WO2002076517A1

WO2002076517A1 - Device for the sterilisation-purification of a fluid flow, in particular of a flow of compressed or forced air.

Info

Publication number: WO2002076517A1
Application number: PCT/IT2002/000196
Authority: WO
Inventors: Guido Ivo Tissi
Original assignee: Guido Ivo Tissi
Priority date: 2001-03-27
Filing date: 2002-03-27
Publication date: 2002-10-03

Abstract

It is provided a device (1) for the sterilisation-purification in particular a compressed or forced air flow: the device has a casing (2) and at least one linear ultraviolet radiation lamp (20) housed inside the casing: in order to increase the time during which the fluid flow is exposed to the sterilising action of the lamp, while keeping the device as a whole compact in size, the casing (2) houses conveying means (22) defining inside the casing a plurality of purification stages, and containing means (24) or containing the radiation emitted by the lamp (20) in each stage.

Description

DEVICE FOR THE STERILISATION-PURIFICATION OF A FLUID FLOW, IN PARTICULAR OF A FLOW OF COMPRESSED OR FORCED AIR

TECHNICAL FIELD The present invention relates to a device for the sterilisation-purification of a fluid flow: in particular, the device of the invention is suitable for application to the treatment of flows of compressed air to be supplied to dental or medical devices or for the treatment of the air in closed places which require the control of the environmental contamination of germs, bacteria, viruses and microorganisms in 'general, being suitable in this case to be installed as a separate unit, while being also suitable to be integrated into pre-existing treatment systems (for example conditioning plants) . BACKGROUND ART

It is known the use of ultraviolet radiation lamps

(UV-C in particular) in devices for the sterilisation- purification of ambient air and service air for medical and dental devices and tools. In particular, devices for sterilising fluid flows are known, including a casing internally housing a linear ultraviolet radiation lamp: the flow to be treated passes through the casing from an end to the other, skimming longitudinally over the lamp, and it is exposed to the sterilising action of the lamp. Devices of this kind are disclosed, for example, in the United States patent n. 4017736 and in the European patent application n. 461310: both these documents disclose devices provided with a series of linear UV lamps placed longitudinally parallel to the direction of the air flow between the input and the output of the device. These devices however have a drawback in that the airflow is exposed to the UV radiation for relatively short time periods, therefore an effective sterilising action requires lamps which are very long and/or powerful and, therefore, costly and highly consuming.

Alternatively, complex and large systems can be used, like the ones used in hospitals: obviously, however, these systems are not suitable for relatively small environments, such as laboratories, medical surgeries and dental surgeries, small rooms (for example, waiting rooms) . DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a sterilisation-purification device that solve at least in part the above mentioned problems of the known art: in particular, it is an object of the invention to provide a device that is compact in size and that has a highly effective purification- sterilisation action, being easy and cheap to be produced and simple and rapid to be maintained, and allowing the use of UV lamps which are relatively not much powerful and therefore economical and low-energy consuming.

The present invention therefore relates to a device for the sterilisation-purification of a fluid flow as defined by enclosed claim 1. Inside the device according to the invention the air flow undergoes a UV irradiation more effective than the known devices and, therefore, more effective in the treatment of the content of the polluting agents: consequently, the device according to the invention allows very high purifications of the air, higher than those obtainable with similar devices currently commercially available, even if it is extremely compact in size: the device of the invention maintains high standards of control of the environmental contamination even if it utilises smaller and less powerful lamps, which are therefore less costly than the known solutions: the device as a whole is therefore very compact in size but also easy and economical to produce and to use. Thanks to the compact size and to the economical production and use, the device according to the invention can be used also in small environments, for example in sterilisation rooms, dental surgeries, analysis laboratories, operating theatres but also production laboratories and places in the food industry.

The high efficiency of the device according to the invention has been confirmed by experimental microbiological analyses, as it will be indicated below: in particular, besides showing a very high efficiency in treating the bacterial agents, significantly higher than the efficiency of the devices known with comparable sizes, a surprising reduction of the viral agents has been also observed, which agents, instead, often survive in significant quantities in the existing devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now further described, purely by way of example, in the following non-limiting embodiments with reference to the accompanying drawings, in which:

- figure 1 shows, schematically and in longitudinal section and with some elements in an exploded view, a first embodiment of the device according to the invention; - figures 2 and 3 show, still schematically and in longitudinal section, respective variations to the device of figure 1;

- figure 4 schematically shows, in partly sectioned front view, a second embodiment of the device according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION With reference to figure 1, number 1 indicates as a whole a device for the sterilisation of a fluid flow, in particular an airflow to be supplied to a medical device: device 1 includes a cylindrical casing 2 delimited by a side cylindrical wall 3: a longitudinal end 4 of casing 2 is closed by a Bottom wall 5 integrally carried by casing 2 and substantially orthogonal to side wall 3, while a longitudinal end 6, opposite to longitudinal end 4, is provided with a removable closing plug 7: through bottom wall 5 and plug 7, in respective eccentric position with respect to a central axis A of casing 2, two openings are formed defining respectively an input 11 and an output 12 for an airflow passing through casing 2 and respectively connected, in a known way, to an inlet tube 13 for connection to a source of the fluid flow to be sterilised and to an outlet tube ^' 14 for the discharge of the irradiated fluid flow: suitable circulation means 15 (known and only schematically shown, for example constituted by fans or compressors) are connected to inlet tube 13 or to outlet tube 14 to determine the forced circulation of the fluid flow to be treated through casing 2. A linear ultraviolet radiation lamp 20 (known) is longitudinally housed inside casing 2, centrally coaxial with respect to casing 2 and delimited by a substantially cylindrical external side surface 21. Inside casing 2 is also housed a conveying element 22, having the shape of a spiral or a helicoidal screw and helicoidally and coaxially wound around lamp 20 and substantially along the full length 'of lamp 20. Conveying element 22 has a plurality of coils or turns 23 having respective intercepting surfaces 24 for the interception of the fluid flow with a substantially radial development with respect to side wall 3 of casing 2: conveying element 22 has a radially internal cylindrical axial seat 25 for housing lamp 20: when lamp 20 is inserted into seat 25, coils 23 abut, radially on the inside, against external side surface 21 of lamp 20, and radially on the outside against an internal side surface 26 of casing 2, so as to define, inside casing 2 and together with casing 2 and lamp 20, a spiral-shaped channel 27 exposed to the radiation emitted by lamp 20. In the non-limitative example shown, plug 7 has a sleeve portion 28 that can be fitted radially on the exterior of longitudinal end 6 of casing 2 and a circular flange portion 29 provided with output 12: sleeve portion 28 is internally provided with a thread 30 for coupling to a corresponding thread 31 made on the exterior of side wall 3, at longitudinal end 6; it is clearly possible to use different means for coupling plug 7 to casing 2, for example plug 7 could be interference fitted to casing 2, or forced fitted on longitudinal end 6. Plug 7 is also provided with one or more sealing rings 32 (known), for example 'made of an elastomeric material and carried by flange portion 29

(for example housed in a suitable annular seat) and axially cooperating in a fluid-tight manner, in use, with a sealing surface 33 of a front edge 34 of casing 2. Electric connections 35 (known) for lamp 20 are housed through flange portion 29: electric connections 35 terminate, inside plug 7, with connectors 36 (known) : in use, connectors 36 contact, in a known way, a first axial end 37 of lamp 20, so that lamp 20 is electrically connected to an external circuit (known and not illustrated) . End wall 5 can be centrally fitted with an internal support 38 for a second axial end 39 of lamp 20. Casing 2 and conveying element 22 are preferably made of metallic material (for example stainless steel) or polymeric material (for example ABS) , and in any case in a material which is not transparent to the ultraviolet radiation emitted by lamp 20: preferably, moreover, internal side surface 26 of casing 2 and interception surfaces 24 which delimit coils 23 are surfaces reflecting the ultraviolet radiation.

In use, the fluid flow to be treated is forced- circulated through casing 2 between input 11 and output 12: the fluid flow passes through spiral-shaped channel 27 remaining constantly exposed to the irradiation of lamp 20, finally going out from device 1 to be sent to the required use. With reference now to figure 2, in which any details similar to or identical with those already described are indicated using the same reference numbers, according to a possible variation of device 1, a tubular element 40, made of a material transparent to the ultraviolet radiation emitted by the lamp, for example a quartz tube, is housed coaxially inside casing 2: tubular element 40 is internally provided with a cylindrical seat 41 for housing lamp 20; conveying element 22 is helicoidally wound coaxially around tubular element 40, substantially for the full length of tubular element 40: coils 23 of conveying element 22 abut, radially on the inside, against a radially external side surface 42 of tubular element 40, and radially internally against internal side surface 26 of casing 2: spiral-shaped channel 27 exposed to the radiation emitted by lamp 20 is therefore radially delimited by casing 2 and by tubular element 40.

Plug 7 has a central through hole 43 for the insertion of lamp 20: hole 43 is aligned to tubular element 40 and constitutes an input hole to seat 41; plug 7 is also provided with a sealing' ring 44, for example made of an elastomeric material, carried by a peripheral edge 45 of hole 43, for example housed in a suitable annular seat, for cooperating axially in a fluid-tight manner, in use, with a sealing surface 46 of a front edge 47 of which the tubular element 40 is provided at one of its axial end 48. A further sealing ring 49, for example housed in an annular seat formed in a support 50 integral with end wall 5, cooperates in a fluid-tight manner with a second axial end 51 of tubular element 40: in this way, spiral-shaped channel 27 is sealed, even when hole 43 is open: hole 43 can however be provided with a suitable removable closing member 52 of any known type. The electrical connections of lamp 20, for example incorporated in a single cable 53 and directly linked to axial end 37 of lamp 20, are arranged through hole

43 for the connection, in a known way, to an external circuit (known and not illustrated).

The variation shown in figure 2 allows an easier replacement of lamp 20, without requiring the removal of plug 7 which could therefore be fixed firmly, in an unmovable way, to casing 2. In figure 3, in which any details similar to or identical with those already described are indicated using the same reference numbers, a further ' embodiment of the invention is schematically shown: similarly to what was previously described, device 1 still comprises a casing 2 that internally houses a lamp 20 and a conveying element 22 wound helicoidally around lamp 20: opposite longitudinal ends 4, 6 of casing 2 are open and connected, for example through tapered connections 55, to an input trunk 56 and, respectively, to an output trunk 57 (both trunks being schematically represented by dotted lines in figure 3) : the coupling between casing 2 and connections 55 or, alternatively, between connections 55 and trunks 56, 57 is of a releasable kind in order to allow the access to the inside of casing 2 and therefore the replacement and/or maintenance of lamp 20. Lamp 20 can be supported by a suitable lamp holder fixed to casing 2, known and not illustrated for the sake of simplicity: electrical connections of lamp 20 are not illustrated either in figure 3 for simplicity, but it is clear that they can be disposed, for example, through a suitable hole formed through a side wall 3 of casing 2. In this case too, circulating means 15 are present, constituted for example by one or more fans (known) . This embodiment of the invention is especially suitable for the treatment of the air in closed spaces: device 1 can be installed directly in the ^''room where the environmental contamination is to be controlled, constituting in that case an independent unit; alternatively, device 1 can be integrated in a preexisting system for the treatment of the air: input and output trunks 56, 57 can in fact be part, for example, of an air conditioning system: in such case, it is sufficient to remove a section of the piping of the system and to replace it with casing 2 and connections 55. Advantageously, circulating means 15 would be in this case the same already used by the pre-existing system.

With reference now to figure 4, number 101 indicates as a whole a device for the purification of the air by ultraviolet radiation, intended for wall installation in rooms with a high risk of air contagion: device 101 contains a casing 102, for example prismatic with a rectangular base, provided with a removable lid 103: casing 102 has on respective opposite ends two openings respectively defining an input 104 and an output 105 for the air circulating in casing 102; in the example, input 104 and output 105 are formed in respective end walls 106, 107 of casing 102 intended to be, once the device is installed, respectively an upper wall and a lower wall. Casing 102 has two opposite sides 108, 109, parallel to' each other and orthogonal to end walls 106, 107, and a bottom wall 110, facing lid 103 and provided on the outside with means (known and not shown) for fastening to a wall of the room where device 101 is to be installed.

Input 104 is provided with a grid (not shown) , for example constituted by a series of through fissures formed in end wall 106, and with a prechamber 111, possibly provided with means for the absorption and/or shielding of the ultraviolet radiation (known and not shown) in order to prevent the ultraviolet radiation from escaping through input 104; at output 105, a pair of axial fans 112 (known) is mounted to cause the forced circulation of an airflow inside casing 102 between input 104 and output 105: fans 112 are placed in a silenced room 113 inside casing 102, while a conveyor 114 (known) is placed outside casing 102 in front of fans 112. Beside silenced chamber 113, casing 102 holds electric and electronic components 115 (known and neither described nor shown in details for the sake of simplicity) .

Conveying means 120 are positioned inside casing 102 to define a labyrinth path for the airflow between input 104 and output 105; a plurality of purification stages 121 is placed in series along the labyrinth path . ' ^"'

Conveying means 120 comprise a plurality of plates 120a, 120b substantially parallel to each other, regularly spaced from one another and orthogonal to bottom wall 110 and to lid 103; plates 120a, 120b are provided with respective windows 122a, 122b staggered between each other: in particular, first plates 120a orthogonally project from side 108 of casing 102 and present respective windows 122a adjacent to side 109, while second plates 120b, intercalated to first plates 120a, orthogonally project from side 109 and present respective windows 122b adjacent side 108.

Purification stages 121 are defined by respective chambers 123 which communicate to one another and are provided with corresponding openings for the input and output, the output opening of each chamber being connected to the input opening of the adjacent chamber. In the example shown, chambers 123 are delimited and separated from one another by plates 120a and 120b and windows 122a, 122b constitute the input and output openings of each chamber: chambers 123 are also delimited from bottom wall 110 and from lid 103. Chambers 123 are located substantially transversally with respect to a longitudinal direction 125 defined between input 104 and output 105 of casing 102. The distance between each plate 120a, 120b and the following plate is far shorter than the length of the plates: each chamber 123 has therefore a linear longitudinal development significantly longer than its own transversal size.

Inside each chamber 123 is placed an ultraviolet radiation lamp 126, in particular a linear lamp (known in itself) placed longitudinally inside the chamber and slightly shorter if compared to the length of plates 120a, 120b and supported by a corresponding lamp holder 127 (also known) : each chamber 123 is also provided with containing means 128 for containing the ultraviolet radiation emitted by the respective lamp 123 in that chamber. Containing means 128 comprise respective reflecting surfaces 129 which reflect the ultraviolet radiation and which are placed on corresponding walls delimiting chambers 123: in particular, reflecting surfaces 129 are placed on respective sides of plates 120a, 120b, on bottom wall 110 and, optionally, on lid 103: for example, reflecting surfaces 129 can be constituted by aluminium sheets glued on the respective walls; alternatively containing means 128 can include layers of materials absorbing the ultraviolet radiation, for example made of polymeric materials, preferably black coloured, always applied on the walls delimiting chambers 123.

Device 101 according to the invention operate as follows: casing 102 is installed in the room where air has to be purified, for example hanging from a wall of the room and with end walls 106, 107 faced respectively upwards and downwards (longitudinal direction 125 being therefore vertical) . By activating fans 112, forced circulation of air through casing 102 starts and lamps 126 are also switched on: the air enters from input 104, passes through the labyrinth path defined by plates 120a, 120b and through each chamber 123, where the air undergoes the irradiation by the respective lamp 126, and then, after crossing fans 112, exit from output 105 to be reintroduced in the room by conveyor 114.

The labyrinth path inside casing 102 not only extends the air stay time inside device 101 and, therefore, the exposure time to the ultraviolet radiation, but more importantly, it exposes the airflow to the series of cascading stages 121 of purification: the action of each stage 121 is added to the action already exercised during the previous stages, thus allowing to push the treatment to very high levels of efficiency.

As an example, some microbiological experimental analyses have been carried out with a device 101 with the following characteristics: - casing size: width 50 cm; depth 15 cm, height 60 cm;

- air real capacity: 35 m³/h;

- average distance of exposition in the single stages: 2.5 cm

- lamps: five 25-W lamps with UV-C radiation at 254 nm (total irradiating power: 125 watt) ;

- results of the microbiological analysis: treatment of bacterial agents, germs, viruses and microorganisms higher than 99%.

It should be noted that similar devices of known type with comparable size do not reach such high values of efficiency (they do not go beyond purifications largely lower than 90%) .

Claims

CLAIMS 1) A device (1; 101) for the sterilisation- purification of a fluid flow, in particular of a flow of compressed or forced air, comprising a casing (2; 102) and at least a electromagnetic radiation lamp (20) housed inside the casing, the device being characterised by comprising conveying means (22; 120) of the fluid flow, defining inside the casing (2; 102) a plurality of purification stages (23; 121) in series, and containment means (24, 26; 128) for containing the radiation emitted by the lamp (20; 126) in each stage (23; 121) . ' ^"'

2)_. A device according to claim 1, characterised in that said conveying means (22) define inside the casing (2) a path substantially spiral-shaped having an axis substantially parallel to the lamp (20) and exposed to the radiation emitted by the lamp.

3) A device according to claim 2, characterised in that said conveying means comprise a spiral-shaped or helicoidal screw shaped conveying element (22) which is coaxially wound around said lamp (20) to define a spiral-shaped channel (27) for said fluid flow.

4) A device according to claim 3, characterised in that said casing (2) has a longitudinal end (4) provided with removable closing means (7) to access the inside of the casing (2) and axially remove the lamp (20) from the casing.

5) A device according to claim 4, characterised in that said closing means comprise a plug (7) provided with first sealing means (32) for cooperating with said longitudinal end (4) of the casing (2).

6) A device according to one of the claim from 3 to 5, characterised in that said conveying element (22) abuts, radially on the inside, against an external side surface (21) of the lamp (20) .

7) A device according to one of the claims from 3 to 5, characterised by comprising a tubular' element (40) , made of a material transparent to the ultraviolet radiation emitted by the lamp (20) and disposed coaxially inside the casing (2) and internally provided with a seat (41) for housing the lamp (20) ; said conveying element (22) abutting, radially on the inside, against a radially external side surface (42) of said tubular element (40) .

8) A device according to claim 7, characterised in that said plug (7) has a through hole (43) for the insertion of the lamp (20) , said hole (43) being aligned to said tubular element (40) to determine a hole for the access to said seat (41), said plug (7) being also provided with second sealing means (44) for cooperating with an axial end (47) of the tubular element (40) .

9) A device according to claim 8, characterised in that said hole (43) is provided with removable closing means (50) .

10) A device according to one of the claims from 3 to 9, characterised in that said lamp (20) is an ultraviolet radiation lamp, said casing (2) having an internal side surface (26) reflecting the ultraviolet radiation and said conveying element (22) having a plurality of coils (23) delimited by surfaces (24) intercepting the fluid flow and reflecting the ultraviolet radiation.

11) A device according to claim 1, characterised in that said conveying mans (120) define a labyrinth path inside said casing (102) and said stages (121) are placed in series along said labyrinth path.

12) A device according to claim 11, characterised in that each stage (121) comprises at least one ultraviolet radiation lamp (26) housed in a respective chamber (123) ; said containment means (128) being suitable for containing the radiation emitted by the lamp in the chamber.

13) A device as claimed in claim 12, characterised in that said stages (121) are defined by respective chambers (123) communicating with one another and provided with respective input and output openings, the output opening of each chamber being connected to the input opening of the adjacent chamber.

14) A device as claimed in claim 13, characterised in that said chambers (123) are positioned substantially transversally with respect to a longitudinal direction (125) defined between an input (104) and an output (105) of the casing (102); each chamber (123) housing a respective linear lamp (126) disposed longitudinally inside the chamber.

15) A device as claimed in claim 14, characterised in that each chamber (123) has a linear longitudinal development significantly longer than its own transversal size.

16) A device as claimed in one of the claims from 11 to 15, characterised in that said conveying means (120) comprise a plurality of plates (120a, 120b) substantially parallel to each other, regularly spaced from one another and orthogonally positioned between a bottom wall (110) and a lid (103) of the casing (102) ; said plates (120a, 120b) being provided with respective windows (122a, 122b) staggered from one another.

17) A device as claimed in claim 16, characterised in that said conveying means (120) comprise first plates (120a) , that orthogonally project from a first side (108) of the casing (102) and have respective windows (122a) adjacent to a second side (109) of the casing (102), opposite to said first side; and second plates (120b) , intercalated to said first plates (120a) and which orthogonally project from said second side (109) and have respective windows (122b) adjacent to said first side (108) .

18) A device as claimed in one of the claims from 11 to 17, characterised in that said containment means (128) comprise respective reflecting surfaces (129) reflecting the ultraviolet radiation an'd provided on respective walls delimiting said stages (121) .