WO2008081489A1

WO2008081489A1 - Nbc filter

Info

Publication number: WO2008081489A1
Application number: PCT/IT2007/000011
Authority: WO
Inventors: Giuseppe Galli
Original assignee: Officine Meccaniche Galli S.R.L.
Priority date: 2007-01-05
Filing date: 2007-01-05
Publication date: 2008-07-10
Also published as: ATE506106T1; EP2099532B1; EP2099532A1; DE602007014095D1

Abstract

An NBC filter of the type comprising two parts, anterior and posterior, fixed to one another, where the anterior part comprises a base, an asymmetrical fastening, the axis of symmetry of which is decentred with respect to the main axis of the filter itself, or a centralised fastening, the main axis of which coincides with the axis of symmetry of the filter, a first perforated membrane, an area containing particles of activated charcoal, and a second perforated membrane, while the posterior part comprises a first perforated disk, an antiaerosol pack constituted by a glass microfibre cartridge, a second perforated disk, and a base with an inlet hole fitted with a plug of known type, characterised in that in order to avoid the first perforated membrane and/or the second perforated membrane bending outwards, it is provided a central pin which, by passing through said area, maintains a constant distance between said membranes, allowing said filter to be resistant to shock or accidental dropping, even repeated, and thus preserving the filtration capacity intact.

Description

NBC FILTER *****

The present invention relates to the NBC protection sector, and in particular, refers to an NBC filter to be applied to the inlet of an NBC face mask. Said filter may be either the type having an asymmetrical fastening, the axis of symmetry of which is off-centred with respect to the main axis of the filter itself, or the type having a centralised fastening, the axis of symmetry of which coincides with the main axis of the filter itself. Recently, traditional metal filters have been replaced by plastic filters allowing reduced costs.

However, a first drawback of the plastic filters currently on the market is that the essentially cylindrical body of the filter is formed by two parts, one anterior and one posterior, fixed together by means of a resin-based glue, which does not ensure the stable fixing of said parts, and which are thus liable to come apart over time. A further drawback is constituted by the fact that said glue releases toxic vapours inside the filter, with the risk of these being inhaled by the individual using the filter itself.

A third drawback is given by the fact that, as a result of shock, or the accidental dropping of the filter, its filtering capacity may be significantly reduced over time, if not indeed lost entirely.

The main scope of the present invention is that of providing an NBC filter made from a reinforced plastic material, preferably fibreglass, capable of resisting accidental, and even repeated shock, while at the same time maintaining its filtering capacity, and avoiding the use of adhesives which can lead to the above- described drawbacks .

This has been achieved, according to the present invention, by providing that the interior of said filter is fitted with a central pin whichpspaces apart two membranes, which delimit a space filled with activated charcoal particles, in order to avoid said membranes to bent outwards and give rise to empty or dead spaces, which could reduce the filtering activity of said particles and thus the filtering capacity of the filter itself.

According to one further characteristic of the invention, the anterior and posterior parts, forming the filter body, are hot blade welded together so that said parts are stably fixed together, avoiding any gluing which can give rise to the above-described drawbacks .

Improved understanding of the invention will be obtained from the following detailed description and by referring to the enclosed figures which show, purely by way of example, two preferred embodiments.

In the figures: figure IA is a diametral cross-section through the centre of the fastening of a first embodiment of an NBC filter having an asymmetrical fastening; figure IB is an enlarged detail of the preceding figure; figures 2A and 2B show a diametral cross-section and a plan view of a valve pusher respectively; figures 3A and 3B show the outer and inner surfaces of the anterior base of the NBC filter of figure IA respectively; figure 4 shows the posterior base of the NBC filter of figure IA; figure 5 is a perspective diametral cross-section through the centre of the fastening of a second embodiment of an NBC filter having a central fastening.

With reference to figures IA to 3B, the essentially cylindrical body of the NBC filter 1 consists of two parts, anterior A and posterior B. The anterior part A comprises a base Al, fitted with an asymmetrical fastening 2 and a valve pusher 3 , a first perforated ^' membrane 4 , an area 5 containing the activated charcoal particles, with a pin 6 passing through centrally, and a second perforated membrane 7, while the posterior part B comprises a first perforated disk 11, an antiaerosol pack 12 constituted by a glass microfibre paper cartridge, a second perforated disk 13, and a base Bl with an inlet hole fitted with a plug 14 of known type.

In particular, the asymmetrical fastening 2 of the filter 1 is essentially constituted by a cylindrical collar which protrudes from the base Al and is positioned so that part of its outer perimeter is aligned with the outer edge of the filter 1 (figure 3A) .

It is appropriate to point out that there are four fins distributed angularly along the inner edge of the asymmetrical fastening 2, with two additional fins arranged facing one another along the outer edge, and two housings formed in the ribbed protrusions which aid fitting of the filter 1 onto the face mask, and at the same time defining the end stops .

The valve^' pusher 3 is inserted into a dedicated through hole 8 in the base Al which is located inside the asymmetrical fastening 2 and runs parallel to it.

Said valve pusher 3 is essentially constituted by a cylindrical collar protruding from the base Al along the inner edge of which are a series of radiating equidistant fins 9 protruding below, and facilitating the correct positioning of said valve pusher 3 inside the through hole 8, by inserting it in appropriate ^WU" shaped housings 21, as will be explained in more detail below (figures 2A and 2B) .

Once inserted, the valve pusher 3 is welded into place.

Each of the perforated membranes 4 and 7 delimiting the activated charcoal area 5 is lined internally with a non-woven fabric 10.

Near the first perforated membrane 4, there is a ring-shaped end-stop 15 which is held in place by a plurality of small teeth projecting from the inner surface of the side wall of the anterior part A, along the edge of the same.

The second perforated membrane 7 is fixed to the anterior part A held pressed against an inner edge 16 which arises from the inner face of the anterior part

A, a short distance from its free end, and which runs parallel to it.

The central pin 6 is interposed between the first perforated membrane 4 and the second 7, and maintains the distance between said membranes, which in the case of shock and/or accidental dropping, with the membranes being bent outwards, could increase, giving rise to dead spaces, which, as already been mentioned, could reduce the filtration capacity of the filter 1. In order to distribute the flow of air from outside the filter over the entire area 5, the base Al has an internal surface with a plurality of ribs 20 running radially with respect to the centre of the through hole 8 into which the valve pusher 3 is inserted, channelling the air towards the valve pusher 3 itself (figure 3B) .

The height of each rib 20 increases towards the through hole 8.

It should be observed that a certain number of said ribs extend from the edge of the base Al to the through hole 8, in the close proximity to which, the free end of each rib has a "U" shaped housing 21 which, as already been mentioned, can house a corresponding fin 9 from the valve pusher 3 when the latter is inserted.

It is obvious that the number of ribs 20 reaching the through hole 8 is equal to the number of fins 9 from the valve pusher 3.

One further advantageous characteristic of the invention is that the base Al has two protruding lugs 18 at 90° to one another with respect to the centre of the through hole 8 acting as visual and tactile points of reference for the user, both for the correct insertion of the filter 1 onto the inlet of the NBC face mask, and for the direction of rotation which allows the user to fix said filter onto the inlet itself (figure 3A) .

In particular, said lugs are "L" shaped, with the long sides oriented radially with respect to the fastening 2 of the filter I₇ and continuing downwards along the side surface of the filter 1 itself, stopping halfway along said surface, while the short sides are perpendicular to the former, giving the direction of rotation for a bayonet connector.

To enhance their roles as reference elements, it is preferable that the lugs 18 are a contrasting colour from that of the filter 1.

The posterior base Bl is fitted with an entry hole which is closed off by a central rubber stopper 14 which must be removed by the user in order to use the filer itself (figure 4) .

According to one advantageous characteristic of the invention, the two parts, anterior A and posterior B, are fixed together by means of hot blade welding which, following the melting of the contact seams, stably fixes the free ends together, thus making a single body without the use of any adhesives .

The second embodiment, shown in figure 5, envisages a filter 1 the base of which Al is fitted with a central fastening 2 ' the axis of symmetry of which coincides with the main axis of the filter itself. Said central fastening 2' is essentially constituted by a cylindrical collar with threading around the outer edge.

In this case, the central fastening 2' does not have the four fins distributed angularly around the inner edge, also the outer edge lacks the further two opposite facing fins and the two housings formed in the ribbed protrusions .

Furthermore, the base Al lacks the valve pusher 3 and the lugs 18. The antiaerosol pack 12 is fixed and sealed onto the posterior base Bl by means of non-toxic glue.

It should be remembered that the free end of the anterior part A just like that of the posterior part B are raised with respect to the corresponding side walls of each part, so that, once said ends are welded together, a circular lug is created which protrudes from the body of the filter 1 and facilitates holding for those wearing gloves and needing to handle the filter 1 itself. The present invention has been described and illustrated in two preferred embodiments, but it is obvious that one skilled in the art might be able to bring about modifications and/or technically equivalent substitutions without embarking from the scope of protection of the present industrial patent.

Claims

CLAIMS :

1. An NBC filter (1) of the type comprising two parts, anterior (A) and posterior (B) , fixed to one another, where the anterior part (A) comprises a base

(Al) , an asymmetrical fastening (2) the axis of symmetry of which is off-centred with respect to the main axis of the filter itself, or a centralised fastening (2') the main axis of which coincides with the axis of symmetry of the filter, a first perforated membrane (4) , an area (5) containing particles of activated charcoal, and a second, perforated membrane

(7) , while the posterior part (B) comprises a first perforated disk (11) , an antiaerosol pack (12) constituted by a glass microfibre cartridge, a second perforated disk (13) , and a base (Bl) with an inlet hole fitted with a plug (14) of known type, characterised in that in order to avoid the first perforated membrane (4) and/or the second perforated membrane (7) bending outwards, it is provided a central pin (6) which, by passing through said area (5) , maintains a constant distance between said membranes, allowing said filter to be resistant to shock or accidental dropping, even repeated, while at the same time preserving the filtration capacity intact.

2. The filter (1) according to the preceding claim characterised in that the asymmetrical fastening

(2) of the filter (1) is essentially constituted by a cylindrical collar which protrudes from the base (Al) and is positioned so that part of its outer edge is aligned with the edge of the filter (1) .

3. The filter (1) according to the preceding claim characterised in that said fastening (2) has four fins arranged angularly around its inner edge, and two further fins facing one another around its outer edge and two housings formed in the ribbed protrusions.

4. The filter (1) according to claims 2 or 3 characterised in that it has a valve pusher (3) which is inserted into an appropriate through hole (8) in the base (Al) ; said valve pusher (3) being located inside the fastening (2) and coaxial with the same, and welded into place.

5. The filter (1) according to the preceding claim characterised in that said valve pusher (3) is essentially constituted by a cylindrical collar which protrudes from the base (Al) and along the inner edge of which are a series of radial fins (9) equidistant from one another and adapted to allowing the correct positioning of the valve pusher (3) itself in the appropriate "U" shaped housings (21) inside the through hole (8) .

6. The filter (1) according to claim 1 characterised in that both the first perforated membrane (4) and the second perforated membrane (7) are lined internally with non woven fabric (10) .

7. The filter (1) according to claim 1 characterised in that the anterior part (A) has one free end which is fixed to the corresponding free end of the posterior part (B) by means of hot blade welding which, by melting the layers in contact, stably fixes said parts (A) and (B) , thus forming a single body.

8. The filter (1) according to the preceding claim characterised in that in order to aid holding by a user wearing gloves, the free end of the side wall of part (A) and that of part (B) are raised with respect to the corresponding side walls, so that, once welded together, a circular lug is created, projecting from the body of the filter (1) .

9. The filter according to claims 7 or 8 characterised in that the second perforated membrane (7) is fixed to the anterior part (A) and held pressed against an inner edge (16) which arises from the inner face of the anterior part (A) , at short distance from its free end, and running parallel to it.

10. The filter (1) according to claim 5 characterised in that in order to distribute the flow of air from the outside over the entire area (5) , the base (Al) has an inner surface with a plurality of ribs (20) arranged radially with respect to the centre of the through hole (8) capable of channelling air towards the valve pusher (3) .

11. The filter (1) according to the preceding claim characterised in that the height of each rib (20) increases towards the through hole (8) .

12. The filter (1) according to claims 10 or 11 characterised in that each of said ribs (20) extends from the edge of the anterior base (Al) to the through hole (8) where, at the free end of each there are "U" shaped housings (21) suitable for housing the fins (9) of the valve pusher (3); the number of ribs (20) reaching the through hole (8) being equal to the number of fins (9) .

13. The filter (1) according to one of the claims 2 to 12 characterised in that the anterior base (Al) has two lugs (18) separated angularly and able to act as visual and tactile reference elements for the user, both for the correct insertion of the filter (1) onto the inlet of an NBC face mask, and for the direction of rotation allowing the user to fix said filter onto the inlet itself.

14. The filter (1) according to the preceding claim characterised in that said lugs (18) are essentially "L" shaped, wherein the long sides, running radially with respect to the asymmetrical fixing (2) of the filter (1) , proceed downwards along the side surface of the filter (1) itself, stopping halfway along said surface, while the short sides are essentially perpendicular to the long sides.

15. The filter (1) according to claim 1 characterised in that the central fastening (2') is essentially constituted by a cylindrical collar with threading on its outer edge.

16. The filter (1) according to claim 1 characterised in that the antiaerosol pack (12) is fixed and sealed inside the filter (1) by means of a non-1oxic adhesive .

17. The filter (1) according to the preceding claims characterised in that there is a ring-shaped end-stop element (15) which is held in place by a plurality of small teeth projecting from the inner surface of the side wall of the anterior part (A) running along the edge of the same.