Note: Descriptions are shown in the official language in which they were submitted.
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DUST PRECIPITATION FROM AIR BY NEGATIVE IONIZATION
BACKGROUND OF THE INVENTION
This invention relates to a system for dust
precipitation from air using negative ionization of the air.
The concept and pcospective commercialization of
negative ionization techniques has been around for decades with
very little progress due to the lack of credibility arising
fcom inappropciate, largely unsuccessful applications and
clouded by exaggerated unsubstantiated claims.
At the same time the effectiveness of the
technique suffered because the equipment to generate and
distribute the required volumes of negative ions was initially
bulky, expensive, cequiring constant maintenance and was
generally unreliable. These circumstances meant that the
effectiveness of applications deteriocated rapidly and became
totally suspect in operation.
The increasing employment of the technology is
being brought about by some basic trends:
- the development of equipment utilizing
electronics and new materials which provide a ~afe, reliable,
inexpensive, and non polluting soucce of negative ions and
their distribution.
- an increasing need to impcove the air quality
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in enclosed enviconments which have been designed to minimize
enecgy costs foc heating, ventilating and aic conditioning
installations.
- highec standards of safety and health in the
wockplace in cegacd to the control of micronic and submicconic
pollutants identified as a health hazacd.
- zero defect objectives in manufacturing
opecations requicing moce effective means to contcol the
migcation of fine dust and pollutants.
- hacd evidence of the effectiveness of
industcial applications and incceasing supportive scientific
evidence as cegacds pcoper electro climate conditions for human
comfoct and wocking efficiency.
Off-shoce countcies, pacticulacly Iscael have
maintained a faicly high level of reseacch and development
effoct into pursuing the effectiveness of negative ionization
techniques in a wide range of applications with considecable
success.
Pcogress in Nocth America in this cespect,
industrially at least, has been limited to the elimination of
static electricity, but with stcong indications of a cecent
revival of aic tceatment by modulac, fan assisted negative ion
dispecsal units.
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Conventional systems to obtain super clean air
with filtcation efficiencies in the micronic and sub-micronic
ranges are capital intensive and expensive to run in terms of
energy consumption and maintenance costs.
At the same time the systems while fully
effective on the air circulated can have little influence to
prevent small pacticulants and pollutants ociginating in the
working plennum producing pcoblems, apact fcom the inherent
dilution cefreshening pcocess allowed by the cycle of aic
change~ supplied to the acea. An investigation into further
pcioc act suggests that while the use of negative ionization
techniques to improve air quality and contain dust pollution in
a general way is gaining gcound, thece is little doubt that the
level of technology available is relatively crude.
Ions are created in natuce by sunlight, cosmic
and tercestcial cadiation and the friction of moving aic and
watec that causes electcons to leave hydrogen, nitrogen and
othec molecules and to attach themselves to oxygen molecules.
Molecules with extca electcons from negative ions
and have a positive effect on the enviconment. They neutralize
odours and contribute to the cleac air and the fc~sh smell we
find in non-industcial, sparsely populated areas and at the
seaside oc healthy holiday cesocts.
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In the Pcairie cegions of Canada, the phenomenon
best manifests itself by the invigoration experienced after a
summer storm with lightning, which relieves the heavy
depressing conditions which gradually build up periodically in
such areas ducing the summer.
Positive ions are produced by car and factory
exhausts, cigacette smoke, dust, soot, fumes from new processes
and other domestic and industcial pollutants.
In the wide open spaces these pollutants are
attcacted to the negative ground and ace harmlessly dischacged.
But in the enclosed enviconments of modern society - metals,
cacs, builings lined and fucbished with synethetic matecials,
etc., these pollutions cannot be dischacged to eacth.
At the same time the enveloping car bodies and
building structures that keep the positive ions in, also keep
the beneficial negative ions out because theic electrical
chacges ace absocbed by steel and conccete, bricks and siding
material.
A controlled output of negative ions can be
produced by electronic means/corona discharge and this source
is an appcoved altecnative foc the Polonium Ionizecs withdcawn
fcom the macket by 3M in Febcuacy 1988. The soucce generation
of ozone is so low as to be almost immeasucable and well below
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the FDA maximum of 0.05 ppm.
SWMMARY OF THE INYENTION
It is one object of the pcesent invention to
pcovide an impcoved method for cleaning aic within a building
using the negative ionization principles in a unique manner to
obtain aic which is cleaned to a hiqh degree with low capital
and maintenance costs.
According to a ficst aspect of the invention,
thecefore, thece i9 pcovided a method of pcecipitating
pacticles fcom aic within a building compcising defining a zone
within the building at least pactly pactitioned fcom a
cemaining part of the building, sepacating the zone from the
building by a scceen which is pecfocated to allow transmission
thecethcough of aic and light, and mounting within the zone a
plurality of emittecs of negatively charged aic ions.
Accocding to a second aspect of the invention,
therefore, there is provided an emitter of negatively chacged
aic ions for use in pcecipitating particleq from aic within a
building compcising an elongate membec defining a channel
thecealong and having a closed fcont sucface, a conductoc
mounted in the channel member, means defining a plucality of
openings in front sucface through which poctions of the
conductor project, and connectoc means on the channel membec
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foc connecting a high voltage to the conductoc such that the
exposed portions of the conductoc generate ions in aic exposed
to the conductoc focwacdly of the fcont face.
The pcovision of the elongate multiple emittec
enables a high very degree of flexibility to be used in the
location and mounting of the emitters for the negative
ionization tceatment so that the units can be installed vecy
quickly and at low capital cost.
The use of the screen to sepacate the zone to be
cleaned fcom the remainder of the building enables a system to
be used known as a "clean-zone" or as an altecnative a "revecse
clean-zone" in which the majoc dust emitting pcocess is mounted
within the zone and the negative ionization tceatment used to
extcact the dust fcom the aic prioc to its celease to the
cemaindec of the building.
The scceen is pcefecably focmed of a matecial
which is pecmeable to aic and light so that the zone can be
mounted within the building without regacd to the location of
the ventilation units and pcovision of lighting. In many
cases, thecefoce, the zone can be developed at an acea leaving
the ventilation systems and lighting systems outside of the
zone so that thece is no interference whatevec with the
existing utilities within the building. The light and aic
movement necessacy foc ventilation can then take place thcough
the scceen with the scceen and the negative ionization system
coopecating to extcact the dust and to prevent its penetcation
thcough the scceen.
The system as installed, const~ntly and
efficiently will precipitate about 99% of the fine dust
pacticles and pollutants in a work acea defined and isolated by
specially constcucted barciec screens.
With the coccectly calculated and distcibuted
negative ion density within the zone, all fucthec migcation of
the pcecipitation micconic and submicconic pacticles will be
ef~ectively and continuously pcevented, as a result of the
electco-climate cceated and maintained in the "Clean Zone"
area.
The emittecs ace prefecably sepacated fcom any
aic flow genecating systems such as fans oc aic duct outlets so
that the ions ace fceely emitted into the area to be cleaned
wihtout passage of the ions oc any aic stceam caccying the ions
through a filtec. Thus the particles ace sepacated fcom the
aic by a pcecipitation technique which causes the pacticles to
fall to the floor foc collection by conventional house cleaning
techniques.
The enclosuce which acts as a cage to isolate and
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define the acea/volume cequiced fof the application, is
considered to be a basic and essential featuce of the "clean
zone" concept. The design, constcuction and matecials
employed, all contcibute to ensucing the effectiveness of the
system.
Installation of the "Clean Zone" enclosuce is
simple and flexible and easily fitted cetco-actively with the
minimum difficulty to accomodate existing equipment.
The light open natuce of the enclosuce gives
little sense of restciction to employees inside the zone and it
is generally unnecessary to upgrade lighting levels in the area
aftec the installation of the zone.
The effectiveness of the system is ceadily
measurable and can be demonstcated by the simple action of
enecgizing and deenecgizing the AC powec input.
The cesults in regard to the contcol of fine
dust, and ceduction of inclusions are fully substantiated in
practical cost effective tecms by satisifed industcial end
usecs in cegard to:
- ceduced level of cejections due to inclusions;
- incceased productivity
- impcoved wocking enviconment inside and outside
the zone.
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Accocding to a thicd aspect of the invention,
there iq provided a method of cleaning particles from air
within an acea of a building comprising mounting emitters of
negatively charged ions in the area of the building separate
from any aic flow accangements for causing air flow within the
acea, causing the ions to engage particles in the area and to
precipitate the particleq downwacdly onto a floor of the acea
and collecting the particles fcom the flooc.
Pceferably the method includes a canopy which
assists in dicecting the pacticles away from a source of the
particles e.g. a dust producing machine towards sides of the
machine for precipitation on the floor.
With the foregoing in view, and othec advantages
as will become apparent to those skilled in the art to which
this invention celates ai this specification proceeds, the
invention is herein desccibed by reference to the accompanying
dcawings forming a part hereof, which includes a description of
the best mode known to the applicant and of the prefecred
typical embodiment of the pcinciples of the present invention,
in which:
DESCRIPTION OF THE DRAWINGS
~igure 1 is an isometcic view showing a scceen
system defining a zone for separation from the cemaindec of
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building and including ionization generating elements mounted
within the zone.
Figure 2 is a top plan view of the zone of Figure
1 showing the location of the ion emittecs.
Figuce 3 is a ccoss-sectional view showing a
modified acrangement of scceen assembly defining a zone within
a building.
Figure 4 is a ccoss-sectional view through an
emittec element of a type shown schematically in Figures 1 and
2.
Figure 5 i3 an isometcic view of the emittec
element of Figure 4,
Figuce 6 is a cross-sectional view through a
second emittec element of the type illustcated schematically in
Figuce 1.
Figuce 7 is an isometcic view of the emittec of
Figure 6.
In the dcawings like chacactecs of cefecence
indicate corcesponding parts in the diffecent figuces.
DETAILED DESCRIPTION
In Figuces 1 and 2 is illustcated a zone defined
by a sucrounding wall structure genecally indicated at 10
within which is mounted a machine 11 which is illustcated
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schematically and is wholly enveloped by the succounding wall
stcuctuce defining the zone.
The wall structure comprises two side walls 12
and 13 together with end walls 14 and 15 each of which includes
an opening 16 and a slidable closing dooc 17. Accoss the top
of the walls is provided a ceiling 19. The height of the walls
is arranged to be approximately equal to the minimum wocking
height of the ocdec of eight feet and up to a maximum of the
ocder of ten feet so that the ceiling 19 is genecally
positioned beneath the coof oc ceiling stcuctuce of the
building and is sepacate fcom the lighting, duct wock and othec
utilities which ace often provided in structural buildings of
an industrial type.
This critical acea oc zone is enclosed using a
slotted metal structuce as the main suppoctive fcamewock,
housing panels coveced with perfocated scceen material of a
type which is pecmeable to aic and light but is cesistant to
teh passage of dust oc othec fine pacticles. One example of
material which can be used is known as TAK Barrier Scceening.
The TAK Bacciec Scceening is a fine gauge fabcic, tceated with
a special tacky cesin. This Bacciec scceening is
electconically compatible with negative ion pcesence and wocks
harmoniously to create a dust fcee enclosuce, tcapping lacge
particles, yet allowing the zone to bceathe without any
inccease in air speeds across the fabric.
The enclosuce which acts as a cage to isolate and
define the acea/volume required for the application is
considered to be a basic and essential featuce of the "clean
zone" concept. The design, construction and materials
employed, all contcibute to ensucing the effectiveness of the
3ystem.
Installation is simple and flexible and easily
10fitted cetroactively with the minimum difficulty to accommodate
existing equipment.
The light open nature of the enclosuce gives
little sense of restriction to employees inside the zone and it
is genecally unnecessary to upgcade lighting levels in the acea
after the installation of the scceens.
Strategically located emitters at ceiling level
within the enclosure produces a bombardment of negative ions to
pcecipitate particles inside the zone. At the same time a high
density is created within the confines of the enclo~uce which
20will not allow particles to penetrate the screens, in either
direction.
All openings into the zone cequired foc access
are protected by a cuctain of ions which comprises a peciphecal
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distcibution of emi~ters to focm an high density concentration
of directed negative ions to pcecipitate any dust which might
otherwise migrate into the area. Altogethec a total screened,
"cage" effect is pcoduced with a fully isolated Clean Zone
sepacate and distinct from the general wocking area of the
facility.
On completion of a Clean Zone, and activation of
the ion generation system, an ultra Clean Zone will be
established foc process within 24 houcs. This pcotection will
be available as long as the system is in opecation with the
necessary negative ions densities being maintained
automatically at the pcopec levels.
The slotted steel frame wock is indicated at 20
and is of a conventional nature available for ceceiving wall
panels and foc bug screens. A solid panel is indicated at 21
and the screen material i3 indicated at 22.
The ceiling is formed in the same stcuctuce
employing wholly the scceen material 22. The enclosure can
thus be focmed relatively simply by the assembly of the frame
work following which the panels ace simply flipped into place
to define the completed zone. In Figures 1 and 2 there is
provided a plurality of emitters of negative ions including two
separate types of emitters indicated at 25 and 26 respectively.
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The details of the emitters 25 are shown in Figuces 6 and 7 and
the details of the emitters 26 are shown in Figuces 4 and 5.
Turning therefore to the emitters 25 shown in
Figuces 6 and 7, this emitter comprises an elongate channel
member 30 formed in two halves 31 and 32 which a~e snap fit
together along a joining line 33 to focm an enclosed elongate
tubular member. End caps 34 are pcovided of a type shown in
Figure 4 which compcise a press fit into the end of the tubular
member thus forming a complete enclosure. The emitter 26 as
shown in Figuce~ 4 and 5 comprise~ the same basic housing
tructuce. The length of the housing can be selected according
to requirements as shown in Figures 4 and 5 the emitter is of a
celatively short length whereas in Figure 6 and 7 the emitter
25 can be significantly longec.
Each of the housings includes a connectoc 36 of a
type including a body 37 which has an outec screw thread 38 and
an end cap 39. The body can thus be attached thcough an
opening in the housing simply by clamping into place by one oc
moce nuts 40 and 41. In the arrangement shown in Figuce 6
there are two nuts provided each on a respective side o~ a wall
of the housing so as to space the end cap 39 away from the
wall. In the arrangement shown in Figure 4, the end cap is
clamped against the end face of the housing by the nut 40 on
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the opposed side of the wall of the housing. The housing
includes a centcal bore which caccies a conductoc 42 and a
volume of the sleeve which projects outwacdly beyond the inner
end of the body to connect to a conductoc 43 pcovided within
the housing. The tubulac connector 42 is thus of a type which
can ceceive simply a single pole connectoc by which high
voltage feom a genecator 45 (Figuce 2) can be connected to the
emittec with a plucality of emittecs arcanged in secies by
connection of a wice fcom each to the next.
The conductoc 43 is focmed of a yacn of a
conductive fibce matecial foc example cacbon fibces which ace
cut into staple fibces and then spun and twisted to focm a
multi fold yacn. The housing is focmed of vecy suitable
insulating plastics matecial so that the conductoc yacn can
simply be thceaded into the housing and can cest against the
housing without focming a shoct ciccuit.
In Figuces 4 and 5, a fcont face of the emittec
which is defined by the uppec face of the uppec pact 31 has a
plucality of openings 48 substantially equidistantly spaced
along the front face in a single line accos~ the centce of the
fcont face. The yacn is then thceaded simply in a stitch
pattecn so that poctions of the yacn ace exposed on the outec
side of the fcont face and poctions of the yarn ace maintained
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on the innef side of t~e ffont ~ace that is within the housing
as indicated at 49 and 50 respectively.
This focm of emittec is substantially
multidicectional so that when a high voltage of the ocder of
6000 volts is applied to the conductor 43 the exposed poctions
49 of the yarn generate a corona effect causing the creation of
ions in the area of the cocona effect with those ions tending
to escape fcom the exposed poftion of the yarn 49 in all
dicections away fcom the front surface. The ions thus tend to
spcead away fcom the emitter in all dicections and to attach to
pacticleq within the aic. A~ the pacticleq ace heaviec than
aic the particles tend toward the ground surface and in view of
the generally positive charge on the ground surface, the
negatively chacged pacticles are attracted to the gcound
surface and fall to the ground surface foc collection on the
gcound sucface both in view of gravity and in view of the
electrostatic attraction.
As shown in Figure 2, the emitters 26 are
arcanged in arcay acound the centre of the zone. In the
example shown thece are fouc rows of the emittefA accanged
substantially equadistantly spaced across the width of the
zone. In this way the full area of the intefioc of the zone is
bombarded with the ions which ace spcead equally throughout the
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centcal acea of the zone. As shown in Figure 1 the emitters 26
are mounted at the ceiling area on suitable suppocts (not
shown). This place~ the height of the emitters generally at
the height of the ceiling which would be in the order of eight
to ten feet from the ground which has been found to be
particularly effective since the ions ace thus prevented from
dissipation to othec aceas of the building befoce they can
caccy out theic function of attachment to particles and
tcansporting those particles to the ground surface.
The e~i~ter 25 shown in ~igures 6 and 7 i3
modified celative ~o the emi~tec 26 in that the conductoc 43 i3
confined into shoct poctions which project outwacdly fcom the
fcont face of the channel membec 31. Thus the fcont face 31
includes foc each poction a pair of holes 55 and 56 which ace
closely positioned togethec with only a naccow separating
portion 57. The conductor is then thceaded thcough the holes
55 and 56 and passes thcough a collar membec 58 succounding the
holes and supporting the outerly pcojecting portion of the
conductoc 43 a~ indicated at 59. The collar member 58 can be
bonded to the front sucface of the channel member or can
compcise a separately manufactuced product which insects fcom
an undecside of the upper surface of the channel membec through
a single hole in the wall 31 and provides by itself the pcopec
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suppoct foc the projecting poction 59.
The pcojecting portion 59 is confined to a short
length of the fcont face of the channel membec is caused to
turn back upon itself at a sharp angle. This tends to cause
individual ones of the staple fibces 60 to pcoject outwardly
from the yarn at the point where it is tucned sharply thus
focming a plurality of spikes which pcoject outwardly from the
sharply tucned portion of the conductoc 43. These spikes have
been found to generate ions in a highly dicectional mannec in
that the ion~ are pcefecentially generated at the apex of the
fibre spike and thus tend to be emitted in a direction
generally at right angles to the front face.
The emitter 25 is therefore much more directional
than the emittecs 26. In view of this propecty, the emittecs
25 ace thus arcanged to generate a curtain of ions lying in a
plane longitudinal of the emittec 25 and at right angles to the
front face.
Turning therefoce to Figure 1 the emitters 25 are
mounted acound the opening 16 along the sides of the opening
and along the top of the opening with the emitters facing
inwardly to generate a cuctain across the plane of the opening
of a high concentcation of ions. This cuctain acts to "attack"
any dust particles attempting to pass through the opening so
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that those particles are acted upon quickly and tend quickly to
fall to the ground at the acea of the opening. As a back up
foc the emitters 25 at the opening, one oc more cows of further
emitters 25 can be positioned inwardly of the opening. Thus in
Figure 2 there ace two further rows of emitters one positioned
just inside the opening and the next behind the first thus
forming three curtains of ions acting specifically on the dust
tending to move through the opening carried by persons or
equipment passing through that opening oc by air movement
thcough the opening.
The cuctain of ions thus act at the openings in
the zone and in addition the genecal level of ions within the
zone acts in coopecation with the permeable tacky scceen to
cause dust and othec particles to be collected at the screen
rather than to pass through the scceen. It has been noted that
the ions have a tendancy to act upon the dust just outside of
the scceen so that lacge quantities of pacticles fall to be
collected on ground oc othec horizontal sucfaces just outside
the screen thus preventing the dust fcom passing through the
screen.
As shown in Figure 3 there ls provided a modified
arrangement including a floor surface 70, a machine 71, a
screen 72, an uppec ceiling 73 of the building and utilities
,
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including duct wock 74 and lighting 75.
In this case the screen is modified in that it
comprises simply a canopy suppocted fccm the ceiling or coof on
support wireq 76. The canopy includes a ceiling 77 formed in
panels similac to the ceiling 19 togethec with four side wall
portions 78 which hang down fcom the side edges of the ceiling.
The details of the constcuction are not shown but are similar
to that ~hown in Figure 1. This of course leaves the side
walls of the zone open for passage of persons or equipment but
generates enough of a 9eparation of the zone from the building
to enable the cleaning of dust from around the machine 71.
Figuce 3 also illustrates the arrangement in which the zone is
separated from the ventilation systems including the duct work
74 and from the lighting systems which are maintained without
modification in the building. The light into the zone is thus
provided by the conventional lighting of the building. The
ventilation or air movement within the zone is provided by the
conventional building ventilation systems including the duct
work 74 and a nozzle 80 which projects aic to move downwardly
through the scceen and into the zone.
In the arrangement of Figuce 3, the dust iq
prevented f~om passing into the intecior of the zone through
the open side walls by the generation of a cuctain of ions
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similac to that at the opening 16. Thus the emittecs 25 aee
po3itioned so as to generate a cuctain pcojecting downwacdly at
the open side walls and this can be backed up by one or moce
fucthec cows of emittecs 25 positioned inwafdly of the side
walls. Also similar to the construction shown in Figures 1 and
2, intecioc emittecs can be of the type illustrated at 26 to
genecate a moce even spcead of ions thcoughout the zone.
In Figures 1 and 2 the machine 11 illustcated
schematically compcises a machine foc caccying out an
indu9trial pcocess of a type which requires vecy clean air for
example a paint spcaying machine oc part molding machine so
that this machine is maintained within a clean zone in which
the dust in the cemaindec of the building is kept outside of
the zone and is pcevented from entering the zone and from
remaining within the zone once it has enteced. The clean zone
must of course be backed up with good housingkeeping pcactices
which will not be explained in detail here.
In the accangement shown in Figuce 3, the zone is
effectively a "ceverse clean zone" in which the machine 71 is
of a type which generatea high levels of dust, foc example a
paper cutting machine or a textile spinning machine. In this
case the machine itself is succounded by a zone which pcotects
the cemaindec of the building fcom ceceiving the high
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quantities of dust generated by the machine itself. In this
way instead of maintaining the w~ole of the building cleaned,
it is only necessary to clean the acea sucrounding the machine
concecned so that the dust fcom that machine is prevented from
escaping to the remain~er of the building and is also contained
within that acea by ~he action of the negative ions on the dust
particles and the tendency to pcecipitate and thus to collect
on the gcound su;cfaces fcom which they can be readily removed
by nocmal housekeeping systems.
The emitte~ are enticely free fcom any focced
air effect so that neithec the ions noc any pacticle laden air
passes thcough a filter. Thus the negatively chacged ions
collect onto the pacticles causing them to conglomerate and to
pcecipitate onto the flooc. The flooc thus acts as a collectoc
foc the particles and thi~ can be ceadily cleaned by
conventional housekeeping practices. In addition, the tendancy
of the pacticles at the acea above the machine is to rise so
that the bombacdment of the pacticles in the aic space of the
canopy with ~he ions causes the pacticles to tend to flow
outwacds of the machine and to pcecipitate out onto the flooc
at the sides of the machine.
The details of the electcical equipment
genecating the high voltage ace not shown as these ace well
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known to one skilled in the act. In addition the wicing
connections and the necessary conduit are not shown.
As an altecnative arrangement for use in some
building structures, the emittec 25 can be used at the exit
nozzle of the ventilation duct wock so that the ions are
dicected into the aic stream which passes thcough the nozzle as
the air emecges fcom the nozzle and is communicated into the
building. The u~e of the emitters in the elongate or stcip
form enables the emittecs to be tailoced to the 3pecific
nozzles concerned by simply cutting to length oc selection fcom
a numbec of available lengths and attachment at the nozzle.
Since various modifications can be made in my
invention as heceinabove described, and many apparently widely
diffecent embodiments of same made within the spicit and scope
of the claims without departing from such spirit and scope, it
is intended that all matter contained in the accompanying
specification shall be interpreted as illustcative only and not
in a limiting sense.
