Note: Descriptions are shown in the official language in which they were submitted.
CA 02211978 1997-07-30
A device for fumigation with a fluid product.
This invention relates to a device for fumigation
using a liquid product such as deodorisers, ambient
scents, insecticides, et~c. The device will find its
application in the treatment of premises such as public
places, offices or hotels and other premises.
Until now, fluid products of the aforementioned type
are usually dispensed in the form of fine droplets with
the help of a spray pump or an aerosol bomb. These
droplets remain momentarily in suspension in the air,
but have a tendency to fall due to their mass, since
these droplets, as their name indicates comprise a
liquid phase of the product and not a gaseous phase.
This sort of fluid product distribution system is
particularly well suited to a localised treatment, since
a large quantity of product can be concentrated into a
small volume. On the other hand, for the treatment of
large volumes, this technique is inappropriate and
results in poor disperslon of product because of the
inexorable falling of the droplets.
Unlike this technique of simple spraying, the
document EP-A-0 401 060 discloses a device in which a
manual pump is activated by electromechanical means to
spray a jet of fluid substance in the form of a fine
spray onto a metal surface. The metal surface is heated
to a temperature greater than the vaporisation
temperature of the fluid substance so that said fluid
substance is instantly vaporised in ~aseous form, hence
with a chan~e of state. In the following, this type of
product distribution will be called fumi~ation. In fact,
since the fluid substance passes into the gaseous phase,
its dispersion in the atmosphere is much better than
with the aerosols which produce droplets in suspension
in the air. Because of this, it is possible to use much
CA 02211978 1997-07-30
less of said substance than with an aerosol in order to
achieve the same result (Avogadro's Law - Ampère),
which, on the one hand is economic and on the other hand
is better for human health and for the environment.
Furthermore, the fine droplets produced by the spray are
instantly vaporised by the heated surface, hence the
fluid substance does not have the time to be degraded by
the heat during vaporisation and preserves all its
properties.
Similarly, the document FR-2 706 330 discloses a
spray and fumigation device which allows both a spray
similar to that of an aerosol, and a fumigation,
according to the form of use desired. To do this, it is
provided with a pump activated by electromagnetic means,
a retractable heating element and a microprocessor which
commands the pump at a predetermined interval of time
when the heating element is opposite the spray nozzle of
the pump. The heating element includes an enclosure open
at its top and bottom faces and containing a thermally
conductive plate extending perpendicular to the
direction of the jet of sprayed product. The plate is in
thermal contact with a resistance. The product, once
broken up into the gaseous state escapes through the top
face of the enclosure, so that air comes into the
enclosure via the bottom face.
However, this prior art fumigation device, like
others, makes provision for the emission of one or
several consecutive doses of product at fixed
predetermined time intervals, which leads, because the
air in a given volume is not static but is subject to
currents of variable intensity, to variations in the
density of gaseous product distributed in relation to
time and because of this, the odour the product releases
is sensed to be more or less intense. These variations
can bring about excessive concentrations of products at
certain times and conversely, a quasi-total
disappearance of odour at other times.
CA 02211978 1997-07-30
An aim of this invention is to provide a fumigation
device capable of maintaining a constant "level" of
odour in the premises to be treated, even though the
premises are subject to disturbances in the air.
To do this, the objective of this invention is a
device for the fumigation of premises with a sprayable
fluid product, comprising :
- at least one reservoir containing the fluid to be
sprayed,
- spray means provided with a spray nozzle.
a heated internal wall, opposite the spray
nozzle, to receive said sprayed product via the spray
means, said heated internal wall having a temperature
greater than the vaporisation temperature of said fluid
product, said heated internal wall being in
communication with the atmosphere via a top opening to
discharge said product in the gaseous state.
- a microprocessor to command the activation of the
spray means and to control the temperature of the heated
internal wall,
characterised in that the microprocessor is programmed
to automatically command the activation of the spray
means at a time interval determined according to a value
representative of the circulation of air inside the
premises to be treated. Hence the quantity of gaseous
product distributed is perfectly regulated in relation
to the replacement of air in the premises, which results
in the expulsion of part of the gaseous product to the
outside from whence the variation in product density
arises. One may thus be sure that for whatever the
volume of new air brought into the premises, a quantity
of gaseous product proportional to this volume will be
added to it. Provision is thereby made for the
maintenance of a constant odour in the premises.
According to a first embodiment, said value
representative of the circulation of air is put into the
microprocessor program as a logged value.
-
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.
According to a second embodiment, means of detection
are provided to measure said representative value for
the circulation of air at predetermined intervals of
time, electronic circuitry being provided to input
successively said values thus measured into the program
of the microprocessor in order to continuously adjust
the quantity of fluid product distributed.
Advantageously, the top opening is connected upstream of
a turbine of an air conditioning system in order to
aspirate the product in the gaseous state, an aeraulic
probe being positioned downstream from the turbine in
order to measure said representative value in the form
of an air flow rate at the outflow of the turbine. In
fact, between the mouths of the air inlets and the
turbine, there is a pressure drop producing an
aspiration effect which can be profitably used to
extract the gaseous product from the enclosure. Using a
fumigation device linked to an air conditioning system
comprises a preferred practical application of the
invention. In this way one may ensure that the whole of
the premises are treated perfectly.
With the enclosure configuration in document
FR-2 706 330, part of the sprayed fluid product does not
come into contact with the heating plate, but falls to
the bottom of the enclosure, that is to say to the open
bottom face. This face, because the outside air is
passing across it is not at a temperature sufficient to
bring about instantaneous vaporisation of the fluid
product. This then results in a residue of product, more
or less dried out at the bottom of the enclosure which
degrades under the influence of the heat released by the
heated plate. The calcination of the residue releases
odours which damage the true scent of the fluid product.
Furthermore, over a long period, this residue can flow
out of the enclosure which is neither aesthetic nor
practical.
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In order to alleviate this problem, the invention
provides, in a particularly advantageous embodiment,
that said spray means include a water pump in fluid
communication with the spray nozzle, to clean the latter
as well as the heated internal wall after spraying the
fluid product. Hence by regular washing of the
components in contact with the fluid product in the
heated zone, any risk of residue formation is eliminated
and perfect cleanliness can be maintained. Incidentally,
this supply of water can equally well be used to
humidify the premises being treated.
More advantageously, cleaning means are provided
able to project under pressure a heated cleaning agent,
in vaporised form against said internal wall.
These means of cleaning under pressure can be
concurrent with the means of rinsing the nozzle.
The cleaning agent, which can be pure water or a
solution of water and oxygenated water enables a real
scouring of the internal wall to be carried out. This is
made possible because the cleaning agent is distributed
under pressure and at an elevated temperature (110 to
150~C). In reality, the cleaning agent is projected
against the inner wall in vaporised form, under
pressure. The impact of the vapour at high temperature
against the internal wall causes effective and rapid
scouring. Furthermore, when the cleaning agent contains
a disinfectant or a bacteriostatic substance such as
oxygenated water, this gives the additional benefit of
removing any bacterial traces from the internal wall,
thereby bringing about perfect cleaning.
According to one embodiment, the cleaning means
include a chamber having an inlet and an outlet and
heating means to heat said chamber. Advantageously, the
inlet of said chamber is provided with non-return valve
means and the outlet of said chamber is fitted with
pressure relief valve means. Superheating the cleaning
agent allows the pressure inside the chamber to be
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increased which causes projection of the cleaning agent
at the chamber outlet. ~ith a pressure relief valve set
at about 5 bars, good projection under pressure is
obtained at a temperature of about 130~C.
In a practical form, the chamber has substantially
the shape of a horse shoe, the heating means being an
electrical resistance extending along the chamber.
On the other hand, according to a first embodiment,
the spray means include a spray pump activated by
mechanical means. One could, for example, use a spray
device as described in the aforementioned document
FR-2 706 330. In this device, the dose of fluid product
is put under pressure in a pump chamber before being
released through a classic nozzle which allows the
dispersion of the fluid in fine droplets.
Moreover, according to a second preferred
embodiment, the spraying means, include an air pump and,
at least one fluid product pump, said spray nozzle being
a mixer nozzle where the fluid product is introduced
into an air flow created by the air pump and is thus
sprayed. This flow of air improves still more the
evacuation of the gaseous product via the top opening.
On the other hand, the configuration of the
enclosure in the aforementioned document does not bring
about a rapid release of the product in the gaseous
state. The gaseous product has, of course, a tendency to
rise because of the temperature but in a natural way at
normal speed.
This invention also aims to remedy the
aforementioned disadvantages of the prior art by
specifying an improved device, particularly with regard
to its fumigation system, that is to say the system for
changing state. Another aim of the invention is also to
arrive at a simple and clean device that allows rapid
release of the gaseous product.
In order to achieve this, said device includes an
enclosure which is closed except for a lower side
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opening and a top opening, said spray nozzle being
positioned opposite said lower side opening, the
interior of said enclosure is, at least partially,
heated at least opposite said lower side opening, to a
temperature greater than the vaporisation temperature of
the fluid product and thereby defines said heated
internal wall, a passage for the supply of air being
provided by said lower side opening in order to create
a current of air inside the enclosure which encourages
lQ the release of said product in the gaseous state through
the top opening. There are numerous advantages in making
the opening for the spray nozzle and the air inlet
opening concurrent. Firstly, the enclosure is perfectly
sealed at the bottom ; no product residue can run out of
it. Secondly the air current does not disturb the jet of
sprayed product since it is coming from the same
direction. Thirdly, the air current allows a constant
cooling of the spray nozzle which is subjected to the
heat which arises in the enclosure. Fourthly, the air
current does not cool down the heated internal wall of
the enclosure which is opposite the nozzle since it
comes into the enclosure in a diametrically opposed
manner. Fifthly, more air current comes into the
enclosure at the spray nozzle due to the air intake
created around the jet of the sprayed product. Finally,
in combination with the flow of air generated by the air
pump, the air current coming into the enclosure via the
side opening enables extraction to be improved even
more.
The lower opening is located at the side. Since this
does not offer any particular advantage, it may also be
envisaged that this lower opening is in the bottom of
the enclosure.
Advantageously, the top opening has a section less
than that of the air supply passage. By adopting this
relationship between cross section areas, a draught
effect is produced inside the enclosure that increases
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the speed of release of the gaseous product at the top
opening. It is a kind of Venturi effect that allows the
gaseous product at the- outlet of the device to be
expelled in an accelerated manner. This permits more
rapid dispersion of the molecules of gas into the air
through an initial vigorous mixing.
According to one embodlment, the air supply passage
is provided by a space defined between the lower side
opening and the spray nozzle positioned in the latter,
remote from contact with it. The air current thus comes
into the enclosure in a uniform manner around the spray
nozzle. The thermodynamic disturbance that the air
current engenders inside the enclosure influences the
internal walls of the enclosure in a manner symmetrical
lS with respect to the jet of sprayed product.
According to an advantageous characteristic of the
invention, the enclosure is made of a thermally
conducting material. On the other hand, the enclosure is
heated by means of a thermostatic jacket which surrounds
the major part of the enclosure in order to maintain
substantially all of the enclosure at a temperature
greater than the vaporisation temperature of the fluid
product. Alternatively, for products which are
particularly volatile, the enclosure has internal
surfaces which are polished smooth. Furthermore, the
enclosure has internal walls which have been sand
blasted to increase the surface contact with the
sprayed fluid product thus providing a catalytic effect.
In this way, one ensures that the enclosure is at an
adequate temperature and that no residue at all will
form. This keeps the enclosure completely clean.
The dose of product sprayed and then vaporised does
not vary, only the temporal distribution is varied
through modifying the time interval between the periods
of activation of the spray means which allows the
quantity of product distributed to be regulated in
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accordance with the circulation of the air in the volume
to be treated.
Advantageously, means are provided to increase the
air current inside the enclosure. According to a first
form of use of the invention, at least one fan is
provided close to the top opening to place the latter
under negative pressure and thus facilitate the
extraction of the gaseous product to the outside of the
enclosure. It is a simple and inexpensive method which
can be used in isolated fumigation devices.
For safety reasons, said fumigation device is placed
in a cabinet equipped with a door and means of detecting
if said door is open. Advantageously, provision is made
for detection means in association with the
microprocessor to monitor correct operation of the
fumigation device and to fit a safety cut-out to the
latter in the event of a malfunction.
Other characteristics, distinctive features and
advantages of the invention will become apparent on
reading the detailed description which follows,
providing non-limiting examples, illustrated in the
attached drawings, of several embodiments of the
invention.
In the drawings:
- Figure 1 is a schematic representation of a first
embodiment of a fumigation device according to
this invention,
- Figure 2 is an enlarged plan view of the spray
nozzle used in the device shown in Figure 1.
- Figure 3 is a cross section view of a second
embodiment of a fumigation device according to
this invention.
- Figure 4 is a plan view of the means of cleaning
under pressure in accordance with this invention
and
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- Figure 5 is a schematic representation of the
fumigation device shown in Figure 1 integrating
the cleaning means shown in Figure 4.
As previously mentioned, the devices according to
this invention are destined for use for the treatment of
premises by fumigation with odoriferous or disinfectant
products. Amongst the odoriferous products, one may list
deodorisers and ambient scents. Another type of
analogous product gives an opposite olfactory result,
that is to say the removal of any odour. The fragrances
on which any odoriferous product is based. are organic
substances active in the air at low concentrations.
However, the fragrances have low solubility in water so
a solutizer is chosen. One can use a polyethoxylated
material in the formulation with 20 to 30% water.
However, since it has been noted that the coefficient of
expansion (the relationship between the volume of gas
generated by vaporisation of a liquid and its boiling
temperature and the initial volume of this liquid)
increases with a decrease in the molecular mass of the
product it is preferable to use a product with a very
high percentage of water since the molecular mass of
water is only 18. This is why it is preferable to use an
emulsion with a polymer in very low quantity (~ 1%)
which allows the presence of at least 90~ water. A very
simple theoretical calculation starting from the law
relating to ideal gases gives a coefficient of expansion
of 1530 for such an emulsion but only 585 for a
formulation made up of 25% water and 65 of surface
active solutizer.
In addition to respecting the demands linked to
environment protection, seeing that it contains no
volatile organic compounds dangerous for the environment
or for health, an emulsion with a high water content is
ideal from the point of view of its coefficient of
expansion taking into account the distribution
temperature employed here. In effect, the fumigation
CA 02211978 1997-07-30
exploits precisely that property that the products have
of considerably increasing in volume as they pass from
their liquid phase to their gaseous phase. Consequently,
the use of a product with a high water content has a
reduced advantage within the context of its use in
fumigation technology.
Of course, all kinds of products can be distributed
with devices produced in accordance with the invention,
but maximum efficiency is obtained with highly aqueous
products. In the rest of the text, the question of the
formulation, composition or nature of the product will
not be discussed further; it will simply be designated
by the generic term "product".
Both of the two embodiments of the devices described
below include spray means, fumigation means and command
means.
Referring now to Figure 1, a complete fumigation
device has been shown in a schematic way. It is a
preferred form of the invention particularly from the
point of view of the spray means. These give the maximum
result in relation to the fineness of the sprayed
droplets and the maintenance of fumigation means.
The spray means comprise a product pump PP and an
air pump PA linked by pipes 41 and 40 respectively to a
mixing spray nozzle 3 an enlarged representation of
which is given in Figure 2. A non-return valve C1 is
mounted in series on pipe 41 to ensure that said pipe is
always full of product. The product pump PP is on the
one hand connected by pipe 42 to an electronically
controlled valve EV, itself connected by respective
pipes 45 and 46 to product reservoirs RP1 and RP2. The
electronically controlled valve EV makes it possible to
draw selectively from one of the two product reservoirs
RP1, RP2 according to their levels.
The air pump PA delivers a flow of air to the mixing
nozzle 3 at a pressure of about 150 mbar. Such a
pressure can be supplied by a linear membrane pump,
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available on the market, for example from the company
WISA who sell the pump under the name LIMA674. Such a
pump comprises two pump chambers each equipped with a
deformable membrane. The membranes are activated in
opposite phase to achieve a regime of constant air flow.
This pump has shown itself to be particularly well
suited for this application.
It is self-evident that any other way of supplying
air and having similar close characteristics can be used
within the scope of the invention, for example, a
compressor. The flow of air must be sufficient to spray
the product without creating excessive aeraulic
disturbance (it will be seen below why such a condition
is demanded).
As for the product pump PP, it supplies precise
doses of product, almost drop by drop to the mixer
nozzle 3. The drops of product are fed into the air flow
created by the air pump PA which causes them to be
sp-rayed in very fine droplets. As an example a LIMA
diaphragm pump WISA D100 available from the company WISA
gives good results. The product pump PP delivers
constant doses of product at will. To increase the
quantity of product sprayed, the frequency of emission
of doses is changed and not the dose itself which is
defined by the volume of the pump chamber.
These two pumps PP, PA allow one to obtain an
optimum spray (fineness of the droplets) with maximum
reliability (sturdiness of the pumps). Furthermore, it
will be seen below that use of an air flow to spray the
product leads to an important advantage for the
fumigation.
The fumigation means comprise essentially an
enclosure 1 closed except for a lower side opening 11
and a top opening 12. The enclosure 1 is preferably
cylindrical and has the shape of a bottle having a
contracted neck (top opening 12) and a side hole (side
opening 11). The enclosure has a sealed bottom 13, a
CA 022ll978 l997-07-30
14
cylindrical body 15 and a bottle neck 14 ending in the
top opening 12. A thermostatic jacket surrounds the
greater part of the enclosure particularly the
cylindrical body part 15 except for the side hole 11.
The thermostatic jacket is supplied electrically in such
a way that the inner walls of the enclosure are brought
to a temperature greater than the vaporisation
temperature of the product which is necessary for its
fumigation. Preferably the enclosure is made of a
thermally conducting material such as a metal or a
conducting ceramic, in such a way that the whole of the
enclosure is at the required temperature. For an
emulsion, such as that specified earlier, a temperature
of 300~C is sufficient. In accordance with an
interesting characteristic, the internal walls of the
enclosure are finely sand blasted to obtain a catalytic
effect by increasing the area of contact with the
sprayed product. Alternatively, the internal walls are,
in a contrary way, extremely smooth in such a way as to
give a mirror effect. Smooth internal walls are
preferred for the distribution of particularly volatile
products which have a tendency to adhere to the internal
walls. On the other hand the finely sand blasted
internal walls are used when the doses of product
distributed are large. The sand blasting allows the size
of the enclosure to be reduced without reducing the
contact surface.
The mixer spray nozzle 3 is positioned opposite the
lower side hole 11 in such a way that the jet of sprayed
product is projected to the inside of the enclosure.
According to the invention, the nozzle does not close up
the side opening 11 so that a passage for the supply of
air 31 is defined through which an air current can pass
into the interior of the enclosure 1. In the embodiment
shown in Figure 1, side opening 11 and the nozzle are
round. The passage 31 is then defined by the annular
space between the side hole 11 and the nozzle 3.
CA 02211978 1997-07-30
Referring now to Figure 2, the mixer nozzle used in the
device of Figure 1 can be seen in enlarged form. The
nozzle 3 comprises a body 30 with three inlets to which
are connected respectively the non-return valve C1, to
the product pump PP, the non-return valve C2 to the
water pump PE and the pipe 40 to the air pump PA by
means of rotating coupling 430. The body of the nozzle
incorporates three internal supply channels (not
visible). The two channels corresponding to the product
pump PP and the water pump PE come out into a jet 330,
whilst the channel corresponding to the air pump PA
comes out into the air nozzle 320. The product or the
water is brought practically without any pressure into
the flow of air which immediately sprays it. Thanks to
this nozzle and to its associated pumps, one can deliver
doses of product with an accuracy of the order of 10
microlitres.
The air current coming into the enclosure has the
effect of encouraging the release of the product reduced
to a gaseous state through the top opening 12 which acts
like a chimney. Of course the gaseous product has
already a tendency to rise because of its raised
temperature and the temperature that prevails within the
enclosure. With the current of air which is coming into
the enclosure through the side opening, the release of
the gas is improved. The latter is in the form of a dry
smoke which has no tendency to fall back to earth, but,
on the contrary disperses itself very easily in the air.
According to an additional characteristic of the
invention, the top opening 12 has a cross section area
less than that of the air supply passage 31. This brings
about an acceleration of the gaseous product at the exit
of the top opening by a Venturi effect. By reducing the
cross section of the top opening 12, a glut of gaseous
product particles is created at the bottleneck 14, but
as the flow rate stays roughly constant, the particles
are accelerated so that the release is in the form of a
CA 022ll978 l997-07-30
16
cloud of active smoke which is rapidly expelled from the
enclosure.
This enclosure configuration has numerous
advantages. The bottom part 13 of the enclosure is
closed off in such a way that no running out of product
residue can take place. This is even more impossible
since the enclosure is heated almost in its entirety. It
should also be noted that the side opening 11 where the
mixer nozzle is located is positioned in such a way with
respect to the thermostatic jacket 2 that the whole of
the jet of sprayed product is projected onto an internal
wall of the enclosure covered by the ~acket 2. One is
assured that the sprayed product comes into contact with
a surface at an adequate temperature. On the other hand,
the fact that the air supply passage 31 surrounds the
nozzle, allows, on the one hand the latter to be cooled
since it is directly subjected to the heat of the
enclosure and, on the other hand means that the internal
wall of the enclosure situated opposite the side
opening 11 and onto which the greater part of the
sprayed product is projected, is not cooled down.
Furthermore the current of air ccming in disturbs the
jet of sprayed product in a uniform manner and not
laterally or transversely, as would be the case if the
air supply passage were to be situated in another place.
In the case where the spray means described above is
used, the flow of air generated by the air pump PA adds
to the air current to improve the release of the gaseous
product. That is why these spray means are preferred.
However the flow of air must not be too high, since
there is a risk of cooling down the internal wall of the
enclosure opposite nozzle 3 which would make any
fumigation impossible. The air pump must be chosen and
adjusted in an optimum manner to spray the fluid product
supplied by the product pump PP as finely as possible,
whilst avoiding cooling down the enclosure.
CA 02211978 1997-07-30
To increase the air current coming into the
enclosure via the side opening 11, defined around the
nozzle, one can make provision for one or several fans
positioned close to said top opening and run at a
distance from said opening in such a way that the latter
is under negative pressure which will facilitate the
extraction of the gaseous product from the enclosure.
This has the effect of increasing the speed at which the
gaseous product is released which means that it is more
rapidly dispersed in the air. Such an arrangement is
particularly well suited to the case where the device is
isolated, that is to say the top opening leads directly
into the atmosphere.
Another arrangement, more practical but particularly
advantageous provides for the top opening to be
connected upstream from a turbine of an air conditioning
system. In effect, in this part of the system there is a
negative pressure which has the effect of drawing in
outside air. Hence by connecting the device, the inside
of the enclosure will be aspirated. In addition to the
current of air which already exists and which brings
about an accelerated release of the gaseous product, the
negative pressure created by the turbine encourages
still further the extraction of the gaseous product
through aspiration. Air conditioning systems have the
advantage that they can treat all the rooms in a
building and they are more and more common in such
buildings as offices and hotels.
According to a very advantageous characteristic of
this invention, the device includes a water pump PE
linked, on the one hand to a reservoir of water RE by a
feed pipe 44 and, on the other hand, to the mixer nozzle
3 by a pipe 43. A non-return valve C2 is mounted in
series in pipe 43 to prevent water present in pipe 43
from returning into pump PE once the latter is switched
off. One can therefore be sure that there is always
water in pipe 43 and more particularly at nozzle 3. When
-
CA 022ll978 l997-07-30
18
water pump PE is activated, the non-return valve C2
opens whilst valve C1 in the product pipe closes. The
water supply to the nozzle serves to rinse it and to
clean the enclosure and, incidentally to humidify the
S air of the premises being treated. Cleaning of the
nozzle is necessary since the fluid product remaining
on the nozzle after spraying has a tendency to dry out
under the effect of the heat released in the enclosure.
In effect, once spraying is finished, the enclosure
still remains hot for a certain time. It is therefore
useful to remove fluid product remaining on the nozzle.
To do this, the nozzle is supplied with water instead of
fluid product and the air pump is activated. The water
is thereby sprayed and is released in gaseous form.
lS Rinsing the nozzle is essential since, if not done,
it will block up but cleaning of the enclosure is
equally important, since it enables any residue that
might possibly form in the enclosure to be removed. The
enclosure is thereby kept perfectly clean. To do this,
it is enough to activate the water pump PE after each
spraying of the product coming from pump PP.
For reasons of safety and public hygiene, the water
which is sprayed has a bactericide added to it to avoid
the spread of bacteria, microbes or other substances
capable of reacting with the human organism.
Alternatively, the water pump PE can be connected by
a pipe to an electronically operated valve to which is
also connected pipe 41 from the product pump PP. The
electronically operated valve makes it possible to
switch selectively between the product pump PP and the
water pump PE and is connected to the mixer nozzle 3 by
a single pipe. The water pump PE must then be run for a
certain time since it is necessary to empty the product
fluid remaining in pipe 41 after spraying. The choking
up of the mixer nozzle is thereby avoided which prolongs
its life.
CA 02211978 1997-07-30
19
To manage the operating cycle of each unit making up
the device, that is to say, the pumps PP, PA and PE, the
valves C1, C2 and electronically operated valve EV and
the thermostatic jacket 2, provision is made for a
S microprocessor M to be connected to each unit by
connections 51-56. The microprocessor can be programmed
to command in the following manner. First it supplies
power to the thermostatic jacket so that it reaches the
required temperature, for example 300~C. Once this
temperature is reached, the microprocessor commands the
activation of air pump PA. Next, it brings product pump
PP into action after having checked the state of
electronically operated valve EV. In the event that
product reservoir RP1 has reached its minimum level, it
lS commands electronically operated valve EV to switch over
to reservoir RP2. Activation of product pump PP
signifies the emission of a dose or a determined series
of doses. Once the activation of product pump PP is
terminated, the microprocessor commands the activation
of water pump PE all the time keeping the air pump PA
running. The water pump PE remains in action until the
mixer nozzle 3 and the enclosure 1 are perfectly
cleaned. If the time interval between each dose or
series of doses of product is small, then water pump PE
will simply be brought into action after the final
spraying of the product, for example at the end of the
evening before the device is shut down for the night.
Finally the microprocessor commands the switching off of
the power supply to the jacket 2.
The frequency of the doses or the series of doses
emitted is dependent on the circulation of the air in
the premises to be treated, on the replacement of air in
the premises and the nature of the product being
distributed. The logged value for the frequency can be
calculated in accordance with the parameters involved,
can be found empirically by testing or determined in
relation to a significant quantity, for example, the
CA 02211978 1997-07-30
instantaneous flow rate from the turbine in an air
conditioning system. In this last case, an aeraulic
probe S communicates the air flow value taken every
three seconds for example, and the microprocessor
determines the frequency for activating product pump PP.
Hence the quantity of gaseous product distributed by the
air conditioning system into the premises to be treated
is directly determined as a function of a real
representative parameter. The fumigation device is thus
perfectly self-contained and adapts itself to the
changing conditions at the site being treated.
To reduce the maintenance of the fumigation device,
provision can be made for a remote monitoring system
which will indicate by means of various sensors such as
pressurestats, any malfunctioning of the device. The
only intervention to be made at the site of the
installation of the device would then be to replace the
product reservoirs RP1, RP2 and the water reservoir RE.
By way of an example, in the case where the
fumigation device is connected to an air conditioning
system, it could be arranged that when the system
turbine stops the fumigation device is made safe so that
product is not used wastefully. Alternatively, the
fumigation device can make itself safe if the air flow
rate in the system drops below a predetermined threshold
value, for example 0.5 m.s~1.
As another safety measure, one can envisage mounting
a manostat on the air pipe which links the air pump PA
to the nozzle 3. In the event of a pressure drop in the
pipe to below a threshold value, for example 80 mbar,
the manostat contact opens and causes the fumigation
device to be made safe. This detection goes back to
detecting the presence of a spray, since it is the air
emitted by the air pump PA which makes the spray
possible.
Provision can equally be made to detect the presence
or not of a plug in the jet of the nozzle by checking
CA 02211978 1997-07-30
the pressure in the water pipe. An excess pressure
during the rinsing/cleaning cycle, of for example, more
than 70 mbars indicates the presence of an obstruction
which causes the contact of a manostat to open which
makes the device safe.
The fumigation device, for safety reasons, can be
placed in a cabinet, the door of which is equipped with
an opening detection system.
An optical sensor, associated with an electronic
logic system powered by an accumulator allows movement
of the strike plate, necessary to open the door, to be
detected. Straightaway, the device moves to a safe
condition, stopping the diffusion of product. The
apparatus can only be started up again once an n figure
code is typed in on an internal keyboard and the door
has been closed again.
Any opening of the door, even with the power supply
switched off, is recorded and causes the device to be
made safe.
The different safety measures described and others
that may be envisaged, are controlled by appropriate
electronic circuitry and the microprocessor in order to
avoid false alarms.
Referring to Figure 3, a second embodiment of a
fumigation device according to this invention will be
described. The spray means are more conventional in this
case since they involve a classic manual spray pump 38
of the type one meets on fluid product distributors for
domestic use. The spray nozzle 3 is integral to a
distribution head 30 in which an outlet channel is
formed. The nozzle can include a whirl chamber which
creates a vortex centred on the spray orifice. The fluid
product is thus sprayed. The outlet channel is connected
to the hollow activating shaft of the pump 38 which is
integral with the piston (not shown). The pump includes
a tube 35 which reaches down to the bottom of a product
reservoir 34. The distribution head is, on the one hand
-
CA 02211978 1997-07-30
connected to a piston 32, mounted so that it may slide
in a solenoid 33. When the solenoid is supplied with
current, the piston is moved towards the bottom, which
activates the pump. A microprocessor is provided to
S control the power supply to the solenoid by regulating
the frequency, that is to say the time interval between
each supply of power.
The microprocessor 36, as in the first embodiment,
shown in Figuré 1, also controls the prior power supply
to the thermostatic jacket 2 which surrounds the
enclosure 1. Furthermore, the microprocessor program
incorporates a logged value which corresponds to the
mean representative value for the circulation of air in
the premises to be treated. This logged value, can, for
example, be measured with appropriate instruments such
as an aeraulic probe. The fumigation device in Figure 3
is a more simple design and lends itself particularly
well to domestic use whilst the device in Figure 1 is
rather more for industrial use. A correlation table may
be supplied with the device with the help of which one
could determine the logged value as a function of the
volume and the nature of the room to be treated. An
entrance hall must be treated in a more intense manner
than a living room. The enclosure 1 in Figure 3 is of
reduced size but operates in the same manner as that in
Figure 1, except that the jet of sprayed product does
not contain an air flow and that the top opening 12
opens directly into the atmosphere. The release of
gaseous product takes place in a unforced way, caused
only by the rise of the gas under the action of the
heat. However, the gaseous product at the outlet of the
top opening 12 acquires a certain speed just the same
due to the reduced cross section area of the top
opening.
This fumigation device can be put into a case fitted
with a release mouthpiece at the top opening to allow
the exit of the gaseous product. Protective insulation
CA 02211978 1997-07-30
23
21 can be provided around the enclosure to prevent the
whole device being heated up.
The enclosure in the two embodiments described plays
the role of a particle accelerator or cyclotron, in the
S sense that the particles which are released through the
top opening do so with a certain speed. This phenomenon
is obtained by introducing an air current into the
enclosure and is encouraged by the carefully chosen
relationship of cross sections of the enclosure
openings.
The enclosures which have just been described are in
the shape of a cylindrical bottle. Of course, one can
imagine all kinds of geometry for an enclosure equipped
with two openings without departing from the scope of
the invention.
Figure 4 shows a preferred form of cleaning means
taken from the fumigation device into which they are
integrated. In the embodiment shown, which is not
limiting, the cleaning means designated in its entirety
by reference number 6, comprises a pressurising chamber
60 which has a general horse-shoe shape. Of course, one
can imagine pressurising chambers of other shapes
without departing from the scope of the invention. The
shape chosen is however preferred, since it takes up
little space and furthermore can be obtained on the
market at low cost.
Chamber 60 includes an inlet 62 and an outlet 61.
Its capacity is of the order of from a few centimetres
cubed to 20 centimetres cubed. The chamber, in reality
is formed from a thermally conducting metal tube, about
30 cm in length, bent so as to give it a folded back
shape, for example, a horse-shoe shape. The tube forming
the chamber 60 has an electrical resistance along its
side which extends, inside the horse-shoe along the
major part of its length. This resistance 65 is
connected to a power supply 66 and has the function of
heating up the pressurisation chamber and because of
CA 02211978 1997-07-30
24
this, its contents. The chamber 60 and the resistance 65
are mounted on a base 63 which holds the chamber by
means of four lugs 64.
The chamber 60 is provided with a valve 7, 8, at
S each of its ends 61, 62. Valve 8 connected to inlet 62
of the chamber is a non-return valve which prevents
liquid from running back. Valve 7 connected to outlet 61
is a pressure relief valve appropriately set to allow
the superheated and hence vaporised liquid to be
released from the chamber.
The non-return valve 8 can include a spring which
presses lightly on the ball 82 on its seat 83, though in
the embodiment illustrated in Figure 4, the valve 8
does not incorporate a spring. Except for the spring,
the two valves 7 and 8 can be identical. They each
comprise a sleeve 71, 81 into which a bush 73, 83 is
inserted which forms the valve seat. The ball 72, 82
sits in the bush 73, 83 and an obstructing element 74,
84 limits movement of the ball within the bush. A spring
75 is compressed between the ball 72 and the obstructing
element 74 to press the ball down onto its seat 73, in
the case of the pressure relief valve 7. Setting the
spring for about 5 bars is perfectly suitable to obtain
sufficient pressure in chamber 60.
The operation in a fumigation device, of the
cleaning means in Figure 4 will now be explained by
referring to Figure 5.
In Figure 4 we have a preferred form of the
invention particularly from the point of view of spray
means.
The device includes a water pump PE connected, on
the one hand to a water reservoir RE by a supply pipe 44
and, on the other hand, by a pipe 43, to valve 8 on the
cleaning means. Another pipe 47 passing into the
enclosure through the bottom is connected to the
pressure relief valve 7. The end of pipe 47 is directed
towards the hot internal wall of the enclosure, opposite
CA 02211978 1997-07-30
the nozzle. Hence superheated steam will be projected
against this hot internal wall. Cleaning under pressure
is thus achieved.
For reasons of safety and public hygiene, the water
S which is vaporised can have added to it a bacteriostatic
substance so as to avoid any spreading of bacteria,
microbes or other substances capable of reacting with
the human organism. Preferably oxygenated water (H~O~)
will be used at a concentration of about 1 %.
To manage the operating cycle of each unit making up
the device, that is to say, the pumps PP, PA and PE, the
valve C1, the electronically operated valve EV the
thermostatic jacket 2 and the cleaning means 6,
provision is made for a microprocessor M to be connected
to each unit by connections 51-56. The microprocessor
can be programmed to command in the following manner.
First it supplies power to the thermostatic jacket so
that it reaches the required tçmperature, for example
300~C. Once this temperature is reached, the
microprocessor commands the activation of air pump PA.
Next, it brings product pump PP into action after having
checked the state of electronically operated valve EV.
In the event that product reservoir RP1 has reached its
minimum level, it commands electronically operated valve
EV to switch over to reservoir RP2. Activation of
product pump PP signifies the emission of a dose or a
determined series of doses. Once the activation of
product pump PP is terminated, the microprocessor
commands the activation of water pump PE which has the
effect of filling the pressurisation chamber 60 with
water (if required containing 1 ~ of H~O~). Once chamber
60 is full, the microprocessor commands the supply of
power to resistance 65. The temperature of the water in
the chamber increases, which brings about an increase in
pressure, given that the non-return valve 8 prevents the
backflow of watçr in pipe 43 and that the pressure
relief valve 7 is only set to open when a predetermined
CA 02211978 1997-07-30
26
pressure of about 5 bars is reached. A pressure of 5
bars is reached in the chamber at a temperature of about
130~C. The pressure relief valve then opens to allow the
release of a jet of superheated water vapour under
pressure. The combined action of the temperature and the
pressure permits rapid and total scouring of the hot
internal wall of the enclosure. It is however preferable
to switch off the supply of power to the thermostatic
jacket during the cleaning operation. Once the pressure
in the chamber falls to below 5 bars again, the pressure
relief valve closes and the non-return valve 8 opens to
allow water to again come into the chamber through the
action of pump PE. Hence the chamber is filled again for
the next cleaning operation.
If the time interval between each dose or series of
doses of product is small, then the activation of water
pump PE and cleaning means 6 can simply be commanded
after the final spraying of the product, for example at
the end of the evening before the device is shut down
for the night. Finally the microprocessor commands the
switching off of the power supply to the jacket 2.
These means 6 of cleaning the internal wall of the
enclosure under pressure can be used together with the
means for cleaning the mixer nczzle 3. The supply of
water to nozzle 3 through conduit 43 (fig. 1) allows
rinsing of the nozzle and a primary cleaning of the hot
internal wall and the means of cleaning under pressure 6
allow a real scouring of the hot internal wall to be
carried out.
