US2779265A

US2779265A - Fume hood

Info

Publication number: US2779265A
Application number: US583542A
Authority: US
Inventors: John M Liptay
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-05-08
Filing date: 1956-05-08
Publication date: 1957-01-29
Anticipated expiration: 1974-01-29

Description

Jam 29, 1957 J. M. LIPTAY 2,779,265

FUME Hoon Filed May 8, 1956 7 Sheets-Sheet l 3 Flan 801/9 1- FE Fls Ff ,7 /9

l im 79? uf' F l 1 -i ,ff/ W* J9 f5 19 d 15* 2 s Z L. L

8 28 /0 [gt/z3 j EL L' l 2 uf 10 .l I L d' lay 65 V) 51? I f6) 2( fz f9 64 L a l w l n Q Ff M l l7) r f/9 l/9 80 v f 5 t FIG. 2 f E ff I F|G.7

`,.5 o 26 5' WEA/mk.v 81] g John M. Lip'toy L T BY ATTORNEY Filed May 8, 1956 J. M. LIPTAY FUME HOOD 7 Sheets-Sheet 2 FIG.3

. INVENTOR.

John M. Liptoy ATTORNEY Jan. 29, 1957 1. M. LIPTAY FUME HOOD Filed May 8, 1956 7 Sheets-Sheet 5 f"I9 E FIGA /'f/ Vl w 2 f@ 29 .7 53 56 28 4l l `he 34 32 INLf'ENToR. John M. Lipfoy BY ATTORNEY Jan. 29, 1957 J. M. LIPTAY 2,779,265

FUME Hoon Filed May 8, 1956 '7 sheetsheet 4 FF 79\ y f7 zz INVENTOR. John M. Lip'roy BY ATTORNEY Jan. 29, 1957 J. M. LIPTAY 2,779,265

FUME: HOOD Filed May 8, 1956 rTSheets-Shee 5 PLC I 6 M Z7 l 45% l a6 44 l l--zf 35 We 40 32 C v F|G.8

INVENToR. John M. Lipoy BY v ATTORNEY Jan. 29, 1957 M, LIPTAY 2,779,265

FUME HOOD Filed May 8, 1956 '7 Sheets-Sheet 6 INVENTOR. John M. Liptoy BY ATTORNEY Jan. 29, 1957 J. M. LIPTAY 2,779,265

FUME HOOD Filed May 8, 1956 '7 Sheets-Sheet '7 vll/011.15 L

INVENTOR.

John M Lipoy BY ATTORNEY United States Patent FUME HOOD John M. Liptay, Manhasset, N. Y.

ApplicationMay

8, 1956, Serial No. 583,542 19 claims. (ci. 984-115) The invention is directed to a novel and serviceable fume hood. One object'of the invention is to provide an improved fume hood permitting safer use and operation thereof together with permitting greater accessibility `in thte matter of bodily adjusting a sloping and unitary irnperforate baffle disposed Within` the fume hood. Another object comprehends a fume hood having a new principle of operation carried into effect upon adjustment of the unitary and sloping bale for changing `the direction of the air flow and velocity of the air flow within vthe fume hood during operation of the fume hood without the needl on the part of anyone touching or entering any part of the interior of the fume hood. Specifically another object of `the invention is to provide conveniently accessible control means outside of the hood to permit 'the operator without entering the inside of the hood to easily and promptly `adjust a slidably guided sloping baffle within the hood in the `'matter of varying the size of fume egress apertures formed `in part by the upper and lower margins of the sloping baffle. Another object is concerned with a rectilinearly displaceable imperforate baffle for s irnultaneously but inversely varying thte upper and lower Vfutile egress apertures. Another object resides in the provision of manipulatable control means accessible attthe front part and outside of the hood for operating adjustable means for bodily and rectilinearly displacing the sloping baille. Other important objects and advantages and functional and structural features of the invention will be apparent from the following detailed specification considered inthe lightof the accompanying drawings wherein Fig. `1 is 'a front view of the fume hood according to my invention, Vshown partly broken away to illustrate the upper fume exhaustaperture.

"Fig, 2 `is a horizontal sectional View on the line 2-2 of Fig. `l.

Fig.y 3 is anI enlarged sectional view on the bent line '3f-37er Fig.I l, illustrating ythe baille adjusted to provide exhaust `apertures of substantiallyA the same area atthe top and bott-om of the baille.

Fig; 4 is` a view similar to Fig. 3 exhibiting theV linearly guided vbafile adjusted `to `fully close the lower aperture and substantially fully open the upper aperture.

Fig. 5 is a view along 'the lines of Fig. 4 but with the `baille fully closing the upper aperture andconcomitantly fully opening ythe lower aperture.

`:Figf is a sectional View on the line 6-.6 of Fig. 3 illustrating-.thespaced, and fixed anterior` guide railsf to .facilitate linear displacement of the baffle.

Fig. 7'cisa sectional view bn the line 7-7 `of" Fig. 3 depicting the vupper `and lower pairs of spaced posterior guide rails likewise cooperating to. linearly guidethe biased bae.

Eig. 8 is an enlarged schematic View on -thetline 8-8` of Fig. `1, showing the control and adjustable meanstfor elevating or loweringthe forwardly ine-lined baiiie.

Fig. 9 is a fragmentary perspective rear View of FigtiS with the slab lor counter' removed andwith itheHfulc-rum ree means for the rockable bell crank lever removed from the xed bracket.

Fig. l0` is an enlarged fragmentary View of the control means for rotating the actuating rod.

Fig. l1 is anenlarged sectional View on the line Ill-11 of Fig. 8.

Fig. 12 is a fragmentary exploded perspective view of baille and yoke which supports the bafile, and

Fig. `13 is an enlarged fragmentary View on the line 13--13 of Fig. 8.

The fume hood generally designated FH is appropriately mounted on stone lslab or counter lll supported `by fixed and spaced sheet metal channels 11 and .l2 suitably carried by the front fixed panel 13 and fixed rear wall 14 respectively of the sheet metal cabinet broadly denoted C. Specifically hood `FH includes spaced sides l5, rear wall 1,6, roof `17, and front panel 18. Corner angle irons 19 constitute a'trame to which spaced sides: 15, rear wall 16, roof 17 andfront panel 18 are appropriately secured. It follows that hood FH characterizes a suitable enclosure delining an internal compartment 20 which is open to the atmosphere through relatively large intake opening 21 between counter 10 and panel 18.

Dividing compartment 2l) into a work chamber WC 4and plenum chamber or duct PC is the inclined stone irnperforate baffle B which slopes upwardly and forwardly away `from rear Wall 16. Duct PC thus progressively expands upwardly communicating withfume egress `opening 22 interrupting roof 17, and secured tothe latter about opening 22 is` the exhaust pipe FE containing a conventional fan (not shown). i

Baffie B is bodily slidable and is guided in its rectilinear movement by spaced anterior rails R and the spaced upper and lower posterior stripsS which also may be considered as rails. Sloping rails R and strips S are.` lixedly `anchored to spaced sides 15 in any well known manner.

Interrupting baffle B medially and along its lower margin is notch 23 (Fig. l2) for reception of bridge 24 of Vshaped yoke 25 having upstanding legs 26 closely straddling the anterior and posterior faces of baie B. Rivets 27 (Figs. 3 and 8) fasten spaced legs 26 to the body of the baille. Integral with yoke 25 is the depending lifting rod 2S slidably guided in bore 29 of slab lli and having a lower threaded part 29 (Figs. 9 and 13) adjustably received in the internal threaded bore of rocker or coupling 3i) having spaced outwardly convex lips or cams 3l. Integral with and depending from rocker or coupling 3) is tongue 32 which is receivable loosely', that is, slidably fitting in guide slot 33 interrupting long leg or arm 34 of bell crankV lever broadly designated BL. Holding tongue 32 loosely in place on arm 34 but against accidental removal is the Cotter pin 35 having its legs 36 passing through a suitable opening in tongue or lug 32. Spaced cam shaped lips 3l rock on top' rectilinear bearing faces 38 (Fig. 13) adjacent slot 33 of the long arm 34. The loose connection just described for coupling `30 in bell crank lever BL permits ease of translating rotational displacement of arm 34 into linear displacement of lifting rod28 as desired.

Bell `crank BL is pivoted on cylindrical shank 40 (Fig. 8) of bolt 4l (Fig. ll). Shank or fulcrum means 40 is held within alined openings 42 in rearwardly projecting lugs :mounted on'bolts 53. However, threaded portions 54 of shanks 52 frictionally, rmly and tightly engage the teeth of internal and alined threaded b-ores 55 of cylindrical nut 56. In other words, teeth of threaded portions 54 are jammed with teeth of alined bores 55, whereby threaded portions 54 of bolts 53 always move bodily with nut 56 having threaded bore 57 perpendicular to alined threaded bores S5 for adjustably receiving threaded part 58 of actuating rod or shaft 59 having at its front end internally threaded socket 6) which receives externally threaded terminal part of shaft 62 which is integral with crank 63 carrying hand grasping or manipulatable portion 64. Upon rotation of rod 59, nut 56 through action of its fixed bolts 53, drives arms 50 of yoke Y to cause tilting of yoke Y relative to fulcrum means 40.

Cotter pin 63 traverses socket 60 and the threaded part 61 of shaft 62. Consequently if crank 63 be revolved, shaft 59 is rotated in bearing or bushing 65 having its flange 66 clamped against fixed panel 13 of cabinet C by nut 67 bearing against flange 68 of angle iron 69. Flange 68 is appropriately welded to panel 13 to reinforce the latter. Flange 68 includes opening 70 in alinement with opening 71 in panel 13 for convenient reception of bushing 65. To facilitate rotation of shaft or spindle 62 on rotation of crank 63, ball bearing carrier 75 is effectively interposed between annular races 76. Carrier 75 and races 76 are rotatably sustained on shaft 62 between flange 66 of bushing 65 and face 77 of crank 63. Incidentally, shaft or rod 59 is retained against longitudinal axial displacement by bushing 65 which constitutes a stop for socket 60 and also by end face 77 of crank 63 which cooperates with an adjacent race 76 (Fig. 10).

Although the invention has been described in connection with an open type of fume hood, it is to be understood that it is equally applicable to the closed type of fume hood wherein a conventional safety sash (not shown) is slidably mounted for removably closing opening 21 permitting viewing safely any hazardous chemical reactions within the hood.

Operation If crank arm 63 be rotated, rod 59 is rotated. Consequently circular nut or driving member S6 is displaced along rod 59. It follows that Shanks 52 of bolts 53 are correspondingly displaced, in that Shanks 52 bodily move with driving nut 56. Since arms 50 of yoke Y are driven by shanks 52 of bolts 53, yoke Y is tiltably displaced. This action causes short arm 47 of bell crank lever BL to be pivoted relative to the ixedly retained fulcrum means or shank 40. If arm 47 be displaced, arm 34 of pivoted bell crank lever BL is correspondingly displaced, since these arms move in unison. Depending upon the direction of rotation of rod 59, displaceable driving nut 56 is shifted either in a direction towards the rear wall 14 (Fig. 8) of cabinet C or away therefrom. If moved Iaway from cabinet C, yoke Y tilts to swing arm 34 downwardly, thereby causing lifting rod 28 to drop. Such action lowers bathe B. If rod 59 be rotated in an opposite direction, driving nut 56 moves towards the cabinet, thus swinging yoke Y to raise arm 34 to lift rod 28 and bathe B is elevated, that is, slidably displaced between guide rails R and S. In actual practice and according to many successful tests effectively carried through prior to ling the application at bar, jamming of nut 56 against threaded portion 58 of the rotatable and adjustable shaft or rod 59 is precluded in that the amplitude of deflection of nut 56, that is, the distance between the highest part of an arc through which nut 56 travels `on rotation of manipulatable control means 63, and the middle part of a cord intersecting the extreme limits of such arc is slight and almost insignificant in comparison to the great length of operating rod 59 and such amplitude of deection in no way affects the proper displacement of nut 56 along rod 59 in the matter of effectively driving at all times the pivoted bell crank lever BL on rotation of control means 63.

In Figs. l and 3, bathe B is spaced from top wall 17 to provide the upper egress aperture and is spaced from counter 10 to provide the lower egress aperture 81. These apertures are thus simultaneously regulated or varied by operating the control means, namely, crank 63 for operating actuating rod 59 in the matter of adjustably setting the tiltable bell crank lever BL which permits the supporting means for bathe B, namely, coupling 30,. rod 28 and its yoke 25 to be raised or lowered. When raised, arm 34. acts on lips 30 to shift rod 28 upwardly. When arm 34 is lowered, rod 28 together with bathe B fall by gravity. It is thus apparent that control means accessible outside of the hood has been provided for adjusting the tilt of the rockable bell crank lever BL for bodily shifting bathe B to simultaneously but inversely vary the areas or size-s of

egress apertures

89 and 81, in other words if imperforate bathe B be adjusted in one direction aperture 80 is made smaller at the same time aperture 81 becomes larger. If bathe B be shifted in an opposite direction, the reverse or opposite is true, namely, aperture 80 becomes larger while aperture 81 grows smaller. By imperforate is meant that bathe B is solid and uninterrupted to allow fumes or gases through the body thereof.

Fresh air enters through opening 2l of the front walty of hood FH (Fig. 3) into work chamber WC where it is divided into two channels, namely, one channel hows' across the upper part of work chamber WC carrying with it the light fumes to upper apertures 80; and the other channel ows across the lower part of the work chamber carrying with it relatively heavy fumes into lower egress aperture 81. After reaching duct PC, the fumes therein are drawn into exhaust conduit FE and then to the atmosphere. By the present arrangement, dead regions within work chamber WC and duct PC where gases might collect are eliminated. The front wall of hood or enclosure FH (Fig. l) is defined by the front upper panel 18 which is spaced from counter 10 and the front spaced corner angle irons 19. In the specification, the expressions linear and rectilinear have been employed. These terms each mean straight line direction and consequently may be used interchangeably. The length of compartment WC should be considered as the distance between the spaced sides 15 of the fume hood (Fig. 2).

Where desirable, bafe B may be set to fully open upper egress aperture 80 and simultaneously fully close off lower aperture 81 as illustrated in Fig. 4 where relatively light fumes are shown passing from beaker 90 to upper aperture 80. Conversely in Fig. 5, upper aperture 80 is shut oi and lower aperture 81 is fully open in which case, heavy fumes emanating from beaker 90 flow to lower aperture 81. During operation of the fume hood and through actuation of crank 63, bathe B may be adjusted to simultaneously vary the size of upper and

lower apertures

80 and 81 and even to sizes of apertures between the extreme limits illustrated in Figs. 4 and 5.

Slidable and sloping bathe B extends almost fully across the length of the internal compartment, that is, `the distance between spaced sides 15 of enclosure FH. Bafhe B also extends across the entire height of the enclosure, that is, the distance between counter 10 and top wall 17 except of course for the combined heights of

apertures

80 and 81. Note Figs. 2, 3, 6 and 7. Balhe B may be said to be interposed between the front air intake opening 21 and the fume exhaust opening 2 2, the latter may be considered to be spaced from and to the rear of the front opening 21.

Rotatable rod 59, nut 56 and its bolts 53 together with pivoted bell crank lever BL in fact constitute adjustable operative means for automatically raising or lowering of the bathe supporting means constituted by yoke 25 and its depending portion 28 upon rotation of control means 63.

Stated in another way, metal operating rod or'shaft 59 is adequately retained against longitudinal displacegegaan@ 'nient exeept 1for inet/trahie nenntaetnripg:teiergnees: and elsareneee all Wins genial and lightpiay .eithengtr s iftreit dnringitsdisplaeement aldngsheft 19. @essentie ng .et'this Shaft hewever inst slightly t0 eetnpensete .for .arenate displacement di tint 56 thereby pr-even ing i nut .56 iernrning t againstshaft. 59

Venetie .ehengesmay lie-made in details pf eenstrne- `tien and .arrangement et parte `without departing .freni `.thespiritof theinventien er sderitieingenypf `the edyentages ,thereof inherent f .therein .1.. Ina .fumeihoedfan enelesure adapted to be seated ...one .counter Qt... cabinet-andi defining therewith .e eeni- Vpertinent and havingspaeed sides `and eredi Well `finti `having afront walltincluding ,a relatively large air intake @petting-,to permit access to apparatus on said counter and rtopehrmitair ,toenter .said `,compartment and having a :top l.wallIaineluding .a .fante exhaust .opening at the rear thereof, atslopingymovably ,arranged imperforate baille withinsaid enclosure; and-.interposedebetween and `Spaeed .from :said 4.Openings `and `having its upper part disposed Ain ,advanee of said `exhaust` opening and having its lower part spaced from said rear wall a distance less than .the `distance between said upper partand said `rea 1wall,said

baileextending almost ,fuily' `across the `length ofsaid t `compartmentbetween said sides;to liirectfurnes towards saidtopwalland/or counterjanddividing said compart- `ment intogawork chamber `f orcontaning saidtapparatus aridan upwardly `expanding exhaustwduct Vin communi- ..Cation with said exhaust opening and `defining with said sides f. and top `wall fand `with s aid counter upper and flowerapertures intcommnnication with said .duet and .,chamberrfor receiving :said fumes from said 4chamber' ifor -receptioninto said duct .during .-,operation of `said hood, ;said slopingbale being of ya height `substantially commensurate withthe `height of said work chamber ex- Yaquifer/the heights of said `apertures,guide means with- {in said enclosurerand securedtosaid `sides for directing linearly and bodily displacementof `said baille,and means for adjustably and `bodily displacing said vba'le for `si- -multaneously regulating the -sizes ofsaid apertures dur- 'irigth'e operation of said fume hood.

2.111 afumehood, an enclosure adapted to beseated `on alxcounter of la cabinet `and deningtherewith a com- `partmenttand having spacedfsides `and a `rear wall `and `having lafrontuwallV includinga relatively largezair intake foperii'ngto `permit access `to `apparatus on said counter and to permit air to enter said compartment and having La top `wall including a `fumeexhaust opening at the rear ythereof, a sloping movably arranged imperforate bafe `within said enclosure .and interposed between and spaced fromfsaid openingsand `having its upper `parttdisposed in advance of sai'd exhaust opening iandhaving i its `lower `partispacedfrom said rear Walla distance less `than the `distance betweenisai'dupper `part and said rear wall, said vibaniiie extending almost fully across `the length of `said compartment between said sides to direct fumes towards vsaid-l top wall and/or counter and dividing said compartmentinto aiwork chamber for containing said apparatus and lan upwardly expanding exhaust duct'in communication with said exhaust-opening and defining with said -sides and topiwall and with said counter upper and'lower apertures incommuriication with said duct and charn- `br=for receiving said fumes from said chamber forreception intolsaid' ductfduring `operation of said hood, said s lping baffle `being of a height substantially commen- -tsuratewithhthe height of'said `wor-k chamber -except for 4itheheightsofsaidapertures, spaced guide means within Lsaid enclosure and secured `to said `sides for directing linearly and bodily displacement of said bale, adjustable means for bodily-displacing `saidibalile for simultaneously Abut inversely varying thefsizes of' said apertures during ftheoperation" ofsaid" fnmeihoo'd; and4 ycontrol means outtsidetof said enclosure: for` actuating said adjustable means.

3. `Iijla fumehood, anenclosure .adapted tobeseated one sprinter .ef n cabinet and .defining therewithlaeorn: partment and having `spaced sides Iand a rear .wall and having .a .front wallincluding a .relatively large air intake opening toperrnit access t to apparatus `on saiducounter and to permit Vair to 4entertsaid compartment andlhavinga top wall including a fume exhaust opening atthe rear thereof, -a sloping movably arranged imperforate bale within `said enclosure and interposed-between and spaced from said openings and having its upper jpart disposed in advance of saidexhaust opening-and having its"lower part spaced from `said rear wall a distance less .than the distance between 1Asaidupper part and said rear wall, said baille extending almostV `fully across the length `of said compartment'between said sides'to direct `fumes towards said top wall and/or counter and dividing said compariment-.into `a work `chamber for containing said apparatus andan upwardly expandingfexhaustduct in communica.- tion with said exhaust `opening and defining wthsaid `sides `andtop wall and withsaid counter upper and 4lower aperturesin communication with said duct and chamber for receivingfsaid-fumes'from said chamber .for reception intotsaidfductfduring operation ofsaid hood, said sloping battle b eingof aheight substantially commensurate with the height of said workchamber except for `the heights of said apertures, spaced guide means within said `en`- closure and carried by said sides for directing linearly and bodily displacement of said baie, adjustablemeans outside of and below said enclosure andcarried `by said `cabinet foribodily displacing said baiile forsimultaneously but inversely varying the sizes of said apertures during the operation: of `thesaid fume hood, and control means near said front `wall and below said counter and outside of saidl `enclosurefor actuating said .adjustable Ameans.

4.11m a fume hood having a counter, an enclosure seated on said counter and provided with an air intake opening and a fume exhaust lopening spaced from said intake/opening, a sloping and slidable baille extending across Vand `disposed within said enclosure and .spaced `from andinterposed between said openings, guide means `within said enclosure for directing linearly and bodily displacement of said `sloping `baiile, a rotatable shaft disposed outside of said enclosure and having a threaded portion, means retaining said shaft against longitudinal axial displacement, displaceable driving means having `means threadably engaging said threadedportioma pivoted bell cranklever having a pair of spaced arms, means carried by said driving means for swingably shifting one of said arms, supporting means secured to said baie and having depending means, a coupling adjustablyl secured to said depending means and havingcam means movably seated `on the other arm of said pair, said last mentioned arm and coupling having a loose connection therebetween, and controlmeans outside of said enclosure for rotating said shaft .to displace said driving means to tilt said lever for bodily elevating. or lowering of said supporting means and bale.

5. ln a fume hood having a counter, an enclosure `seated on said counter and provided with an air intake opening and a fume exhaust opening spaced from said intake opening, a vsloping and slidable imperforate baie extending across and disposed within said enclosure and spaced' from and interposed rbetween said openings, guide means within said enclosure for directing linearly and bodily displacement of said sloping bale, a rotatable shaft disposed `outside of said enclosure and having a threaded portion, means retaining said shaft against longitudinal axial displacement, displaceable driving means having means threadably engaging -said threaded portion, a pivoted bell crank lever having a yoke and an arm diverged from said yoke,` means carried by said driving means for swingably shiftingsaid yoke for pivotally dis- 'placing said lever,'supporting means secured to said `baille and having dependinglmeans, a coupling adjustably secured to said depending means and having vca'm'means movably seated on said arm, said arm having a slot and said coupling having a lug loosely guided in said slot, means to preclude removal of said lug from said slot, and control means outside of said enclosure for rotating said shaft to displace said driving means to tilt said lever for bodily elevating or lowering of said supporting means and baille.

6. In a fume hood, an enclosure adapted to be seated on a counter and defining therewith a compartmentand having spaced sides and a rear wall and having a front wall including a relatively large intake opening to permit access to apparatus on said counter and to permit air to enter said enclosure and having a top wall including a fume exhaust opening, a slidable imperforate baille spaced from said front and rear walls and extending substantially fully across said compartment between said sides to define an aperture with a part of said enclosure and at least in part dividing said compartment into a work chamber in communication with said intake open- 'ing and aperture and an exhaust duct in communication with said aperture and said exhaust opening, displaceable supporting means carrying said baille, spaced means carried by said sides and within said enclosure for bodily and rectilinearly guiding said baille, operative means cooperating with said supporting means for bodily and vlinearly displacing said baille relative to said counter for 'adjusting said aperture, manipulatable control means for actuating said operative means, and means to guide said supporting means.

7. A fume hood for cooperating with a counter comprising an `enclosure deilning with `said counter a cornpartment and having a front wall including an air in- 'sloping relative to said counter and interposed between and spaced from said intake and exhaust openings and dividing said compartment into a work chamber in communication with said intake opening and an upwardly expanding duct in communication with said exhaust opening, said sloping baille having an upper longitudinal marginal portion deiining with the upper part of said enclosure an upper aperture in communication with said chamber and duct and having a lower longitudinal marginal portion defining with the lower part of said enclosure and said counter a lower aperture in communication with said chamber and duct, means bodily and rectilinearly guiding said sloping baille, operative means for bodily shifting said baille to vary simultaneously but inversely the sizes of said apertures, and control means for actuating -said operative means.

8. A fume hood for cooperating with a counter comprising an enclosure defining with said counter a compartment having a front wall including an air intake opening and having a top wall including'a fume exhaust opening spaced from said intake opening, a movable imperforate one piece inclined baille within said enclosure and sloping relative to said counter and interposed between and spaced from said intake and exhaust openings and dividing said compartment into a work chamber in communication with said intake opening and an upwardly expanding duct in communication with said exhaust opening, said inclined baille having an upper longitudinal marginal portion deilning with raid top wall an upper aperture in communication with said chamber and duct and having a lower` longitudinal marginal portion deiining with the lower part of said enclosure and vsaid counter a lower aperture in communication with 4simultaneously but inversely the sizes of said apertures, and rotatable control means for actuating said operative -means.

9. A fume hood for cooperating with a counter com- 8 prisingI an enclosure defining with said counter a conpartment and `having a front wall including an air intake opening and having a top wall including a fume exhaust opening spaced from said intake opening, a movable imperforate inclined baille within said enclosure and sloping relative to said counter and interposed between and spaced from said intake and exhaust openings and dividing said compartment into a work chamber in communication with said intake opening and an upwardly expanding duct in communication with said exhaust opening, said inclined baille having an upper longitudinal marginal portion deilning with said top wall an upper aperture in communication with said chamber and duct and having a lower longitudinal marginal portion deiining with the lower part of said enclosure and said counter a lower aperture in communication with said chamber and duct, means carried by said enclosure for bodily and rectilinearly guiding said sloping baille, supporting means carrying said baille, operative means to displace said sup porting means for bodily shifting said baille to vary simultaneously the sizes of said apertures, and control means outside of said enclosure for actuating said operative means.

l0. A fume hood for cooperating with a counter comprising an enclosure defining with said counter a com partment and having a front wall including an air intake opening :and a top wall including a fume exhaust opening spaced from said intake opening, a movable imperforate inclined baille within said enclosure and sloping relative to said counter and interposed between and spaced from said intake and exhaust openings and dividing said compartment into a work chamber in communication with said intake opening and an upwardly expanding duct in communication with said exhaust opening, said inclined bafile having an upper longitudinal marginal portion deining with said top wall an upper aperture in communication with said chamber and duct and having a lower longitudinal portion defining with the lower part of said enclosure and said counter a lower aperture in communication with said chamber and duct, means carried by said enclosure for bodily and rectilinearly guiding said sloping baille, operative means for bodily shifting said baille to vary the sizes of said apertures, and manipulatable control means outside of said enclosure for actuating said operative means, said baille extending almost fully across the length of said compartment and extending across the height of said compartment except for the heights of said apertures.

11. A fume hood comprising an enclosure adapted to be seated on a counter to deiine therewith a compartment and including a front wall having a relatively large air intake opening and having a top wall including a fume exhaust opening to the rear of and spaced from said intake opening, an inclined movably disposed imperforate;

baille interposed between and spaced from said openings and arranged within said compartment and dividing the latter into a work chamber and an upwardly expanding vduct and deilning with said enclosure and counter upper and lower apertures in communication with said work chamber and duct, spaced guide means within and carried by said enclosure for rectilinearly and bodily directing displacementof said baille, movable supporting means xedly carrying said baille, operative means coacting with said supporting means to bodily raise or lower said baille relative to said counter and enclosure to vary the sizes of said apertures, and control means to actuate said operative means, said baille extending almost fully across the length of said compartment and extending across the height of said compartment except for the combined heights of said apertures.

l2. A fume hood comprising an enclosure adapted to be seated on a counter to deiine therewith a compartment and including a relatively large air intake opening and a fume exhaust opening to the rear of andy spaced jfromzr said :intake opening, a sloping movably. disposed imperforate `baille f interposed between `and .spaced'from :saidopenings aridarranged within said compartment and -.dividing tlielatter into asviork chamber and an upwardly .expandingxduct tand deiining with .,saidaenclosure Vand counter :upperand lower :apertures `in Communication i withsaid work chamber .and duct, guide means for rectilinearly .and :bodily directing; displacement .of :said baille,

lsupporting.means ins-.part` disposed `within and in part fdutsideaofrsaid enclosureuand .carrying said baille, movand including a relatively large air intake opening and a i fume exhaust opening to` the rear of `and spaced from .said'intake opening, a sloping movably disposed im- `perlforate bailleinterposed between and spaced from,` said openings A and arranged within said `compartment and dividing ,the latter into a` work chamber and an` upwardly `expanding yduct and deiining with said enclosureand counter upper and lower apertures in communication with said work-chamber and ductVguide means for rectilinearly and bodily directing displacement of said Lbaille, adjustableoperativemeans outside of said enclosure, supporting means carrying said baille and seated on a part of said operative means for bodily raising or lowering said baille relative to said enclosure to simultaneously vary the sizes of said apertures, and control means outside and at the front part of said hood and outside of said enclosure to actuate said adjustable means.

14. In a fume hood, an enclosure Iadapted to be seated on a counter and defining therewith a compartment and having spaced sides and a rear wall and having a front wall including a relatively large fair intake opening to permit access to apparatus on said counter and to permit air to enter said compartment and having a top wall including a fume exhaust opening at the rear thereof, a sloping movably arranged imperforate baille Within said enclosure and having its upper part spaced from but disposed in advance of said exhaust opening and having its lower part spaced from said rear wall a distance less than the distance between said upper part and said rear wall, said baille extending almost fully across the length of said compartment between said sides to direct fumes towards said top wall and/or counter and dividing said compartment into a work chamber for containing said apparatus and an upwardly expanding exhaust duct in communication with said exhaust opening and deiining with said sides and top wall and with said counter upper and lower apertures in communication with said duct and chamber for receiving said fumes from said chamber, spaced guide means Within said enclosure for rectilinearly and bodily directing displacement of said baille, operative means to bodily raise or lower said baille relative to said counter and enclosure to vary the sizes of said apertures, and manipulatable control means outside of said enclosure to actuate said operative means, said sloping baille extending fully across the height of said compartment except for the combined heights of said apertures.

15. A fume hood comprising an enclosure adapted to be seated on a counter to deiine therewith a compartment and including an air intake opening and a fume exhaust opening spaced from said intake opening, a movable support, a sloping imperforate baille within said enclosure and exposed to said intake opening but interposed between and spaced from said openings and dividing said enclosure into fa work chamber and an upwardly expanding duct and defining with said enclosure and counter upper and lower apertures in communication with said work chamber and duct, means securing the lower part of Said baille to said movable support, spaced means iixed to said. enclosure for bodilyand rectilinearly guiding-said sloping baille Aalong'itheqheight oftsald enclosure,said baille occupying almost the sentire length `of -tsaidpen- `closure and extending along `the entire height of rsaid chamber except for the combinedvheights of saidapertures, adjustableoperative meansfor raisingto'r lowering said `support `relative to :said `counter `and enclosure t, for bodily raising or` lowering of said baille along theheight of said compartment to simultaneously 'but inversely Vvary the sizes of saidapertures, control means outside` of .said enclosure toactuate saidoperative meansVandmeans for movablyyguiding :said support.

16. Aiume hoodcomprising an enclosure adaptedto be seated on a counter to define therewith acompartment and including a relatively large vair intake opening `and a fume exhaust opening tothe rear of and Nspaced `from `said intaketo'pening, a sloping movably disposed imperforate baille interposed between and spaced from said openings and arranged withinisaid compartment' and dividing `the latter into a work `chamber and an upwardly expandingwduct wanddeiining with'tsaid enclosure and `counter upper andlower apertures in `communication with'` said Workcharnbrl and duct, guide meansfor rectilinearly and bodily ,directing displacement of `said baille,

`said `baille extendingSubstantially fully :across the length t ofsaid compartment end extendingfully `across the height f off, said compartrnentexe.cpt4 1 for the. heights of SaidA enerrtures, arotatablerod, means retaining: said rod against means for displacing said support upon displacement of said lever, and control means for rotating said rod.

17. A fume hood comprising an enclosure adapted to be seated on a counter to deiine therewith a compartment and including a relatively large air intake opening and a fume exhaust opening to the rear of and spaced from said intake opening, a sloping movably disposed imperforate baille interposed between and spaced from said openings and arranged within said compartment and dividing the latter into a work chamber and an upwardly expanding duct and deiining with said enclosure and counter upper and lower apertures in communication with said work chamber and duct, guide means for rectilinearly and bodily directing displacement of said baille, said baille extending substantially fully across the length of said compartment 'and extending fully across the height of said compartment except for the combined heights of said apertures, a rotatable rod having a threaded portion, means retaining said rod against longitudinal axial displacement, driving means threadably engaging said portion, a pivoted bell crank lever having a pair of arms, said lever and driving means having means to shift one of said arms for pivotally displacing said lever to tilt the other arm of said pair, :a movable support bodily carrying said baille, means for guiding displacement of said support upon displacement of said lever, means to lift said support upon tilting of said other arm, and control means outside of said enclosure for rotating said rod.

i8. A fume hood comprising an enclosure adapted to be seated on a counter to define therewith a compartment and including a relatively large air intake opening and a fume exhaust opening to the rear of and spaced from said intake opening, a sloping movably disposed imperforate baille interposed between and spaced from said openings and arranged within said compartment and dividing the latter into a work chamber and an upwardly expanding duct and defining with said enclosure and counter upper and lower apertures in communication with said work chamber and duct, guide means for rectilinearly and bodily directing displacement of said baille, said baille extending substantially fully across the length of said 'compartment and extending fully across the height of said compartment except for the combined heights of said apertures, a rotatable rod having a threaded portion, means retaining said rod against longitudinal axial displacement, driving means threadably engaging said vportion, a pivoted bell crank lever having a pair of arms, said lever and driving means having means to shift one of said arms for privotally displacing said lever to tilt the other arm of said pair, a movable support bodily carrying said baffle and movably seated on said other arm, means for guiding displacement of said support upon displacement of said lever, said other arm and support having means defining a loose connection, and control means for rotating said rod.

19. A fume hood comprising an enclosure adapted to be seated on a counter to dene therewith a compartmentand including a relatively large air intake opening and a fume exhaust opening to the rear of and spaced from ysaid intake opening, a sloping movably disposed impercompartment except for the combined heights of said apertures, a rotatable rod having a threaded portion, means retaining said rod against longitudinal axial displacement, driving means threadably engaging said portion, a pivoted bell crank lever having a pair of arms, said lever and driving means having means to shift one of said arms for pivotally displacing said lever to tilt the other arm of said pair, a movable support bodily carrying said baille and having depending means, means for guiding displacement of said depending means upon displacement of said lever, said other arm having means for loosely receiving said depending means, means to pre- `clude removal of said depending means from said other arm, and control means for rotating said rod.

References Cited in the le of this patent UNITED STATES PATENTS 1,198,144 ORourke Sept. 12, 1916 1,491,005 Fauser et al Apr. 24, 1924 1,934,808 Liptay Nov. 14, 1933 2,549,042 Angermueller Apr. 17, 1951 2,567,622 Taylor Sept. 11, 1951 2,585,122 Hartman Feb. 12, 1952 2,704,505 Morrison Mar. 22, 1955 FOREIGN PATENTS 423,682 Great Britain Feb. 6, 1936,