Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
BACKGROUN D
~ilany laboratory fume hoods use an auxiliary air source from outside
the building in which the fume hood is located. This auxiliary air supply is
directed either internally into the fume hood or externally into the room so that
the auxiliary air can be swept into the fume hood along with other room air. Thepurpose of the auxiliary air supply is to reduce the amount of either heated or
cooled room air being drawn into the fume hood and exhausted through the fume
hood's exhaust system. An example of an auxiliary air type fume hood is
described in the Turko et al Patent 3,747,504. In this patent, a vertically movable
sash functions to open and close an internal dispensing opening between the
auxiliary air supply and the fume hood. When the sash is up, auxiliary air is
dispensed in the room, and conversely, when the sash is down, auxiliary air is
dispensed directly into the fume hood.
The simple auxiliary air control system described in Turko et al works
only for vertically movable sash type fume hoods. In horizontally movable sash
type fume hood's control of auxiliary air flow is a much more difficult problem.The Nelson Patent 3,604,333 attempts to solve this problem by an elaborate duct
work system that has dampers coupled to horizontally sliding sashes. These
dampers (such as 26a, 26b, and 26c) open and close in passage between the
auxiliary air distribution chamber and duct work leading to a room air dispensing.
Because the dampers moved in direct relationship to the sashes; i.e., the dampers
opened as the sash is opened and closed as the sash is closed, elaborate duct work
was required. This duct work was necessary to bring the auxiliary air in behind
the dampers, control its flow direction out through the dampers (when open)
directly above the sashes, and then direct the auxiliary air out through duct work
into the room. When the horizontal sashes were closed, the auxiliary air behind
the dampers passed through other bypass ports to a chamber in front of the
dampers and is returned back through a port directly over the sashes. Essentially
all of the complicated duct work above the fume hood was required for the
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auxiliary air con~rol. This is substanti;llly different thall t:he simple
duct wor~ at a frollt of the Tur~o et al .~uxilia~y air fume hood.
SUMMARY OF THE INV~NTION
The present invention overcomes the above problems with control-
].ing auxiliary air in fume hoods with llorizontally slidable saslles. The
fume ilood includes an auxiliary air supply with one dispensing opening
directly into the fume hood and a room dispensing openirlg. The horizontal-
ly sli.dable sash is coupled to a damper that opens and closes the
dispensing opening between the auxiliary air supply and t}-le fume hood in
an inverse manner to the closing and opening of the hori~ontal sash. Thus,
as the sash opens, the damper closes and vice versa. This inverse rela-
tionship permits very simple duct work without the need for complicated
routing of the auxiliary air.
~EEAT~D APPLICATIONS
The following co-pending, co-owned applications are related.
"liorizontal Sash Fume Hood With Auxiliary ~ir Control", filed
December 12, 1980, S N. 366~637, Zboralski; "Fume Hood With Dual Room
Air Inlet Systems", filed Decernber 12. 1980, S.N. 366,6477 Zboralski; and
"Method of Controlling Room Air Flow Into A Fume Hood", filed
December 12~ 1980, S,N. 366,636 Zboralski.
THE DRAWINGS
Figure 1 is a front elevational view of a first ~mbodiment of the
fume hood with auxiliary air supply system;
Figure 2 is a front elevational view of the fume hooù similar to
Figure 1, but with the auxiliary air duct removed;
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Figure 3 is a side elevational view of the fume hood schematically
showing the auxiliary air path in the fume hood of Figure 2 with sashes closed;
Figu~e 4 is a front elevational view of the fume hood with right s&sh
partially open;
5Figure 5 is a left end schematic view of the fume hood showing the
auxiliary air path of the fume hood in Figure 4;
Pigure 6 is a front elevation view of the fume hood showing the right
sash completely open;
Figure 7 is a front elevational view of the fume hood showing the left
10and right end sashes open;
Figure 8 is a side elevational schematic view of the fume hood showing
the auxiliary air path of the fume hood of Figure 7;
Figure 9 is a front elevational view of the fume hood with left and
right center panels open;
15Figure 10 is a front elevational view of the fume hood with left center
and right end sash panels open;
Figure 11 is a front elevational view of the fume hood with only right
center sash panel open;
Figure 12 is a front elevational view of a second embodiment of the
20fume hood with both sash panels closed; and
Figure 13 is a front elevational view of the second embodiment of the
fume hood with right sash panel open.
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DETAILEl) DESCRIPTION
Figure 1 shows a laboratory fume hood with an auxiliary air source 1
that leads into a front duct 2 for distributing the auxiliary air across the width of
the fume hood. The fume hood in the first embodiment shown in Figure 1 has
horizontally slidable sashes 3, 4, 5, and 6. These sashes are preferably of glass
and are transparent, but vertical dotted lines are used in the drawings to show
that sash 4 and sash 6 are located in front of sash 3 and sash 5.
In Figure 2, the front duct 2 has been removed to expose the wall
panel 7 shown partially cut away in Figure 3. Wall panel 7 segregates an auxiliary
air chamber 8 at a front of the fume hood. It can readily be seen that the duct
work for auxiliary air chamber 8 is extremely simple. The schematic showing of
the fume hood in Figure 3 has a typical baffle system shown in dotted line at 9
and an exhaust duct 10.
With all sash panels closed as in Figure 2, sash 4 is shown with a
connecting bar member 12, located against an abutment 13 on horizontal sliding
damper 14. Because sash 4 is wider than damper 14, sash panel 4 can horizontallymove between abutment 13 and abutment 15 on damper panel 14 without moving
the damper panel. When sash panel 4 is in the position shown in Figure 2, a
dispensing opening 16 between the auxiliary air chamber 8 and an interior of thefume hood is open. Likewise, a dispensing opening 17 into the fume hood is also
open. As can be seen, sash panel 6 has its own bar member which can laterally
slide between abutment members on a damper 18. When the bar member contacts
such abutment members, it thereafter slides the damper along with the sash
panel.
In Figure 4, the right end panel 6 has been partially opened, which in
turn partially closes the dispensing opening 17. Dispensing opening 16 remains
open because sash panels 3 and 4 are in the positions shown in Figure 4. In Figure
'5
5, the auxiliary air is directed through dispensing openings 16 and 17 directly into
the fume hood's interior. There is also an external dispensing opening designated
at 20, which is located outside the fume hood and through which auxiliary air can
enter the room containing the fume hood. Thus, as the fume hood draws in room
air, it will also draw in a portion of the auxiliary air to reduce the loss of heated
or cooled room air. With the sash panel positions shown in Figure 6, it can be seen
that the completely opening of sash panel 6 automatically causes damper panel 18to completely close off dispensing opening 17. Dispensing opening 16 above panel4 remains open.
When both left and right end sash panels are open as shown in Figure 7,
sash panel 4 is directly in front of sash panel 3. Also, sash panel 6 is directly in
front of sash panel S. Here sash panel 3 has a bar member 22 that engages an
abutment member (not shown) on damper panel 23. Damper panel 23 is located
behind wall panel 7 and slidingly moves with sash panel 3 in much the same way
damper panel 14 moves with sash panel 4. As shown in Figures 7 and 8, with both
dispensing openings 16 and 17 being fully closed, all auxiliary air dumps into the
room containing the fume hood and is sucked into the open sashes.
When the two center sash panels are open as illustrated in Figure 9,
damper panel 14 closes dispensing opening 16 and damper panel 25 is moved by a
bar member 26 on sash panels 5 when sash panel 5 is movea to the right directly
behind sash panel 6. Damper panel 25 has laterally spaced abutment members
(not shown) projecting from its rear surface for contacting bar member 26. It
should be recognized that damper panel 25 is behind wall panel 7.
In still another opening configuration of Figure 10, the left center and
right end sash panels are opened. This causes damper panel 14 to close off
dispensing passage 16 and damper panel 18 to close off dispensing opening 17.
Thus, all of the auxiliary air is dispensed into the room containing the fume hood.
Figure 11 shows an opening configuration in which the right center
sash panel is open. ~lere damper panel 25, located behind wall panel 7, is movedby sash panel 5 to close off dispensing opening 17. Sash panel 5 is located directly
behind sash panel 6. Dispensing opening 16 remains open so that the auxiliary air
is proportioned between direct flow into the fume hood and dispenseà into the
room containing the fume hood.
In the above Figures 1-11, a first embodiment of the fume hood has
been illustrated which has four independently slidable horizontal sash panels. In
Figures 12 and 13, a second embodiment of the invention is shown which has two
independently slidable horizontal sash panels. In Figure 12, sash panels 40 and 41
are closed so that a damper panel 42 is moved to expose a dispensing opening 43
directly into the fume hood. In Figure 13, sash panel 41 is moved to the left and
il3 in front of sash panel 40. This causes damper panel~t to move to the left and
cover dispensing opening 43.
The sash panels and damper panels can slide along a track system
shown generally as 45. Preferably, the sash panels are suspended from rollers that
ride along track system 45 and damper panels, such as 42, have rollers at their
base for riding in such track system.
In the foregoing description, specific examples have been used to
describe the invention. However, it is understood by those skilled in the art that
certain modifications can be made to these examples without departing from the
spirit and scope of the invention.
