US3425335A - Laboratory fume hood - Google Patents
Laboratory fume hood Download PDFInfo
- Publication number
- US3425335A US3425335A US700167A US3425335DA US3425335A US 3425335 A US3425335 A US 3425335A US 700167 A US700167 A US 700167A US 3425335D A US3425335D A US 3425335DA US 3425335 A US3425335 A US 3425335A
- Authority
- US
- United States
- Prior art keywords
- air
- hood
- grill
- fume
- curtain
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B15/00—Preventing escape of dirt or fumes from the area where they are produced; Collecting or removing dirt or fumes from that area
- B08B15/02—Preventing escape of dirt or fumes from the area where they are produced; Collecting or removing dirt or fumes from that area using chambers or hoods covering the area
- B08B15/023—Fume cabinets or cupboards, e.g. for laboratories
Definitions
- Two air sources are generally used in air fume hoods.
- the first is a pressurized air supply such as is produced by a fan or blower.
- a second air supply is the general environment of the hood which is enlisted by the entrainment of air at the open front of the hood.
- Such hoods are auxiliary air fume hoods.
- a fume hood obviating the disadvantage of prior known fume hoods. It is another object to provide a fume hood wherein turbulence within the working zone in the fume hood is avoided. It is a further object to provide a fume hood wherein a spilling out of fumes is positively prevented. It is a still further object of the invention to provide a fume hood enabling relatively great volumes of air to be swept through the fume hood and with quite small components of conditioned environmental air.
- a method of operating a fume hood to control outflow of unwanted material from the hood interior toward the operator which includes confining all input air to the hood in a single, generally vertical curtain of air rising from the bottom front of the hood toward the top thereof and inducing generally circular flow within the hood around the working zone therein by the curtain flow to sweep the hood interior without turbulence in the working zone.
- the circular air movement is about the elongated central portion of the hood interior, the working zone, specifically downwardly along the back of the hood interior and forwardly along the bottom of the hood interior.
- At the top of the hood air may be exhausted all across the hood width to maintain the curtain of air extending fully across the hood front.
- safe operation of the hood even with the hood front wall not in place may be realized by biologically conditioning the air to control organism species entrained therein as by adding a biologically active material, e.g., bacteriostat to be airborne in the air curtain stream.
- a biologically active material e.g., bacteriostat
- Apparatus useful for carrying out the method is provided in the form of a fume hood structure comprising a chamber including an openable front wall, a top wall, a bottom wall providing a working surface, side walls and a rear wall, an elongated air flow-directing grill mounted in the bottom wall to underlie the front wall, means forming a reduced pressure zone along the top wall and having an elongated inlet spaced from the rear wall, a pressurized supply of auxiliary air communicating with the grill and operating to displace air through the grill when the front wall is open in a vertical air curtain flow pattern across the open front of the chamber and toward the reduced pressure zone inlet, said air curtain flow acting to positively separate auxiliary chamber air from outside air and to induce a circular flow of air in a rolling pattern within the chamber downwardly along the rear wall and forwardly along the working surface, to join the air curtain flow, the circular pattern air defining a central zone free of turbulent air within the chamber.
- the air flow directing grill may comprise a perforate plate or other means having an arrangement of openings which are preferably alined to provide multilaminar flow vertically upward from the working surface.
- the reduced pressure zone is typically formed by a generally horizontal baffle extending across the hood width and in spaced relation with the top wall to form therewith the zone inlet.
- the baffle slopes downwardly to the rear of the chamber to join the rear wall.
- baffles parallel to and closely spaced from the rear wall are not required and indeed are deterimental to maintenance of the desired flow pattern.
- control of the biological properties of the air curtain may be desirable.
- FIG. 1 is an isometric view of the fume hood of the present invention
- FIG. 2 is aside elevation in section of the fume hood shown in FIG. 1 taken along line 22 in FIG. 1;
- FIG. 3 is an enlarged fragmentary plan view of the air inlet grill taken along line 33 in FIG. 2.
- FIGS. 1 and 2 there is shown in FIGS. 1 and 2 a generally rectangular fume hood structure indicated at comprising a chamber generally having side walls 12, rear wall 14, front wall 16 provided with a sliding sash 18 containing pane 19 and movable in opening 16a by sash lifting knob 18a.
- Chamber 10 is supported on a table or platform 20, representative of a counter or other structure of convenient height resting on the flooring 21.
- a table or platform 20 representative of a counter or other structure of convenient height resting on the flooring 21.
- Within the chamber 10 there is a generally horizontal floor providing a working surface 22.
- exhaust pipe 26 Leading from the interior of the fume hood through eduction outlet or orifice 25 in top wall 24'is exhaust pipe 26 having a suction means or an exhaust devicesuch as a fan 26a.
- a typical reaction set-up including stand 32, Bunsen burner 34 and flask 36.
- Exhaust orifice 25 is above and behind horizontal baffle 40, so that as air is exhausted from chamber 62 by fan 26a, a reduced pressure zone i9 created by a partial vacuum being generated in cham ber 52 defined by baffle 40, top wall 24 and rear wall 14.
- Air inlet means in the form of grill 28 are provided adjacent the working surface 22 along the openable side of the chamber cut the chamber floor as shown in FIG. 2 or at the front peripheral edge of the floor. As shown in FIG. 2, grill 28 overlies a channel 27 having walls 29 formed just forward of the working surface 22 and within the plane of the sash 18 of wall 16.
- Grill 28 is shown as a perforated barrier plate having a plurality of holes 281 therein placed in the path of the air flow as shown in FIG. 2.
- Air from port 50 passes through grill holes 281 and is sent substantially vertically upwardl to the interior of fume hood 10 as a multilaminar wide, thin column herein termed an air curtain (see arrows) and generally indicated at 42. Simultaneously, air is entrained from the open front face of the hood through opening 16a by a venturi effect caused by air directed upward and drawn by the force of the fan 26a at orifice 25. In general, the extent of entrainment of environmental air will be determined by the ratio of the volume of air forced through pressurized air inlet grill 28 and the volume of air being exhausted through orifice 25.
- 125 cubic feet per minute (c.f.m.) of air are provided through grill 28, 150 c.f.m. are eX- hausted through orifice 25 and correspondingl 25 c.f.m.
- Air through the face opening at a linear velocity as low as 10 feet per minutes can be drawn through the front opening under these conditions.
- the pressurized air volume should be less than the exhaust air volume to ensure air intake from the front of the hood.
- Front intake of as low as 1% of tht exhaust volume may be adequate to turn the air curtain inward for partially open hood fronts, for fully open fronts, however, at least 35% of the exhaust air volume should be drawn through the front opening 16a for efficient fume removal.
- All air to exhaust orifice 25 as described is drawn either through the space between baffie upper edge 40a and top wall 24.
- the result is an entraining of fume laden air into the air curtain 42 rising between working zone 23 and front opening 16a, indicated by the substantially vertical arrows in FIG. 2, and the conveying of this fume laden air to the educating orifice 25 without its being commingled with the environment-derived air also being entrained in the air curtain.
- a second result is the entertainment of relatively heavy particles, vapors and gases by an air sweep forwardly across the working surface into the air curtain 42. It will thus be seen that an inflow of environmental air is not.
- this quantity of air can be substantially reduced; in fact reduced to only enough volume to turn the air curtain inward under sash 18. Additionally, the lowermost portion of the fume hood, particularly the areas immediately adjacent the working surface 22 where heavy vapors collect are traversed by a partial vacuum induced flow of air along working surface 22.
- Air curtain 42 entrains air from the working zone 23. This results in creation of a partial vacuum in this zone. Accordingly at points generally lying on a line just below the baffle edge 40a a portion of the air curtain 42 air is induced to move inwardly under the baffle 40. This air indicated at 44 moves to the rear of the chamber interior to the rear wall 14 whence it proceeds downwardly to the greater partial vacuum created inwardly adjacent the grill 28. The result is a rolling clockwise circular or cylindrical air flow from the air curtain 42 at the baffle 40 and to the air curtain at the working surface 22. This cylinder of air revolves about and thus defines the working zone 23. The zone 23 is thereby substantially free of turbulence since all air flows around it are concurrent and no air is forced directly through the zone.
- Means such as grill 28 direct air essentially vertically upwardly uniformly across the face of the hood.
- the normal effect of the air entrained from without the hood is to cause the air curtain to incline inwardly to thereby create a natural fluid barrier between the worker at the hood and the fumes to be withdrawn.
- this air curtain can be temporarily disturbed without loss of effectiveness. For example, arms extended through the air curtain to adjust reaction equipment or whatever and withdrawn do not deleteriously affect the air curtain performance; the upward draft being sufficient to rebuild the curtain rapidly and overcome the temporary interruption caused by movement of solid objects therethrough.
- This performance is to be contrasted with the effect realized when a downward draft fume hood air flow pattern is disturbed. In such devices the result is a spill-out of fumes and hood failures which can only be overcome by drawing extraordinary amounts of air through the front of the hood.
- Various configurations can be used to provide desired air direction through grill 28. It is only required that a substantially uniform, substantial vertically upward flow of air across the entire hood front be provided. Uniformity of flow is obtained by providing a barrier means having a uniform opening or array of openings which offer a pressure equalizing restriction of the air flow path in duct 53 to the air flow from air supply 50. Perforations, reticulations and packed fibers in patterns, shapes and/ or sizes, affording substantially equal air flow open areas across the hood front as well as slotted arrangements can be used. To ensure uniformity of air flow across the air outlet, a slight back pressure should be maintained in duct 53. In general, backpressures measuring as little as 0.01 inch of water is adequate with 0.02 inch and up to 0.15 inch being preferred with up to l-inch offering advantage.
- fluorescent bulbs 46 are provided in the upper inner forward corner of the apparatus 10.
- bacteriostat is provided in the form of container 48 in open communication with the inlet side of blower 51 whereby contents of the container are educted through delivery tube 49 at a predetermined rate into the air stream emanating from the blower 51 for delivery through grill 28.
- Suitable bacteriostats include quaternary ammonium compounds, phenolic compounds, metal salts, halogens, alcohols and aldehydes in appropriate form e.g. solution, for dispersion or aspiration into an air stream.
- a fume hood structure comprising (A) a chamber including an openable front wall, a top wall, a bottom wall providing a working surface, side walls and a rear wall;
- (C) means forming a reduced pressure zone along the top wall and having an elongated inlet spaced from said rear wall;
- (D) pressurized air supply communicating with the grill and operating to displace air through the grill when the front wall is open in a vertical air curtain flow pattern across the open front of the chamber and toward said reduced pressure zone inlet, said air curtain flow acting to positively separate chamber air from outside air and to induce a circular flow of air within the chamber downwardly along the rear Wall and forwardly along the working surface to join the air curtain flow, said circular air flow defining a central zone free of turbulent air within said chamber.
- Fume hood structure according to claim 1 in which said grill includes an arrangement of openings providing multilaminar flow vertically upward from the working surface.
- Fume hood structure according to claim 1 including also means to 'biologically isolate the chamber comprising a supply of biologically active material arranged for addition to said air supply for delivery through said grill.
Landscapes
- Devices For Use In Laboratory Experiments (AREA)
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US70016768A | 1968-01-24 | 1968-01-24 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3425335A true US3425335A (en) | 1969-02-04 |
Family
ID=24812440
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US700167A Expired - Lifetime US3425335A (en) | 1968-01-24 | 1968-01-24 | Laboratory fume hood |
Country Status (1)
Country | Link |
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US (1) | US3425335A (en) |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3782362A (en) * | 1971-06-01 | 1974-01-01 | E Puzio | Baby incubator |
US4050367A (en) * | 1976-05-06 | 1977-09-27 | Marion L. Eakes Co. | Ventilating system for industrial machines |
US4050368A (en) * | 1976-01-02 | 1977-09-27 | Marion L. Eakes Co. | Exhaust system for industrial processes |
US4269615A (en) * | 1977-03-10 | 1981-05-26 | American Hospital Supply Corporation | Filter assembly |
US4315456A (en) * | 1979-12-05 | 1982-02-16 | Sanko Air Plant, Ltd. | Air-curtaining apparatus for fire protection |
US5042456A (en) * | 1988-08-19 | 1991-08-27 | Cameron Cote | Air canopy ventilation system |
US5251608A (en) * | 1988-08-19 | 1993-10-12 | Cameron Cote | Air canopy ventilation system |
US5622538A (en) * | 1995-03-28 | 1997-04-22 | Helical Dynamics, Inc. | Source capture sytem for an air cleaning system |
US5637124A (en) * | 1995-03-23 | 1997-06-10 | Helical Dynamics, Inc. | Modular air cleaning system |
US5662521A (en) * | 1995-04-06 | 1997-09-02 | Heraeus Instruments Gmbh | Safety work bench with arm rest |
US20040148753A1 (en) * | 1996-07-26 | 2004-08-05 | Dubuc Paul C. | Solid surface material fabrication station |
US20060105694A1 (en) * | 2004-06-14 | 2006-05-18 | Giovanni Tartaglia | Device and method for isolating contaminated bodies and materials |
JP2012198008A (en) * | 2011-03-22 | 2012-10-18 | National Taiwan Univ Of Science & Technology | Exhaust device having deflection plates |
US20170312797A1 (en) * | 2016-05-02 | 2017-11-02 | Kewaunee Scientific Corporation | Laboratory hood with venturi effect air intake device for anti-turbulent air flow control |
ITUA20164642A1 (en) * | 2016-06-24 | 2017-12-24 | Luca Spagolla | SUCTION DEVICE |
US10041687B1 (en) | 2005-05-17 | 2018-08-07 | Mary Ann Caneba | Vent extender method having intake air option for conveying ventilation to close proximity of a fume and odor source |
EP3797886A1 (en) * | 2019-09-25 | 2021-03-31 | Krones Aktiengesellschaft | Pretreatment machine and pretreatment method for containers |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1270613A (en) * | 1917-05-31 | 1918-06-25 | Frank A Gustavson | Ventilator and air-purifying apparatus. |
US1968532A (en) * | 1930-11-22 | 1934-07-31 | John M Liptay | Dual draft fume hood |
US2709954A (en) * | 1952-07-24 | 1955-06-07 | Arthur K Baker | Work tables |
GB864738A (en) * | 1956-06-22 | 1961-04-06 | Matthew Hall & Company Ltd | Improvements in and relating to ventilation |
-
1968
- 1968-01-24 US US700167A patent/US3425335A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1270613A (en) * | 1917-05-31 | 1918-06-25 | Frank A Gustavson | Ventilator and air-purifying apparatus. |
US1968532A (en) * | 1930-11-22 | 1934-07-31 | John M Liptay | Dual draft fume hood |
US2709954A (en) * | 1952-07-24 | 1955-06-07 | Arthur K Baker | Work tables |
GB864738A (en) * | 1956-06-22 | 1961-04-06 | Matthew Hall & Company Ltd | Improvements in and relating to ventilation |
Cited By (25)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3782362A (en) * | 1971-06-01 | 1974-01-01 | E Puzio | Baby incubator |
US4050368A (en) * | 1976-01-02 | 1977-09-27 | Marion L. Eakes Co. | Exhaust system for industrial processes |
US4050367A (en) * | 1976-05-06 | 1977-09-27 | Marion L. Eakes Co. | Ventilating system for industrial machines |
US4108051A (en) * | 1976-05-06 | 1978-08-22 | Marion L. Eakes Company | Ventilating system for industrial machines |
US4125062A (en) * | 1976-05-06 | 1978-11-14 | M. L. Eakes Co. | Ventilating system for industrial machines |
US4269615A (en) * | 1977-03-10 | 1981-05-26 | American Hospital Supply Corporation | Filter assembly |
US4315456A (en) * | 1979-12-05 | 1982-02-16 | Sanko Air Plant, Ltd. | Air-curtaining apparatus for fire protection |
US5042456A (en) * | 1988-08-19 | 1991-08-27 | Cameron Cote | Air canopy ventilation system |
US5251608A (en) * | 1988-08-19 | 1993-10-12 | Cameron Cote | Air canopy ventilation system |
US5651803A (en) * | 1995-03-23 | 1997-07-29 | Helical Dynamics, Inc. | Modular air-handling system with sealing devices |
US5637124A (en) * | 1995-03-23 | 1997-06-10 | Helical Dynamics, Inc. | Modular air cleaning system |
US5641331A (en) * | 1995-03-23 | 1997-06-24 | Helical Dynamics, Inc. | Filter suspension system for a modular air handling system |
US5656049A (en) * | 1995-03-23 | 1997-08-12 | Helical Dynamics, Inc. | Separator suspension system for a modular air handling system |
US5669947A (en) * | 1995-03-23 | 1997-09-23 | Helical Dynamics, Inc. | Latch for modular air handling system |
US5622538A (en) * | 1995-03-28 | 1997-04-22 | Helical Dynamics, Inc. | Source capture sytem for an air cleaning system |
US5662521A (en) * | 1995-04-06 | 1997-09-02 | Heraeus Instruments Gmbh | Safety work bench with arm rest |
US20040148753A1 (en) * | 1996-07-26 | 2004-08-05 | Dubuc Paul C. | Solid surface material fabrication station |
US7080443B2 (en) * | 1996-07-26 | 2006-07-25 | Dubuc Paul C | Solid surface material fabrication station |
US20060105694A1 (en) * | 2004-06-14 | 2006-05-18 | Giovanni Tartaglia | Device and method for isolating contaminated bodies and materials |
US10041687B1 (en) | 2005-05-17 | 2018-08-07 | Mary Ann Caneba | Vent extender method having intake air option for conveying ventilation to close proximity of a fume and odor source |
JP2012198008A (en) * | 2011-03-22 | 2012-10-18 | National Taiwan Univ Of Science & Technology | Exhaust device having deflection plates |
US20170312797A1 (en) * | 2016-05-02 | 2017-11-02 | Kewaunee Scientific Corporation | Laboratory hood with venturi effect air intake device for anti-turbulent air flow control |
US10807131B2 (en) * | 2016-05-02 | 2020-10-20 | Kewaunee Scientific Corporation | Laboratory hood with venturi effect air intake device for anti-turbulent air flow control |
ITUA20164642A1 (en) * | 2016-06-24 | 2017-12-24 | Luca Spagolla | SUCTION DEVICE |
EP3797886A1 (en) * | 2019-09-25 | 2021-03-31 | Krones Aktiengesellschaft | Pretreatment machine and pretreatment method for containers |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: TP INDUSTRIAL, INC. Free format text: CHANGE OF NAME;ASSIGNOR:PUREX CORPORATION;REEL/FRAME:004561/0588 Effective date: 19860418 |
|
AS | Assignment |
Owner name: TURCO PRODUCTS, INC., CALIFORNIA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:TP INDUSTRIAL, INC., A CORP OF CA.;REEL/FRAME:004561/0581 Effective date: 19860603 Owner name: PUREX CORPORATION Free format text: CHANGE OF NAME;ASSIGNOR:PUREX CORPORATION, LTD.;REEL/FRAME:004561/0586 Effective date: 19851211 Owner name: TURCO PRODUCTS, INC., 5101 CLARK AVENUE, LAKEWOOD, Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:TP INDUSTRIAL, INC., A CORP OF CA.;REEL/FRAME:004561/0581 Effective date: 19860603 |