FILTER CARTRIDGE

Abstract: A filter cartridge incorporates a layer of granular material (4d) for adsorbing gases and/or vapours retained in position by porous retaining means (4e, 4f, 4g). The cartridge comprises a housing (2) and a closure element (3) for closing the housing. The closure element (3) is associated with a compression element (10) which during assembly of the closure (3) on the housing (2) acts against the retaining means (4e, 4f, 4g) to compress the granular material (4).

Description: FILTER CARTRIDGE The present invention relates to a filter cartridge such as may be incorporated in a mask to be 5 worn by personnel operating in hazardous industrial environments, the cartridge serving to remove harmful gases/vapours from air to be inhaled by the user. Filter cartridges for fulfilling the above function are already known and comprise a layer of 10 granular carbon (for adsorbing harmful gases/vapours) and frequently also a filter element (usually of glass-fibre paper) for removing particulate matter. At least one porous retaining element is provided between the carbon, and the filter element for I 5 retaining the carbon in position. However, the known cartridges are relatively complicated to 'manufacture. Thus one known cartridge is produced by introducing the carbon and the porous element into a cylindrical metal housing followed by rolling a -20 circumferential groove in the outside of the housing so that an inner circumferential ridge is formed to retain the porous element in position. Subsequently, the filter element for removing particulate matter is introduced into the housing, located in position by 2_> an O-ring seal provided between the housing and the peripheral edge of the filter element a grill is provided on top of the filter element, and the top of the housing is turned over to form a lip to retain the grill and filter element in position. 30 It is an object of the present invention to provide a filter cartridge which is of simplified construction as compared to the prior art cartridges. According to the present invention there is provided a filter cartridge incorporating a layer of ■3 *5 granular material for adsorbing gases and/or vapours retained in position by a porous retaining element, the cartridge having an air inlet and an air outlet to allow passage of air through the cartridge, the cartridge comprising a housing and a closure element closing the housing, the closure element being associated with a compression element which during assembly of the closure element on the housing acts against the retaining element to compress the granular material. 10 The filter cartridge preferably also includes a filter element for the removal of particulate matter. Preferably the compression element is a flange provided around the closure element and locating within the housing. Preferably also the this filter " element for particulate material (when used) is located within the bounds of said flange. The invention will be further described by way of example only with reference to the accompanying drawings, in which: 20 Fig. 1 is an exploded view of one embodiment of filter cartridge in accordance with the invention; Fig. 2 is a sectional view of the housing of the cartridge shown in Fig. l∑ Fig. 3 is a part sectional view (on the line 25 III-III of Fig. 4) of the closure element of the cartridge shown in Fig. 1; Fig. 4 is a top plan view of the closure element shown in Fig. 3; Fig. 5 is an underside plan view of the closure 0 element shown in Fig. .3; and Fig. 6 is a sectional view of the assembled cartridge. Referring to Fig. 1, the illustrated cartridge 1 comprises a plastics housing 2, a plastics closure 5 element 3, and an arrangement 4 of filter elements which will be described in more detail below. Housing 2 is illustrated in Fig. ' 2 and will be seen to comprise an open-topped generally cylindrical body 5 with a base 6 in which is an aperture 7 bounded by a screw-threaded abutment 8. Base 6 slopes slightly (e.g. at 2l/ 2 °) from body 5 to aperture 7 and fins 6a are provided on the base 6 to provide a level support for filter elements 4. Closure element 3 is illustrated in Figs. 3 to 5 0 and will be seen to comprise a generally circular top portion 9, a first annular flange 10 provided generally around, but slightly inwardly of, the peripheral edge region of top portion 9, and a second annular flange 11 encircling flange 10. As will be 5 seen from Fig. 3, flange 10 is of greater height than flange 11, for reasons which will be described. Additionally, the outer diameter of flange 10 is slightly less than 'the inner diameter of body 5 of housing 2 whereas the inner and outer diameters of 0 flange 11 correspond to those of the body 5. Top portion 9 has a central aperture in which is provided a grill formation defined by plurality of circular grill elements 12 held in concentric spaced apart relationship by a plurality of radially 5 disposed ribs 13 on the undersurface of top portion 9 (see Fig. 5). The filter elements 4 to be incorporated in the cartridge comprise a plastics grille 4a, a filter paper 4b, a layer of foam material 4c, particulate carbon 4d, a further layer of foam material 4e, a further filter paper 4f, a further grille 4g, and a pleated glass-fibre paper filter element 4h. Although not detailed in the drawings, filter element 4h is of generally disc-like configuration and Ϊ > comprises radially fluted filter paper. It should be noted that the axial thickness of filter element 4h is less than the height of flange 10. Assembly of the filter cartridge 1 is as follows. Firstly, filter element 4h is positioned within 5 flange 10 such that the flange 10 projects a short distance (say 1mm) beyond the filter element 4h. The peripheral edge of filter element 4h is then bonded to the inner surface of flange 10. Next, filter elements 4a to 4g are positioned in 10 housing 2 in the order shown in Fig. 1, it being noted that the carbon 4d is added in granular form rather than in the form of a cart-ridge. Subsequently, the closure element 3 is positined on housing 2 with the flange 10 locating within the 5 body 5. Closure element 3 is pushed into housing 2 until flange 11 abuts against the rim of body 5. ' During this operation, the lower edge of flange 10 compresses the asse'mbly of filter elements 4a-4g so that they are firmly located in housing 2. Since -20 this compression is effected by the flange 10, no stress is placed on the fluted filter element 4h. Simultaneously with the end of the abovedescribed pressing operation, flange 11 is bonded to the body 5 to complete assembly of 25 cartridge 1. This bonding may be by means of adhesive or may be a 'welding' type operation. Thus, when the housing 2 and closure element are of crystalline plastics material they may be ultrasonically welded together. In the case of 30 polyolefins (e.g. polyethylene) the components may be hot plate welded together. Alternatively, induction welding may be used. This consists of inserting a conductive ring between the housing and the closure element and then 3 inductively heating the ring. A number of modifications may be made to the above-described assembly procedure. * For example, after introduction of the grille 4g into the housing, this grille 4g may be pressed downwardly (by means not shown) to effect a pre-compression of carbon 4b. Alternatively or additionally, after introduction of the grille 4g the top rim of the housing 2 may be 'sliced' off so as to ensure that, for all cartridges, the distance between grill 4g and the upper rim of housing is constant. A number of modifications may be made to the illustrated construction. Thus, for example, the undersurface of top portion 9 may be provided with a projecting finger of the same height as flange 10. This finger will locate through an aperture (not shown) in the , centre of filter element 4h and will assist in the abovedescibed pressing operation. Alternatively or additionally, a water repellant gauze may be provided between the filter element 4h and the top portion 9 of closure element 3 to prevent water entering through the grill • in the closure element entering the element 4h.

Claims: 6. CLAIMS : 1. A filter cartridge incorporating a layer of granular material for adsorbing gases and/or vapours retained in position by porous retaining means, the cartridge having an air inlet and an air outlet to allow passage of air through the cartridge, the cartridge comprising a housing and a closure element closing the housing, the closure element being associated with a compression element which during assembly of the closure element on the housing causes the retaining means to compress the granular material. 2. A cartridge as claimed in claim 1 wherein the compression element is integral with the closure element. 3. A cartridge as claimed in claim 2 wherein ' the compression element is a ' first flange provided around the closure' element and locating within the housing. 4. A cartridge as claimed in claim 3 wherein the closure element has a central positioned projection on the same side as said first flange and being of the same height thereof, said projection serving as an additional compression element. 5. cartridge as claimed in claim 3 wherein the closure element has a second flange positioned outwardly of the first flange and being adapted to located against the rim of the housing. 6. A cartridge as claimed in claim 3 wherein a filter element for removing particulate matter is located within the bounds of the first flange such that this flange projects beyond said filter element. 7. A cartridge as claimed in claim 1 wherein the inlet is provided as a grill formation in said closure element. 8. A filter cartridge which incorporates a filter element for removing particulate matter and a layer of granular material for adsorbing gases and/or vapours retained in position by porous retaining means, the cartridge having an air inlet and an outlet to allow passage of air through the cartridge, the cartridge comprising a housing and a closure element closing the housing, the closure element being associated with a compression element which during assembly of the closure element on the housing causes the retaining means to compress the granular material.

Inventors: FEENEY JOHN ROBERT, FEENEY, JOHN, ROBERT
Applicants: PROTECTOR SAFETY LTD, PROTECTOR SAFETY LIMITED
Application year: 1986
Main classification: B01D46
IPC codes: B01D46, B01D53