Fume hood and method for operating a fume hood

FIELD OF INVENTION

The present invention relates to a fume hood, and more particularly, to a fume

hood capable of providing an auxiliary gas into its working space. Furthermore,

the present invention further relates to a method for operating a fume hood.

BACKGROUND OF THE INVENTION

A fume hood is a common basic laboratory instrument and is used to force

fumes (gases), especially pernicious gases produced by an experiment within its

working space, be exhausted through a given outlet rather than leaking into other

areas of a laboratory. For chemical workers, fume hoods are their protectors. To

some extent, laboratory safety depends on proper functioning and operation of the

fume hoods.

A fume hood typically exhausts the gases inside its cabinet by compulsive

suction. For a conventional fume hood, supplementary gases such as air, from the

room in which the hood is situated usually flows into the cabinet through an

opening to make up for the pressure imbalance caused by the exhausted gases. This

may have adverse effects on the air flow and air pressure in the room, causing the

load and energy consumption of the air conditioner if the room is air conditioned.

The amount of air taken to supplement the exhausted gases can be very large if a

large number of fume hoods are operating in a laboratory. So the air flow and air

pressure in the laboratory can be significantly impacted, causing a large amount of

outside air to enter the laboratory through other channels (such as windows and

doors), largely increasing energy consumption by the air conditioner.

Therefore, it is desirable to develop a fume hood containing an auxiliary gas

device that efficiently channels an auxiliary gas into the cabinet from an outside

space without having the auxiliary gas go through a room in which the fume hood

is situated.

SUMMARY OF THE INVENTION

In one aspect, an embodiment of the present invention provides a fume hood

comprising a cabinet, an exhaust outlet and an auxiliary gas device. The cabinet

defines an enclosed working space and the exhaust outlet communicates to the

working space. The auxiliary gas device comprises an auxiliary gas passage and

the auxiliary gas passage communicates to the working space through an outlet of

the auxiliary gas passage. The auxiliary gas device can direct auxiliary gases into

the working space from an outside space or environment relative to a room the

fume hood located. Specially, the outlet of the auxiliary gas passage is adjustable

so as to control at least one of a location and direction at which the auxiliary gas

enters the working space. For example, the outlet can be adjusted to adjust a

position of the outlet, a size of an opening of the outlet, a direction of the auxiliary

gas out of the outlet, and combinations thereof. For example, the outlet can be

adjusted to adjust the outlet up and down movement, left and right movement, and

the like.

In another aspect, an embodiment of the present invention provides a method

of operating a fume hood. The fume hood has a cabinet and a working platform

inside the cabinet for holding pernicious gases generating materials. The cabinet

includes an exhaust outlet and defining a working space of about 0.5 cubic meter

to about 3 cubic meter in size above the working platform. The method comprises

steps of directing auxiliary gases from an outdoor environment into the working

space, and adjusting at least one of a location and a direction at which the auxiliary

gases enter the working space such that the auxiliary gases flow along a desired

path to bring pernicious gases out of the working space through the exhaust outlet.

During this process, the auxiliary gas can be directed into the working space in

different position and/or different flow direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1 is a side cutaway view of a fume hood to illustrate its sash in a half open

status according to one embodiment of the present invention;

Fig.2 is a side cutaway view of the fume hood in Fig.l to illustrate its sash in

a closed status;

Fig.3 is a front cutaway view of the fume hood in Fig. l;

Fig.4 is a side cutaway view of a fume hood to illustrate its sash in a closed

status according to another embodiment of the present invention;

Fig.5 is a sketch view of a steering device of the fume hood in Fig.4;

Fig.6 is a sketch view of another steering device of the fume hood in Fig.4;

Fig.7 is a side cutaway view of a fume hood according to yet another

embodiment of the present invention;

Fig.8 is a front cutaway view of the fume hood in Fig.7.

Fig.9 is a layout view of a fume hood according to one embodiment of the

present invention;

Fig.10 is a layout view of a fume hood according to another embodiment of

the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In embodiments of the present invention, supplementary gases for a fume

hood are taken from two sources. One source is ambient gases, mainly natural air,

in a room in which the fume hood is installed or situated. Another source is an

auxiliary gas or gases, from an outside space or environment other than the room

in which the fume hood is installed or situated. The auxiliary gas may also be gases

from a special gas source, such as air, nitrogen, carbon dioxide, and so on, in a

container. The auxiliary gas can be directed into a working space of a cabinet of

the fume hood through a gas supply device and an auxiliary gas device. Compared

to the ambient gas, the auxiliary gas is a main source of the supplementary gas.

Therefore, a utilization of the ambient gas is reduced and the load of air

conditioner is decreased accordingly.

Below, detailed description on embodiments of the present invention will be

given with reference to the attached figures.

Referring to Fig.l to Fig.3, a fume hood 100 according to one embodiment of

the present invention comprises a cabinet 1, an exhaust outlet 2 and an auxiliary

gas device 3 containing an inlet 31 (mainly for the auxiliary gas), a diffuser

chamber 32, an auxiliary gas passage 33 and outlet 34 of the auxiliary gas passage

33.

Alternatively or additionally, one side 10 of the cabinet 1 is open (hereinafter

referred to as "the open side" 10), and a sash capable of being opened and closed is

mounted on the open side 10. For example, in one embodiment the sash is selected

as a sliding sash 331 capable of moving up and down and the sliding sash 331 is

one wall of the auxiliary gas passage 33. The up and down movement of the

sliding sash 331 can be achieved by any related means in the existing or following

developed technique, such as by guiding orbits located on a front portion of two

side panels of the cabinet 1.

In different embodiments the sash can be a movable sash capable of moving

up and down, or can be a movable sash capable of moving left and right, or there

can be other means, and whatever the means is, it is called as a sash in the present

invention. Of course, in some embodiments there is no need to set such a sash, for

example, under a condition that a wall of the auxiliary gas passage 33 can be

naturally used as the sash of the open side 10.

Other sides of the cabinet 1 are closed. A working platform 11 is set up on a

bottom panel of the cabinet 1. In one embodiment, the working platform 11 is part

or whole of the bottom panel of the cabinet 1. Opposite the working platform 11 is

a top panel 12 of the cabinet 1, and opposite the open side 10 is a back panel 13 of

the cabinet 1. The cabinet 1 has other sides, which are referred as to side panels 14

of the cabinet 1. The cabinet 1 defines a working space 15, which can be part or all

of an internal space of the cabinet 1. In one embodiment, the working space 15 is

of about 0.5 cubic meter to about 3 cubic meter in size, alternatively, is of about 1

cubic meter to about 2 cubic meter in size. A portion of the working space 15 near

the open side 10 is referred as to a front portion of the working space 15.

In one embodiment, the inlet 31 can be located on an upper portion of the

auxiliary gas device 3 and connected to a gas supply device (not shown) positioned

above the cabinet 1. The diffuser chamber 32 is located between the inlet 31 and

the auxiliary gas passage 33. The inlet 31 and the diffuser chamber 32 can be

fixedly mounted near a rear upper portion of the open side 10. The auxiliary gas

passage 33 can be up and down movably mounted near the open side 10.

In other embodiment, if a separate sash is mounted on the open side 10, the

auxiliary gas passage 33 can be located, but not limited to, at a rear side of the sash,

namely the front portion of the working space 15; or at a front side of the sash,

namely an exterior of the working space 15 directly facing an operator when he is

standing before the open side 10 for handling or observing an experiment in the

working space 15; or on the open side 10 if without a separate sash, for example,

this condition happens when the sash acts as one wall of the auxiliary gas passage

33 (for example, as the arrangement shown in Fig.l); or near a side panel or other

positions of the cabinet 1.

The auxiliary gas passage 33 can be a cuboid chamber. In one embodiment,

the sliding sash 331 is configured as a front wall of the auxiliary gas passage 33,

namely one wall facing the above-mentioned operator. Therefore, when the sash

331 is closed, the auxiliary gas passage 33 can still provide the auxiliary gas into

the working space 15. Furthermore, the fume hood can be operated easily and be

simplified its structure, so that manufacture costs are saved for the sash 331 and

the auxiliary gas passage 33 being combined.

In one embodiment, the front wall 331 and a back wall 332 opposite to the

front wall 331 of the auxiliary gas passage 33 can be configured to move up and

down as a whole relative to other elements of the fume hood. Therefore the up and

down movement of the sash 331 will drive the whole auxiliary gas passage 33 to

move up and down, so that the outlet 34 of the auxiliary gas passage can move up

and down accordingly.

For the auxiliary gas passage 33 capable of up and down movement, in other

embodiment, the front wall 331 and the back wall 332 can be configured to move

up and down against each other, namely, not only relative to other elements of the

fume hood, but also relative to each other. Therefore, both a position of the outlet

and a size of an opening of the outlet 34 can be adjusted.

According to embodiments of the present invention, the up and down

movement of the auxiliary gas passage 33 can be achieved by many means. When

an up and down sliding sash is mounted on the open side 10, the auxiliary gas

passage 33 can be set to move up and down with the sliding sash. For example, the

auxiliary gas passage 33 is mounted on the sliding sash, and when the sash moves

it will lead the auxiliary gas passage 33 to move. Alternatively, as the fume hood

illustrated in Fig.1 , the sliding sash is configured as one wall or portion of one wall

of the auxiliary gas passage 33, and the up and down movement of the sash can

drive the movement of the auxiliary gas passage 33; or there can be other means to

make the auxiliary gas passage 33 move with the up and down movement of the

sash. For any type of sash or for no sash available, the auxiliary gas passage 33 can

be positioned at the open side 10 of the cabinet 1 , and be set to move up and down

independent of the sash or other elements of the cabinet. For example, a guiding

orbit can be mounted separately on a front portion of the two side panels 14 of the

cabinet 1 (namely, a portion adjacent to the open side 10, e.g. a jamb of the two

side panels 14), and the auxiliary gas passage 33 can be easily set to move up and

down once mounted on the guiding orbit. The detailed means for the up and down

movement of the auxiliary gas passage 33 can be any means related to the existing

technique or later developed techniques, and more description is omitted here.

As for the auxiliary gas passage 33, it can be a passage with any structure that

functions to guide gases. The auxiliary gas passage 33 can be alternatively

configured with affiliated devices like a leading device and/or a steering device.

In one embodiment, the two walls of the auxiliary gas passage 33 facing the

working space 15 can be parallel to each other, for example, the front wall 331 and

the back wall 332 of the auxiliary gas passage 33 are parallel, so that the auxiliary

gas can flow evenly along the whole length of the auxiliary gas passage 33 without

turbulence resulted from pressing against the gas flow because of size changes in

the cross section of the auxiliary gas passage 33.

In one embodiment, the auxiliary gas device 3 further comprises a steering

device, which can be used to control a flow direction of the auxiliary gas into the

working space 15. The steering device can be positioned in the auxiliary gas

passage 33. The steering device can also be positioned out of the auxiliary gas

passage 33, for example the working platform 11 of the cabinet 1 corresponding to

the outlet 34 of the auxiliary gas passage 33. In one embodiment, the steering

device is positioned at the outlet 34 of the auxiliary gas passage 33. Therefore, a

direction of the auxiliary gas out of the outlet 34 is adjustable.

For the fume hood 100 as shown in Fig.l, the steering device includes a baffle

333 tilted towards the working space 15 and at a bottom portion of the auxiliary

gas passage, for example, at a bottom of the front wall 331 of the auxiliary gas

passage 33. The baffle 333 can be planar or curving. The baffle 333 acts as the

steering device for controlling the flow direction of the auxiliary gas into the

working space 15.

The baffle 333 can be integrally formed with the front wall 33 lor fixedly

attached on the front wall 331 of the auxiliary gas passage 33. In one embodiment,

there is an acute angle between the baffle 331 and a downward stretched direction

of the front wall 333. Alternatively, the acute angle is at 30°to 60°. Alternatively,

the acute angle is at 40°to 50°.

At a bottom of the auxiliary gas passage 33, in one embodiment, a horizontal

altitude of a bottom rim of the back wall 332 is higher than that of a bottom rim of

the baffle 333. Alternatively, a height difference between the back wall 332 and the

total height of the front wall 331 and the baffle 333 is about 0.5-50% of the total

height. Alternatively, the height difference is about 3-25% of the total height.

Alternatively, the height difference is about 5-15% of the total height. The optimal

value of acute angle and the height difference shall be calculated based on an

exhaust amount and a size of the auxiliary gas passage.

Of course, in other embodiments, the bottom rim of the back wall 332 can

also be at the same horizontal level with the bottom rim of the baffle 333, or under

the horizontal level of the bottom rim of the baffle 333, as long as the auxiliary gas

can be directed into the working space 15.

In this embodiment, the auxiliary gas passage 33 is set to have a same width

with that of the open side 10. However, in other embodiments, the auxiliary gas

passage 33 can be set only to cover a portion of the open side 10.

In other embodiment of the present invention, the baffle 333 can be capable of

rotating relative to the front wall 331 of the auxiliary gas passage 33, for example,

the baffle 333 is rotatably mounted at the bottom of the auxiliary gas passage such

as the bottom of the front wall 331. Therefore, the angle between the baffle 333

and the front wall 331 can be adjusted based on practical needs. Accordingly, the

flow direction of the auxiliary gases into the working space 15 can be adjusted.

In one embodiment, due to the height difference between the back wall 332

and the front wall 331, and the fact that the back wall 332 is the less one in height,

and further that the baffle 333 is tilted towards at the bottom of the front wall 331,

when the auxiliary gases are diverted towards the working space 15 after

encountering the baffle 333, they flow freely into the working space 15 almost

without any restriction, and almost no auxiliary gases escape into the room in

which the fume hood is installed or situated. When the auxiliary gas passage 33 is

adjusted to move up, due to the height difference and the baffle 333, almost all the

auxiliary gases are directed into an upper portion of the working space 15, while

ambient gases (mainly room air) flow into a lower portion of the working space.

When the auxiliary gas passage 33 is adjusted to move down to the working

platform 11, the baffle 333 is basically close to the working platform 11 so that

almost no ambient gases are permitted to flow into the working space 15 and

fumes in the working space 15 is efficiently prevented from leaking into the room.

Further, there is a big gap between the passage 33 and the working platform 11

since the back wall 332 of the auxiliary gas passage 33 is on a relatively high level.

Therefore, the auxiliary gases can still be led into the working space 15 and the

supplementary gases entering into the working space 15 are mainly the auxiliary

gases from the auxiliary gas passage 33.

In one embodiment, the diffuser chamber 32 is configured to spread the

auxiliary gas toward two opposite sides of the cabinet 1 , and a diffuser means for

uniformly diffusing the auxiliary gas is mounted within the diffuser chamber 32.

As shown in Fig.3, the diffuser means is selected as several boards abreast located

within the diffuser chamber 32, and further these boards are located along the air

flow direction and angled to each other. Therefore, the auxiliary gas can be

directed to be uniformly distributed and a continuous gas curtain is formed within

the auxiliary gas passage 33.

In other embodiment, the diffuser chamber 32 can be configured with at least

one porous board positioned vertical to the flow direction; or configured with other

structure capable of directing the auxiliary gas into the auxiliary gas passage 33

with the gas being evenly distributed on the cross section vertical to the flow

direction, so as to make the gas uniformly distributed and to form a continuous gas

curtain within the auxiliary gas passage 33.

As shown in Figs.9 and 10, in one embodiment, the fume hood 100 is located

in a laboratory room 60, which can be part or all of a building 70. The term

"outdoor space or environment" means a space or environment outside the

laboratory room 60 or building 70.

In one embodiment, an auxiliary gas supply device can be positioned at the

top of the cabinet 1 and the auxiliary gas supply device communicates to the inlet

31 of the auxiliary gas device 3. The auxiliary gas supply device can exemplarily

comprise a supply pipe or channel, a draft fan, controlling elements for controlling

a flow and pressure of the auxiliary gas, and other elements (not shown), such that

it is capable of guiding the auxiliary gas from the outside space or a special gas

source into the auxiliary gas device 3 through the inlet 31.

For example, as shown in Fig.9, the inlet 31 of the auxiliary gas device 3

communicates with a supply channel 35 leading to the outdoor environment

relative to the building 70. The auxiliary gases from the outdoor environment are

led into the supply channel 35 through its one port 351. And then the auxiliary

gases within the supply channel 35 are directed into the working space 15 through

the outlet 34 of the auxiliary gas device 3 after passing through the auxiliary gas

device 3. Alternatively, as shown in Fig.10, the inlet 31 of the auxiliary gas device

3 communicates with a supply channel 35 leading to the building 70, and the

supply channel 35 is part of a special gas source 50 located in the building 70.

In another embodiment, under a condition that a plurality of fume hoods are

be in use, these fume hoods can share a general auxiliary gas supply device for

guiding the auxiliary gas into each auxiliary gas device. After entering into the

auxiliary gas device, the auxiliary gas is diffused by the diffuser chamber 32, and

then directed into the auxiliary passage 33, until it finally enters into the working

space 15 through the outlet 34 of the auxiliary passage 33.

In one embodiment, the exhaust outlet 2 can be located on the top panel 12 of

the cabinet 1, and connected to an exhaust passage 21 for discharging the fumes in

the working space 15 to an outside of the room in which the fume hood is installed

or situated. As shown in Fig.l, the exhaust outlet 2 is positioned on a rear half

portion of the top panel 12, for example, on a middle rear portion of the top panel

12.

However, in other embodiment, for example, when a fume hood is mainly

used to those experiments, which will produce fumes heavier than the air and

consequently the fumes to be exhausted are mainly accumulated in a middle and

lower portion of the working space 15, it is better to have the exhaust outlet 2

located on the bottom panel 11 of the cabinet or on a lower portion of the side panel

14 or the back panel 13 of the cabinet 1.

When the exhaust outlet 2 is located on the top panel 12 of the cabinet 1, in

one embodiment, a baffle (not shown) can be set in the cabinet 1 and positioned in

front of the back panle 13. Consequently, a passage is accordingly formed between

this baffle and the back panle 13 and is for leading the fumes in the working space

15 flow towards the exhaust outlet 2. Therefore, a performance of the fume hood

can be optimized.

In one embodiment, a draining device (not shown) or other similarly

functional means can be mounted at the exhaust outlet 2 and/or in an exhaust

passage 21 to compulsively form a lower or negative pressure around the exhaust

outlet 2 for easily discharging the fumes out of the working space 15; or under a

condition that a plurality of fume hoods are used, a general draining device can be

shared by all the fume hoods to compulsively form a lower or negative pressure

around each exhaust outlet 2. Further, a purifying device (not shown) can be

mounted at the exhaust outlet 2 and/or in the exhaust passage 21 to treat poisonous

or pernicious fumes before they are discharged out.

The fume hood 100 can be positioned on a bottom cabinet 200 (the bottom

cabinet 200 is only sketched in the Fig. 1 and Fig.2 without being cutaway) and the

bottom cabinet 200 can serve as a supporter for holding the cabinet 1. In one

embodiment, the bottom cabinet 200 can be used to store reagents, tools, and other

materials.

Referring to Fig.3, the auxiliary gas supply device directs the auxiliary gas

from the outside space or a special gas source net into the auxiliary gas device 3

through the inlet 31. After entering into the auxiliary gas device 3, the auxiliary gas

is diffused by the diffuser chamber 32 to flow evenly in a cross section vertical to

the flow direction into the auxiliary gas passage 33. Due to the auxiliary gas

passage 33 being a regular cuboid, the gas thereof is uniformly distributed along

the flow direction to form a continuous gas curtain within the whole auxiliary gas

passage 33.

Referring to Fig.l, when the auxiliary gas passage 33 is adjusted down to a

middle position of the open side 10, at the outlet 34 of the auxiliary gas passage 33

the flowing gas is met with the baffle 333, and the baffle 333 will force the flowing

gas diverted inwardly into an upper portion of the working space 15. The

environmental air enters into a lower portion of the working space 15 to provide

supplemental gas.

Referring to Fig.2, when the auxiliary gas passage 33 is further adjusted down

to the working platform 11, the baffle 333 is basically close to the bottom surface

of the cabinet, so that the ambient gases are restricted from flowing into the

working space 15 and the fumes therefrom as well as the auxiliary gas are

prohibited from escaping into the room in which the fume hood is installed or

situated. Due to the height difference between the front and back walls of the

auxiliary gas passage 33, the auxiliary gas is almost completely directed into a

lower portion of the working space 15 from a gap between the back wall 332 of the

auxiliary gas passage 33 and the bottom surface of the cabinet. So the

supplementary gases for the working space are mainly the auxiliary gases from the

auxiliary gas passage 33.

Wherever the auxiliary gas passage 33 is positioned on the open side 10, due

to the height difference between the back wall and the front wall of the auxiliary

gas passage 33, when the auxiliary gases are inwardly diverted into the working

space 15 after encountering the baffle 333, they flow freely into the working space

15 almost without any restriction, and almost no auxiliary gases leak into the room

in which the fume hood is installed or situated.

The fumes within the working space 15 are discharged out of the working

space through the exhaust outlet 2 with the flow of the auxiliary gas. Alternatively,

a lower or negative pressure around the exhaust outlet 2 can be formed with help

of the draining device or other compulsive means for promoting the fumes out of

the working space 15.

Therefore, by the up and down movement of the auxiliary gas passage 33, the

auxiliary gases can be directed into the working space 15 from different height of

the open side 10. Not only the heavy fumes accumulated in the lower portion of

the working space 15 but also the light fumes accumulated in the upper portion can

be taken out of the working space 15 by the auxiliary gases.

Fig.4 is a side view of a fume hood 300 according to another embodiment of

the present invention. The fume hood 300 is similar to the fume hood 100 shown in

Fig. l . However, for the fume hood 300, , its auxiliary gas passage 33a is separate

form its sliding sash 331a and they can be respectively operated to move up and

down, namely, a front wall 334 of the auxiliary gas passage 33a and the sliding

sash 331a are separately configured. In one embodiment, the auxiliary gas passage

33a can be located at a rear side of the sliding sash 331a. Consequently, the

auxiliary gas passage 33a and the sliding sash 331a can move up and down

relatively to each other. In one embodiment, at a bottom of the auxiliary gas

passage 33a, its back wall 332a and front wall 334 can be on a same horizontal

level. In one embodiment, the baffle 333 of the fume hood 100 can be replaced by

a steering passage 333a positioned on an outlet 34a of the auxiliary gas passage

33a. The steering passage 333a can be rotatably pivoted to a lower portion of the

auxiliary gas passage 33a.

The auxiliary gas passage 33a can be mounted to be moveable up and down

on a guiding orbit (not shown) and the guiding orbit can be positioned on a front

portion of the two side panels of the cabinet 1. Therefore the sliding sash 331a and

the auxiliary gas passage 33a can be separately operated. In one embodiment, the

auxiliary gas passage 33a is located at the rear side of the sliding sash 331a,

wherever the sash 331a is located, the auxiliary gas passage 33a can provide the

auxiliary gas into the working space 15 with flexible up and down movement.

Especially when poisonous experiments are carried out in the working space 15,

the sash 331a can be closed so as to avoid emitting poisonous fumes into the room.

The fume hood can be completely dependent on the auxiliary gas passage 33a to

provide the auxiliary gas, and the auxiliary gas passage33a is still capable of

directing the auxiliary gas into the working space 15 with flexible up and down

movement.

The steering passage 333a is rotatably pivoted on the auxiliary gas passage

33a so that a flow direction of the auxiliary gases into the working space 15 can be

adjusted through controlling an angle between the steering passage 333a and the

auxiliary gas passage 33a. Of course, in other embodiments, the steering passage

333a can be fixedly connected to the auxiliary gas passage 33a or be integrally

formed with the auxiliary gas passage 33a.

Referring to Fig.5, an upper portion of the steering passage 333a can be

cylinder-shaped so as to keep a tangential connection with the auxiliary gas

passage 33a when the steering passage 333a rotates within a specific range. A

lower portion of the steering passage 333a can be a cuboid chamber, of course, it

also can be an outstretched or compressed chamber with a trapezia-shape or other

shape. An inlet 3331 on the upper portion of the steering passage 333a can be

configured for directing the auxiliary gas into the steering passage 333a from the

auxiliary gas passage 33a. An outlet 3332 on the lower portion of the steering

passage 333a can be configured for directing the auxiliary gas into the working

space 15 from the steering passage 333a.

Therefore, wherever the sliding sash 331a is located on the open side, the

auxiliary gas passage 33a can move up and down so as to provide auxiliary gases

into the working space 15 in different horizontal level. Furthermore, the auxiliary

gases are directed into the working space 15 at different flow direction by

adjusting the angle between the steering passage 333a and the auxiliary gas

passage 33a. Fig.4 shows that the sliding sash 331a is closed and that the cabinet

completely depends on the auxiliary gas device to provide supplementary gas, and

that the auxiliary gas passage 33a is moved to a middle position of the open side to

provide auxiliary gas into the working space 15. Therefore, the fume hood 300 can

maintain quality performance although its sliding sash 331a is closed, which is

very helpful for experiments involving poisonous materials.

In one embodiment, the fume hood 300 can also employ a steering device as

shown in Fig.6. The steering device is a steering block 333b and can be rotatably

pivoted to a bottom of two side walls of the auxiliary gas passage 33a through its

two side surfaces. A side cross section of the steering block 333b can be

fan-shaped with an obtuse angle. The flow direction of the auxiliary gas into the

working space 15 can be adjusted by adjusting the steering block 333b. Of course,

in other embodiments, the side cross section of the steering block 333b can be

falciform, airfoil-shaped, and the like. The steering block 333b can also be fixedly

connected to the auxiliary gas passage or be integrally formed with the auxiliary

gas passage.

As to the steering device, besides the abovementioned forms, it can be any

other structure as long as it can adjust the flow direction of the auxiliary gas out of

the outlet of the auxiliary gas passage, and accordingly, the flow direction of the

auxiliary gases into the working space can be adjusted. The steering device can be

fixedly or rotatably mounted at the outlet of the auxiliary gas passage.

Alternatively, the steering device can be fixedly or rotatably located on the

working platform in a form of a baffle, for example, on a portion of the bottom

surface of the cabinet corresponding to the outlet of the auxiliary gas passage.

Fig.7 and Fig.8 are sketch drawings for a fume hood 400 of another

embodiment of the present invention. The fume hood 400 is similar to the fume

hood 100. However, for the fume hood 400, a front wall 334c and a back wall 332c

of its auxiliary gas passage 33c, as well as its sliding sash 331c, are separate

elements. Therefore, the auxiliary gas passage 33c and the sliding sash 331c can be

respectively operated to move up and down, and the front wall 334c and the back

wall 332c of the auxiliary gas passage 33c can also be respectively operated to up

and down move. Alternatively, two operating windows 4 can be set on a middle

lower portion of the sliding sash 331c. Therefore, it is convenient for an operator to

handle experiment in the working space through the operating window when the

sash 331c is closed.

The independent up and down movement of the front wall 334c and back wall

332c of the auxiliary gas passage 33c, as well as the sliding sash 331c can be

achieved by many means. For example, guiding orbits can be mounted on a front

portion of two side panels of the cabinet for respectively installing the front wall

334c, back wall 332c and the sliding sash 331c. Alternatively, controlling devices

can be mounted on an outside surface of the side panels of the cabinet or other

position for respectively controlling the front wall 334c, back wall 332c and the

sliding sash 331c move up and down. In one embodiment, the front wall 334c,

back wall 332c and the sliding sash 331c can be all made from transparent

materials like glass.

Consequently, the fume hood 400 has a special advantage for those

experiments like chemical or biology experiments involving poisonous gas. During

the experiment, the sliding sash 331c can be closed for preventing the poisonous

gas flowing into the room in which the fume hood is installed or situated. However,

it is still convenient for an operator to handle the experiment within the working

space 15 through the operating window 4. Alternatively, the front wall 334c and

the back wall 332c can be separately operated to move up and down through the

controlling devices. Accordingly, a position of the outlet 34c, as well as a size of an

opening of the outlet 34c can be adjusted. Therefore, the fume hood 400 can

completely depend on the auxiliary gas passage 33c to provide auxiliary gas for

compulsively discharging the fumes out of the working space 15.

Commonly, the front wall and back wall of the auxiliary gas passage can be

made of transparent materials such as glass or the likes; or they can be made of

opaque materials such as stainless steel. For the latter configuration, it is better to

set an observing window on each walls, so that when the auxiliary gas passage is

located at a position of the lower portion of the open side, it is convenient to

observe an experiment in the working space through the observing windows.

Commonly, a water faucet, a lamp and other common experimental devices

can be set in the working space of the cabinet. Further, a heating device and/or a

temperature controlling device can be mounted for adjusting and controlling a

temperature of the working space.

According to one embodiment of the present invention, the auxiliary gas

passage can be wholly up and down movably mounted on the open side of the

cabinet. Alternatively, portion of the auxiliary gas passage is up and down movably

mounted on the open side and other portion of the auxiliary gas passage is fixedly

mounted on the open side or other position. Alternatively, the auxiliary gas passage

can be left and right movably mounted on the open side of the cabinet.

Alternatively, the auxiliary gas passage can be mounted on the open side of the

cabinet and is capable of simultaneously moving left and right as well as moving

up and down. The implementation for these different arrangements is omitted for

they are similar to the up and down arrangement.

Alternatively, the whole or portion (e.g. upper portion) of the auxiliary gas

passage can be selected as a soft tube. Thus, it is convenient and easy to move the

auxiliary gas passage up and down and/or left and right. Consequently, the position

of the auxiliary gas passage can be adjusted accordingly.

Adjustment on the outlet of the auxiliary gas passage can be manipulated by

hand or by an automatic controlling device.

Alternatively, the fume hood involving in the embodiment of the present

invention can comprise other supplemental auxiliary gas devices, for example, an

auxiliary gas device mounted at a front rim of the bottom panel of the cabinet, or

an auxiliary gas device mounted in a front portion of the side panel of the cabinet;

or the like. Therefore, the auxiliary gases can be directed into the working space

simultaneously from the upper and the lower, or from the whole periphery of the

open side.

The foregoing description is mainly aiming at a fume hood with an open side.

However, the fume hood and the method according to embodiments of the present

invention can also be a totally enclosed fume hood (possibly an operating window

or the like can be set for communicating the working space with the outside), or be

a fume hood with only a portion of one side being opened and closed.

The fume hood according to an embodiment of the present invention is

suitable to any experiment in the chemical engineering, oil, biology and other

fields, which will or possibly will produce pernicious or/and poisonous gases, or to

which pernicious or/and poisonous gases are reactants or as other material

participating in, or during which there will be or possibly be material affecting the

environment. Of course, the fume hood can also be used in other aspects without

being limited to the abovementioned.

Because the outlet of the auxiliary gas passage is designed as adjustable,

especially under the configuration that the position of the outlet is adjustable, the

auxiliary gas can be directed into the working space of the cabinet from different

position of the open side. For example, the outlet in the form of the up and down

movement, the auxiliary gas can be directed into the working space from different

altitude of the open side. Not only the heavy fume accumulated in the lower

portion of the working space but also the light fumes accumulated in the upper

portion can be taken out of the working space by the auxiliary gases. Commonly,

there is no need to set other supplemental auxiliary gas devices at the front rim of

the bottom panel of the cabinet or in the front portion of the side panel of the

cabinet. Therefore, the fume hood according to an embodiment of the present

invention, with its simple structure, can be flexibly applied to any situation.

The supplementary gas for the fume hood according to an embodiment of the

present invention is mainly the auxiliary gas from the auxiliary gas passage.

Consequently, the supplementary gas comes from a single source, and the

supplementary gas can flow better uniformly. Therefore, the gas flow within the

working space is more uniform than that of a conventional fume hood. Based on a

simulation of the gas flow in the working space through a large scale CAE

software by means of limited elements analysis, the inventor of the present

invention found that the fume hood can still achieve quality performance even

though it only utilizes the auxiliary gas passage without a baffle arranged in the

working space. Consequently, the fume hood can exert little influence on the air

flow and air pressure of the room in which the fume hood is installed or situated,

and power consumption of the air conditioner is saved.

In conclusion, compared to techniques in the prior arts, the fume hood

according to an embodiment of the present invention has some advantages. For

example, based on the configuration that the outlet of the auxiliary gas passage is

adjustable, which means that the outlet of the auxiliary gas passage can be adjusted

to adjust a position of the outlet, or a size of an opening of the outlet, or a direction

of the auxiliary gas out of the outlet, or combinations thereof, the position and/or

direction of the auxiliary gas flowing into the working space can be adjusted

according to practical need. Therefore, the auxiliary gas can be directed into the

working space in various modes. On the other hand, the supplementary gas for the

fume hood according to an embodiment of the present invention is mainly the

auxiliary gas from the auxiliary gas passage and almost all of the auxiliary gas can

be directed into the working space. Therefore, the fume hood according to an

embodiment of the present invention can be flexibly applied to any situation; will

exert little influence on the air flow and air pressure of the room in which the fume

hood is installed or situated, and will save power consumption by the air

conditioner.

As to the method of operating a fume hood, in one embodiment, taking

example of the fume hood 100 described, the method comprises: directing

auxiliary gases from an outdoor environment into the working space through the

auxiliary gas device 3; and adjusting the auxiliary gas passage 33 up and down

movement for adjusting a location at which the auxiliary gases enter the working

space 15 such that the auxiliary gases flow along a desired path to bring pernicious

gases out of the working space 15 through the exhaust outlet 2. Alternatively, the

step of adjustment can include or be achieved by adjusting the steering device for

controlling a flow direction of the auxiliary gas into the working space 15.

Generally, the fume hood is located in a laboratory room, which is part or all

of a building. In one embodiment, the auxiliary gases from an outdoor

environment relative to the laboratory room or the building are directed in the

working space 15 after orderly passing through the supply channel 35 and the

auxiliary gas device 3. Of course, the channel 35 and the auxiliary gas device 3 can

be deemed as a channel as whole. The auxiliary gases from an outdoor

environment are led into the channel 35 through the port 351, and then the

auxiliary gases within the channel 35 and the auxiliary gas device 3 are directed

into the working space 15 through the outlet 34 of the auxiliary gas device 3.

As to the method of operating a fume hood, since the embodiments of the

fume hood also illustrate the method, more details on the method can refer to the

above-mentioned description.

The description, example and data given in the foregoing embodiments are

just for demonstration and exemplification, and do not limit the protection scope of

the present invention. Any non-essential modification on the present invention

does not depart from the scope thereof. Therefore, the spirit and scope of the

attached claims are not limited to the description here.