US 2733333 A
Description (OCR text may contain errors)
3 56 v. N. PETERS 2,733,333
INSECTICIDE VAPORIZER Filed June 50. 1952 2 Sheets-Sheet l INVENTOR. V/E 6/4. M 957-525 llVVF 2 Jan. 31, 1956 v PETERS 2,733,333
INSECTICIDE VAPORIZER Filed June 30, 1952 2 Sheets-Sheet 2 INVENTOR. Wee/4 M 05 TEES A Tree Y United States Patent 2,733,333 INSECTICIDE VAPORIZER Virgil N. Peters, Stevens Point, Wis.,
assignor to Miles Henninger, Milwaukee,
This invention relates to improvements in devices for subliming or directly vaporizing from the solid to the gaseous state, an insecticidal material by the use of an electrical heating element of which the heat output is limited regardless of the conditions under which the device is operated and which cannot over-heat even upon complete failure of the heating element.
The use of insecticides, such as lindane (99% gamma isomer of hexachlorocyclohexane or benzene hexachloride) which are possibly toxic to humans, is controlled by regulations issued cooperatively by several Federal agencies, such as the Food and Drug Administration and Public Health Service of the Federal Security Agency and the Insecticide Division of the U. S. Department of Agriculture. The primary requisite for a device for subliming and vaporizing the lindane, is that such device be inherently safe from or protected against such operating conditions as might vaporize more than a given amount of the material in a given period. The standards of performance now in use for such devices limits the maximum weight of lindane vaporized to not more than 1 gm. per 24 hours and the devices must be so constructed that output in excess of the above quantity is impossible.
When a vaporizer for lindane is electrically heated by resistance elements, it is possible for the vaporizer to overheat and thus vaporize more than the given amount of material, for a considerable period of time before the heating element actually fails. Hence, the present standards specify that a fuse be included in the device for preventing such over-heating and failure of the device from the viewpoint of vaporizing excessive amounts of material. However, if the heating element is a lamp bulb of the incandescent filament type, only a readily determinable and a constant amount of heat can be produced during operation of the bulb. if any condition occurs within the bulb tending to increase the fiow of electric current through the bulb filament, only a momentary increase in heating eifect is possible before the filament breaks and thereby automatically puts the device completely out of operation.
Hence, the incandescent filament type of bulb when used as a heater, is inherently limited to production of an amount of heat dependent on the size of the bulb and does not require a fuse for preventing over-heating. Such bulb fails safe when used as either a source of light or heat. If the bulb is so combined with other elements of a lindane vaporizer as to make it impossible for the user to insert an incandescent filament bulb larger than a given size, the output of the vaporizer is inherently limited to a maximum weight of the lindane per period of time and such weight cannot be exceeded under any conditions. Hence, such device is safe both against mechanical failure and misuse.
It is therefore one object of the present invention to provide an electrically heated device for vaporizing an insecticidal material which may possibly be toxic to humans, and which device is inherently safe under all conditions against overheating and hence against vaporizing more insecticidal material than a predeterminable and misuse is made very difficult.
Another object of the invention is to provide a vaporizer for insecticidal material, which is electrically heated and in which the amount of the heat is automatically limited by the nature of the electrical heater for thereby limiting the rate of vaporization of the insecticide.
Another object of the invention is to provide an electrically heated vaporizer for an insecticide, in which the electrical heating element fails safe in that the heating element can produce an increased amount of heat for only such a short period as will be ineffective for materially increasing the quantity of material vaporized, and thereafter completely puts the device out of operation.
Another object of the invention is to provide a vaporizer for an insecticidal material, which vaporizer uses the same incandescent filament lamp bulb for both a heating element and as a part of an indicator that the vaporizer is in operation, and in which it is impossible for the user to increase the size of the bulb or the amount of heat transferred to the insecticidal material except by considerable change in the construction of the vaporizer.
And a further object of the invention is to provide a vaporizer for an insecticide which is to be sublimed by an electric heater of the incandescent filament bulb type and in which a thermally responsive fuse interrupts the circuit to the heater if any condition permits radiation of a greater amount of heat than a predetermined amount.
Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing in which:
Fig. 1 is a perspective view of one present invention.
Fig. 2 is a side elevation with some parts separated from one another to indicate the relationships between such parts.
Fig. 3 is a cross-sectional view taken on a vertical plane and on the longitudinal axis of those parts shown in section.
Fig. 4 is a transverse vertical cross-section on the plane of line 4-4 of Fig. 3.
Fig. 5 is a view partially in side elevation and partially in section of another embodiment of the invention having thermally responsive means for interrupting the electric circuit to a heating element.
Fig. 6 is an end view of the structure shown in Fig. 5.
Fig. 7 is a transverse cross-sectional view on the vertical plane of line 7-7 of Fig. 5.
Fig. 8 is a perspective view rotated approximately of one sub-assembly of parts shown in Fig. 5.
Fig. 9 is a view partially in side elevation and partially in vertical section of a construction generally similar to that of Figs. 1 through 4 excepting for changes in dimension of one of the parts and the addition of parts thereto; and
Fig. 10 is a perspective view of an adapter for a heat bulb in combination with a fuse to be utilized to support and connect the heater bulb.
Generally, the present device comprises a socket for an incandescent filament lamp bulb, with a manually-operable circuit breaker or switch incorporated in the socket. The socket may be of the type having prongs for insertion into an electrical receptacle or outlet or may be mounted on a conduit box through which electrical conductors extend for connection to the socket or switch conductors.
One portion of the socket encloses the switch and is of relatively large size and another portion of the socket receives the heater bulb and is of smaller size, thus providing a shoulder on which the remainder of the device is seated. The socket is of such size as to receive only a bulb with a candelabra base and such bulbs are comamount,
embodiment of the mercially available only in a few sizes for the usual l-120 v. electric-supply; the SlZUllmliililOl'lS applying to both the electric currentaconducting capacity and to linear dimensions of the bulbs. Means are mounted on the heater bulb receiving portionof the socket for quickly 0 attaching and detaching a housing enclosing the bee bulb'in a chamber of such dimensions that only a bLllD of given size may be used.
The housing also provides a chamber for recezvm insecticidal material to be vaporized, the mater l enclosed in a textile bag of particular material and for retaining the finely divided solid particles of the secticide while allowing ready escape of such materim when converted to gaseous form. The textile an chamber for receiving th'e same have particular dii sionalfrelationships so that the bag may expose the mum surface area consistent with the rate of vaporization of the unit.
7 the limiting the loss of solid particles of the mater in one modification of the present device, a t
Prongs 2'2, 23 extend from the socket portio insertion into the usual electrical receptacle or outlet or for connection otherwise to electrical supply conductors. The base and intermediate socket portions enclose an electric circuit breaker or switch of the, over-cent type of which only the handle 24is shown through 4, and which will be described detail bel and electrical receptacle of usual construction candelabra size. The exterior longitudinal surface at least the. smallest socket portion 17 is preferably c lindrical and is formed with a peripheral groove which is seated-a helical spring -6 joined at the ends form a garter about theisockct. The spring i free to expand and contractor to be somewhat deformed and o move in-i'tsgroove as required by coactiou with elements of the structure.
Atube of good heat conductive material is divided by a partition 31 with a peripheral flange 32, into chan bers 3.4 and 35 and;the.tube is. of such size as to-pass over the socket portion 17 and over the spring The tubular housing 39 is formed with-anutnber i internalprojectionsfi at one end for deforming the spring as the tube passes thereoverand to engage the side or the spring when the end of the housing is seated on the socket shoulder 18 whereby the housing is readily attached to and detached from thesocket. At least three internal projections 36 are provided but the number thereof may be increased as desired dependent only on the oven hung weight of the structure to be supported on the spring.
When the parts are assembled as shown, the housing chamber 34' hasonly' a given lateral and longitudinal clearance or spacing from-anelectrical heating element which is-an electric lampbulb-40 of the incandescent fila iii.
ment type. The heater bulb All has a base of standard candelabra size and shape and the size of the transparent envelope for the filament is also standardized for a given bulb wattage. Thus, a 6 w. bulb has an overal length of 17 8 inches and a maximum diameter of inch tor a rated to operate at not more than v. When the bulb operates at the normal range of voltage supply, the resistance of the filament is such that the bulb can only produce a given amounttof heat, the maximum temes of a bare. 6 w. bulb being 93 F. A 1 Jib of 7 a is 2% inches in overall length and larger bulbs .ve larger longitudinal dimention. Hence, it" the heater chamber. 3 3 of the housing fail is made to provide only a given clearance between the end of the 6 w. heater bulb the partition when the parts are assembled as shown, 31 a 6 w. heater bulb may be used unless the partition e toward the open end of the housing for the i for the insecticide. Upon use of a goodhea conductive tube having a lateral clearance approxitely /4 it eh and a longitudinal clearance of only inch for a 6 w. bulb, it has been found by test that the maximum temperatures in the insecticide chamber is of the order of lS5--2=30 F.' dependent on ambient condithe tightness with which the end of the thericneter is pressed against the partition. it is accordwent temperatures as high P.
lindane is contained within a textile ba is? o 4.00 yd. o 4-0 in.
of 8% x 80. rial of the bag is such to avoid any possibility with the insecticide and the weave is such as to fit the loss of lindane lines while permitting r ady escape or" lindane vapor.
When lindane is used as the insecticide, the wall of insecticide chamber 35 is provided with holes 33 which 3 inch in diameter and in two diam -ric rows of holes and the holes are spaced on ch centers. The end holes, adjacent the open end or the insecticide chamber and adjacent" the partition 31, are severally es from such end and the partition by i", .ch to the er of such adjacent'holes. The above at ent of holes has been found necessary in coaction 1 th the particular weave of bag used to allow complete diffusion of the vaporized lindane from the present device (continually operated) and with only a small amount-of condensation of vapor on the inside surface of hte insecticide chamber.
The bag is preferably made substantially longer and wider than the length of the insecticide chamber and the iarneter thereof (the ratios being :l'Z s and. l- /szl lg in inches res ectively): For the present device using a 6 w. heater bulb, the initial charge of lindane is 15 gm. /2 oz). Insertion of the bag in they insecticide chamber automatically provides the maximum surface area of lindane Within the chamber. If excessive condensation'occurred the housing, very small crystals we id be formed outside of the bag with loss of the solid inst ticide and with possible. danger to human be larly if the crystalswere somehow ingested.
Animperforate cover 41 is provided for the open end of the tube 31) and the cover is tightly held in p e. The
s particucover is disk-likewith,itsperiphery formed inwardly as greases resilient and can accordingly be easily inserted into the open end of the insecticide chamber where the crease edges engage the chamber surface. The cover flange is accordingly so securely and tightly held against the end of the housing as to require more effort and skill for removal of the cover, than can be exerted by children.
A button of a colored plastic material having edge lighting effect, such as methyl methacrylate, is mounted in the housing to give a glowing or iridescent effect when the bulb filament is heated to incandescence for providing an indicator or pilot light visible even in daylight or bright artificial light. The button should be of thermosetting material for thermal stability, machinability and color-fastness.
Referring to Fig. 3, the button 50 has a base flange 51 larger than an aperture through which the button protrudes from the housing. The button is held against movement in one direction, by the flange 32 of the housing partition, the flange having a small indent at one portion thereof for receiving the base of the button.
The embodiment shown in Figs. 5 through 8 is generally similar in structure to the first embodiment descibed above except that a thermally responsive fuse is connected in series in the electric circuit to the heater bulb. The fuse is of a known construction comprising a tube 55 of glass or other insulating material with metallic end caps 56 and an electrically conductive link 57 connecting the end caps, the link being under spring tension. The link is a metallic alloy which loses its tensile strength at a predetermined temperature which, in the fuse, disclosed herein, may be made of any value between 28"- 400" F. Upon loss of tensile strength of the fuse link, the springs break the link and interrupt the circuit therethrough.
The fuse is placed inside an electric and heat-resistive tube 53 to prevent electrical bridging of the end caps of the fuse if the fuse should be brought into contact with any other portions of the device. insulated conductors 62, 63 extend from the fuse end caps through the housing and through a channel 64 cut into the socket parts 16 and It? beneath the garter spring 26. The fuse conductors then pass through an aperture in the socket portion and into the interior of such socket portion. Fuse conductor 62 is connected with prong 22 which is held the socket in insulated relation to all other conductive parts of the socket sub-assembly, while fuse conductor 63 is connected with one fixed contact 68 of a switch.
The switch further comprises a movable member 69 pivoting on the pivot for the switch handle 24 and the free end of the movable switch member is connected with an extension from the switch handle 24 by a compression spring 1 d. All of the above parts are particularly shown in Fig. 6, the switch then being in the open position. The switch has another fixed contact 71 which is best shown in Fig. 5 and which is connected with the center terminal 75 of the socket. The threaded shell or liner forming the side terminal 76 of the socket is connected with the prong 23. When the switch is closed as shown in Fig. the switch movable member 69 bridges between the switch fixed contacts as and 71. Hence, an electrical circuit is completed from the prong 22 through the fuse lead 6' the fuse link 57, the fuse lead 63, the fixed switch contact 63, the movable switch member 69, the fixed switch contact 71, the central socket terminal 75, he central terminal of the heater bulb 40, the bulb filament, the bulb side terminal, the socket side terminal 76 and the prong 23.
Assuming that the fuse link is of a composition losing its tensile stren th at 200 F. and that the insecticide chamber temperature is of the order of 18 'l90 F. (as has been shown by tests), the than 1 or 2 above the difference between the temperature of the heater chamber 34 and the fuse opening temperature or 21, 22, to 31, 32 above the normal temfuse will open at no more perature for the insecticide chamber. It is possible for the heater bulb filament to be partially short-circuited or otherwise capable of producing higher than the normal temperature in the heater chamber, for a short time. But if the bulb filament does not itself fuse quickly and a temperature of more than 200 F. is produced in the heater chamber, the fuse will open and break the electrical circuit. Thus the fuse adds another safety feature to the inherent safety of the bulb as a heater, and the structure of Figs. 5 through 8 conforms to even the strictest interpretation of the present standard for a vaporizer for lindane. It will be understood that the heater chamber must now be lengthened sufficiently to receive both the heater bulb and the fuse which should be located at the hottest position in the heater chamber, and which is on the longitudinal axis through the heater bulb and adjacent the partition within the housing.
Figs. 9 and 10 show a second modification of the construction which is especially adapted for use in a fixed location and where inspections may be made by a person in authority to make sure that the unit is being used according to instructions. The present modification is similar to the construction shown in Figs. 1 through 4 excepting that some dimensions are changed and that the unit is now permanently mounted on a conduit box 55 and the rongs are permanently fastened to electric supply conductors 81 and 32. The heater bulb chamber 34- is now made sufficiently longer to permit use of an adaptor socket and fuse combination which is less expensive than modifying the socket structure as shown in Figs. 5 through 8.
The heater-fuse combination comprises a base member with a central terminal 85 insulated from a threaded side terminal 86 and which provides a socket into which the heater bulb is threaded. The threaded portion of the socket is of electrically conductive material and is electrically connected only with one fuse conductor or lead 9"). The other fuse conductor or lead 91 is connected with the adapter side terminal 86. In the present embodiment the two fuse conductors 90 and 91 are preferably imbedded in a deformable insulation to which a fuse covering tube 92 is attached, and thus provides a structure for supporting the fuse and the parts associated directly therewith. An electrical circuit to the heater bulb 41' can thus be made only in series with the fuse when the bulb is properly placed in the adapter-socket and when the adapter-fuse unit is properly placed in the socket 15-18.
It will be apparent that the heater bulb chamber 34 in the housing 30, must now be of a length to accommodate the additional length of the adapter and fuse. Such in creased length might permit the use of a 7 w. bulb as a heater (such bulb being 2 /2 inches in length), when the adapter-fuse are not used. However, even a 7 w. lamp will not produce sufficient heat to vaporize more than the maximum weight of lindane permitted by the present standards of the Interdepartment Committee on Pest Control. Care is taken that the length of the chamber 34 is sufficient to receive a 6 w. bulb heater and the adapterfuse unit, but is less than 334 inch which would permit the insertion of a 15 w. bulb in the unit, the 15 w. bulb being the largest bulb now made with a candelabra base.
The effect of a fuse can also be obtained in the plain heater bulb shown herein by use of a bulb in which one of the lead-in conductors is an alloy melting at the desired temperature.
It will thus be seen that the present invention provides an electrically heated vaporizer for lindane in which the heater is a bulb of the incandescent filament type and of which only a given size can be used. In all the embodiments of the present application, use is made of the inherent inability of a bulb of the incandescent filament type to produce more than a given amount of heat while in normal operation, to overheat for any material length of time under any conditions and in which the heater fails sare.
In the two embodiments of the invention, the above inherent safety qualities of the bulb heater are retained and a thermally-responsive fuse is placed in series with the bulb filament to open the electrical circuit supplying the filament under certain conditions. If the bulb heater should for any reason produce more than a given amount of heat for even the short time required for a fuse to reach the temperature at Which the fuse opens, the fuse will interrupt the heater circuit.
In the second embodiment of the invention, the parts are so related that it is impossible for a user to place a heater bulb of larger than 6 w. without considerable reconstruction of the unit. In the third embodiment of the invention, it is possible for a user to increase the size of the heater bulb to some extent, but the third embodiment is designed for use only in such locations as are under the control of a person in authority.
Each of the three embodiments of the present device is accordingly safe as to all of the functional or performance requisites of the present Federal standards and the second and third embodiments meet all of the requirements of such standards under any interpretation thereof. Each of the present Vaporizers is of much simpler construction, cheaper and less obtrusive than the devices now in use and an equivalent number of the present devices will give better vapor distribution than the devices now in use. Each of the present Vaporizers includes not only the safety features required by the Federal standards but other safety features of preventing contact of persons with the lindane either while charging the device or thereafter, and in shielding of the lindane charge so as to minimize the possibilities of condensation of the lindane on a wall or ceiling adjacent the vaporizer.
Although but three embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without'departing from the spirit of the'invention or from the scope of the appended claims.
1. in an electrically-heated vaporizer for solid insecticides, an electric socket of the screw type having different external dimensions to form a shoulder around the socket and having a groove about a smaller portion of the socket, a garter spring seated in the socket groove, a. housing fitting over the smaller socket portion and extending therefrom, the housing abutting on the socket shoulder and being retained on the socket by the spring for overhanging extension from the socket, a heating element of the incandescent bulb type threaded into the socket and wholly enclosed within the housing, a textile envelope for the insecticide, the envelope being wholly enclosed in the housing in heat-receiving relation with the heating element for vaporization of the insecticide, and means for indicating energization of the heating element.
2. In an electrically-heated vaporizer for solid insecticides, an electric socket of the screw threaded type, a tubular heat conductive housing mounted on the socket and extending coaxially therewith and therefrom, the housing being divided into a substantially closed chamber and a chamber having holes through the housing Wall, a heating element of the incandescent bulb type threaded into the socket and enclosed in the substantially closed housing chamber, the closed chamber being dimensioned for receiving only a heating element below a predetermined size whereby the heating element extends closely adjacent the housing walls defining the closed chamber, a textile envelope for the insecticideenclosed in the other housing chamber for vaporization of the insecticide, and means for indicating energization of the heating element.
3. In an electrically-heated vaporizer for insecticides, an electric socket of the screw thread type, an electric 8 heating element of the incandescent lamp type adapted to be placed in the socket, a tubular housing mounted on the socket and extending therefrom, the housing being heat conductive material and being divided into an imperforate portion and a perforated portion, the holes in the perforated portion being arranged in two rows longitudinally of the housing and the rows being diametrically opposite, a textile envelope for the insecticide for enclosure in the perforated housing chamber for vaporization of the insecticide upon energization of the heating element, and means for indicating energization of the heating element, the vaporizer being adapted for horizontal extension from an electrical receptacle in a wall and the housing being rotatable relative to the socket whereby the holes may be brought into planes varying in direction from horizontal to vertical for controlling the amount of insecticide discharged upon operation of the vaporizer.
4. in an electrically-heated vaporizer for solid insecticides, an electric socket of the screw threaded type, a housing mounted on the socket and extending therefrom, a heating element of the incandescent bulb type threaded into the socket and extending to substantially midway of the length of the housing, a textile envelope enclosed in the housing for retaining the insecticide in solid form and passing the insecticide in vapor form upon energization of the heating element, and a light-transmitting button mounted in the housing for receiving light from the heating element and for transmitting the light exteriorly of the housing.
5. In an electrically-heated vaporizer for solid insecticides, an electric socket of the screw threaded type, a housing mounted on the socket and extending therefrom, a peripherally flanged partition dividing the housing substantially midway of its length, the housing having a hole adjacent the partition, a heating element of the incandescent bulb type threaded into the socket and extending to adjacent the housing partition, a textile envelope enclosed in the housing for retaining the insecticide in solid form and passing the insecticide in vapor form after energization of the heating element sufficiently to vaporize the material, and a button of a material for transmitting light axially thereof upon energization of the heating element and being adapted to indicate such energization, the button having a peripheral flange adjacent one end thereof and extending through the hole in the housing and being held in the housing hole by engagement of the flange between the housing wall and the fiange of the housing partition.
6. In an electrically-heated vaporizer for solid insecticides, an electric socket of the screw thread type, a housing mounted on the socket and extending therefrom, a heating element of the incandescent bulb type threaded into the socket and enclosed within the housing, a textile bag for retaining the insecticide in solid form and allowing passage of the vaporized insecticide therefrom, the bag being enclosed in the housing in heat-receiving relation with the heating element, means for receiving energy from the heating element and indicating the energization of the heating element for observation exteriorly of the housing, and electrically-conductive means connected with the heating element and responsive to the temperature thereabout for interrupting the circuit of the heating element upon rise thereof above a given temperature.
7. In an electrically-heated vaporizer for solid insecticides, an electric socket of the screw thread type, a housing mounted on the socket and extending therefrom, a heating element of the incandescent bulb type threaded into the socket and enclosed within the housing, a textile bag for retaining the insecticide in solid form and passing the vaporized insecticide, the envelope being enclosed in the housing in heat-receiving relation with the heating element, means for receiving energy from the heating element and for indicating the energization of the heating element for observation exteriorly of the housing, and means connected in series circuit with the heating element and responsive to the temperature adjacent the heating element for interrupting the supply of electric current thereto in response to temperature rise of the heating element above a given value.
8. In an electrically-heated vaporizer for solid insecti cides, an electric socket of the screw thread type, a housing supported on the socket and extending therefrom, a partition dividing the housing into two chambers, a heating element of the incandescent bulb type threaded into the socket and enclosed within the housing, a textile bag for retaining the insecticide in solid form and passing the vaporized insecticide, the bag being enclosed in the housing in heat-receiving relation with the heating element, means for receiving energy from the heating element and adapted for indicating the energization of the heating ele ment for observation exteriorly of the housing, and electrically conductive and temperature response means mounted adjacent the housing partition and the heating element for cutting off energization of the heating element upon rise of the temperature thereof above a given value.
9. In an electrically-heated vaporizer for solid insecticides, an electric socket of the screw thread type, a housing supported on the socket and extending therefrom, a partition dividing the housing into a substantially closed chamber and a chamber open to atmosphere, a heating element of the incandescent bulb type threaded into the socket and enclosed within the substantially closed chamber of the housing, a textile bag for retaining the insecticide in solid form and passing the vaporized insecticide, the bag being enclosed in the housing chamber open to atmosphere in heat receiving relation with the heating element, means for receiving energy from the heating element and indicating the energization of the heating element for observation exteriorly of the housing, and electrically conductive means mounted in the closed housing chamber between the housing partition and the heating element and responsive to the temperature in the chamber for cutting off energization of the heating element upon rise in temperature above a predetermined value about the means.
10. In an electrically-heated vaporizer for solid insecticides, an electric socket of the screw thread type, a housing supported only on the socket and extending therefrom, a heating element of the incandescent bulb type threaded into the socket and wholly enclosed within the housing, a textile bag for retaining the insecticide in solid form and allowing passage of the vaporized insecticide therefrom, the bag being wholly enclosed in the housing in heat-receiving relation with the heating element, lighttransmitting means for receiving light from the heating element and adapted for indicating the energization of the heating element for observation exteriorly of the housing, and an adapter-fuse unit including an electrically-conductive and thermally fusible link and fitting into the socket for providing another socket for receiving one end of the heating element, the fusible link being in electric series circuit with the heating element and being supported in space beyond the other end of the heating element whereby rise in temperature above a given value about the heating element interrupts the supply of electric current to the heating element.
11. In a vaporizer for insecticides, an electric socket of the screw-thread type adapted to be connected with and supported by an electrical receptacle in a building wall, a tubular heat conductive housing mounted on the socket and extending coaxially therewith and therefrom, the housing being divided into a chamber substantially closed against air flow therethrough and a chamber having a pair of series of holes through the housing, an incandescent lamp threaded into the socket and wholly enclosed in the substantially closed housing chamber to serve as a heating element, a textile envelope for enclosing the insecticide in the open housing chamber and for vaporization of the insecticide therefrom, and means for indicating energization of the heating element, the socket and the lamp being adapted for horizontal mounting and the series of holes being severally formed in diametrically opposite housing wall portions, the housing being rotatable on the socket for placing the holes in different planes from horizontal to vertical and thereby controlling the amount of insecticide discharged from the vaporizer.
References Cited in the file of this patent UNITED STATES PATENTS 1,565,500 Ritter Dec. 15, 1925 1,988,617 Adams Jan. 22, 1935 1,992,684 Weinberger Feb. 26, 1935 2,231,095 Sommer et al Feb. 11, 1941 2,469,656 Lienert May 10, 1949 2,607,874 Schiedler Aug. 19, 1952 2,616,024 Laibow Oct. 28, 1952