Note: Descriptions are shown in the official language in which they were submitted.
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THERMAL FUMIGATOR FOR DRUGS
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to a thermal fumigator for drugs
such as insecticides, fungicides, room aromatizes, and
deodorants.
DESCRIPTION OF PRIOR ART
Devices such as electric mosquito killers which
fumigate a room interior by heating a mat impregnated
with drugs such as insecticides, thereby releasing the drugs
in fume form from the mat, have been known to the art. Since
these devices utilize electricity as a heat source for heating
the mat, they inevitably suffer from complicated
construction. Besides, the use of electricity entails a
disadvantage that the devices require electric cables for
their power sources and, consequently, their uses are limited
to those places which are provided with electric powers.
Although the practice of keeping mosquito coils burning
outdoors for protection against insect bites has been popular,
unfortunately this practice is not necessarily safe
because-it inevitably requires continuous presence of fire
at the leading ends of such mosquito coils until the desired
protection becomes no longer necessary.
UP
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The liquefied gas fumigator designed to operate on
the principle of the pocket warmer has also been known in the
art. In this fumigator, the principle of the pocket warmer
(in which the fuel such as Bunsen is converted into
a heat-carrying vapor by combustion aided by a wad of asbestos
impregnated with a catalyst such as platinum or palladium)
is diverted without any alteration to fumigation of an insecticide.
Although this principle is completely satisfactory for the
purpose of retaining warmth, it is not fit for an insecticide
fumigator which must maintain accurate temperature
control.
This known method suffers from the disadvantage
that it fails to attain the object of retaining the temperature
at a constant level because:
(1) the platinum wad provides no homogeneous catalyst
action and
(2) the supply of oxygen is not uniform enough to
permit formation of a uniform mixture of the fuel with oxygen.
SUMMARY OF THE INVENTION
This invention originated in the determination
to eliminate the aforementioned drawbacks inherent in the
conventional thermal fumigators for drugs and preclude the
danger due to the use of fire. It provides a catalyst-heating
type thermal fumigator for drugs which utilizes as its heat
source the reaction heat caused when a volatile fuel
(such as alcohol) or a liquefied gas fuel (such as liquefied
petroleum gas or dim ethyl ether) is brought into contact with
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a catalyst of platinum or palladium in air. It
is simple in construction and finds no need for a cable for
power source connection and imposes no limitation on the
selection of places for service.
To be specific, the thermal fumigator for drugs (hereinafter
referred to as "thermal fumigator of the present invention is
characterized by comprising in a case a receptacle for a
volatile fuel or liquefied gas fuel, a metal catalyst disposed above
the aforementioned receptacle across a proper intervening space,
and a heat radiating plate disposed above the aforementioned
metal catalyst across said space and adapted to permit thermal
fumigation of a drug, It it further characterized by a passage
in the aforementioned case for supply of air and/or release
of combustion gas.
In another aspect, the thermal fumigator of this invention
is characterized by comprising in a case a container
for sealing a liquefied gas, a nozzle communicated via a valve
with the aforementioned container, a metal catalyst disposed
at a position where the gas spurted from the nozzle collides
with the metal catalyst, and a heat radiating plate disposed
near the aforementioned catalyst and adapted to permit thermal
fumigation of a drug. Also provided in the case is
a passage for supply of air and/or release of combustion gas
and a control means for regulating the opening and closing
of the aforementioned valve.
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I 9
The thermal fumigator of the present invention accomplishes
the heretofore unattainable uniform retention of effective
temperature by interposing a fixed space between the fuel container
and the metal catalyst to ensure thorough mixture of the fuel
gas with oxygen and further interposing a fixed space between
the metal catalyst and the heat radiating plate for fumigation
of the drug to produce efficient progress of the convectional
flow of the combustion gas.
In a preferred embodiment of this invention, the thermal fumigator
may be of a construction such that the space formed above the
fuel receptacle and the space formed above the metal catalyst
to embrace therein the heat radiating plate for thermal fumigation
of` the drug may be partitioned from each other with a thermally
insulating plate.
The thermal fumigator may be of a construction such that
a member for retaining the metal catalyst in position and the
heat radiating plate for thermal fumigation of the drug may
be interconnected to each other with a common metal member.
Further, the thermal fumigator may be of a construction
such that the fuel receptacle may be a container of the type
capable of keeping its content replenished or of the type
capable of keeping its content sealed therein so as to carry
thereon or receive and retain therein a volatile solid fuel,
a volatile liquid fuel, or a liquefied gas fuel.
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BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a plan view illustrating a typical thermal fumigator
of the present invention. Fig 2 is a cross section taken
along the line II-II of Fig. 1. Fig. 3 (A) and (B) are
each a perspective view of a typical heat radiating member
of this invention. Fig. 4 is a plan view of a thermal
fumigator of this invention. Fig. 5 is a cross section
taken along the line III-III of Fig. 4. Fig. 6 is an enlarged
view of a valve control means B in the thermal fumigator.
Fig. 7 is a plan view of another thermal fumigator of this
invention. Fig. 8 is a cross section taken along the line
IV-IV of Fig. 7. Fig. 9 is an enlarged view of an injection
valve mechanism A in the thermal fumigator of this invention.
Fig. 10 is a graph showing the results of Test 1.
DESCRIPTION OF A PREFERRED EMBODIMENT OF THIS INVENTION
One typical thermal fumigator of this invention is
illustrated in Fig. 1 and Fig. 2. In the figures, 1 denotes
a case body of the shape of a blind tube, with the interior
thereof divided into a fuel receptacle lb and a water reservoir
to with an internally formed cylindrical inner wall lay
A lateral wall (outer wall) id of the case body 1 extends
upwardly above the aforementioned inner wall lay On the
inner side at the upper extremity of the extended portion
of the outer wall id, a stepped part to is formed throughout
the entire circumference thereof to be fitted by a case
lid.
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I
By 2 is denoted a case lid which is a member comprising
a circular top plate 21 and a cylindrical lateral wall
27 and having a cross section substantially of the letter "U" shape.
The top plate 21 is provided substantially at the center
thereof with a rectangular opening Andy outside the edges
of the opening 22 with air vents 23. The opening 22 on
the upper side aye of the top plate has a rectangular shape
similar to and slightly larger than an insecticidal mat
3 which is set in position within the thermal fumigator,
On its lower side 22b it has a rectangular
shape similar to and slightly larger than the upper end
of a heat radiating member 4 serving to support thereon
the insecticidal mat 3. The inner wall defining the opening
22, relative to the direction in which the opening 22 is
bored in the case lid 2, is divided by a plane passing
near the middle of the thickness of the top plate 21 into
upper vertical wall 22c and lower downwardly inclined wall
22d. Owing to a gap A (see Fig. 1) to be formed between
the insecticidal mat 3 and the vertical wall 22c of the
opening 22 and a gap B (see Fig. 2) to be formed between
the heat radiating member 4 and the inclined wall 22d of
the opening 22, an air escape gap 24 serving as a free
air passage between the interior and the exterior of the
case lid 2 is secured intact even after the insecticidal
mat 3 has been set in position on the heat radiating member
4. Denoted by 25 are inward protuberances formed
on the wall of the opening 22. These protuberances are
SLY
intended for enabling the insecticidal ma-t
3 to be accurately set at the center of the opening 22
and far rectifying the flow of air through the air escape gap
24 between the insecticidal mat 3 and -the
wall of the opening 22. Denoted by 26 are depressions
in which the upper surface of the top plate
21 and smoothly inclined downwardly in the direction from
the periphery to the center of the top plate 21, They terminate
along the pair of major sides of the opening 22. These
depressions 26 are intended for the purpose of enhancing
the ease with which the insecticidal mat 3 is (a) inserted
into the opening 22 and mounted on the heat radiating member
4 or (b) removed from the thermal fumigator.
On the inner side of the portion at which the top plate
21 and the lateral wall 27 of the case lid 2 adjoin each
other, a shoulder part 28 is formed along the entire circumference
of the lateral wall 27. This shoulder 28 is intended for
the purpose of steadily holding a support member 6 serving
to support in position a catalyst 5 which will be fully
described below and the heat radiating member 4 for
receiving and retaining the catalyst therein. Denoted
by aye are holes for screws to be used for fastening the
support member. By aye is denoted a stepped part formed
along the entire periphery in the lower portion of -the
lateral wall 27. This stepped part aye is shaped
so as to be tightly fitted into a stepped part
to which is formed on the outer wall id of the case body 1.
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The case lid 2 is enabled to cover the upper side of the case
body 1 and complete a whole case by causing the stepped part aye
of the lateral wall to be snugly fitted into the stepped
part to of the outer wall of the case body 1. Matching
threads may be cut in advance on the lateral surfaces of
the case 2 and the inner wall of the case body so that
the case body 1 and -the case lid 2 will be helically joined
with each other.
The insecticidal mat 3 is a rectangular plate of compressed
fibers impregnated with an insecticidal active drug
solution. This rectangular shape is not critical to the
function to be fulfilled by the insecticidal mat 3. This
mat 3 may be in any shape so far as it can be inserted
into the opening 22 of the case lid 2.
The heat radiating member 4 is intended for the purpose
of supporting thereon the insecticidal mat 3 and applying
heat thereto and enabling the mat 3 to release the insecticidal
active drug in fumes. This heat radiating member 4 is made
of a heat radiating plate formed as joined with a catalyst
retaining part. An enlarged perspective view of this heat
radiating member is given in Fig- I.
The heat radiating member 4 comprises a horizontal
heat radiating plate 41 adapted to support thereon the
insecticidal mat 3 and apply heat thereto, lateral parts
42 extended from the opposite ends of the heat radiating
plate 41 downwardly and slightly inclined toward each other,
I
lower plates 43 extending from the lower ends of the aforementioned
lateral parts 42 toward each other parallel to the aforementioned
heat radiating plate 41, and a catalyst retaining part 44 formed
by a pair of catalyst retaining pieces 441 extended downwardly
from the opposed edges of the lower plates 43. The opposed
edges aye of each of the catalyst retaining pieces 441
are bent so as to protrude inwardly toward the center of
the heat radiating plate and the lower edge 441b thereof
is similarly bent so as to protrude inwardly toward the
center. A catalyst 5 is held in position by the inwardly
extended lateral edges aye and lower edges 441b. The
heat radiating member 4 is integrally formed with a metal
plate excelling in thermal conductivity.
Optionally, the lateral parts 42 may be provided with
air passage holes aye through which air will be supplied
to the catalyst and the combustion gas emanating from the
catalyst 5 will be discharged out of the heat radiating
member 4. The heat radiating plate 41 may be porous, so
that part of the combustion gas emanating from the monolithic
catalyst 5 will find outlet through the bores of the heat
radiating plate 41 to accelerate the oxidation reaction
of the fuel in the monolithic catalyst 5 and refrain from
interfering with the thermal convection of the combustion
gas. This provision of bores of the heat radiating plate
41 is not critical to the function of the heat radiating
member 4.
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Between the heat radiating plate 41 and the lower plates
43, there is embraced a space C having a height fixed by the lateral
parts 42. Owing to the space C thus formed, the catalyst 5
is prevented from coming into direct contact with the heat
radiating plate 41. The distance of the space C, namely the
interval separating the catalyst and the heat radiating plate
(the part for heating the drug) from each other (indicated
as C cm in Fig. 2) is desired to be at least 0.2 cm and more
desirably to fall in the range of 0.3 to 3.0 cm. If the catalyst
and the heat radiating plate are held in mutual contact or if
they are separated by too small an interval (C< 0.2 cm), the
desired convection of the combustion gas and the oxidation reaction
of the fuel are obstructed and the heat radiating plate fails
to apply ample heating. It is only when the catalyst and
the upper plate are separated from each other by an interval
of at least 0.2 cm that the heat radiating plate can be
most efficiently heated to a desired elevated temperature
by the convection of the combustion gas emanating from
the catalyst.
One modification of the heat radiating member is illustrated
in Fig. I. In substantially the same construction as the heat
radiating plate so far described, this modified heat radiating
Piper comprises heat radiating plate 41, lateral plates 42, lower parts
43, and four slender leg parts 442 extended downwardly
from the inner edges of the lower parts 42. Each of the
leg parts 442 comprises a slender lateral wall aye having
a cross section in the shape of the letter L and a horizontal
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:~2~279~
bottom part 442b extended inwardly from the lower end of the lateral
wall aye and adapted to support the catalyst in position.
Two such leg parts 442 are attached as opposed to each
other in the stated position of each of the aforementioned
lower parts 43. The total of four leg parts 442 collectively
constitutes a catalyst retaining part 44.
This modified heat radiating member has the advantage
that the conduction of heat from the catalyst 5 to the
heat radiating plate 41 is carried out without any obstacle
and the heat radiating member 4 itself enjoys reduction
in weight because the catalyst retaining part 44 is formed
of four slender leg parts 442.
The monolithic catalyst 5 is formed in an angular
shape fit for snug- insertion in the angular pillar part
44 ox the aforementioned heat radiating plate 4. It comprises
a ceramic carrier in a honeycomb structure and a catalytically
active metal such as platinum or palladium deposited on
the ceramic carrier. The catalyst 5 to be used in this
invention is not limited to this description as a matter
of course. It may be in the form an aggregate of beads
or a mass of wool) etch as occasion demands.
Denoted by 6 is a the~mal3v insulating plate ox support Myra serving to secure
the heat radiating member 4 and the catalyst 5 to the case
lid 2. It is a circular plate having a diameter such that
the periphery thereof can intimately abut the inner surface of the
lateral wall 27 of the lid 2. Ike thermally insulating plate or sort member
6 is provided near the center thereof with a hollow part
pa capable of receiving insertion of the angular pillar
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part 44 of the aforementioned heat radiating member q. The formally
insulating plate or support mar 6 is other provided at suitable positions
with holes 6b for insertion of setscrews 7 which are fastened
to the lid PA The holes 6b for the insertion of these
setscrews are bored as accurately aligned with the screw
holes aye which are formed in the shoulder 28 of the lid. Although
the ma tat of the they'll insulating plate or support mar 6 is not
specifically limited, it is either impervious to air or
slightly previous to air and is desired to resist heat
and prevent passage of heat. It is desirably formed of
glass fibers, for example.
By 8 is denoted a fuel container which is mounted
in the fuel receptacle-lb. It is open in the top side
and is adapted to be filled with a volatile fuel in the
interior thereon. The fuel container 8 filled with the
fuel is stowed in the fuel receptacle lb of the case body
1. Between the fuel container 8 and the catalyst 5, a
space D having a fixed height is retained.
The fuel to be used in the thermal fumigator illustrated
in Fig. 1 and Fig. 2 is required to possess volatility
and induce an exothermal reaction with the aforementioned
catalyst. Exemplary of fuels fulfilling this requirement
are alcohols. Methanol or ethanol is a preferred choice
among other alcohols Concrete forms in which such alcohols
are effectively usable herein are liquid alcohols, carboxyvinyl
polymer, copolymer of malefic android with isobutylene,
copolymers of vinyl alcohols with acrylic acid, alcohols
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golfed with starch derivatives, and solid fuel having alcohols
as main components.
In the thermal fumigator described above with referenced
to Fig. 1 and Fig. 2, the insecticidal mat 3 is inserted
into the opening 22 of the case lid 2 and set in position
on the heat radiating plate 41 of the heat radiating member
4. The alcohol fuel rising in fumes from the fuel container
8 fills up the space D and then ascends through the catalyst
5 disposed above the fuel container 8. During the passage
through the catalyst, the fuel alcohol is oxidized by the
catalyst of platinum or palladium. The resultant combustion
gas is discharged from the catalyst 5. The combustion
gas continues to rise, fills up the space C, finds its
way through the air vents aye, flows out through the gap
B and the gap A and passes into the ambient air. The heat
of the reaction generated by the oxidation of the alcohol
fuel at the catalyst 5 is transferred by the convection
flow of the combustion gas to the heat radiating plate
41 of the heat radiating member 4 situated above the catalyst
5 to cause an elevation of the temperature of the plate
41. Separately, the heat of the reaction originating in
the catalyst is transferred by conduction from the lower
parts 43 through the lateral plates 42 to the heat radiating
plate 41. Thus, the temperature of the heat radiating
plate 41 is uniformly elevated. As the plate 41 has its
temperature so elevated, the insecticidal mat 3 mounted
thereof is uniformly heated. Consequently, the insecticidal
active component contained in the insecticidal mat 3 is
diffused in fumes into the ambient air through the opening 22
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of the case lid 2. Meanwhile, tile air indispensable to the
oxidation reaction of the alcohol fuel in the catalyst
5 flows in through the air vents 23 formed on the top plate
21 of the case lid 2, passes through the air holes aye of the lateral
plates I and reaches the catalyst 5 as its designation.
Part of the air thus necessary for the oxidation reaction
in the catalyst 5 is separately supplied through the gaps
A and B to the catalyst 5. The water resulting from the
oxidation reaction of the fuel is collected and stored in the water
reservoir to of the case body 1. By providing a filament heater
(Nichrome wire, platinum wire etc.) or ceramic heater connected to
a battery near the catalyst 5 and heating the catalyst 5 for several
seconds to a desired temperature, starting of the oxidation reaction
of the fuel in the catalyst 5 may be promoted.
Now, the operation of the modified thermal fumigator
of this invention by the use of a liquefied gas as its
fuel will be described. This fumigator is characterized
by comprising in a case a container for sealing
a liquefied gas therein, a nozzle communicating with the
aforementioned container via a valve, a metal catalyst
disposed at a position at which the gas emanating from
the nozzle collides with the metal catalyst, and a heat
radiating part disposed near the catalyst and adapted to
provide heat for vaporization of the drug and by also having
provided in the aforementioned case a passage for supply
of air and/or release of combustion gas and a control means
for regulating the opening and closing of the aforementioned
valve.
In one aspect of this modification, the metal catalyst
may be disposed above the nozzle across a space of a certain
height and the heat radiating member for the thermal fumigation
of the drug may be disposed above the metal catalyst across
a space of a certain height.
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Fig. 4 is a plan view illustrating a typical thermal
fumigator conforming to the modification described above
and Fig. 5 is a cross section taken along the line III-III
of Fig. 4. In Fig. 4 and Fig. 5, 1 denotes a blind tubular
case body enclosing therein a container wish is provided
with an injection valve mechanism for sealing a liquefied
gas in the container, The container 8' is partitioned off from
the rest of the case body 1 in the middle part of the case body 1.
The case body 1 is further provided with air vents 23'.
Denoted by 2 is a case lid. In the present embodiment,
this case lid 2 is a member having a cross section substantially
of the shape of letter "U'!, comprising a circular top plate
21 and a tubular lateral wall 27. The opening 22 on the
front side aye of the top plate has a rectangular shape
similar to and slightly larger than the insecticidal mat
3 set in position within the thermal fumigator and also
similar to the upper side of the heat radiating member
4 serving to support thereon the insecticidal mat 3. The
wall defining the opening 22, relative to the direction
in which the opening 22 is bored in the top plate comprises
vertical surface 22c parallel to the direction of the thickness
of the top plate 21. Denoted by 25 are protuberances formed
on the vertical wall 22c of the opening as raised inwardly
into the interior of the opening 22. These protuberances
are intended for the purpose of allowing the insecticidal
mat 3 to be accurately set in position at the center of
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the opening 22 and preventing it from randomly falling
out of position. By 26 are denoted depressions in
the surface of the top plate 21 smoothly inclined
downwardly in the direction from the periphery to the center
of the top plate and terminated along the pair of major
sides of the opening 22. These depressions 26 are intended
for the purpose of enhancing the ease with which the insecticidal
mat 3 is inserted into the opening 22 and mounted on the
heat radiating member 4 or removed from the thermal
fumigator.
The tubular lateral wall 27 is provided with air vents
23 which permit free flow of air and release of combustion gas.
The case lid 2 is hinged to the case body 1 by means
of a fulcrum 51 formed on the lateral wall id of the case
body at the lowermost part of the lateral wall 27 of the case
lid and can be opened and closed freely relative to the
case body 1.
On the rear side of the portion at which the top plate
21 and the lateral wall 27 of the case lid 2 join each
other, a shoulder part 28 is formed along the entire periphery
of the lateral wall 27. This shoulder part 28 is intended
four the purpose of fastening in position the catalyst 5
("which will be described more fully below) and the heat radiating
member 4 receiving and retaining therein the catalyst 5.
By aye are denoted holes for insertion of screws serving
to fasten the heat radiating member 4.
Denoted by 3 is an insecticidal mat which is a rectangular
plate of compressed fibers impregnated with an insecticidal
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active component solution. This rectangular shape is not
critical to the function to be fulfilled by the insecticidal
mat, This mat 3 may be in any desired shape insofar as
it can be inserted into the opening 22 of the case lid
2.
Denoted by 4 is a heat radiating member whose function
is to support thereon the insecticidal mat 3 and apply heat
thereto in order that the mat 3 may release the insecticidal
component in fumes. The heat radiating member 4 comprises
a heat radiating plate 41 adapted to support thereon the insecticidal
mat 3 and apply heat thereto, a lateral tubular part 42 extended
downwardly from substantially the center of the heat radiating
plate 41, and a tubular member 44 extended further downwardly
from the lateral tubular member and adapted to retain the
catalyst therein. All the component members of the heat radiating
member 4 are made of a metal material. The lateral tubular
member 42 is provided with air passage holes aye through which
the combustion gas emanating from the catalyst can be released
into the ambient air. The heat radiating plate 41 may be
porous. The bores of the heat radiating plate 41
will permit escape of part of the combustion gas being issued
from the monolithic catalyst 5. They advantageously serve
as means for promoting the oxidation reaction of the fuel
in the monolithic catalyst 5 and enabling the convection of
the combustion gas to proceed without any obstacle. The provision
of these bores is not critical to the function of the heat
radiating plate. The tubular member 44 is provided at the lower
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end thereof with a flange aye protruding inwardly into the
interior of the tubular member 44, so that when the monolithic
catalyst 5 is stowed in this tubular member 44, it may be
safely retained on the flange aye. Between the heat radiating
member 4 and the catalyst 5, there is formed a space C having
a fixed height. This space C serves to keep the monolithic
catalyst 5 separated from the heat radiating plate 41 supporting
the insecticidal mat 3 thereon.
The monolithic catalyst 5 is in a tubular shape fit for
insertion in the tubular member 44 of the aforementioned heat
radiating member 4. It comprises a ceramic carrier of honeycomb
structure and a catalytically active metal such as platinum
or palladium deposited on the ceramic carrier. The catalyst
5 to be used in this invention is not limited to this particular
shape. It may be in the form of an aggregate of beads or
in a mass ox wad, for example.
It is advantageous to isolate the space above the nozzle
from the space above the metal catalyst with a thermally insulating
plate to separate the holes for feed air and the holes for
release of the combustion gas and concurrently use this thermally
insulating plate as a catalyst retaining member.
Denoted by 8' is a container for sealing in a liquefied
gas. The container is provided with a nozzle 65 which is
communicated with the interior of the container via a valve (Fig.
6). This container 8' is filled with a liquefied gas which
serves as the fuel.
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As the fuel, any liquefied gas may be used insofar as
the gas is capable of causing an oxidation reaction with the
aid of the aforementioned catalyst 5. Concrete examples of
the liquefied gas satisfying this requirement are liquefied
petroleum gas (LUG), dim ethyl ether, hexane, Bunsen, and
gases usable for cigarette lighters. The container 8' is
provided thereon with valve control means F capable of regulating
the opening and closing of the valve x serving to adjust the
release of the liquefied gas. This control means B is interlocked
with a switch 61 which is provided in the case body so as
to control the supply of the liquefied gas to the
medium of the catalyst 5 to consequently uniforms the temperature
of the heat radiating member 4.
In the thermal fumigator constructed as described above t
the insecticidal mat 3 is inserted into the opening 22 of
the case lid 2 and then set in position on the heat radiating
plate 41 of the heat radiating member 4. The liquefied gas
fuel issued from the container 8 and passed through the nozzle
and the air admitted through the air vents 23, 23' jointly
pass through the catalyst 5 disposed above the container 8'.
In the catalyst 5, the liquefied gas fuel is oxidized through
the catalysts of platinum or palladium and the resultant combustion
gas is released from the catalyst 5. This combustion gas
further rises to fill up the space C, passes through the air
holes aye formed in the lateral tubular member 42 of the heat
radiating member 4, and passes into the ambient air through
the air vents 23. The heat of the reaction generated in
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12279~9
consequence of the oxidation of the liquefied gas fuel in
the catalyst 5 is transferred by convection to -the heat radiating
plate 41 of the heat radiating member 4 disposed above the
catalyst to cause an elevation in the -temperature of the heat
radiating plate 41. The heat of the reaction produced inside
the catalyst 5 is also transferred by conduction through the
lateral tubular member 42 of the heat radiating member 4 made
of a metallic material to the heat radiating plate 41. Consequently,
the temperature of the heat radiating plate 41 is uniformized.
As the temperature of the heat radiating plate 41 is thus
elevated, the insecticidal mat 3 mounted on the heat radiating
plate 41 is uniformly heated enough for -the insecticidal
active component contained in the insecticidal mat 3 to be
dispersed in fumes into the ambient air through the opening
22 of the case lid 2. Meanwhile, the air necessary for
the oxidation reaction of the liquefied gas fuel in the catalyst
is admitted through the air vents 23 formed in the top plate
21 of the case lid 2 and the air holes 23' in the case body
and supplied to the catalyst 5.
Now, the operation of the valve control means during
the actual service of the -thermal fumigator of the alone-
mentioned construction will be described.
Fig. 6 is an enlarged view of the valve control means
B for use in the thermal fumigator of this invention.
First a stopper 70 is released and then
a switch 61 is pushed up to the valve opening position (for
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release of the gas). Consequently, a swinging plate 62 is
actuated to raise a support metal 63 and the support metal 63
thus raised compresses a spring 64. The upwardly energizing
force thus exerted by the spring pushes up a movable valve body
66 which is provided with a nozzle 65.
The upward motion of the movable valve body 66 causes
separation of a valve member 67 from a stationary valve seat 68
and consequently opens the valve x which is composed of the
valve member 67 and the stationary valve seat 68. This opening
of the valve x enables the liquefied gas to be passed through
a guide hole 69 formed in the movable valve body and then
released through the nozzle 65.
At this time, the case lid 2 is opened to expose the nozzle 65
and the liquefied gas issuing from the nozzle 65 is ignited with a match
or a lighter. Then the case lid 2 is replaced tightly on the case body
1 and the combustion of the liquefied gas is continued for several
seconds up to 10-odd seconds until the temperature of the catalyst 5 is
elevated to a prescribed level. Further the healing the catalyst 5 to
a desired temperature may be done by an electric heater means consisting
of for example a filament heater (Nichrome wire, platinum wire etc.) or
ceramic heater connected to a battery.
At this stage, the stopper 70 is pushed to be released of
confinement and the switch 61 is pushed up further.
A pushup plate 71 projected from the switch 61 cons-
quaintly rotates a rotary plate 72 in the direction of the arrow
mark and imparts a downward motion to the leading end of a
pushdown device 73 integrally fastened to the rotary plate 72.
The nozzle 65 which is engaged with the leading end of the
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pushdown device 73 is moved downwardly to bring the valve
member 68 into fast contact with the stationary valve seat 68,
thus closing the valve x.
By this closure of the valve I the release of the pique-
fled gas through the nozzle 65 is discontinued and the flame
of the liquefied gas is extinguished. After this, the switch
61 is moved downwardly and the stopper 70 is locked at the
valve opening position. By this locking of the stopper at its
valve opening position, the valve x is opened again and the
release of the gas through the nozzle 65 is maintained con-
tenuously.
Since the catalyst 5 is now retained in its prescribed
-heated condition, the liquefied gas released through the
nozzle 65 is caused to undergo the reaction rapidly and the
catalyst 5 is kept heated.
ow to prevent the catalyst 5 from possible overheating,
a bimetal 75 is actuated to control the flow volume of the
liquefied gas through the valve x. To be specific, if the
movable valve body 66 is left standing in its resilient stat,
it is kept energized upwardly in the position indicated in the
figure. Thus, the bimetal 75 is constructed so that the free
end thereof may press down the nozzle 65 against the energizing
force. The amount of the depression of the nozzle 65, namely
the amount of the displacement of the movable valve body 65,
depends on the temperature of the catalyst 5 through this
bimetal. Consequently, the valve body 67 and the stationary
- 22 -
2~79~S~
valve seat 68 are caused by the depressing force of the bimetal
75 to Mary the extent of the closing of the valve.
As the result, the amount of the liquefied gas to be
released through the nozzle 65 is automatically controlled by
the temperature of the catalyst 5, with the natural consequence
that the reaction temperature in the catalyst 5 is retained
at a fixed level. Then the heat of the reaction generated in
the catalyst 5 in effect maintains the temperature of the teat
radiating plate 41 of the heat radiating member 4 at a uniform level
as described above and the insecticidal mat 3 mounted on the heat
radiating plate 41 is uniformly heated in order for the insecticidal
active component to be released in fumes from the mat 3.
Termination of the use of the thermal fumigator
of this invention is accomplished by releasing the stopper of
its confinement and subsequently moving the switch 61 downwardly
to the valve closing position. This downward motion of the
switch 61 causes the swinging plate 62 to be rotated counter-
clockwise and, consequently, the support metal 63 engaged in
the swinging plate 62 is moved downwardly. By this downward
motion of the support metal, the energizing force of the spring
64 exerted in the direction of lifting the nozzle 65 is weakened.
Consequently, the nozzle 65 is allowed to move downwardly and
the valve member 65 is brought down to settle on the stationary
valve seat 68. Thus, the valve x is closed.
The thermal fumigator of this invention modified
to operate with the liquefied gas as its fuel is not limited
~'7!~9
to the construction illustrated in Fig. 4 and Fig. 5. When
desired, a tubular heat radiating part may be disposed along
the lateral side of the catalyst 5 and a doughnut-shaped
insecticidal mat 3 may be inserted in the heat radiating member.
An typical thermal fumigator incorporating such a
tubular heat radiating member and consequently using a doughnut-
shaped insecticidal mat is illustrated in jig. 7 and Fig. 8.
Fig. 7 is a plan view illustrating another modification
of the thermal fumigator using a liquefied gas fuel
and Fig. 8 is a cross section taken along the line IV-IV of
the Fig. 8.
In Fig. 8, a case body 1 has a container pharaoh sealing
in a liquefied gas. The container 8~c~mmunicates with a nozzle
659 with valve control means F disposed there between. These
parts of the fumigator are identical with the counterparts used
in the embodiment illustrated in F1go 5 and Fig. 6.
Denoted by 100 is a tubular case body, which comprises
a circular top plate 101 incorporating therein a circular
opening 103 and a tubular lateral wall 102. The circular
opening 103 constitutes a tube in csn~unction with an inner
tubular lateral wall 104 which forms part of the tubular case
body 100. The tubular lateral wall 102 is Joined via its lower
end to a perforated lateral wall 105. Inside the lateral wall
105, a metal gauze 106 is disposed. Thus, the air is admitted
freely into the interior of the tubular case body and the
drug released in fumes from the insecticidal mat is
_ I -
I
discharged freely out of the tubular case body through the
lateral fall 105.
The metal catalyst 5 is attached to the inner tubular
lateral wall 104 integrally with a heat radiating tube 107.
Around the heat radiating tube 107, a metal member 108 is
formed, which is further encircled with an insecticidal Nat
holder 109.
For use in the thermal fumigator constructed as
described above, the insecticidal mat 3 is wormed in the shape
of a doughnut so as to be inserted around the holder 109.
Preparatory to the actual use of this fumigator, therefore,
the tubular case body is opened by moans of a hinge of the
fulcrum 51 in order that the insecticidal mat 3 may be inserted
around the holder 109.
The liquefied gas released through the nozzle 65 undergoes
an oxidation reaction in the catalyst 5 which is heated by
the heat of the reaction, with the result that the heat radiating
tube 107 is simultaneously heated. This heat is transferred
by conduction through the metal member 108 to the holder 109
spent in uniformly heating the insecticidal mat 3 wrapped around
the holder 109. By this heating, the insecticidal active
component contained in the mat 3 is liberated in fumes and
dispersed from the interior of the tubular case body 100 into
the ambient air through the metal gauze 106 and the porous
lateral wall 105. The combustion gas which results from the
reaction Or the liquefied gas fuel in the catalyst 5 is disk
charged outwardly through the circular opening.
... ..
. ,.~
- 25 -
~227~
Also in this fumigator, to ensure uniformization Or the
floating temperature, the valve for the release of the liquefied
gas fuel is controlled with the bimetal 75. The control thus
effected is similar to that already described with reference
to Fig. 2 and Fig. 3.
On the fumigator constructed as described above, the
metal member 108 may be formed in the shape of a pillar having
a semicircular cross section and the insecticidal mat holder
may be formed in the shape of a flat plate so that an insect-
tidal mat formed in the shape of a flat plate will be inserted
in position.
In the embodiments so far described, the container 8 for
sealing in a liquefied gas are invariably built in the resee-
live case bodies 1 and are provided with an injection valve
mechanism E (Fig. 5) capable of freely introducing the liquefied gas
into the container 8.
An enlarged view of the injection valve mechanism E is
illustrated in Fig. 9.
This inaction valve mechanism E is similar in operating
principle to the injection valve mechanismsusuallyfound in
gas lighters. To be specific, a movable member 81 is closed
with a seal 82 through the agency of the energizing force
exerted by a spring 83. During the injection of the liquefied
was, the movable member 81 is moved upwardly relative to
figure 9) inconsequently the seal 82 is also moved upwardly
to give rise to an injection hole (open valve). Thus, the
- I -
12279~9
liquefied gas is injected through the open valve into the
container.
The container 8 for sealing in the liquefied gas is not
limited to that which is built in the case body 1.
Optionally, a cartridge type liquefied gas container resembling
a gas cylinder may be formed separately of the case body 1 and
used independently of the case body 1.
The insecticide which can be used by the thermal
fumigator of this invention may be any of the various insect-
tidal agents heretofore adopted for use with. for instance, electric
mosquito killers. Typical examples of such insecticides include
pyrethroidal insecticides such as 3-allyl-2-methylcyclopenta-
2-en-4-one-1-yl dl-cis/trans-chrysanthemate (allethrin), allele-
2-methylcyclopenta-2-en-4-one-1-yl d-cis/trans-chrysanthemate,
d-3-allyl-2-methylcyclopentan-2--en-4-one-1-yl d-trans-
chrysanthemate, 5-propargyl-2-furylmethyl d-cis/trans-
chrysanthemate, l-ethynyl-2-methylpenta-2-en-1-yl d-cis/trans-
chrysanthemate, and l-ethynyl-2-methylpenta-2-en-1-yl 2,2,3,3-
tetramethyl cyclopropane carboxylate. Further, piperonyl
but oxide, N-(2-ethylhexyl)-1-isopropyl-4 methylbicyclo-[2,2,2]-
octo-5-en-2,3-dicarboxy imide, and octachlorodipropyl ether
are typical examples of the pyrethroidal Advent which can
be used in combination with the aforementioned insecticidal
agent. These insecticidal components are incorporated
by impregnation in a mat of compressed fibers. The mat may
further incorporate therein, besides the insecticidal components
~!l2279~9
mentioned above, an antioxidant such as BUT, BRA, or DBH
capable of serving as stabilizers for insecticidal component,
distaffs which, on exposure to heat, discolor and thereby
indicate whether the mat has already been use or not, and perfumes.
In the thermal fumigator of the present invention,
an aluminum container filled with a solid chemical capable of
being vaporized in fumes fit for the fumigation aimed at by
the present invention may be used in the place of the mat
impregnated with the insecticidal active component solution.
When necessary, the insecticide may be substituted
with a fungicidal agent, a room aromatize, or a disinfectant.
Any of the various fungicidal agents which possess the vote-
utility of alcohols or dioxides can be used for this purpose.
The thermal fumigator of the present invention
is not limited to the constructions illustrated in Fig. 1
through Fig. 8. For example, the air vents are indispensable
to the supply of air necessary for the catalytic oxidation
reaction of the fuel and to the release of the combustion gas
resulting from the oxidation reaction from the interior of the
case body to the ambient air. When necessary, they may be
formed in the lateral wall of the case lid or in the outer
wall of the case body other than the positions illustrated in
such figures. When the air holes for the supply of air
are formed in the outer wall of the case body, they are required
to be formed in the lowest possible portion of the outer wall
of the case body or in the bottom of the case body lest the
- 28 -
9~9
volatilized fuel should lead through the air holes. Optionally,
one air hole may be used simultaneously for the supply of air
and for the release of the combustion gas. In this case, the
gap formed between the insecticidal mat and the opening may be
utilized as the air hole and no other air hole is required.
The shape of the heat radiating plate is not limited to
any of the shapes illustrated in the figures. Also the shape
of the catalyst is not limited to any of the shapes illustrated
in the figures. or example, for the purpose of protecting
the catalyst against adhesion of the chemical released from
the mat, it is advantageous to eliminate the gap formed around
the heat radiating plate for release of air and dispose an
opening for air discharge at a level far below the heat radiating
plate.
It is permissible to stow the catalyst in a receptacle
member formed separately of the aforementioned flat shape of
heat radiating plate and set in position as pierced through
the supporting member. In this case, the receptacle member
may comprise vertically opposed retaining pieces adapted to
nip the catalyst there between. The lateral member may be
omitted when the catalyst receptacle member is formed separately
of the heat radiating plate as described above. It is never the-
less necessary that the space C of a fixed height should be
interposed between the heat radiating plate and the catalyst.
The height of this space C, namely the interval separating the
catalyst and the heat radiating plate from each other (indicated
- 29 -
~l2Z7~
as C cm in Fig. 2) is required to be at least 0.2 cm and is
preferred to fall in the range of from 0.3 to 3.0 cm. If the
catalyst and the heat radiating plate are held in intimate
contact (C = O cm) or they are separated by too small a distance
(C ~0.2 cm), amply heating of the heat radiating plate is not
obtained because the convection of the combustion gas and the
oxidation reaction are prevented from proceeding smoothly in
this interval. It is only when the catalyst and the heat
radiating plate are separated from each other by a distance
of at least 0.2 cm that the heat radiating plate can be most
efficiently heated to the elevated temperature by the convect
lion of the heat of the combustion gas emanating from the
catalyst.
The shape of the catalyst is not limited to any of the
shapes illustrated in the figures. The catalyst may be a
monolithic catalyst of the shape of a cylinder.
The container filled with the fuel functions effectively in
the thermal fumigator of the present invention so far
as it has an opening in the upper end thereof and the fuel
contained therein is efficiently vaporized by the fumigator.
To prohibit return of the water formed during the oxidation
reaction to the fuel container, there may be provided inside
the fumigator a water receptacle of the shape of a funnel.
Otherwise the part of the fuel container above the neck
thereof may be flared upwardly to give rise to a water Rosetta-
ale of the shape of a funnel.
- 30 -
~227~
When a fuel in a golfed form or a solid fuel is adopted,
the practice of using the fuel as wrapped in a coarse cloth
such as gauze or non-woven fabric a foamed or porous ceramic
or plastic material, or other material which offers no obstruct
lion to the vaporization of the drug proves advantageous
for the purpose of preventing the fuel from leaking out of
the container or adjusting the amount of the fuel Jo be
vaporized.
The height of the space D, namely the distance, d,
separating the fuel and the catalyst from each other is desired
to be at least 0.3 cm and preferred to fall in the range of
from 0.5 to 10.0 cm. If the fuel and the catalyst are held
in intimate contact with each other (d = O cm) or if they are
separated from each other by too small a distance (d< 0.3 cm),
there ensues the disadvantage that the volatilized fuel does
not efficiently flow into the catalyst and the fuel is wasted.
It is only when the fuel and the catalyst are separated from
each other by a distance of at least 0.3 cm that the volatilized
fuel is allowed to pass the catalyst smoothly and the oxidation
reaction is generated advantageously.
When a volatile solid fuel or volatile liquid fuel is
adopted a fuel receptacle for receiving and retaining the fuel
may be constructed so as to serve as a container capable of
being replenished with new supply and it may be used in the
place of a container specifically designed for the purpose
of containing the fuel.
~2~7~
Now, the thermal fumigator of this invention will
be described specifically below with reference to working
examples.
Example 1:
5 g of 5-propargyl-2-furylmethyl-~-cis/trans-
chrysanthemate, 15 g of N-(2-ethylhexyl)-1-isopropyl-4-methyl-
bicycle [2,2,23 oct-5-en-2,3-dicarboxy imide, 1.5 g ox DBH,
and 0.2 g of 1,4-diisopropyl aminoanthraquinone were diluted to a
total volume of 100 ml with acetone. A plate of compressed fibers 35
x 22 x 2.8 mm was impregnated with 1 ml of the resultant soul-
lion. The wet plate was dried in draft to produce an insecticidal
mat. This insecticidal mat was used as mounted on the heat
radiating plate of the thermal fumigator illustrated
in Fig. 1 and Fig. 2.
Example 2:
6g of 3-allyl-2-methylcyclopenta-2-en-4-on-1-yl d-cis/trans-
chrysanthemate, 4 g of piperonyl but oxide, 2 g of BUT, and 0.3
g of 1,4-dimethyl aminoanthraquinone were dissolved to a total
volume of 100 ml with acetone. The same plate of
compressed fibers as used in Example 1 was impregnated with
1 ml of the resultant solution and similarly treated to produce
an insecticidal mat. This mat was used as mounted on the heat
radiating plate of the thermal fumigator illustrated
in Fig. 1 and Fig. 2.
Example 3:
A solution was prepared by mixing 10 g of ethanol-
- 32 -
79~9
methylpenta-2-en-1-yl d-cis/trans-chrysanthemate, 8 g of No
ethylhexyl)-l-isopropyl-4-methylbicyclo [2,2,2] octane-
dicarboxy imide, 1 g of DBH, owe g of perfume, 0.2 g of 1,4-
diisopropyl aminoan~hraquinone, and 10 g of odorless kerosene
and heating the resultant mixture to facilitate dissolution
of solids. The same plate of compressed fibers as used in
Example 1 was impregnated with 0.3 g of the solution and
similarly treated to produce an insecticidal mat. This mat
was used as mounted on the heat radiating plate of the
thermal fumigator illustrated in Fig. 1 and Fig. 2. This
fumigator was tried on culices and was found to manifest the
same effect as that of any commercially available mosquito
coil for more than ten hours.
example 4:
A ceramic plate 30 x 20 x 3 mm was impregnated with 2 ml
of ethanol solution of 1 g of dioxin. The wet ceramic plate
was used as mounted on the heat radiating plate of the thermal
fumigator illustrated in Fig. 1 and Fig. 2 to fumigate
the interior of a room. The numbers of germs in the room
before and after the fumigation were compared by the putter
dish method using an ajar culture medium. Thy fumigation
was found to have decreased the number of germs in the room
to less than 1%.
Example 5:
A gel was prepared by dissolving 1 g of carboxyvinyl
polymer (a product marketed under trademark designation of
- 33 -
Hobbs Waco 1~4~ in 47 g of an ethanol solution containing 5 g
of perfume and subsequently adding 2 g of an aqueous 2% in-
ethanol amine solution to the resultant solution. An aluminum
container was filled with 20 g of the gel, mounted on the heat
radiating plate of the thermal fumigator illustrated
in Fig. l and Fig. 2, and used as a room aromatize.
Example 6:
The same plate of compressed fibers as used in Example l
was impregnated with l ml of an alcohol solution of 0.5 g of
alcohol extract of the deodorant principle present in live leaves
of a Camellia plant of the family Thus. It juicy mounted
on the heat radiating plate of the thermal fumigator
illustrated in Fig. l and Fig. 2 and used in a water closet
to test for deodorizing effect. The fumigation resulted in
thorough elimination of the offensive odor of the water closet.
Now, the present invention will be described below with
reference to tests.
Test 1:
The thermal fumigator illustrated in Fig. 1 and
Fig. 2 was tested for time-course insecticidal effect on
culices, with the insecticidal mats obtained in Example 1 and
Example 2 each mounted on the heat radiating plate and 25 g
of a gel prepared from 90 parts of methanol, 8 parts of ethanol,
and 2 parts of a benzylidene derivative of D-sorbit (marketed
under trademark designation of Jollily D) placed in the fuel
container. The results were as shown in Fig. lo The term
- 34 -
~.~27~
"relative effect" used in the figure means the change of
effect of the fumigant as determined at intervals of one hour
and expressed relatively based on the effect determined on
elapse of the first hour taken as 1Ø It is clearly noted
from Fig. 10 that the insecticidal mats of Example 1 and
Example 2 showed high insecticidal effects.
Test 2:
In the thermal fumigator illustrated in Fig. 1
and Fig. 2, the temperature of the heat radiating member 4 was
measured while the distance (c cm) between the catalyst 5 and
the heat radiating plate 41 and the distance (d cm) between the
catalyst 5 and the fuel container 8 filled with the fuel to
the upper end of the opening thereof were varied from one test
run to another and the gas passage kept opened in some test
runs and closed in the other test runs. The results were as
shown in Table 1. In this test, a solid fuel prepared by
thermally dissolving 6 parts ox Starkey acid in 86 parts of
methanol and adding to the resultant solution 8 parts of an
aqueous 12.5% sodium hydroxide solution (water : methanol =
1 : 8) was used as the fuel for the fumigator. The tempera-
lure of the room in which the test was conducted was kept at
25C i 1C.
- 35 -
I
Table 1
Run Distance Distance Use of gas Average temperature of
No. (c cm) (d cm) assay heat radiating Lotte (C)
_ _ Jo
1 0.3 0 Yes 57
2 0.3 0.2 Yes 67
3. 0.3 0.3 Yes 120
4 0.3 0.7 Yes 140
5 0.3 1.0 Yes 140
6 0.3 3.0 Yes 143
7 0.3 5.0 Yes 125
8 0.3 7.0 Yes 100
9 0.3 10.0 Yes 86
10 0.3 12.0 Yes 64
11 0 1.0 Yes 63
12 0.1 1.0 Yes 72
13 0.2 1.0 Yes 119
14 0.5 1.0 Yes 134
15 1.0 1.0 Yes 113
16 3.0 1.0 Yes 91
17 4.0 1.0 Yes Jo
lo 0.3 lo No 54
* The "average temperature" means the average of the
temperatures measured hourly between the elapse of the
first hour and that of a total of ten hours.
The results of Table 1 indicate the following facts.
Comparison of the data of Run No. 1 and those of Run Nos. 2-10
reveals that interposition of a distance between the fuel
container (fuel 8 and the catalyst 5 is necessary and that
the temperature of the heat radiating member 4 can be controlled
- 36 -
~l.22~
by this distance. Interposition of a distance between the
catalyst 5 and the heat radiating plate 41 is also found to be
necessary from the comparison of the data ox Run No. 5 and Run
No. 11. It is shown by comparison of the data of Run No. 5
and those of Run Nos. 11-17 that the size of this distance
(c cm) affects the temperature of the heat radiating plate
41. This means thaw proper combination of the distances, c cm
and d cm, permits selection of the temperature of the heat
radiating plate depending on the kind of drug and the
purpose of fumigation. Comparison of the data of Run No. 4
and those of Run No. 18 reveals that the presence of the gas
passage is indispensable for the function of the fumigator.
A separate test conducted with respect to the size and number
of gas passages formed in the fumigator yielded results which
indicate that absolute absence of an elevation in the tempera-
lure of the heat radiating plate cannot occur in the presence
of a gas passage and that the temperature of the heat radiating
plate is fixed when the size of the gas passage is fixed.
The data also indicate that the gas passage should not nieces-
sanity be formed in the top plate 21 of the case lid 2 and
that the effect of the provision of the gas passage is the
same when the gas passage is formed in the lateral wall 27 of
the case lid 2 and when it is formed in the outer wall id of
the case body 1.
The data also indicates that the size of the opening in
the upper side of the fuel container is variable with the kind
- 37 -
-~lZ27~
of the fuel actually used and the distance between the
fuel container and the catalyst but that the temperature of
the heat radiating plate is stable when all these conditions
are fixed.
From the results of the test described above, it is noted
that for the heat radiating plate in the thermal
fumigator of this invention to be efficiently heated with a
given heat source, it is imperative to interpose a fixed
distance between the fuel container and the catalyst and a
fixed distance between the catalyst and the heat radiating
plate and further to provide the fumigator with a gas passage
and that the other conditions of the fumigator may be suitably
varied depending on the object of fumigation, the kinds of
drug and fuel, etc.
Test 3:
In the thermal fumigator of Fig. 1 and Fig. 2
and that of Fig. 4 and Fig. 5, the temperatures of the respect
live heat radiating plates were measured while the kind of
volatile fuel used was varied from one run to another. The
temperature of the room in which the test was conducted was
kept at 25C 1C.
- 38 -
7''3~
. Average temperature
Run Volatile fuel of heat radiating
o. slate* (C)
. _
1 Methanol 141
2 Solid fuel made of methanol 145
3 Solid fuel made of methanol and 139
4 Hexane 136
5 Bunsen 140
6 Liquefied petroleum gas 144
7 Dim ethyl ether 140
8 Gas for cigarette lighter 137
The "average temperature" means the average of the
temperatures measured hourly between the elapse of the
first hour and that of a total of ten hours.
From the results of Test 3 described above, it is noted
that in the thermal fumigator of this invention, the
heat radiating plate obtains its expected temperature insofar
as the fuel used therein possesses volatility at normal room
temperature and that the variation in the kind of the volatile
fuel has no significant difference in this respect.
In Run Nos. 4-8, brief application of heat to the catalyst
at the time that the fumigator was put to use served to heighten
the speed of heat generation.
As is clear from the foregoing description the thermal
fumigator of the present invention accomplishes desired
thermal vaporization of a given drug by placing in the
fumigator case a volatile fuel or liquefied gas fuel, disposing
a catalyst above the fuel across a fixed space, enabling the
- 39 -
12;~ 9
fuel to undergo an oxidation reaction in the catalyst, allowing
the heat of this oxidation reaction to be transferred to a heat
radiating plate disposed above the catalyst across a fixed
space, and inducing an elevation in the temperature of the heat
radiating plate and thereby causing the heat radiating plate
to heat the drug deposited thereon. Compared with the
conventional drug fumigator which utilizes electricity as
the source of heat or the vaporization of a drug, the
thermal fumigator of this invention has an advantage
that it is simple in construction and is not limited by the
place of service. Since the heat radiating plate is uniformly
heated by oxidation of the fuel in the presence
of the catalyst and, consequently, the drug is vaporized
uniformly the drug incorporated by impregnation in a mat
of compressed fibers can be evenly vaporized out of the mat.
This fumigator has a salient merit that it provides the uniform
retention of available temperature heretofore considered hardly
attainable with the conventional fumigator.
Particularly the thermal fumigator of this
invention permits use of a liquefied gas as a fuel capable of
generating an oxidation reaction in the presence of a metal
catalyst and, accordingly, proves highly convenient in that
it enables the liquefied gas to be freely replenished and allows
the release of the fuel to be freely regulated. Thus, it enjoys
high portability.
- I -
