GB2331358A - Aerodynamic system to eliminate polluting substances from fume cupboards - Google Patents

Abstract

An aerodynamic system to eliminate polluting substances contained within the hoods (10) for scientific laboratories, said system comprises two air inlet frontal openings (11, 12) into the hood (10), said openings are positioned on the sides of a barrier (13) vertically movable and suitable to allow an operator to have adequate access to the intake chamber (14) in order to perform the required operations. Further, by substituting a flat surface screen (15), positioned on the rear wall (16) of the aspiration chamber (14), with a tridimensional perforated screen (17), which enhances the distribution of the elimination (extraction) surface of the gaseous substances, allows to obtain an air flow more uniform and more efficient inside the aspiration chamber (14) in comparison with the traditional solution, so as to eliminate more rapidly the polluting substances and to improve the operator safety conditions.

Description

1 2331358 AERODYNAMIC SYSTEM TO ELIMINATE POLLUTING SUBSTANCES CONTAINED

WITHIN THE HOODS USED FOR SCIENTIFIC LABORATORIES The nresent invention refers to an aerodynamic system to eliminate polluting substances contained within the hoods for scientific laboratories.

The environmental conditions of a laboratory, whether of the chemical, biological, medical or pharmaceutical type, must satisfy different requirements, as for instance the guarantee of the comfort, the health and the maximum safety of the operators as well as the compliance with the process specifications related to the particular scientific experiment to be conducted.

In particular, the most important structural and environmental requirements of a laboratory must refer to the operator protection and, in general, to the protection of anybody who is inside the laboratory, against the potential risks due to the discharge of the harmful fumes, vapours which can contaminate the surrounding environment.

In fact, the European and the international regulations set specific limits to the emission maximum levels of polluting substances and vapours inside the laboratories, indicate the behaviour to follow in said environments and indicate the devices needed in order to 2 prevent fires or explosions.

Further, it would be preferred that said objectives were obtained by using low amounts of energy thus at substantially reduced costs.

However, since the primary objectives of the requirements refer to the safety and to the health of the operators, the structure of a laboratory must take into account said factors.

In particular, physical barriers are generally used so as to be positioned between the operator and the environment wherein the scientific experiment is conducted in order to prevent the contact and/or the exposure of any part of the operator body to substances dangerous for the human body and, therefore, to protect the laboratory personnel from the potential risks of certain kinds of experiments.

The most common barriers in the chemical and pharmaceutical laboratories are the so called hoods, which comprise an aspiration chamber, connected to an air forced aspiration system, suitable to carry and to eliminate any harmful vapour or fume which can spread during a chemical reaction. The suction chamber comprises a closed space wherein the experiments conducted by an operator, said chamber is provided with one or more closing latches, made of a transparent material, which can be completely or partially lifted, 3 in order to allow a variable access level adequate to the operations to be performed within the closed space.

The main requirement of a hood is to capture, carry and eliminate, in the shortest possible time, the harmful fumes and vapours produced during a chemical reaction, by using, as a transport means, an air flow at a constant and controlled speed.

Currently, many types of hoods are available and said hoods are different from each other in the outer shapes, in dimensions, materials and external accessories.

Generally, all the traditional hoods eliminate substantially the same amount of polluted air, independently from the position of the latches and one of their main disadvantages is due to the fact that it is not possible to maintain a uniform speed of the air flow at the interface between the inner closed space and the outside environment when the latch positions change.

Said air speed change causes an elevated consumption of air conditioning and it can further create turbulence inside the aspiration chamber.

Finally, the turbulence can influence the development of the experiment currently conducted.

A possible remedy is to install an expensive electronic device to control the air speed entering into the suction chamber, said device changes the volume of sucked air in function of the open surface of the front 4 latch.

A purpose of the present invention is to disclose an aerodynamic system to eliminate the polluting substances inside the hoods used for scientific laboratories, and to overcome the above mentioned disadvantages, and to disclose an aerodynamic system to allow an air flow more uniform and more efficient inside a suction chamber, in comparison with the traditional solution, in order to eliminate more rapidly the harmful substances from within the chamber.

Another purpose of the present invention is to realise an aerodynamic system suitable to eliminate the polluting substances contained within an aspiration chamber, said system allows a reduced consumption of treated air (heated or conditioned), without using external supporting apparatus, as for instance air intake ducts, conditioning systems, and a reduced consumption of energy.

Another purpose of the present invention is to disclose an aerodynamic system to eliminate the polluting substances of hoods for scientific laboratories, said system shall be in compliance with the requirements of the European and international regulations regarding the environmental safety.

Another purpose of the present invention is to realise an aerodynamic system to eliminate polluting substances from within the aspiration chambers of the scientific laboratories, in order to improve the health, safety and comfort conditions of the operator, in comparison with the traditional systems, both during stationary and working conditions, at the same level of working efficiency and of reliability of the scientific experiments conducted inside the aspiration chambers.

Another, not least, purpose of the present invention is to realise an aerodynamic system to eliminate the polluting substances for hoods of scientific laboratories at reduced costs and without using complex or expensive technologies.

Said purposes are achieved through an aerodynamic system to eliminate the gaseous substances contained inside the hoods used for scientific laboratories, according to claim 1, taken as reference herein.

Advantageously, according to the present invention, an efficient solution is provided to define the inner aerodynamics of the hoods, i. e. of the air flow which carries the various fumes, vapours or dangerous and harmful gases.

The aerodynamic system suitable to eliminate said polluting substances, according to the invention, comprises the introduction of two additional vertical openings, in comparison with the traditional hoods, said openings are positioned, respectively, on the two sides

6 of the latch and allow a larger amount of air to enter inside the aspiration chamber.

Further, by substituting a flat surface screen, having' air intake slots, usually provided on the rear wall of the suction chamber, with a perforated tridimensional screen, it is possible to increase the elimination surface distribution in the rear portion (back, sides, ceiling) of the aspiration chamber of the hood.

In conclusion, the result which can be obtained by using this new hood aerodynamic system is the fact that, inside the suction chamber, a more efficient and uniform air flow can be obtained when compared to the conventional solutions.

Further purposes and advantages of the present invention will be better understood from the following description and from the attached drawings, provided as a non limiting example, wherein:

- Figure 1 is a partial front elevation view of a hood for scientific laboratories of the traditional type; - Figure 2 is a perspective diagrammatic and partial view of a suction chamber provided inside a traditional hood, as shown in Figure 1; - Figure 3 is a perspective diagrammatic and partial view of the suction chamber of figure 2, wherein the directions of the air flows are graphically represented; 7 - Figure 4 view of a wherein an invention, substances; Figure 5 is a perspective diagrammatic and partial view of the suction chamber of figure 4, wherein the directions of the air flows are graphically represented, according to the invention.

Referring to the mentioned figures, 10 generally indicates a hood for scientific laboratories, whereon a window 13 is provided on its front wall 17, called in particular latch, realised with a transparent material which is movable in the vertical direction and/or in the horizontal direction, so that the operator can have access, at least with his or her arms, inside a suction chamber, indicated by 14, wherein a specific scientific experiment is conducted; further, numeral 20 indicates article holding boxes and/or drawers, provided on the wall 17 of the hood 10, while numeral 21 indicates, generally, a control device of the flow speed of the air entering the chamber 14.

Numeral 18 indicates a discharge duct of the fumes or vapours present inside the chamber 14, said fumes or vapours are sucked through a forced suction system, not shown, while numeral 16 indicates a wall of the chamber is a perspective diagrammatic and partial suction chamber provided inside a hood, aerodynamic system, according to the present for the elimination of the polluting 8 14. said wall is provided in the rear portion and is parallel to the latch 13 and numeral 15 indicates a rectangular or square screen, which defines, by being smaller than the back-wall 16, peripheral air passages, since said screen is detached from said wall 16, as well as it is detached both from the upper wall 25 and from the lower wall 26 of the chamber 14, as it is clearly shown in figure 2.

Said screen 15 has a flat surface and it is bent, by a 10 predefined angle, along a line 19, parallel to the longer sides.

With specific reference to figure 3, the arrows F indicate the main directions of the air flow which enters into a suction chamber 14 of the traditional type and which circulates inside said chamber 14.

It has to be noted that the rate of speed of the air flow F which enters into the chamber 14 through the opening 22, which is formed by lifting the latch 13, is as much higher as the area corresponding to the opening 22 is smaller.

This creates turbulent motions of the air flow F inside the suction chamber 14, as indicated by the arrows Fl of figure 3, said turbulent motions cause the formation of vortices of polluted air, which remains for a long period of time inside the chamber 14 before being discharged, through the discharge duct 18, along the 9 direction of arrow FO; then, in this case, it is possible that harmful and/or dangerous substances can flow back outside the chamber 14 and get in direct contact with the operator.

This dangerous inconvenience is overcome by using an aerodynamic system for the elimination of polluting substances, according to the present invention; in particular, in a non limiting, preferred embodiment of the invention, two additional vertical openings, indicated with numeral 24, for sucking the air inside the chamber 14 are provided on the front wall 23 of the suction chamber 14, said openings are positioned on the sides of the latch 13. Further, the traditional rear screen 15 is substituted by a perforated tridimensional screen, indicated by numeral 17, which has a U-shaped cross section, a downward tapered profile and it is connected to the upper wall of the chamber 14.

By using this particular type of screen 17, it is possible to increase the suction surface distribution of the harmful fumes or vapours in the rear portion of the suction chamber 14 of the hood 10, i.e., more precisely, in relation to the rear wall or back 16, the lateral walls or sides 27 and 28 and the upper wall 25.

The result so obtained is an air flow more uniform and 25 efficient inside the chamber 14, in comparison with the conventional solutions; in fact, as it is clearly shown in figure 5, the air flow, indicated by the arrows F2, enters from the opening 22 and from the openings 24 and it is evenly distributed inside the chamber 14 which is' fully permeated by said air flow along the directions indicated by the arrows F3.

By providing additional openings on the front wall 23 of the chamber 14, it is possible to obtain lower inlet speeds of the air flow (i.e., the speed of the air which enters into the hood 10 through the opening 22 provided below the latch 13) in comparison with the traditional solution, at the same level of contained air volume.

This causes the flow to go quickly through the whole perforated surface of the screen 17 and, therefore, the elimination of the polluting substances, which are sucked through the discharge duct 18 along the direction of the arrow FO, is quicker and more efficient in comparison with the known art.

Further, as a consequencef there are significant reductions of the energy consumption and of the size of the supporting apparatus, as for instance the aspirators, the flow control devices, the air ducts, the conditioning system.

In practice, it has been experimentally demonstrated that, by eliminating the polluted air vortices, which are formed right downstream of the latch 13 in the traditional hoods 10, it is further possible to obtain 11 the elimination of the polluting substances from the chamber 14 in less time, down to 60%, in comparison with the usual elimination time of said substances.

From the above description the characteristics, as well as the advantages, of the aerodynamic system for the elimination of polluting substances from the hoods of scientific laboratories, according to the present invention, are clearly shown.

In particular, the characteristics and the advantages 10 are as follows:

- quicker elimination of the polluting substances in comparison with the traditional systems; - elimination of the vortices of polluted air inside the suction chamber of the hood; - lower front inlet speed of the air flow entering into the suction chamber in comparison with the traditional system, at the same level of contained air volume of the hood and, therefore, significant reductions of the size of the supporting apparatus and of the energy consumption; - improvement, in comparison with the traditional systems, of the operator comfort and safety, both in stationary or dynamic conditions, when the latch is in motion; - limited costs, in comparison with the traditional systems, considering the attained advantages.

12 Finallv, it is clear that various changes can be introduced in the aerodynamic system of the invention without departing from the innovative ideas of the' invention, as well as it is clear that, in the embodiments of the invention, the materials, the shapes and the dimensions of the shown details could change according to needs and said details could be replaced by other, technically equivalent, details.

For instance, the additional air inlet openings can be 10 obtained in various ways, as, by way of non limiting examples, by means of slots positioned on the sides of the latch, by spacing the sides of the hood and the vertical pilot columns for the latch motion, by means of slanting ventilation openings channelled through the front angles of the hood by means of planes with aerodynamic profiles (the so called "aerofoils"), etc.

Likewise, the distribution of the perforations of the tridimensional screen inside the suction chamber can be of various types, without departing from the principles of the present invention.

In fact, said perforation distributions can comprise, but not be limited to, a regular perforation along the whole screen surface, an asymmetric type of perforation, a slot distribution or any combination of the previously mentioned perforations.

13

Claims (7)

1. An aerodynamic system to eliminate polluting substances contained within the hoods (10) for scientific laboratories, said system comprises at least a first inlet opening (22) for an air flow (F, F1, F2, F3), said opening is positioned below at least a mobile windows or latch (13), suitable to prevent the leakage of material from said hood (10) to the outside environment and to allow a variable level of adequate access to the operations to be performed, said latch (13) is positioned on a front wall (23) of a suction chamber (14), wherein scientific experiments are conducted and wherefrom said polluting substances are sucked by said air flow, through the connection to a forced suction system and to a discharge duct (18) of harmful or dangerous fumes and/or vapours, said system further comprises at least a screen (15), provided with air intake slots and positioned inside said suction chamber (14) on a wall (16) of said chamber (14), said wall being placed in the rearward area of said latch (13), characterised in that at least a second inlet opening (24) of said air flow (F, F1, F2, F3) and characterised in that said screen (15) comprises a tridimensional perforated screen (17), shaped so as to increase the distribution of the elimination surface of the polluting substances in an inner area of said 14 suction chamber (14), said area is substantially positioned near said wall (16) placed rearward said latch (13).

2. An aerodynamic system as claimed in claim 1, 5 characterised in that two second intake openings (24) of the air f low (F, F1, F2, F3) are provided on the front (23) of said chamber (14), said openings being positioned on the vertical sides of said latch (13).

3. An aerodynamic system as claimed in claim 2, 10 characterised in that said second openings (24) are formed by slots positioned on the sides of said latch (13), i.e. said slots are obtained by spacing the two side walls of said hood (10) or two side walls (27, 28) of said suction chamber (14) and by inserting vertical pilot columns for said latch (13).

4. An aerodynamic system as claimed in claim 2, characterised in that said second openings (24) are slanting ventilation openings, which are channelled through the front angles of said hood (10), by means of planes with an aerodynamic profile.

5. An aerodynamic system as claimed in claim 1, characterised in that said tridimensional screen (17) is integral with said wall (16) rearward the latch (13) and is further connected, at least partially, to an upper wall (25) of the suction chamber (14), said tridimensional screen (17) is substantially shaped as a hollow parallelepiped cap, tapered from bottom portion and with an opening on the side surfaces, so as that the cross cap has substantially a rotated U shape.

6. An aerodynamic system as claimed characterised in that said tridimensional provided with a distribution of slots or its surface, said slots or perforations have a regular or asymmetric distribution at on one portion of said surface or a combination of slots and/or perforations having a configuration according to the previously mentioned solutions.

7. An aerodynamic system as substantially described and shown in the attached figures.

the top to the at least one of section of said- in claim 1, screen (17) is perforations on