figs. 1 and 2 ;t will be app~
~^~ 10 reciated that a basically re-circulating air system
is employed, thus generating a clean zone beneath the
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air delivery means and a swept air zone surrounding the
! delivery means. This results in a clean zone of effect-
ively larger area than the area of the apparatus 10.
The recirculating feature also means that the filters
,. have to be replaced at ~ess frequent intervals as they
are not oontînuously ~iltering dirty amb;ent air as they
: would be în a non-circulatory system.
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,l A short 2anopy 42 (Fig. 1~ can be provided to give
~ 20 some guidance to the downwardly flowing air.
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It will be appreciated that the present invention
.. is equally applicable to apparatus whereln only a single
stream of air is provided, the distributed inlets
still providing the increased area feature and encour-
aging a downwardly, outwardly and then upwardly flowîng
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air stream. There is always a flow of air away
from the centre of the zone which inhibits the
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ingress of contamination, even from objects and
persons entering the outer areas of the aone.
The apparatus can be wall mounted, and gen-
erate a downward flow, in which case Elow would
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:~ be outwards from three sides of a rectan~ular
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area, the inlets being distributed about the three
free sides of the apparatus. As a further alter-
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`` 10 native, the apparatus could be mounted ~for examp-
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~ ple on a wall~ to supply air travelling initially
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in a horizontal direction, the distributed inlets
encouraging the same flow away from the centre of the
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cleaned zone. The apparatus can also direct air at
any other convenient practicable angle to generate
r,!'~",, a clean air zone as may be desired.
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