US3722838A - Humidifier - Google Patents

Abstract

A humidifier comprises a housing formed from prefinished metal sheets in such a manner as to provide a water reservoir, an inclined filter pad carried by a water trough, an impeller disposed below the high point of the filter pad and consisting of a hub carrying a pair of axially spaced plate-like bodies, each of the bodies having two semicircular water-throwing edges of different radii, a ring carried by the impeller and disposed partly in the water reservoir, a two-speed motor for rotating the impeller, and a combined shutoff and indicator apparatus which functions to show the amount of water left in the reservoir and to turn off the motor when the water level drops below a predetermined value.

Description

ite. tates Swimmer et a1.

[ 1 HUMIDIFIER [76] Inventors: James A. Swimmer; Martin Harris,

Chicago, 111.

[22] Filed: Dec. 17, 1971 [21] Appl. No.: 209,393

Related [1.8. Application Data [62] Division of Ser. No. 887,236, Dec. 22, 1969, Pat. No.

[52] 11.8. C1 ..261/72 R, 261/100, 220/62, 220/77, 220/81 [51] lint. Cl. B01i 3/04 [58] Field of Search ......261/29, 72, 100; 220/62,- 77, 220/76, 81

[56] References Cited UNITED STATES PATENTS 82,766 10/1968 Stone ..220/76 647,423 4/1900 Payzant ...220/77 3,113,694 12/1963 Sulzer ....220/62 3,223,393 12/1965 Goettl ..26l/28 3,253,820 5/1966 Seil ..261/29 X FOREIGN PATENTS OR APPLICATIONS 524,251 8/1940 Great Britain ..220/81 Primary ExaminerTim R. Miles Attorney-Lettvin & Gerstman [57] ABSTRACT A humidifier comprises a housing formed from prefinished metal sheets in such a manner as to provide a water reservoir,'an inclined filter pad carried by a water trough, an impeller disposed below the high point of the filter pad and consisting of a hub carrying a pair of axially spaced plate-like bodies, each of the bodies having two semicircular water-throwing edges of different radii, a ring carried by the impeller and disposed partly in the water reservoir, a two-speed motor for rotating the impeller, and a combined shutoff and indicator apparatus which functions to show the amount of water. left in the reservoir and to turn off the motor when the water level drops below a predetermined value.

3 Claims, 12 Drawing Figures PATENTEDmzmrs 7 3 SHEET 1 BF 5 FIG! PATENTEUHARZYIHIS 3 ,722, 3

SHEET 30F 5 PATENTEDmzmu 3, 722,838

SHEET 4 BF 5 '(IIIIIIIIIIII) PATENTEDHARZY I973 SHEET 5 BF 5 HUMIDIFIER This is a division of application Ser. No. 887,236 filed Dec. 22, 1969, now U.S. Pat. No. 3,637,194.

It is an important object of the present invention to provide a humidifier which is capable of delivering humidified air at two different rates.

Another object is to provide a humidifier that is exceptionally quiet during operation.

Still another object is to provide a humidifier comprising a single motor that drives both an impeller which distributes water onto a filter pad and a fan blade which blows air through the pad.

In connection with the foregoing object, it is another object to provide the impeller with two plate-like bodies, each consisting of a pair of semicircular waterthrowing edges, to minimize the amount of water dropping into the reservoir and water droplets being propelled through the filter pad.

Yet another object is to provide a housing for a humidifier, which consists of prefinished metal sheets formed into a watertight reservoir without spot welding.

A further object of the present invention is to provide a frame for supporting the filter pad in a humidifier, constructed to prevent excess water from dropping to the humidifiers reservoir.

In connection with the foregoing object, it is another object to support the filter pad in a trough that causes excess water to gravitate on the side walls as opposed to free falling into the humidifiers reservoir.

A still further object is to provide a combined shutoff and indicator apparatus that shows how much water is in the humidifiers reservoir and shuts off the humidifier when the water level drops below a certain value.

A yet further object is to provide a housing for a humidifier, which does not require sealing around fasteners.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features and construction, arrangement, and a combination of parts hereinafter fully described, illustrated in the accompanying drawings and particularly pointed out in the appended claims, it being understood that various changes in the form, proportions, size, and minor details of the structure and the method may be made without departing from the FIG. 4 is an enlarged view in vertical section of the humidifier in FIG. 2, along the lines 4-4 thereof, with portions of the back wall broken away;

FIG. 4A is an enlarged fragmentary view of one of the casters and its connection to the humidifier;

FIG. 5 is an enlarged view of the frame and filter pad;

FIG. 6 is a greatly enlarged sectional view of a fragmentary portion of one of the walls making up the humidifier housing;

FIG. 7 is a fragmentary bottom plan view on an enlarged scale of a caster mounted on the humidifier housing;

to FIGS. 1 to 4 and 11, thereof, there is shown a humidifier 20 embodying the principles of the present invention. Thehumidifier 20 comprises a housing 30 formed from two pieces of prefmished sheet metal, one of which is generally U-shaped to form a front wall 31 and a pair of side walls 32. The bottom of the front wall 31 isbent about 90 to form an inwardly-directed bottom flange 33; similarly, the bottoms of the side walls 32 are respectively bent about 90 to form inwardlydir'ected flanges 34. The rear portions of the side walls 32 are bent about 90 toward one another to form inwardly directed side flanges 35; similarly, the top of the front wall 31 and the tops of the side walls 32 are bent about 90 to form an inwardly directed top flange 36, which flange carries an offset ledge 36a.

Referring to FIG. 6, the sheeting bent to form the parts 31-360 consists of a metal sheet 37 carrying on one side thereof a decorative vinyl coating 38 and on the other side thereof a waterproof coating 39. The waterproof coating 39 surrounds the interior of the housing 30, as will be described, and the decorative spirit or sacrificing any of the advantages of the inven- 1 tion.

For the purpose of facilitating an understanding of the invention, there has been illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, and considered in connection with the following description, the inventions mode of construction, operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawings:

FIG. 1 is a perspective view of a humidifier embodying the principles of the present invention;

FIG. 2 is a top plan view on an enlarged scale of the humidifier shown in FIG. 1;

FIG. 3 is an enlarged view in vertical section of the humidifier shown in FIG. 2, taken along the lines 33 thereof;

vinyl coating 38, which, for example, may have a woodgrain appearance, covers at least the front wall 31, the side walls 32, and the top flange 36, so that the outside of the humidifier 20 presents an attractive appearance.

The housing 30 also comprises a second metal sheet which may also be prefinished on either or both sides as shown in FIG. 6. This second sheet is bent to form a bottom wall 40 and an upstanding back wall 41, the back wall 41 having a height much shorter than the height of the front wall 31. The front of the bottom wall 40 is bent about to form a downwardly directed front flange 42 which, in turn, carries an inturned flange 42a disposed generally parallel to the bottom wall 40. The sides of the bottom wall 40 are bent about 90 to form a pair of downwardly-directed sideflanges 43 which, in turn, respectively carry inturned flanges 43a disposed generally parallel to the bottom wall 40.

The sides of the back wall 41 are bent about 90 to form a pair of outwardly-directed side flanges 44 which, in turn, respectively carry inturned flanges 44a disposed substantially parallel to the back wall 41. The top of the back wall 41 is bent inwardly about 90 so as to extend parallel to the bottom wall 40.

In connecting together the two pieces of bent, prefinished sheet metal, the inturned .flange 42a is placed on top of the bottom flange 33, so that the front flange 42 is spaced rearwardly of the front 'wall 31. Also, the inturned flanges 43a are respectively placed on the side flanges 35, so that the side flanges 43 are spaced respectively from the side walls 32. Finally, the inturned flanges 44a are respectively placed against the side flanges 35, so that the side'flanges 44 are respectively spaced from the side walls 32. Sheet metal screws 47 are then used to connect the flanges 34 and 43a, the flanges 33 and 42a, and the flanges 35 and 44a, in such a manner that the screw heads are on the outside of the housing. The space between the flange 42 and the front wall 31, the spaces between the side flanges 43 and the side walls 32, and the spaces between the side flanges 44 and the side walls 32 are filled with a sealant 46. There are also provided reinforcement plates 48 to strengthen the bend in the prefinished sheet metal between the walls 40 and 41. The five joints thus described are watertight and define a reservoir 49.

As explained previously, the sheeting used to form at least the parts 31-36a is prefinished with a decorative coating 39 on the outside and a waterproof coating 39 on the inside. It would be undesirable to weld together the parts of such a construction since to spotweld, a means to expose bare metal is necessary, and the heat created during welding would damage one or both of the coatings. In addition, it is desirable, from an economic standpoint, that the housing be formed so as to constitute the reservoir, rather than provide a separate reservoir. Finally, it is advantageous not to have any screws extending into the water reservoir, which are difficult to seal and might eventually result in leaks. The novel construction of the housing 30 described above accomplishes these objectives, as may be seen in FIG. 4a which depicts in cross section one of the five joints, that connects the two pieces of prefinished sheet metal. By virtue of this construction, none of the screws 47 extends into the interior of the housing 30, thereby to reduce substantially the chances of a leak occurring. The interior'of the reservoir 49 is completely waterproof by virtue of the waterproof coating 39 on the interior of each wall and by virtue of the sealant 46 in each of the joints.

Supporting the housing 30 is a set of four casters 60. As is most clearly shown in FIG. 11, each caster 60 includes a mounting plate 61 having a pair of openings 62 and a pair of openings 63. The mounting of the two casters toward the back of the housing 30 is best shown in FIGS. 4A and 11. Sheet metal screws 66 pass through the openings 63 and through the juxtaposed flanges 43a and 34. There is provided a spacer 64 having a pair of fingers 65 that fit into the other pair of openings 62, the opposing edge of the spacer 64 bearing against the bottom wall 40 so as securely to mount and support each of the rear casters 60. The mounting of the front casters 60 is most clearly shown in FIG. 7, wherein it can be seen-that sheet metal screws 66 pass through all four openings, through the juxtaposed flanges 33 and 42a and through the juxtaposed flanges 34 and 43a.

As is best seen in FIGS. 3, 4, and 11, the humidifier includes a rear panel 70 having a series of vents 71 generally centrally therein. Formed in an inwardly directed portion 74 of the rear panel 70 is a cutout 72 and a curved support 73, the purpose of which will be explained subsequently. The rear panel is attached to the upper portion of each of the side flanges 35 by screws or the like. There is also provided an L-shaped angle iron including an abutment plate 81 and an attachment flange 82 which is secured to the inwardly directed portion 74 of the rear panel 70. There is also provided a cover 83 having a slot 84 therein that is in substantial alignment with the cutout 72 and the support 73 on the rear panel 70. The cover includes a pair of side flanges 85 that rest on the inwardly directed portion 74 of the rear panel 70. A ledge 86 is struckfrom one of the side flanges 35 so as to be aligned with the offset ledge 36a provided on the front wall 31 and the side walls 32, whereby a substantially continuous ledge is provided. The inwardly-directed portion 74 also carries a three-position switch 90 and a humidistat 91, the shafts of which extend through openings in the cover 83 and are attached respectively to knobs 92 and 93. An indicator light 94 is also mounted in the inwardly directed portion 74 so as to be viewable through an opening in the cover 83.

The humidifier 20 further comprises a water trough (see FIG. 5) including a pair of attachment flanges 101 on either end thereof which are mounted to the side walls 32 of the housing 30. The interior wall 102 of the water trough 100 is inclined at a predetermined acute angle with respect to the horizontal. For reasons to be explained hereinafter, the length of the interior wall 102 of the trough 100 is very slightly less than the distance between the side walls 32 so as to furnish a slight space between each end of the interior wall 102 and the adjacent side wall 32. There is provided a filter support frame 103 which is generally rectangular in shape and includes a set of three lips 104 and a plurality of cross members 105. Resting on the frame 103 is a porous, air-permeable liquid-receiving member or filter pad 108. The lips 104 maintain the pad 108 in position. Further details of the frame 103 and the filter pad 108 thereon are shown in FIG. 5 which illustrates each cross member 105 as having a generally flat top 106 and a curved bottom 107 for purposes to be explained presently. One margin of the frame 103 rests in the water trough 100 and has a width such that the opposing margin thereof rests against the abutment plate 80 at an acute angle with respect to the horizontal. The parts are so dimensioned that the angle between the interior wall 102 of the water trough 100 and the horizontal is less than the angle between the frame 103 and the horizontal, for purposes to be explained presently.

Disposed directly above the filter pad 108 and supported by the ledges 36a and 86 is a decorative grill 109. In'order to fill the humidifier 20, the grill 109 is simply lifted off of its supporting ledge, and the frame 103 and the pad 108 are removed to expose the reservoir 49.

The humidifier 20 further comprises a combined shutoff and indicator apparatus 110 shown in FIGS. 4 v

and 11. The apparatus includes an L-shaped transparent tube 111, one leg of which rests on the support 73 of the panel 70 and the other leg of which extends downwardly through the cutout 72. A pair of stabilizer brackets 112 and 112a is affixed to the rear panel 70 and has a hole therein to receive the downwardly extending leg of the tube 111. There is provided an elongated flexible member 113 carrying on one end thereof an enlarged head 114 and on the other end thereof an enlarged tail 115. A rigid rod 116 has one end thereof press-fitted in an opening in the tail 115. The other end of the rod 116 is bent as shown so as to pass through an opening in a float 117. A washer 118, followed by a push-on fastener 119 holds the float 117 in place on the rod 116 and provides sufficient weight to actuate the switch 120 when the-water level recedes. The member 113 is at least partially disposed in the tube 111 and is adapted to move therein as will be explained.

There is also provided a switch 120 mounted on the rear panel 70 by a speed nut 122, the switch having a pivotal actuating arm 121. The switch 120 operates a motor 132. A switch linkage in the form of a rod 123 has a loop 124 on one end thereof and is attached to the actuating arm 121 at the other end thereof. The rod 116 is disposed in the opening of the loop 124. If the member 113 is lowered, the enlarged tail 115 engages the loop 124 to lower the rod 123 and consequently lower the arm 121 and thereby open the switch 120.

There is provided an air guide 130 to which is mounted a bracket 131. A two-speed motor 132 is mounted on the bracket 131 and is also secured to the rear panel 70 by means of nuts and bolts 133, thereby to mount not only the motor 132 but also the air guide 130. The motor 132 has a shaft 134 consisting of a rotates the ring l70 through the water in the reservoir 49.- The ring 170 deposits water on the impeller 140, which then forms the water'into a spray 175, striking .the uppermost region of the pad 108. The water gravitates through the pad by virtue of being inclined and also moves throughout the pad by capillary action, thereby to saturate the pad. in an operating embodiment, the filter pad 108 was formed of a polyurethane foam thathad 20 pores per square inch. If the porosity is excessive, the droplets will pass through the pad 108 into the air, whereas, if the porosity is insufficient, the air will have difficulty passing.

The rotating shaft 134 of the motor 132 also causes the fan blade 136 to rotate so as to draw air from the surrounding area through the vents 71 in the rear panel 70, through the air guide 131,- and forces the air upwardly through the wetted filter pad 108 so as to humidify the air. The humidified air passes out of the humidifier 20 through the decorative grill 109.

The excess water in the filter pad 108 drops onto the frame 103 and runs down the cross members 105 thereof into the trough 100. Because the bottom 107 of each of the cross members 105 is rounded, the quantity of water that will drop into the reservoir 49 is reduced. It is, of course, undesirable for the water to drop into the reservoir since that would make the humidifier. noisy during operation thereof. In addition, it should be noted that the frame 103 consists 'only of cross members that run in the direction of inclination so that water flows therealong into the trough 100. There are no longitudinally extending members which would increase the likelihood of water droplets falling directly into the reservoir.

The fact that the inclination of the frame 103 is greater than the inclination of the interior wall 102 of the water trough 100 results in a V-shaped space between the wall 102 and the frame 103. This'assures that the water on the frame 103' will flow into the trough 100 rather than impinge on the longitudinal edge thereof and then drop into the reservoir 49. Also, the fact that the end of'the interior wall 102 are spaced slightly from the adjacent side walls 32 of the housing 30 means that the water in the trough 100 will flow into the reservoir 49 as sheets along on the walls 32 as opposed to dropping into the reservoir 49. Each of these factors contributes to the noise-free operation of the humidifier 20.

I The 3-position switch 90 is attached to the 2-speed motor 132, so that rotating the knob 92 to its first position turns off the motor 132; rotating it to its second position causes the motor 132 to operate at a low speed; and rotating it to its third position causes the motor to operate at a high speed. The humidistat 91, also connected to the motor 132, operates to turn off the motor 132 when a selected humidity is attained, determined by the setting of the knob 93.

The combonation shutoff and indicator apparatus comprises a minimum'number of parts, both to turn off the motor 132 when the water level drops below a predetermined value and to indicate the quantity of water in the reservoir 49. The water will raise or lower the float 117, depending upon the water level, so as to move the enlarged head 114 in the horizontally disposed leg of the tube 111. As is most clearly shown in FIG. 2, the head 114 will point to the appropriate in-, dicia to indicate the quantity of water in the reservoir 49. When the water drops below a certain level, the enlarged tail 115 engages the loop 124 to pull down the actuating arm 121 of the switch 120, via the rod 123, which turns off the motor 132. Filling up the reservoir 49 causes the float 117 again to turn on the motor 132. The indicator light 94 is connected to the switch 120, so that, when the light is off (or on, if desired), there is sufficient water in the reservoir 49 to permit themotor 132 to operate,-whereas, when the light is on, the water level has dropped below the requisite minimum value.

Referring now to FIGS. 8 and 9, the details of construction of the impeller will be described. The impeller 140 includes a hub 141 that has a bore 141a extending therethrough and carries a pair of axially spaced, plate- like bodies 142 and 152. The body 142 has an inwardly facing surface 143 that is generally conically shaped and is divided into a central portion 144 and an outer portion .145. The inwardly facing surface 143 in the central portion 144 is inclined at a given angle with respect to the axis of rotation of the impeller 140, whereas the inwardly facing surface 143 of the outer portion 145 is inclined at a lesser angle'with respect to that axis. The body 142 alsohas an outwardly facing surface 146 with a dished-out region 147 formed therein in order to save material. Along the periphery of about one-half of the body 142 is a beveled surface 148 that meets the inwardly facing surface 143 to define a semicircular water-throwing edge 149, having a given radius. Along the periphery of the other half of the body 142 is a beveled surface 150 that meets the inwardly facing surface 143 to define a second semicircular water-throwing edge 151 having a shorter radius. The other plate-like body 152 is precisely the same as the body 142 and is numbered with corresponding reference numerals plus a factor of 10. In the interest of brevity, further detailed description of the plate-like body 152 will be omitted.

The semicircular water-throwing edge 159 of the body 152-, having the longer radius, is diametrically opposed in position to the semicircular water-throwing edge 149 of the other body 142, having the longer radius. Similarly, the semicircular water-throwing edge 161, having the shorter radius, is diametrically opposed to the corresponding semicircular water-throwing edge 151 on the body 142, having the shorter radius. The positioning of the water-throwing edges at diametrically opposite positions provides for dynamic balance of the impeller 140. To provide further dynamic balance, it may be desirable to add some material to the dished-out region 147 where the radius is less, so that the mass of either plate-like body on one side of any diameter thereof equals the mass on the other side of that diameter. A careful selection of material for the impeller 140 is important. If it is too soft, the ring 170 squishes against it to cause noisy operation of the humidifier; whereas, if it is too hard, the ring 170 makes a metallic sound against it, again noisy. In an operating embodiment of the invention, the impeller 140 was constructed of a synthetic copolymer of a 60 to 80 durometer hardness rating.

Referring now to FIGS. 3, 9, and 10, the ring 170 is circular and rigid and has a pair of side surfaces 171 that slope toward one another towards the center of the ring. The slope of each of the surfaces 171 is selected to be equal to the slope of the inwardly facing surfaces 143 and 153 of the central portions 144 and 154. Accordingly, one side surface 171 will mate with the inwardly facing surface 143 of the'central portion 144, and the other side surface 171 will mate with the inwardly facing surface 153 of the central portion 154. The ring 170 has a curved outer surface 172 and a flat annular inner surface 173. The ring 170 is laterally dimensioned, so that the surface 173 is spaced from the hub 141 to achieve best support of the ring. Both the ring 170 and the inwardly facing surfaces 143 and 153 are constructed as carefully as possible to be smooth and thereby minimize points at which water can drop from and into the reservoir. It is pointed out that the amount of contact between the side surfaces 171 and the inwardly facing surfaces 143 and 153 controls the amount of water that will be deposited by the ring 170 onto the impeller 140. Thus, the dimension of the surfaces may be selected to cause the desiredquantity of water to be deposited. Of course, the fact that the ring 170 is rigid permits it to be constructed to be smooth and thereby minimize noise. Also, the rigidity of the ring maintains it in the desired configuration.

The construction of the impeller 140 as described contributes to a basic objective of the humidifier 20, i.e., to reduce the noise during operation thereof. If the water-throwing edge had a constant radius of a value selected to insure ,that'the spray 175 would not pass through the filter pad 108 when the motor 132 was operating at its high speed, then the velocity of the spray at the low speed of the motor 132 would be so slow that much of the spray would drop into the reservoir 49 and thereby make noise. On the other hand, if the water-throwing edge of each plate-like body had a constant radius of a value selected to insure that the spray 175 had sufficient initial velocity at the slower speed of the motor 132 to reach the filter pad 108, then at the higher speed of the motor 132 the spray would be propelled fast enough undesirably topass through the filter pad 108.

The impeller 140 described above strikes a compromise, by reducing both the quantity of spray 175 capable of passing through the filter pad 108 and the quantity of spray 175 that drops into the reservoir 49. Thus, the humidifier 20 operates efficiently to humidify the air quietly and without dispensing spray at both speeds of the motor 132. For example, the user, at night, when very quiet operation is important, positions the knob 92 in its low" position to operate the motor 132 in its less noisy, low-speed condition. On the other hand, when maximum humidification is desired, the knob 92 is placed in its high" position to rotate the fan 136, the impeller 140, and the ring 170 at high speed. Of course, the humidistat 91, as determined by the setting of the knob 93, will turn off the motor 132 when the desired humidity is reached, whether the motor is operating at its high speed or its low speed.

It is believed that the invention, its mode of construction and assembly, and many of its advantages should be readily understood from the foregoing without further description, and that it should also be manifest that, while a preferred embodiment of the invention has been shown and described for illustrative purposes, the structural details, nevertheless, are capable of a wide variation within the purview of the invention as defined in the appended claims.

What is claimed is:

1. In a humidifier, a water reservoir having five panels including a rectangular bottom wall and four side walls extending upright adjacent the edges of the rectangular bottom wallto define a space for holding liquid therein, the improvement comprising, in combination: two prefinished sheet metal parts adapted for securement together for defining a reservoir that, without welding, is liquid-tight, a first of the two parts defining the bottom wall and one upright side wall and the second part defining the remaining three upright sides of the reservoir, and means providing liquid-tight joints between adjacent portions of the two parts adjacent each free edge of the bottom wall and the two upright edges of the upright wall of the first sheet metal part, each joint comprising an in-turned abutment flange formed on one of the upright sides of the second part,,and two flanges formed at a free edge of a panel on the first part, one flange on the first part extending transversely of the panel and the second flange extending from the one flange inwardly and parallel to and spaced from the panel, the sizes of the parts and flanges being selected and arranged so that when the parts are assembled the transverse flange on the first part is spaced from but parallel to the upright side of the second panel to provide a channel therebetween and with the second flange of the first part abutting the screw fasteners that screw through the abutting flanges 9 l abutment flange on the second part, a sealant in the part from the panels that define the reservoir. channel, and means forcing the abutting flanges 3. A construction as in claim 1 wherein casters are together. provided for the humidifier, and the abutting flanges 2. A construction as in claim 1 wherein the means for Provide Yigidified means to hich the casters may be atforcing the .abutting flanges together are removable 5 tached without danger of effecting a leak through y of the panels that bound theliquid reservoir.

but are spaced by the one transverse flange on the first

Claims (3)

1. In a humidifier, a water reservoir having five panels including a rectangular bottom wall and four side walls extending upright adjacent the edges of the rectangular bottom wall to define a space for holding liquid therein, the improvement comprising, in combination: two prefinished sheet metal parts adapted for securement together for defining a reservoir that, without welding, is liquid-tight, a first of the two parts defining the bottom wall and one upright side wall and the second part defining the remAining three upright sides of the reservoir, and means providing liquid-tight joints between adjacent portions of the two parts adjacent each free edge of the bottom wall and the two upright edges of the upright wall of the first sheet metal part, each joint comprising an in-turned abutment flange formed on one of the upright sides of the second part, and two flanges formed at a free edge of a panel on the first part, one flange on the first part extending transversely of the panel and the second flange extending from the one flange inwardly and parallel to and spaced from the panel, the sizes of the parts and flanges being selected and arranged so that when the parts are assembled the transverse flange on the first part is spaced from but parallel to the upright side of the second panel to provide a channel therebetween and with the second flange of the first part abutting the abutment flange on the second part, a sealant in the channel, and means forcing the abutting flanges together.

2. A construction as in claim 1 wherein the means for forcing the abutting flanges together are removable screw fasteners that screw through the abutting flanges but are spaced by the one transverse flange on the first part from the panels that define the reservoir.

3. A construction as in claim 1 wherein casters are provided for the humidifier, and the abutting flanges provide rigidified means to which the casters may be attached without danger of effecting a leak through any of the panels that bound the liquid reservoir.

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