GB2045093A - Respirator - Google Patents

Abstract

A respirator has a mask portion 1, for covering the nose and mouth of the wearer, made of a material adapted to filter gas flowing therethrough, and is provided with a sealing strip 9 extending from the periphery 8 of the mask portion inwardly thereof so as, in use, to contact the face of the wearer. The sealing strip may extend continuously around the periphery 8 or cover only part of it. <IMAGE>

Description

SPECIFICATION Improvements in respirators The present invention relates to improvements in respirators and specifically filtering facepieces or orinasal masks which cover the nose and mouth of the wearer and serve to filter air flowing to or from the wearer.

Such masks have for many years been used in medicine to protect the wearer from germs inthe atmosphere or to protect other people from germs contained in the wearer's breath. These masks, made from one or more layers of a sheet material e.g. paper, are held on the face by tapes or rubber bands and provide no measured degree of filtration.

In recent years filtering facepieces have been introduced in industry to offer a degree of protection which has hitherto not been obtainabie to the wearer from non-noxious but nuisance dusts in the atmosphere. These industrial facepieces either take the form of a moulded cup or a flat pleated bag similar in construction to medical facepieces.

The moulded cup is made by sandwiching a filtration material between two low resistance fibrous cup -shaped elements which are jointed together at their edges. Either one or two rubber bands are attached to hold the cup against the wearers face and usually a deformable metal piece is included to extend over the nose of the wearer, and which is deformed by the wearer around his nose to increase the sealing around the nose.

The flat pleated bag facepiece is made from sheet material which is folded to provide pleats in the bag to-increase the filtration area available and hence to decrease the resistance to air passing through the material. The pleated material is sealed together at the edges to create the bag and again one or two bands are attached to hold the bag against the face of the wearer.

The principle defect of both the above types of industrial facepieces relates to the degree of sealing which they provide between the facepiece and the wearer's face. These types of facepieces are not inherently closely fitting and therefore the leakage of unfiltered air between the wearer's face and the facepiece is generally substantial. Efforts have been made to improve the sealing particularly in the region of the nose by providing the metal strip which extends over the nose and is intended to be deformed by the wearer around his nose. However this is not the only area in which leakage occurs and, it will be appreciated, any leakage substantially reduces the effectiveness and efficiency of the facepiece.Additionally the requirement that the user should deform the metal nose strip, where provided, himself in order to make the facepiece fit him, is regarded-as a major disadvantage because it is believed that the facepiece should fit the wearer without a conscious action on the part of the wearer.

According to one aspect of the present invention there is provided a filtering facepiece comprising a filtering mask portion which is intended in use to cover the mouth and nose of the wearer and is made of a material adapted filter gas flowing therethrough, means for attaching the mask portion to.the wearer's head, and a sealing strip extending from at least part of the periphery of the mask portion inwardly thereof so as, in use, to contact the face of the wearer.

According to another aspect of the presentinven- tion there is provided a filtering facepiece comprising a filtering mask portion which is intended in use to cover the mouth and nose of the wearer and is made from flexible sheet material which is adapted to filter gas flowing therethrough and which is seamed to the form of a flat pocket having an open mouth, and a sealing strip extending from at least part of the periphery of the mouth of the pocket inwardly thereof, the sealing strip being adapted, when the mouth of the pocket is opened for use, to become a seal adapted to lie against the face of the wearer inwardly of the periphery of the mouth of the pocket.

The sealing strip may extend at least to each side of the ends of the mouth of the pocket when flat. The sealing strip may extend continuously along the one side of the pocket intended to extend over the nose of the wearer or around the entire periphery of the mouth of the pocket Where the sealing strip extends continuously aroundthe periphery of the mouth of the pocket, it may, in the flat condition, have a generally frustoconical shape, the apex of the cone being directed towards the inside of the pocket.

Where the sealing strip extends overthat portion of the periphery of the pocket mouth intended to cover the nose of the wearer, that portion may be provided with a deformable element or may itself be deformable to conform more closely to the nose of the wearer.

The present invention will be more fully understood from the following description of embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a plan view of an embodiment of a filter facepiece according to the present invention; Figure2 is a section on the line ll-ll of Figure 1 showing the facepiece of Figure 1 in a partly opened condition; Figure 3 is a perspective view of the embodiment of Figure 1 showing the facepiece in fully open condition; Figure 4 is a diagrammatic sectional view of part ofthefacepiece of Figure 1 in use; and Figures 5 and 6 are perspective views of other embodiments of filtering facepieces according to the present invention.

The facepiece shown in Figures 1 to 3 of the drawings comprises a filtering mask portion 1 which is made from flexible sheet material in the form of a flat pocket having-opposed side walls 2,3 which are pleated. The sheet material forms or comprises a filtering material suitable for the particular purpose for which the facepiece is intended. The material may itself be a filtering material or may for example comprise a filtering material sandwiched between two layers of low resistance material which merely serve to contain the filtering material. For example the sheet material may comprise a semi-elecfrdstaric microfibre filtering material which is sandwiched between two thin non-woven fibrous sheets.

As shown, the pocket 1 is made from a single piece of sheet material which is folded to provide a bottom pleat 4 and two pleats 5 in each side wall 2,3. It will however be appreciated that the pocket may take other forms with more or fewer pleats and/or pleats of different dimensions, or the surface area of the sheet material may be increased in other ways, for example by corrugating it. The side walls 2,3 are connected together at the edges 6, 7 for example by sonic or heat welding or adhesive depending on the sheet material. One or more retaining straps 8a, for example elastic bands, are attached to the seams at or adjacent the mouth 8 of the pocket 1.

As is conventional, in use the side walls 2,3 of the pocket are pulled apart a sufficient distance to accommodate part of the nose and chin of the wearer and the pocket is fitted over the face of the wearer with the side walls 2,3 extending over the nose and under the chin respectively of the wearer and the seams at edges 6,7 extending along the sides of the face of the wearer. The strap 8a extends round the back of the head from about the level of the ears.

In the embodiment illustrated in Figures 1 to 3, the facepiece includes a sealing strip 9 which extends from the periphery of the mouth 8 of the pocket inwardly thereof and is arranged so that, as the mouth of the pocket is opened in use the strip 9 will move from its flat condition towards the plane of the open mouth of the pocket to form a seal which will come into positive contact with the face of the wearer around the mouth of the pocket.

With the pocket in a flat condition, as shown in Figure 1,the sealing strip 9 comprises two parts 9a, 9b each of which underlies a respective side wall 2,3 of the pocket and each of which is generally trapezoidal in shape. The two parts 9a, 9b are connected together along the inclined edges 10 of the trapeziums and the angle a these edges 10 make with the mouth 8 of the pocket is determined so as to cause the sealing strip to lie in the required position when the pocket is opened so as to positively contact the face of the wearer while not restricting entry of the face of the wearer into the pocket.

The facepiece thus no longer relies on contact between the periphery of the mouth of the pocket and the wearer's face to provide a seal, sealing being provided independently of the periphery of the mouth of the pocket by the sealing strip 9.

As shown the free edge 11 of the sealing strip is shaped to fit the face of the wearer and has a varying width to provide maximum width in those regions where the gap between the periphery of the mouth of the pocket and the wearers face is greatest.

The sealing strip 9 may be made of the same material as the pocket 1 and may be formed integrally therewith. Alternatively the sealing strip may be made of a different material which may not be permeable to air, for example rubber or a plastics such as PVC. Where the strip 9 is formed separately from the pocket 1, it is connected to the pocket along the periphery of the mouth 8 thereof in any suitable way, for example by welding or by adhesive.

To improve the seal provided by the sealing strip 9 around the nose of the wearer, the sealing strip 9 may be deformable in the region which bridges the nose of the wearer. For example the sealing strip 9 may be provided with a deformable metal strip 12 in this region, the strip 12 being bent to a generally U-shape to fit round the nose of the wearer.

Preferably the facepiece is supplies to the user folded in half along the broken line 13 in Figure 1 with the side wall 2 outermost so that the strip 12 is predeformed to U-shape. There is then no need.for the wearer to adjust the curvature of the metal strip 12 but he may do so for comfort.

Figure 4 shows diagrammatically the position of the sealing strip 9 relative to the face 14 of the wearer and the pocket 1 when the facepiece is in use.

A modification of the above described embodiment is illustrated in Figure 5, the sealing strip 9 is omitted along that portion of the periphery of the open mouth of the pocket that extends under the chin. In this region the seal provided between the periphery of the mouth of the pocket and the wearers face is best and therefore the sealing strip may be omitted with only a slight reduction in efficiency of the facepiece.

A further modification of the embodiment of Figure 1 is shown in Figure 6 and in this embodiment the strip 9 is omitted both in the region of the periphery of the mouth of the pocket which extends underthe chin and the region which extends over the nose. In the latter region sealing is improved, as in existing facepieces, by the provision of a deformable strip, e.g. a metal strip 15 which is provided adjacent the periphery of the mouth of the pocket and is preferably precurved by folding of the facepiece in its flat condition.

Claims (13)

1. A filtering facepiece comprising a filtering mask portion which is intended, in use, to cover the mouth and nose of the wearer and is made of a material adapted to filter gas flowing therethrough, means for attaching the mask portion to the wearer's head, and a sealing strip extending form at least part of the periphery of the mask portion inwardly thereof so as, in use, to contact the face of the wearer.

2. A facepiece according to claim 1, wherein the mask portion is made from flexible sheet material which is seamed in the form of a flat pocket having an open mouth providing the periphery of the mask portion, the sealing strip extending from at least part of the periphery of the mouth of the pocket.

3. A facepiece according to either claim 1, or claim 2, wherein the sealing strip extends from at least those parts of the periphery of the mask portion intermediate the portions which, in use, overlie the nose and underlie the chin of the wearer.

4. A facepiece according to claim 3, wherein the sealing strip extends from that part of the periphery of the mask portion which, in use, overlies the nose of the wearer.

5. A facepiece according to claim 4, wherein the part of the sealing strip which, in use, overlies the nose of the wearer is deformable for closely engag ing the nose of the wearer.

6. Afacepiece according to claim 5, wherein the deformable part of the sealing strip is predeformed to U-shape for engaging the nose of the wearer.

7. A facepiece according to either claim 4 or claim 5, wherein the deformable part of the sealing strip includes a deformable element.

8. A facepiece according to any one of claims 4 to 7, wherein the sealing strip extends continuously around the periphery of the mask portion.

9. Afacepiece according to any one of the preceding claims, wherein the sealing strip in use has the shape of at least part of a frusto-cone, the apex of the cone of which is directed towards the inside of the mask portion.

10. A facepiece according to any one of the preceding claims, wherein the width of the sealing strip varies along the length thereof.

11. Afacepiece according to anyone ofthe preceding claims, wherein the sealing strip is made of the same material as the mask portion and is formed integrally therewith.

12. A facepiece according to any one of the preceding claims, wherein the mask portion is made in the form of a flat pocket, the edges of the pocket being intended in use to extend at the sides of the face of the wearer, and is folded along the axis of symmetry of the pocket with that side of the pocket intended to overlie the nose of the wearer outermost so that the part of the mask portion intended to overlie the nose of the wearer is preshaped to better conform to the shape of the nose of the wearer.

13. A filtering facepiece substantially as herein described with reference to Figures 1 to 4 or Figure 5 or Figure 6 of the accompanying drawings.