US3752056A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laboratory exhaust hood
Assignee: EH Sheldon and Co
•
Filing: 1970-11-04
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Granted: 1973-08-14
•
Expires: 1990-11-04
Abstract
Abstract A laboratory exhaust hood is described including in combination a hood superstructure and a novel auxiliary air supply plenum. The auxiliary air supply plenum is of modular design suitable for use wherever an efficient conversion of a relatively high energy air stream of a given cross sectional area to a much lower energy laminar air stream of larger cross sectional area is desired. In particular, the auxiliary air supply is adapted for incorporation with a conventional laboratory exhaust hood, and has exterior vertical front, rear and end walls and a cover and interior baffles which define an air entry chamber, an air slot at the top of said chamber, an expansion chamber extending downward from the slot, an air balance chamber and an air supply outlet. Within the plenum, an air vector controller is positioned between the expansion chamber and the air balance chamber, and the final air balance means, including a back pressure plate, an air jet entrainment eliminator, and a shallow chamber therebetween, is positioned between the air balance chamber and the air outlet. The combination of the hood superstructure and the auxiliary air supply plenum includes a movable vertical closure sash and immediately above it, when the sash is closed, a sight-tight bypass. Beneath the closed sash is a horizontal air foil for the provision of a flow of air across the work surface of the hood, by the entrainment of room air in auxiliary air jets.
Inventors
- 👤 R Chamberlin
- 👤 J Leahy
- 👤 F Viles
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:34
CPC Classifications
B; B08; B08B; B08B15/00; B08B15/02; B08B15/023
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
117 words
Apparatus for converting a rapidly moving air stream to slower air having substantially laminar flow free of localized non-uniform energy comprising: receiving means comprising an entry chamber for receiving said air stream; means including two diverging walls for expanding the flow of said stream substantially uniformly across the cross-section of its flow; and means for distributing the flow of said stream substantially uniformly from said receiving means to said expansion means; said distributing means comprising an elongated slot having a crosssectional area which is sufficiently smaller than the crosssectional area of said entry chamber transverse to the flow of said air to promote a spreading of the flow of said air into such slot along its length.
Claim 2
Dependent Claim
117 words
Apparatus for converting a rapidly moving air stream to slower air having substantially laminar flow free of localized non-uniform energy comprising: receiving means comprising an entry chamber for receiving said air stream; means including two diverging walls for expanding the flow of said stream substantially uniformly across the cross-section of its flow; and means for distributing the flow of said stream substantially uniformly from said receiving means to said expansion means; said distributing means comprising an elongated slot having a crosssectional area which is sufficiently smaller than the crosssectional area of said entry chamber transverse to the flow of said air to promote a spreading of the flow of said air into such slot along its length.
Claim 3
Dependent Claim
115 words
Apparatus for converting a rapidly moving air stream to slower air having substantially laminar flow free of localized non-uniform energy, comprising: receiving means comprising an entry chamber for receiving said air streams; means including two diverging walls for expanding the flow of said stream substantially uniformly across the cross-section of its flow; and means comprising a passage between said receiving means and said expansion means for distributing the flow of said stream substantially uniformly from said receiving means to said expansion means, wherein said entry chamber and air expansion means are adjacent, share one of said walls as a common wall, and are constructed and arranged to reverse the direction of flow of said stream.
Claim 4
Dependent Claim
115 words
Apparatus for converting a rapidly moving air stream to slower air having substantially laminar flow free of localized non-uniform energy, comprising: receiving means comprising an entry chamber for receiving said air streams; means including two diverging walls for expanding the flow of said stream substantially uniformly across the cross-section of its flow; and means comprising a passage between said receiving means and said expansion means for distributing the flow of said stream substantially uniformly from said receiving means to said expansion means, wherein said entry chamber and air expansion means are adjacent, share one of said walls as a common wall, and are constructed and arranged to reverse the direction of flow of said stream.
Claim 5
Dependent Claim
116 words
Apparatus for converting a rapidly moving air stream to slower moving air having substantially laminar free flow of localized non-uniform energy, comprising means for receiving said air stream; means including two diverging walls for expanding flow of said stream substantially uniformly across the cross section of its flow; means comprising a passage between said receiving means and said expansion means for distributing the flow of said stream substantially uniformly from said receiving means to said expansion means; and means for air jet entrainment being downstream of said expansion means and including a multiplicity of closely spaced widely distributed air flow openings, together with means operatively associated with said openings upstream thereof for effecting a slight back-pressure.
Claim 6
Dependent Claim
116 words
Apparatus for converting a rapidly moving air stream to slower moving air having substantially laminar free flow of localized non-uniform energy, comprising means for receiving said air stream; means including two diverging walls for expanding flow of said stream substantially uniformly across the cross section of its flow; means comprising a passage between said receiving means and said expansion means for distributing the flow of said stream substantially uniformly from said receiving means to said expansion means; and means for air jet entrainment being downstream of said expansion means and including a multiplicity of closely spaced widely distributed air flow openings, together with means operatively associated with said openings upstream thereof for effecting a slight back-pressure.
Claim 7
Dependent Claim
24 words
The apparatus of claim 3 further characterized by an air balance chamber between said air expansion means and said air jet entrainment elimination means.
Claim 8
Dependent Claim
142 words
An auxiliary air supply plenum of modular design suitable for incorporation with a conventional laboratory exhaust hood, which hood is provided with an air exhaust means, an interior work space, a front face, and a movable closure sash in said face for supplying a substantially uniform laminar flow of auxiliary air to said exhaust hood, said auxiliary air supply comprising: exterior front, rear and end walls, a cover and interior baffles defining (1) an air entry chamber, (2) a slot along the upper edge of one wall of said entry chamber, (3) an expansion chamber extending vertically downwardly from said slot toward the interior of the plenum and (4) an air supply outlet downstream of said expansion chamber; wherein said chambers, slot and outlet extend substantially the length of said plenum and said outlet extends substantially across the width of said plenum.
Claim 9
Dependent Claim
142 words
An auxiliary air supply plenum of modular design suitable for incorporation with a conventional laboratory exhaust hood, which hood is provided with an air exhaust means, an interior work space, a front face, and a movable closure sash in said face for supplying a substantially uniform laminar flow of auxiliary air to said exhaust hood, said auxiliary air supply comprising: exterior front, rear and end walls, a cover and interior baffles defining (1) an air entry chamber, (2) a slot along the upper edge of one wall of said entry chamber, (3) an expansion chamber extending vertically downwardly from said slot toward the interior of the plenum and (4) an air supply outlet downstream of said expansion chamber; wherein said chambers, slot and outlet extend substantially the length of said plenum and said outlet extends substantially across the width of said plenum.
Claim 10
Dependent Claim
43 words
The air supply plenum of claim 5 wherein the width of said slot is no more than one-half the height of said entry chamber, and said entry chamber and said expansion chamber share a common wall havIng said slot at the top thereof.
Claim 11
Dependent Claim
66 words
The air supply plenum of claim 5, wherein an air balance chamber and final air balance means are provided between said expansion chamber and said outlet, said air balance means including (1) a back pressure plate perforated with laminar flow holes substantially uniformly across its width and length, (2) an air jet entrainment eliminator, and (3) a shallow chamber between said plate and said entrainment eliminator.
Claim 12
Dependent Claim
86 words
The air supply plenum of claim 7, wherein the dimensions and orientation of the elements thereof are such that: kAfw s + 2(l+h) tan ( theta /2) ; wherein k is at least 1.4, Af is the free area of said plate, w is the width of said plenum, s, the width of said slot, is 1.4-1.8 inches, l is the length of said expansion chamber, h is the height of said balance chamber, and theta , the expansion angle of said expansion chamber, is 7*-12*.
Claim 13
Dependent Claim
88 words
The air supply plenum of claim 7, wherein said air supply outlet is provided on each of its end walls with curved profile vanes, whereby air exiting said plenum tends to assume a flow rate profile parabolic in shape along the length of the outlet, and the portion of the front wall defining the front of the air supply outlet is an adjustable vane hinged at the top and adjustable from the vertical toward the rear wall of the outlet, whereby the auxiliary air velocity may be varied.
Claim 14
Dependent Claim
46 words
The air supply plenum of claim 7 wherein said back pressure plate is a fin-tube heat exchanger, whereby auxiliary air may be heated between said air balance chamber and said shallow chamber without affecting the substantially uniform laminar flow of air from said air supply outlet.
Claim 15
Dependent Claim
129 words
A laboratory exhaust hood, having an open face, a bypass incorporated in said hood above said open face, a movable closure sash adapted to move from an open position, in which it closes said bypass and opens said face, to a closed position in which it opens said bypass and closes said open face, and means to maintain the total volumetric flow of air into said hood substantially constant during movement of said movable closure sash from its open position to its closed position comprising a plurality of substantially parallel walls arranged in said bypass sequentially in angular relation to provide a sight-tight labyrinth, wherein the angular relation of said walls forming said labyrinth to change direction within the range of substantially 50* to 70* at any one corner.
Claim 16
Dependent Claim
129 words
A laboratory exhaust hood, having an open face, a bypass incorporated in said hood above said open face, a movable closure sash adapted to move from an open position, in which it closes said bypass and opens said face, to a closed position in which it opens said bypass and closes said open face, and means to maintain the total volumetric flow of air into said hood substantially constant during movement of said movable closure sash from its open position to its closed position comprising a plurality of substantially parallel walls arranged in said bypass sequentially in angular relation to provide a sight-tight labyrinth, wherein the angular relation of said walls forming said labyrinth to change direction within the range of substantially 50* to 70* at any one corner.
Claim 17
Dependent Claim
73 words
The laboratory exhaust hood of claim 11, wherein said hood has a front wall in which said open face is located, and said hood is also provided with an auxiliary air supply plenum located above said open face, and wherein said bypass is constructed of a series of angled louver vanes extending horizontally across the length of said front wall from the bottom of said plenum to the top of said open face.
Claim 18
Dependent Claim
34 words
The laboratory exhaust hood bypass of claim 12, wherein said louver vanes are angled to form a vertical series of V-shaped passages and adapted to induce an upward direction upon air traversing said bypass.
Claim 19
Dependent Claim
122 words
A laboratory exhaust hood including in combination a hood superstructure having a vertical, rectangular face and a movable vertical closure sash, and an auxiliary air supply plenum, comprising: means within said auxiliary air supply plenum to provide auxiliary air substantially vertically downwardly from said plenum toward said open face of said hood superstructure and in substantially uniform laminar flow; bypass means operative upon the closing of said movable, vertical closure sash to direct at least a portion of said auxiliary air into said hood super-structure by passage through a sight-tight by-pass above said sash; and means to maintain the total volumetric flow of air into said hood superstructure substantially constant during movement of saId movable closure between its open and closed positions.
Claim 20
Dependent Claim
122 words
A laboratory exhaust hood including in combination a hood superstructure having a vertical, rectangular face and a movable vertical closure sash, and an auxiliary air supply plenum, comprising: means within said auxiliary air supply plenum to provide auxiliary air substantially vertically downwardly from said plenum toward said open face of said hood superstructure and in substantially uniform laminar flow; bypass means operative upon the closing of said movable, vertical closure sash to direct at least a portion of said auxiliary air into said hood super-structure by passage through a sight-tight by-pass above said sash; and means to maintain the total volumetric flow of air into said hood superstructure substantially constant during movement of saId movable closure between its open and closed positions.
Claim 21
Dependent Claim
58 words
The laboratory exhaust hood combination of claim 14, wherein further means are provided to control the maximum face velocity of the air entering the hood superstructure through said rectangular open face during the movement of said movable closure from its open position to its closed position between 2-3 times that of normal operation, with a fully opened sash.
Claim 22
Dependent Claim
122 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; and b. auxiliary air supply means including means to provide auxiliary air from a point above said open vertical face downwardly to substantially all parts of said open face in a substantially uniform laminar flow: wherein said auxiliary air supply means comprises an entry chamber, a slot in one wall of said entry chamber having a width no more than one-half the dimension of said entry chamber parallel to said slot, and an expansion chamber extending from said slot.
Claim 23
Dependent Claim
122 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; and b. auxiliary air supply means including means to provide auxiliary air from a point above said open vertical face downwardly to substantially all parts of said open face in a substantially uniform laminar flow: wherein said auxiliary air supply means comprises an entry chamber, a slot in one wall of said entry chamber having a width no more than one-half the dimension of said entry chamber parallel to said slot, and an expansion chamber extending from said slot.
Claim 24
Dependent Claim
141 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; and b. auxiliary air supply means including means to provide auxiliary air from a point above said open vertical face downwardly to substantially all parts of said open face in a substantially uniform laminar flow: wherein said auxiliary air supply means comprises an entry chamber, a slot in one wall of said entry chamber having a width no more than one-half the dimension of said entry chamber parallel to said slot, and an expansion chamber extending from said slot and having an expansion angle of about 7*-12*, an air balance chamber, and means for air jet entrainment elimination.
Claim 25
Dependent Claim
141 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; and b. auxiliary air supply means including means to provide auxiliary air from a point above said open vertical face downwardly to substantially all parts of said open face in a substantially uniform laminar flow: wherein said auxiliary air supply means comprises an entry chamber, a slot in one wall of said entry chamber having a width no more than one-half the dimension of said entry chamber parallel to said slot, and an expansion chamber extending from said slot and having an expansion angle of about 7*-12*, an air balance chamber, and means for air jet entrainment elimination.
Claim 26
Dependent Claim
132 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; and b. auxiliary air supply means including means to provide auxiliary air from a point above said open vertical face downwardly to substantially all parts of said open face in a substantially uniform laminar flow: wherein a bottom air foil is provided in front of and immediately above said horizontal work surface to define the bottom edge of said open face and air conduit means are provided between said auxiliary air supply means and said airfoil, including means to entrain room air across said work surface under said airfoil.
Claim 27
Dependent Claim
132 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; and b. auxiliary air supply means including means to provide auxiliary air from a point above said open vertical face downwardly to substantially all parts of said open face in a substantially uniform laminar flow: wherein a bottom air foil is provided in front of and immediately above said horizontal work surface to define the bottom edge of said open face and air conduit means are provided between said auxiliary air supply means and said airfoil, including means to entrain room air across said work surface under said airfoil.
Claim 28
Dependent Claim
182 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow; wherein said auxiliary air supply means comprises an entry chamber, a slot in one wall of said entry chamber having a width no more than one-half the dimension of said entry chamber parallel to said slot, and an expansion chamber extending from said slot.
Claim 29
Dependent Claim
182 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow; wherein said auxiliary air supply means comprises an entry chamber, a slot in one wall of said entry chamber having a width no more than one-half the dimension of said entry chamber parallel to said slot, and an expansion chamber extending from said slot.
Claim 30
Dependent Claim
222 words
A laboratorY exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow: wherein said auxiliary air supply means comprises: exterior vertical front, rear and end walls, a cover and interior baffles defining (1) an air entry chamber, (2) a slot at the top of the plenum and said entry chamber, (3) an expansion chamber extending vertically downwardly from said slot toward the interior of the plenum, and (4) an air supply outlet; wherein said chambers, slot and outlet extend substantially the length of said plenum, and said outlet extends substantially across the width of said plenum.
Claim 31
Dependent Claim
222 words
A laboratorY exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow: wherein said auxiliary air supply means comprises: exterior vertical front, rear and end walls, a cover and interior baffles defining (1) an air entry chamber, (2) a slot at the top of the plenum and said entry chamber, (3) an expansion chamber extending vertically downwardly from said slot toward the interior of the plenum, and (4) an air supply outlet; wherein said chambers, slot and outlet extend substantially the length of said plenum, and said outlet extends substantially across the width of said plenum.
Claim 32
Dependent Claim
192 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow: wherein a bottom air foil is provided in front of and immediately above said horizontal work surface to define the bottom edge of said open face, and air conduit means are provided between said auxiliary air supply means and said airfoil, including means to entrain room air across said work surface under said airfoil.
Claim 33
Dependent Claim
192 words
A laboratory exhaust hood including in combination a hood superstructure and an auxiliary air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow: wherein a bottom air foil is provided in front of and immediately above said horizontal work surface to define the bottom edge of said open face, and air conduit means are provided between said auxiliary air supply means and said airfoil, including means to entrain room air across said work surface under said airfoil.
Claim 34
Dependent Claim
209 words
A laboratory exhaust hood including in combination a hood superstructure and an air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly through an outlet at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow; said auxiliary air supply means also including an air balance chamber provided with a perforated back pressure plate and a shallow chamber between said air balance chamber and said outlet; wherein said back pressure plate is a fin-tube heat exchanger, whereby auxiliary air may be heated between said air balance chamber and said shallow chamber without affecting the substantially uniform laminar flow of air from said air supply outlet.
Claim 35
Dependent Claim
209 words
A laboratory exhaust hood including in combination a hood superstructure and an air supply plenum, comprising: a. a horizontal work surface, a rear wall, side walls, and a front wall including an open vertical face immediately in front of said work surface; b. a sight-tight bypass within said front wall immediately above said open face; c. a movable, vertical closure sash located on tracks immediately inside said front wall and operable to open such face and to close said bypass when at the upper end of said tracks and to close said face and to open said bypass when at the lower end; and d. auxiliary air supply means including means to provide auxiliary air substantially vertically downwardly through an outlet at a point above said open vertical face and in front of said bypass in substantially uniform laminar flow; said auxiliary air supply means also including an air balance chamber provided with a perforated back pressure plate and a shallow chamber between said air balance chamber and said outlet; wherein said back pressure plate is a fin-tube heat exchanger, whereby auxiliary air may be heated between said air balance chamber and said shallow chamber without affecting the substantially uniform laminar flow of air from said air supply outlet.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-13 | 1977-02-12 | 1977-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-13 | 1981-02-12 | 1981-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-13 | 1985-02-12 | 1985-08-14 | $7700.00 | Window Closed / Lapsed |