Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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LOCALISED EXTRACTION SYSTEM
The present invention relates to an extraction system for containing
and removing vapours generated during application of films to a surface and,
in particular, but not exclusively to the safe removal of spray mists,
particulates and vapours generated during body repair and/or repainting of a
vehicle.
A vehicle requiring body repair and/or repainting is subject to a number
of different processes depending on the type of repair or repaint. For example
the repainting process comprises a number of distinct stages including for
example preparation for the paint, typically involving sanding the original
surface to provide adhesion for the extra paint layers to be applied, or the
removal of the paint film to provide adhesion for the layers of shaping filler
that are to be applied to a dent and/or blemish in the surface. Polyester
filler
is normaliy used to reshape damaged areas to the pre-damaged state. After
shaping, final surface preparation requires the application of a hi-build
primer
to enable final levelling and filling of very small imperfections. The hi-
build
primer or paint is usually applied using a spray gun or aerosol with a
material
transfer efficiency of between 50 to 80%. The spray gun or aerosol atomizes
the paint or primer into a fine spray by using either compressed air or a
propellant. The nature of this spray requires that undamaged surfaces
adjacent the area to be repaired or repainted must be masked-off, that is
covered, to prevent migration of the spray onto such.
The masked-off areas not only include adjacent surfaces of the vehicle,
but often also adjacent vehicles and surfaces of the workshop, this is because
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if spray or overspray contacted clean or undamaged surfaces this would give
rise to time consuming and costly removal thereof.
The paints, primers "and materials used produce noxious vapours and
environment and government regulations therefore require that these
processes be carried out in a controlled environment such as a spray booth,
preparation station or limited finish work station. Conventionally a dedicated
spraybooth is provided within the workshop which provides an enclosed
environment and all or part of the spraying process is carried out inside the
controlled environment of the spraybooth. The spraybooth is usually
equipped with an extraction system which draws the air containing the
noxious vapours from the booth and then filters out hazardous chemicals
therein before release of the cleaned extracted air into the atmosphere.
After the hi-build primer has been applied then it must be sanded to
allow for any imperfections to be removed. Since the dedicated controlled
environment is a critical resource within the workshop the vehicle or vehicle
part is removed therefrom for this sanding operation. Once the sanding
operations is complete the vehicle or part is re-masked and re-entered into
the controlled environment for the further or final top coat of paint.
During re-assembly of painted parts of vehicles it is not uncommon to
damage small areas of the newly painted surface. Typically this damaged
area would have to be prepared and then repainted within the controlled
environment, such as a spraybooth or limited finish workstation.
The dedicated controlled environment such as a spraybooth as
mentioned above is a critical resource and the efficient and cost effective
use
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thereof is essential to ensure profitability of the workshop. The continuous
removal and re-entry of the vehicle or part thereof, whilst done to free the
spraybooth for spraying and/or curing operations nevertheless leads to
downtime reducing effective use of this facility. Furthermore, such a
controlled environment requires a large building to house it and it is an
expensive item to purchase, meaning that it is . often not possible for local
small workshops and garages to offer a paint and repair service. This is not
only an inconvenience to the customers who must then take their vehicle to a
remote dedicated bodyshop facility, but is also a loss of custom for the local
workshop. Furthermore, such facilities are not mobile making it impossible to
take such a repair and paint service to the customer, that is to provide a
mobile repair and paint service. Without containment of paint or primer
fumes, vapours or particulates produced during spraying and/or curing, such
fumes vapours or particulates would enter the atmosphere leading to
environmental pollution and the breathing of hazardous chemicals by the
operator. Furthermore, contaminates such as dust and insects could be
entrained therein, leading to a poor finish. Due to the limitations of the
present systems government regulations concerning painting are often flouted
with subsequent health and safety issues arising.
It is an object of the present invention to provide an extraction system
which overcomes or alleviates the above described drawbacks.
In accordance with a first aspect of the present invention there is
provided an extraction system comprising a containment unit with means to
enciose a selected area on a surface of an object to the sprayed and/or dried,
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the unit having an outlet which is connectable to an extraction unit and an
inlet
connectable to an air source. This has the advantage that localised spraying
and for drying can take place within the containment unit with any overspray
and/or fumes being extracted to the extraction unit. This enables spraying
and drying to take place outside the confines of a spraybooth or limited
finish
workstation, since only the area which is being sprayed and/or dried is
confined.
The extraction system may comprise at least one flexible duct
connectable between an inlet of an extraction unit and the outlet of the
containment unit. This has the advantage that the duct enables movement
between the extraction unit and the containment unit , enabling the
containment unit to be selectively located at a position remote from the
extraction unit. The extraction system may include a moveable mounting for
the duct. This will enable further flexibility in the placement of the
containment
unit.
The extraction system may comprise an extraction unit which may
comprise at least one of an inlet, an extraction pump adapted to draw fluid
into the extraction unit through the inlet, a filter adapted to remove
particulate
and hazardous contaminates from the fluid, and an exhaust to expel cleaned
fluid into the atmosphere. The extraction unit may additionally include a
removable container to collect said removed contaminates and particulates.
The extraction unit may be mobile. This enables the extraction system
to be used outside the confines of a workshop.
The containment unit may include at least one deflector.
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The containment unit inlet may form an opening to the containment unit
and may enable direction of a spray from a spray gun and/or aerosol into the
containment unit. The deflector may be provided about the inlet. The
deflector may include a movable shield, which may be located at least
5 partially over the containment unit inlet any may be located adjacent said
containment unit outlet.
The containment means may include a frame and the enclosing means
may be a flexible media. The flexible media may comprise means to enable
its attachment to at least one of the surface of the object to be sprayed
and/or
painted or the frame. The flexible nature of the media enables the
containment means to be readily adapted to enclose a variety of different
sized surface areas.
The flexible media may be replaceable and may be in the form of
flexible sheeting, the attachment means may be in the form of adhesive tape.
The extraction system may comprise a curing unit.
The curing unit may comprise a light source to effect curing of a
painted surface. The light source may be an ultraviolet light source and/or
infrared light source. The curing unit may be adapted to fit into said
containment unit inlet. The curing unit may have means to seal the inlet to
contain the light from the source within the enclosure. This has the advantage
that light from the light source does not leave the containment unit
preventing
damage by fugitive rays to operators' and bystanders' eyes. Furthermore the
curing operation may give rise to hazardous gas which can be readily
extracted via the extraction unit.
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The curing unit may have cooling vents to enable air to enter the
containment unit, this enables replacement of air extracted. The cooling vents
may be shielded to prevent leakage of light from the unit.
In one embodiment the extraction system may comprise a forced air
supply which may be heated. The forced air supply may be provided on an
articulated arm to enable its accurate placement.
In accordance with a second aspect of the present invention there is
provided a method of fluid extraction comprising the steps of enclosing a
section of a surface to be sprayed and/or cured and/or dried within a
containment unit and extracting fluid from the containment unit using an
extraction unit.
In a preferred embodiment the method includes the step of spraying
within the containment unit the said surface with a paint and/or primer whilst
at the same time extracting fluid from the containment unit,
In a further preferred embodiment the method includes the step of
drying or curing a painted surface within the containment unit at the same
time as extracting said fluid.
The method may comprise the step of filtering said extracted fluid to
remove particulate and/or contaminates.
The method may include the step of deflecting said spray within the
containment unit.
By spraying within the containment unit dust and/or insects are not
entrained within the spray leading to a smoother/cleaner finish. Furthermore
any overspray, or fumes created are contained and safely extracted with the
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fluid, thereby not polluting the atmosphere or creating a breathing hazard for
the operator. Also since only the area that is being painted is enclosed the
unit can be small and rendered portable and usable in a confined space:
The method may include the step of heating air within the containment
unit prior to spraying. This has the advantage of creating a warm air
environment prior to application of paint materials. Compliant coatings,
waterbourne base coat and ultra high solid top coats cannot be effectively
applied if the temperature is below 15 C. This enables repairs to be carried
out in unheated buildings and outdoors when the temperature is low, by
creating an idea environment for the application of a particular material.
Additionally by applying the heat prior to the application of a further
coating, it
is possible to dry or flash-off the presently painted surface.
By way of example only, specific embodiments of the invention will now
be described, with reference to the accompanying drawings, in which:-
Fig. 1 is a perspective view of a first embodiment extraction system
constructed in accordance with the invention;
Fig. 2 is a perspective view of the hood and hood stand of the
extraction system of Fig. 1;
Fig. 3 is perspective view showing the masked off area of a part to be
painted to illustrate a first step in the method of using the extraction
system of
Fig. 1;
Fig. 4 is a perspective view of a second step of the method of Fig. 3
showing the hood positioned over the area to be repainted;
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Fig. 5 is a perspective view showing the attachment of the masking to
the hood,
Fig. 6 is a perspective view showing the masking fully attached and
paint being sprayed into the hood;
Fig. 7 is a plan view of the enclosure created by arrangement of Fig. 6
the dotted lines showing the internal cavity leading to the extraction outlet
the
view additionally shows spray from a spraygun and the flow path of the spray
within the hood;
Fig. 8 is a sectional view through line A-A of Fig. 7;
Figs. 9 and 10 are details of areas marked B and C respectively of Fig
8;
Fig. 11 is a view similar to Fig. 7 showing the reverse plan;
Fig. 12 is a sectional view along the line D-D of Fig. 11;
Fig. 13 is a perspective view of the hood showing the internal deflection
surfaces and filter;
Fig. 14 is a perspective view showing use of a curing unit with the
hood, the heating unit located in the opening to the hood's frame;
Fig. 15 is an oppositive side view similar to Fig. 14, showing the curing
unit pivoted out of the opening;
Fig. 16 is a view similar to Fig. 2 of a second embodiment of extraction
unit;
Fig. 17 is a schematic view of a third embodiment of extraction system
constructed in accordance with the invention;
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Fig. 18 is a perspective view of a fourth embodiment of extraction
system constructed in accordance with the invention;
Fig. 19 is an exploded view of the extraction system of Fig. 18;
Fig. 20 is a sectional view of the extraction system of Fig. 18; and
Fig. 21 and 22 are details of areas B and C respectively of Fig. 20.
In a first embodiment of extraction system 2, as best illustrated in Fig. 1
the system comprises an extraction unit 4, a containment unit or hood 6, and
a flexible duct 8 connecting the hood 6 to the extraction unit 4.
The hood 6 is adapted to contain a selected area to be resprayed and
in use paint is sprayed into the hood 6 on to the selected area, whilst the
extraction unit 4 sucks air from the hood 6 via the duct 8. The interior of
the
hood 6 is designed to provide an aerodynamic foil which retains over-spray for
extraction with the air from the hood 6. The system comprises a filter for
removing hazardous gases and particulates from the extracted air, before the
cleaned air is then released into the atmosphere via exhaust flue 12 of the
extraction unit 4.
As best illustrated in Figs. 1 and 2 the hood 6 is mounted on a
substantially H-shaped, wheeled stand 12. The stand 12 has a mast 14
extending substantially vertically thereof which is provided with a
longitudinally
extending glide section 16 in which is slidably retained a hood support
bracket
18. The hood support bracket 18 has a vertical adjustment handle 20 which is
operable to fix the hood support bracket 18 at a desired vertical height on
the
mast 14, or to release the hood support bracket 18 for movement along the
mast 14. The hood 6 is connected to the hood support bracket 18 for
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selected vertical reciprocal movement therewith by a hood guide bracket 22
which is fixed to the hood support bracket 18. A horizontally extending
mounting tube 24 extends between the hood 6 and the hood guide bracket
22, with the hood 6 being fixed at one end of the mounting tube 24. The hood
5 guide bracket 22 is in the form of a grip type retaining ring and the other
end
of the mounting tube 24 is slidably retained therein. The hood guide bracket
22 is provided with a swivel adjustment handle 26 which is operable to lock
the position of the mounting tube 24 and thereby that of the hood 6; and a
position whereby the mounting tube 24 is movable and thereby therewith the
10 hood 6 in a transverse plane relative to the vertical plane of the mast 14,
and
in which the mounting tube 24 and thereby the hood 6 can also be rotated
relative to its mounting in the guide bracket 22. The above described possible
adjustments to the hood 6 enable a full range of movement of the hood 6
enabling its accurate positioning over a surface to be resprayed or dried.
The H-shaped stand 12 comprises two spaced apart parallel bars 12a,
12b interconnected by a cross-bar 12c. The vertically extending mast 14 is
mounted to the cross bar 12c. The parallel bars 12a, 12b are provided with
swizel castors 28, which enable the stand 12, 14 to be manoeuvred to a
selected location such as a vehicle, a panel of which requires respray. The
orientation of the hood 6 is then adjusted in order for the hood 6 to contain
the
panel or area requiring respray (which will be described further hereinunder).
Each end of the parallel bars is provided with a moulded rubber bumper 30
which prevents damage to the wheels of the vehicle, in the instance that the
stand is accidentally manoeuvred into the tyre. Furthermore the height of the
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stand 12 is such that the parallel bars 12a, 12b can be manoeuvred, at least
partially under the chassis of the vehicle, enabling the hood 6 to be placed
for
example on a top surface of the vehicle, such as the hood or roof. The
parallel bars 12a, 12b are spaced apart at a distance which enable them to
straddle the width of the wheel.
The mast 14 additionally carries a spray gun connection pipe 32
extending from a filter regulator 34. The filter regulation 34 has for example
a
maximum pressure setting of 1.5 bar to ensure correct air pressure for
atomisation of paint materials within the hood. In use a spray gun is attached
to the free end of the spray gun connection pipe 32.
The hood 6 is a heavy duty plastics moulded design edged with a soft
rubber strip to protect vehicles during use. In the illustrated example the
hood
6 has a substantially rectangular outer frame 36 surrounding a through
opening 38, the said hood opening 38 providing access into the containment
zone created by the hood 6 for a spray gun. The hood 6 is provided with an
outlet 40, which is connectable to the flexible ducting 8. The outlet 40 is
connected to the hood opening 38 via an internal cavity 4 (as best illustrated
in Fig. 7) provided in one of the walls of the outer frame 36. The inlet 42
the
internal cavity is provided with a primary filter 42, in the form of a
disposable
cassette type filter. This filter removes a large proportion of the
contaminants
preventing such from entering the ducting 8. The interior 44 of the hood
surrounding its opening 38 is shaped to provide deflection surfaces which will
be described further hereinunder.
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The flexible ducting 8 connecting the hood to the extraction unit 4 is
provided with a quick release coupling 46 to enable its connection to the
outlet
40 of the hood 6. The ducting 8 is constructed from a galvanised steel helix,
which provides the ducting with strength and flexibility. The ducting 8 is
coated with a PVC beading to protect vehicles from accidental damage when
moving the ducting around the workshop.
The opposite end of the ducting 8 is connected to the extraction unit 4.
The extraction unit 4 is provided with an extraction fan (not illustrated) in
the
form of a centrifugal type unit which develops high pressure to overcome
system resistance, and also has a motor and a control unit. Down stream of
the extraction fan the extraction unit 4 is provided with a secondary stage
filter
in the form of a filter bag which removes residual particles from the air
stream
which remain after primary filtration in the hood. This protects the
components of the extraction unit from contamination, and hence prolongs the
life of the extraction unit 4 and reduces maintenance costs.
The extraction unit 4 is additionally provided with a low airflow indicator
and an alarm. The low airflow indicator monitors the suction of the extraction
unit 4 and if it drops below a preset value, which would indicate that one or
more of the filters are blinded and thereby require changing, the low airflow
indicator is adapted to trigger the alarm to provide a visual and/or audible
signal that the fiiter(s) needs changing.
The extraction system 2 is operated as follows:
As best illustrated in Figs. 3 to 6 the areas of the item around the area
to be repainted are masked using a plastics or paper media 48. The edges of
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the media 48 are attached around the area to be repainted 50 using masking
tape 52. The hood 6 is then moved over the area 50 to be painted and the
free edges 54 of the media 48 remote from the area 50 to be painted are then
pulled fuNy round the exterior of the hood 6 and attached thereto using a
resilient masking band 56 provided about the outer frame 36 of the hood 6.
This opening 38 in the frame 36 thereby provides an enclosure 39 about the
area to be repainted 50 which is seafed to the vehicles surface.
Access to the area to be repainted is provided through the opening 38
in the hood 6.
As best illustrated in Figs. 7 to 13 during a spraying operation the spray
nozzle 58 is placed through the opening 38 into the enclosure 39 of the frame
36 and the extraction unit 4 is switched on thereby drawing air out of the
enclosure 39 via ducting 8. During spraying material 60 is applied via the
spray nozzle 58 to the surface to be painted 50. Fresh air 66 is drawn in
through the opening 38 from the atmosphere due to the partial vacuum
created in the enclosures 39. Excess material/gases forced to the bottom
edge of the enclosure 39 is extracted through the primary filter 42 into the
internal cavity 41. Any excess material 62 which is deflected upwards from
the corners is unable to leave the enclosure 39 via the opening 38 because
the frame 36 acts as a spoiler and contact with the interior of the frame 36
causes the material 66 to lose inertia and to be deflected back down into the
enclosure 39 via entrainment in the flow of incoming fresh air 66 towards the
entrance 42 to the internal cavity 41.
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The frame 36 is provided with overhanging shoulders 68 which extend
inwardly across the hoods opening 38, these shoulders 68 provide additional
deflection surfaces, to increase containment. One of the shoulders 68a
located adjacent the point of extraction 42 provides a larger defection
surface
in this region. This is because close to the point of extraction 42 there is
more disruption created and the resultant turbulence can deflect more
material 62 upwards at this region. The remaining shoulders 68 of the frame
3b create a further surface area to deflect and thereby contain any excess
material.
In a second embodiment of extraction unit as best illustrated in Fig. 14
and 15. Once spraying is complete, the spraying nozzle 50 can be removed,
a curing unit 70 then can be fitted to the enclosure 39. To this end a curing
unit mounting bracket 72 is provided on the mounting tube 24, which bracket
72 provides a pivotal stand for the curing unit 70 . The curing unit 70 is
then
adapted to seal the enclosure 39 by pivoting it to fit into the opening 38 of
the
frame 36 to provide a completely sealed unit for a curing operation. ' To this
end the frame 36 of the hood 6 and the surface of the curing unit is provided
with complementary slopping mating surfaces 74 which provide a light fast
seal. The curing unit 70 can comprise a light source 76 such as an infrared or
ultra violet light source to cure the paint. The curing unit 70 has a power
supply and a control unit which is used to program the curing cycle. The
curing unit is provided with a microswitch which only allows operation of the
curing unit when it is fully within the opening so as to provide a light seal.
The
curing unit 70 is also provided with cooling vents 78 enabling air to be drawn
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in to the enclosure 39. The cooling vents 78 are provided with a light seal.
During use of the curing unit 70 the extraction unit 4 is operated to draw air
from the enclosure 39, thus removing and containing any gases created
during curing.
5 In a second embodiment of extraction system as illustrated in Fig. 16
the system 2 comprises a heating unit which comprises an articulated arm 80
mounted at one end to the mast 14. The other end of the arm 80 carries an
air blowing system 82 having an outlet nozzle 84, the air blowing system
comprises a heater for warming the air. In use the articulated arm 80 is
10 foldable to hold the air blowing system 82 remote from the opening 38 to
the
hood 6, or can be deployed to insert the outlet nozzle 84 of the air blowing
system through the opening 38 at a desired location, or to direct an air
stream
from the blowing system into the hood 6. The air blowing system 80 is
particular useful for drying water based paints in colder climates by
providing
15 additional turbulence and heat about the surface of the area to be dried
and
creating correct temperature for drying; water based paints generally require
temperatures in the region of 15 to 40 C to dry. The air blowing system 80
can be directed to provide an air jet obliquely towards the surface to be
dried
and thereby obliquely to the inflow of air through the opening into the hood
created by the operation of the extraction unit 4, by this means the air from
the air blowing system 80 disrupts the inflowing downdraft of air into the
enclosure 39 of the hood 6 causing turbulence therein, with the formation of
air vortices along the painted surfaces which accelerates drying thereof. The
extraction of air during the drying process by the extraction unit 4 also
extracts
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vapours and particulates from the drying paint for safe containment, whilst
the
deflection of the hoods internal surfaces 44 contain such within the hood for
extraction.
It is to be understood that the hood 6 can be of any shape and/or size
and that the deflection shoulders could be omitted, or the deflection surfaces
could be adjustable. Also a variety of different hoods could be provided with
each extraction unit 4, by this means a suitably sized and shaped hood can
be selected for the area requiring repainting. Alternatively the hood can have
adjustable sides. Likewise the curing unit could be adapted to provide a fit
to
a variety of hoods. A plurality of curing units could be provided each having
a
different curing system, such that a means of curing most suitable to the type
of paint to be cured can be selected. Alternatively a plurality of different
curing means may be provided within a single unit. Although the curing unit
has been described as fitting into the opening, other arrangements could be
envisaged, for example the curing unit could be fixed in the containment unit.
Whilst a manual adjustment of the position of the hood as been described, the
stand and mast could be provided with pneumatic means to power the
adjustment of the orientation of the head.
Although a fixed extraction unit has been described, other forms of
extraction unit could be used for example a mobile extraction unit on wheels.
The extraction unit could be provided with a containment unit to collect the
extracted contaminants for safe disposal. In a third embodiment of extraction
system as best illustrated in Fig. 17 the duct is mounted on a rail 200 via a
trolley moveable 202 along the rail. The rail 200 can be fitted at a low level
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close to the floor of a workshop, or to a ceiling of a working shop. The duct
8
and hood 6 can then be moved around the workshop to an area where it is
required. The duct 8 is connected into a fixed extraction and filtration unit
(not
illustrated). This can be that of the fixed spraybooth in the workshop, or a
separately provided system. As illustrated a plurality of different ducts can
be
connected into the extraction and filtration unit, enabling several repair
operations to be simultaneously performed, or for different lengths of duct to
be used.
It is to be understood that although the duct has been described as
being moveably mounted to a rail, the duct may be fixed directly to the
filtration and extraction unit.
Although the enclosure has been described as being formed by the
attachment of a flexible sheeting to the hood by means such as masking
band, other forms of attachment could be used such as for example masking
tape or Velcro (TM). Also, the hood could alternatively include a flexible
skirt
with magnetic means to enable its attachment to metallic surface of an item to
be repaired, thereby dispensing with the need for separate sheeting.
Although the hood has been described as being constructed of a heavy duty
plastics material, it could be constructed from other materials.
Although vehicles have been specifically described it is to be
understood that other items requiring spraying and for drying are included
such as garage doors, furniture including garden furniture, fencing and
appliances requiring repair.
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In a fourth embodiment of extraction system 2 as illustrated in Figs. 18
to 22 the extraction system 2 is specially adapted to contain a portion of a
particular item to be sprayed, in this instance the hub 90 of a wheel. In this
embodiment the extraction unit 4 provides a base upon which the wheel is
mounted. A seal ring 92 is provided about the inlet 94 to the extraction unit
4.
The sealing ring 92 is rotatable, thereby providing a turntable. The hood 6
comprises a fume ring 96 and a masking ring 98. The fume ring 96 and
masking ring 98 each have outwardly inclined surfaces 96a and 98b
respectively and are fitted together to form an enclosure 39. The central
aperture 100 to the fume ring 96 forms the opening 38 to the hood 6, whilst
the central aperture 102 to the masking ring 98 forms the outlet 10 to the
hood
6. The central aperture 102 of the masking ring 98 is provided with inwardly
extending shoulders 104 inclined surfaces 96a, 98b of the rings 96, 98 form
the internal deflection surfaces of the hood 6.
In use the tyre 106 of a wheel whose hub 90 requires respray is
deflated and placed over the inlet 94 of the extraction unit 4 such that its
sealing ring 92 contacts the tyre 106 or the wheel. The hood 6 is then placed
over the wheel by initially placing the masking ring 98 about the exposed hub
90 surface by fitting its inwardly extending shoulders 104 under the rim 106
of
the hub 90, as best illustrated in Fig. 21, which is accessible due to the
deflation of the tyre 106. The fume ring 96 is then placed over the masking
ring 98 to complete the hood 6.
The system is operated by switching on the extraction unit 4 which
draws air into the hood 6 opening 38 down through the hood 6, through the
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aperture provided in the hub 90, into the extraction unit 4. The hub 90 is
sprayed by spraying into the opening 38 of the hood 6, with the overspray
being contained as in previous embodiments by deflection by the effective
aerofoil created by the internal surfaces of the hood. The operation of the
extraction unit 4 helps to provide an air tight enclosure about the hub 90,
whilst the masking rings 96 shoulders 104 protect the tyre 106 from the paint
spray.
The masking ring 98 is adjustable in that is annular shape is created by
a strip which is overlapped with a sliding fit, with the degree of overlap
being
adjusted to alter the size of the central aperture 102 to best fit about the
rim
106 of the particular hub 90. The fume ring 96 has a greater outer diameter
108 than that of that of the masking ring 98, in that it always overlaps its
outer
edge of the masking ring 96 regardless of the size its diameter is adjusted
to.
A curing unit and/or heating unit can be inserted into or adjacent to the
opening into the hood to facilitate curing and/or drying as per the previous
embodiment.
Although the base has been described as the extraction unit, the base
could merely provide an inlet to the extraction unit which unit may be
provided
remotely and connected thereto by ducting.
The invention is not restricted to the above described embodiments
and many modifications and variations will readily occur to one skilled in the
art.
