CA1227919A

CA1227919A - Thermal fumigator for drugs

Info

Publication number: CA1227919A
Application number: CA000440627A
Authority: CA
Inventors: Yoshio Katsuda; Sadao Yoshinaga; Hiroyoshi Mashine
Original assignee: Dainihon Jochugiku Co Ltd
Current assignee: Dainihon Jochugiku Co Ltd
Priority date: 1982-11-08
Filing date: 1983-11-08
Publication date: 1987-10-13
Also published as: IT1197739B; KR900007933B1; PH22758A; KR840006596A; IT8349281A0; GR78739B

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to a thermal fumigator which heats the compressed mat, impregnated with a drug, with the use of reaction heat generated by contact of a volatile fuel or liquefied gas fuel with a metal catalyst in the presence of air, thereby fumigating the drug.

Description

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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

Zig 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 ~Z;~9~

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.

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.

~2~7'33~9 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.

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.

79~9 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.

~75?~9 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 :~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 ,",,~ / I
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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 ~2Z~ 9 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 ~ZZ7~9 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 , ,, ~79~

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 ~lZZ7~9 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 ~llZ~7~

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.

79~5~

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 ' 1 1 9 , 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 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 ~Z;27~

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 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.

... ..

. ,.~

~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 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 ~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.

~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-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 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 ~.~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.

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 ~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 -~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.

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 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 -

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A thermal fumigator for the fumigation of a drug, characterized by having enclosed in a fumigator case a fuel receptacle, a metal catalyst disposed above said fuel receptacle at a predetermined space from said fuel receptacle, and a heat radiating plate for effecting thermal vaporization of said drug and disposed above said metal catalyst at a predetermined space from said metal catalyst, said fumigator case being provided with a gas passage.

2. A thermal fumigator according to Claim 1, wherein said space formed above said fuel receptacle and said space between said heat radiating plate and said metal catalyst are partitioned off from each other with a thermally insulating plate.

3. A thermal fumigator according to Claim 1, wherein a supporting member for said metal catalyst thereon and said heat radiating plate for thermal vaporization of said drug are joined to each other with a metal member.

4. A thermal fumigator according to claim 1, wherein said space formed above said fuel receptacle and said space between said heat radiating plate and said metal catalyst are partitioned off from each other with a thermally insulating plate and a supporting member for said metal catalyst and said heat radiating plate for thermal vaporization of said drug are joined to each other with a metal member.

,

5. A thermal fumigator according to Claim 1, wherein said fuel receptacle is constructed so as to enable a fuel selected from a volatile solid fuel, a volatile liquid fuel, and a liquefied gas fuel to be supported thereon.

6. A thermal fumigator according to Claim 1, wherein said fuel receptacle is constructed so as to enable a fuel selected from a volatile solid fuel, a volatile liquid fuel, and a liquefied gas fuel to be received and retained therein.

7. A thermal fumigator according to any of claims 1, 4 and 5, wherein said fuel receptacle is constructed so as to enable a fuel selected from a volatile solid fuel, a volatile liquid fuel, or a liquefied gas fuel to be supported thereon, said space formed above said fuel receptacle and said space between said heat radiating plate and said metal catalyst are partitioned off from each other with a thermally insulating plate, and a supporting member for said metal catalyst and said heat radiating plate for thermal vaporization of said drug are joined to each other with a metal member.

8. A thermal fumigator according to any of claims 1, 4 and 6, wherein said fuel receptacle is constructed so as to enable a fuel selected from a volatile solid fuel, a volatile liquid fuel, or a liquefied gas fuel to be received and retained therein, said space formed above said fuel receptacle and said space between said heat radiating plate and said metal catalyst are partitioned off from each other with a thermally insulating plate, and a supporting member for said metal catalyst and said heat radiating plate for thermal vaporization of said drug are joined to each other with a metal member.

9. A thermal fumigator according to Claim 1, wherein said fuel receptacle is constructed so as to be filled with a fuel selected from volatile solid fuel, a volatile liquid fuel, and a liquefied gas fuel.

10. A thermal fumigator according to any of Claims 1 and 9, wherein an upper surface of said fuel receptacle and the metal catalyst are separated from each other by a distance of 0.3 and 10.0 cm to permit thorough mixture of said fuel and air.

11. A thermal fumigator according to any of Claims 1 and 7, wherein said metal catalyst and said heat radiating plate for thermal vaporization of said drug are separated from each other by a distance of 0.2 and 3.0 cm to permit effective convection of heat of said combustion gas.

12. A thermal fumigator according to Claim 1, wherein said fumigator case encloses therein a container filled with a liquefied gas, a nozzle communicating with said container via a valve, a metal catalyst disposed at a position at which said liquefied gas spurted out of said nozzle collides against said metal catalyst, and a said heat radiating plate for thermal vaporization of said drug disposed near said metal catalyst, and said fumigator case is provided with a gas passage for entry of air and/or release of combustion gas and is further provided with valve control means capable of regulating the opening and closing of said valve.

13. A thermal fumigator according to Claim 12, wherein said metal catalyst is disposed above said nozzle across a fixed space and said heat radiating plate for thermal vaporization Or said drug is disposed above said metal catalyst across a fixed space.

14. A thermal fumigator according to Claim 12 or Claim 13, wherein the upper surface of said container filled with said liquefied gas and said metal catalyst are separated from each other by a distance of 0.3 to 10.0 cm to permit through mixture of said fuel and air.

15. A thermal fumigator according to Claim 12 or Claim 13, wherein said metal catalyst and said heat radiating plate for thermal vaporization of said drug are separated from each other by a distance of 0.2 to 3.0 cm to permit effective convection of heat of said combustion g as.

16. A thermal fumigator for a drug, said fumigator comprising a fumigator case, said fumigator case enclosing a fuel receptacle, a support member for a metal catalyst, a heat radiat-ing plate to uniformly disperse heat, and a thermally insulating member, said member for supporting a metal catalyst being posi-tioned above said fuel receptacle and defining a space therebe-tween, said heat radiating plate being positioned above said metal catalyst support member and defining a space therebetween, said thermally insulating member being positioned between said member for supporting a metal catalyst and said fumigator case, said fumigator further comprising a gas passage in said fumigator case.

17. The thermal fumigator of claim 16, further com-prising a lateral part connecting said support member and said heat radiating plate, said support member being made of metal.

18. The thermal fumigator of claim 16, wherein said space between said member for supporting a metal catalyst and said fuel receptacle is between 0.3 cm and 10 cm.

19. The thermal fumigator of claim 16, wherein said space between said heat radiating plate and said metal catalyst is between 0.2 cm and 3.0 cm.

20. The thermal fumigator of claim 16, further com-prising a valve and a nozzle communicating with said fuel recep-tacle and a metal catalyst positioned on said support member, said nozzle directed so that fuel emitted from said nozzle impinges on said catalyst.

21. The thermal fumigator of claim 16, further com-prising a control valve for said gas passage.