US2220374A - Respirator - Google Patents

Description

H. B. LEWIS Nov. 5, I940.

nasnmvroa Filed Nov. '23, 193a 2 Sheets-Shoot 1 ATTORNEY.

and Nov. 23. 19:6 2 shuts-shun 2 //v (/s/v TOR HOWARD 5. LEW/J Br I ATTORNEK Patented Nov. 5, 1940 UNITED STATES PATENT OFFICE I nnsrma'ron Howard B. Lewisflios Anzeies, cam.

Application November 23, 1936, Serial No. 112,234 Claims) (cum-14s) My invention relates to respirators and particularly to the type of respirator adapted for purifying smoke-charged or dust-laden air to prevent these orother deleterious impurities in the 5 air from being breathed by the wearer.

' It is a general object of the invention to provide such a respiratorwhich is constantLv ready for use without preliminary adjustment, is efficient,

- light in weight, and comfortable for the wearer.

1 Another object resides in the provision of a respirator including a rigid mask adapted toextend around the mouth and nostrils of the wearer,

and having a nostril covering p rtion conforming substantially to the shape of the lower portion of the nose and extending only slightly beyond the nose so that normal vision is not obstructed and so that the wearer may wear glasses or prothe material of the mold being deformable normal to the face-engaging surface so that an airexcluding seal is formed between the wearer's face and the face-engaging surface when the mold is pressed against the face.

It is a further object of the invention to provide in a respirator -a rigid mask and a face mold readily attachable to and detachable therefrom.

More specifically, it is one of my objects to provide a mask having a rim extending around the mouth and nostrils of the wearer, therebeing a. pair of forwardly projecting hook portions on the rim adjacent the nose covering portion thereof; and a face mold formed of sponge rubber, or the like, having a groove for receiving the rim of the mask and having pockets formed in the groove for engaging the hook portions to retain the face mold on the 'rimin air-excluding relation there- .wlth. 7 6 It is a further object to form the face mold, mentioned in the above paragraph,- in the shape of a substantially flat continuous ring having the contoured face-engaging surface formed on one side thereof and having the groove formed in the 0 inner peripheral "edge thereof so that when the mold is mounted on the rim o'fthe mask, the inold which'includes a mask having an airiulet openstantially to the facial contour of the wearerand f ing and a filtering means covering the opening and comprising a shell having perforations in at least three sides thereof, a filtering means in the shell, and a filter spreading member adapted to hold the filtering material in a position exposing a. greater area thereof to direct contact with the air entering the perforations than the combined area of the perforations. V It is a still further object of the invention to provide in a respirator a filtering means covering the air inletand comprising a perforated cover, a sheet of filtering material and an inner filter spreading member formed so as to hold the sheet in a position exposing four spaced faces thereof to direct contact with air entering the 15 perforations, each of the faces having an area substantially equal to the greatest cross-sectional area of the cover,

Another object resides in .the provision of a respirator, as described in the above paragraph, 90 in which the cover and the filter spreader are vprovided with Opposed surfaces adapted to grip the entire marginal area of the filter sheet in sealing engagement therewith.

It is another object to provide deformable hook portions on the rim of the mask so that they may be bent laterally, permitting the nose covering portion of the face mold to be made narrower or wider to adapt this portion of the mold to different facial contours of various wearers.

It is another object to provide a respirator of the character described above having an outlet valve comprising a flexible valve plate secured to the outer surface of the mask and covering an outlet opening of the mask, the valve plate being adapted for outward movement relative to the mask to uncover the opening; and aguar'd strip detachably secured tothe mask and covering the valve plate in spaced relation therewith.

These and other'objects of the invention, as 40 well as numerous important features of construc-' tion, which combine to make an eficient, cheaply constructed respirator of the type specified, will bemade clear in the following part of the specification taken in connection with the accompany- 5 ing drawings and the appended claims.

In the drawings: v I

Fig, l is an elevational perspective view of the respirator embodying the features of my invention. l0

' Fig. 2 is a side elevation of the respirator with a portion broken away to illustrate a feature of the invention.

' Fig. 3 is a vertical section through the respira; tor taken as indicated by the Intel-3 of Fig. 4'. ll

Fig. 4 is a front elevation with a portion of the filtering means broken away to substantially a medial plane.

Fig. 5 is a top plan view of the respirator. 5 Fig. 6 is a horizontal section through the novel filtering means of the invention taken as indicated-by the line 6-6 of Fig. 4.

Fig. '7 is a perspective view of the filter spreading member of the invention, there being portions of this figure broken away to more clearly illustrate certain features of the construction thereof.

My novel respirator, generally designated in the drawings by the numeral Ill, includes a rigid mask l2 adapted to cover the nostrils and mouth of a wearer; a face mold l3 secured to the mask and adapted for air-excluding contact with the face of the wearer; an air filtering means I4; and a valved air outlet l5.

The mask I2 is formed of a rigid material, preferably metal, and is shaped to provide a rim 20 conforming generally to the contour of the wearers face and adapted to cover the mouth and nostrils. The body of the mask I2 is shaped to provide a nose covering portion 2|, conforming substantially to the contour of the lower portion of the wearers nose and extending only slightly forward of'the nose; and a mouth covering portion 22 conforming generally to the shape of the mouth and chin, as best shown in Fig. 3. Formed n the rim 20 adjacent the nose covering portion 2| and disposed on opposite sides thereof are two forwardly projecting hook portions 23. The hook portions are preferably provided to be laterally deformable, for a purpose to be explained later;

The edge of the rim 20 is preferably flared outwardly, as indicated at 24 in Figs. 2 and 3, for a purpose which will hereinafter be described.

For economy in manufacture, the face mold I3 is preferably molded in the form of a flat con- 40 tinuous ring of sponge rubber and is provided with a groove 25 formed in the inner peripheral edge 26 thereof for receiving the rim 2!]. The groove extends entirely around the lower portion of the mold and terminates in pockets 2? into 45 which the forwardly projecting hook portions 23 extend, as best shown in Fig. 2; the engagement of the hook portions in the pockets, the resiliency of the rubber and the outwardly flared edges 24 of the rim 20 serving to retain the face mold I3 50 on the rim in air-excluding relation therewith.

The forward portion 28 of the face mold extending between the pockets 21 forming the end of the groove 25 is adapted to be stretched around the flared rim of the nose covering portion, sub- 55 stantially as shown. The face mold I3 is preferably formed with a bead on the outer edge 29, the bead extending entirely around the rim 24 for the purpose of increasing the tensional strength thereof. Likewise, it is preferable to provide an 00 inner bead 30 extending substantially the entire length of the groove 25, as shown. The inner face-engaging surface M is preferably formed to substantially conform to the facial contour of the wearer after it is mounted on the rim 20. This 35 may be best accomplished by increasing the thickness of the mold [3 in certain portions and decreasing the thickness thereof in other portions. As best shown in Fig. 5, the wall thickness of the mold I3 is increased, as indicated at 32 and 33, 70 to provide inwardly projecting portions adapted to substantially conform to the hollows on each side of the wearer's nose. 1 The wall thickness of the mold is decreased, as shown at 34, to provide a comparatively thin, more flexible portion 7' adapted to extend across the bridge of the wearers nose and to conform substantially to the contour thereof. Other suitable thickened portions or thinned portions may be provided, as desired, to adapt the face mold to a more perfect fit with the wearer's face.

A head strap 40 having suitable adjustment means 4| is secured to the mask 12 as by suitable snap buttons 42 so as to extend around the wearer's head and hold the respirator in place.

The filtering means I4 is novel in construction and function and includes a cap 45 for securing the filtering means to the mask 12, a cover 46, filtering means 41, and an inner filter spreading means or form 48. The cap 45 is preferably rectangular in shape and provides up- Wardly sloping end walls 50 and upwardly sloping side walls terminating in an upper flat wall 52 in which is provided a pair of openings 53 having upwardly extending flanges 54 adapted to extend through openings 55 formed in the bottom wall 56 of the mask l2, the upper peripheral portions of the flanges 54 being swaged over the peripheral edge of the openings 55 securing the cap 45 to the mask l2 in air-excluding relation therewith.

The cap 45 serves to rigidly support the filter spreading member 48. Any suitable means such as soldering, welding, or the like, may be'employed to secure the filter spreading member 48 to the cap 45 but one preferred manner for accomplishing this purpose is indicated in the drawings with particular reference to Figs. 3, 4, 6, and '7. The filter spreading member 48 includes a rectangular upper frame 60 having a'pair of relatively spaced legs 6| and 62 extending downwardly therefrom. The upper frame Bll preferably is provided with a downwardly extending marginal flange 63, the portion of the flange extending across the ends of the frame 60 being increased in width, as shown at 64 in Figs. 4 and 7, for a purpose which will be described later. In order to secure the member 48 to the cap 45, a downwardly extending marginal flange 65 is provided to extend entirely around the four sides of the cap 45. The frame 60 is inserted within the marginal flange 65 of the cap 45 and the lower edge of the flange 65 is rolled along the sides of the cap 45 to extend under and around the flange 64 substantially as shown in Fig. 3. The portion of the marginal flange 65 extending across the ends of the cap 45 are not rolled around the flange 64 but are bent inwardly to provide an inwardly extending ledge 66 at each endf the cap, as shown in Fig. 4.

The legs 6| and 62 extend longitudinally of the frame 48 and terminate short of the flange 64 extending across the end of the frame so that" these portions of the flange overhang the ends of the legs BI and 62, in the manner shown' in Fig. 4, to provide a space 61 between these portions of the flange and the ends of the legs BI and 62.

Likewise, the outer side walls 68 and 69 of the' legs 6| and 62 are spaced inwardly from the rolled side edges of the flange 65 to provide a I space 10 therebetween as shown in Fig. 3.

The frame 60 and the legs 6| and 62 are preferably formed by stamping from light sheet metal. As shown in Figs. 3 and 7, the legs are formed by drawing the metal so that the walls The openings I5 and I8 extend from a point closely adjacent the ends of the legs'8i and 82 to a point adjacent to and equally spaced from the center of the legs 8I and 82 to provide a center portion TI, the outer portions 18 and I9 thereof being bent inwardly, as shown in Figs. 6 and 7, to provide a center ridge dividing the openings I5 and I8 and extending from the bottom to the top 8| thereof. The inner walls 82 and 83 of the legs 8| and 82 are-entirely cut away to provide an opening extending from a point even with the outer end of the opening I5 to a point even with theouter end of the opening I8, substantially as shown in Figs. 6 and 7. The end portions of the outer walls 88 and 88 and the inner walls 82 and 83 form continuous W-shaped surfaces and 88 at opposite ends of the legs GI and 82 for a purpose which will be hereinafter described. 1

The cover 48 comprises a rectangular box-like shell having side walls 80, end walls 9|, a bottom wall 92, and an open top, as indicated at 93 in Figs. 3 and 4. Secured to the opposite end walls 9| are suitable resilient latch members 84 having engager portions 85 adapted to engage the inwardly extended ledges 88 formed on the cap 45 when the open top of the cover is inserted 4 so that when the shell is secured to the cap 45,

the space between the side walls 80 and the outer walls 88 and 88 of the legs 8| and 82 is greater adjacent the bottom of the cover than at the top thereof. The end portions 81 and 88 ofthe side walls adjacent the end walls 8| are set inwardly and taper downwardly at the same angle as the outer walls 88 and 89 of the legs 82.

Mounted on the end walls 8| of the cover-48 so as to be. positioned between the inner walls 82 and 83 of the legs 8| and 82 are upwardly tapered wedge members I00. The opposite side walls I 0| of the wedgemembers are tapered to a degree to be exactly parallel with the downwardly. tapered inner walls 82 and 83 of the legs 8I and 82. The end portions of the bottom wall 02 which form continuations .of the end portions 91 and 98 of the side walls 80 are arcuated, as

shown at I02 and I03, to form continuations of the outer tapered walls IOI of the wedge member,

spaced relationship with the W-shaped surfaces 85 and 88 of the filter spreadingmember 48.

The preferred form of filtering means 41 consists of a sheet of filtering material,such as a comparatively heavy felt, orthe like.

sinuous path provided by the w -shaped space between the legs 8I and 82 and the cover 48. It will be seen that with the sheet of filtering material disposed as just described, the oppositely disposed marginal edges I05 and I08 respectively are confined between the W-shaped surfaces 85 and 88 provided by the walls of the legs 8| and 82 and the W'-shaped surface provided by the end portions of the cover and the wedge IN. The remaining oppositely disposed marformed button I2l adapted to be pressed through slow outward movement thereof. The manner of on opposite sides of the depression II 8.

be arranged so that the upper edge of the valve 4 In prac-. tice the filtering material 41 is provided in the form of a rectangular sheet-positioned in the sembled as heretofore described, themask is 90 of the shell and the upper portions of the outer walls 88 and 80 of the legs 8I and 82. Formed in both of the side walls 90 of the shell 48 is a seriesof perforations H0, these perfora-- I tibns preferably extending to points closely ad- 5 jacent the end portions 81 and 98' and closely adjacent to the arcuate bottom wall of the shell and the cap 45.

The intermediate longitudinally extending fiat portion ,HIof the bottom wall of the shell islikel0 wise preferably perforated, as shown at 2.111 Figs.4and 6.

The novel outlet valve l5 of my invention comprises a plate of flexible material H5, formed. of rubber, Cellophane, or the like, securedto the 15 outer side of the front wall H8 of the-mouth iv 5 covering'portion of the mask I2, the valve plate H5 covering an outlet opening I", and being outwardly'm'ovable by the exhalation of. air by the wearer of the'mask; In the preferred form" shown, the valve plate H5 is positioned 'inan: outwardly facing depression H8 formed in the wall H8, the depression H8 being deeper at the lower portion thereof than at .the upper'portion' and extending substantially across the entire front wall H8, as shown at I20 in Figs. 1 and 4.; A plurality-of the openings I I1 is preferably pro-Q; vided in that portion ofthe wall H8 which forms the rear wall of the depression H8, asshown in Fig. 5. The valve plate H5 is secured to the wall H8 above the outlet openings H1, by isuitf-ji able means such as a. rivet or an integr'ally a hole I22-in" the wall H8.

Detachably secured to the mask I2 isa guard strip' I23 which extends entirely over-the-valve plate H5 in spaced relationship therewith to aldetachablysecuring the guard strip I23 to the mask preferably comprises a shallow recess- I24 formed in the outer surface of the mask I2 on each side thereof, therecesses being disposed parallel with the portions of the front wall H8 The guard strip is provided with a pair of rearwardly extending fingers I25 disposed on opposite ends of the strip, the fingers having beads I28formed, thereon adapted to snap into the recesses I24. ,4 In this preferred form, it will be seen that the upper edge of the guard strip I23 is disposed 50 closely adjacent theupper edge of the valve plate H5 and the lower 1 edge thereof is relatively to uncover the outlets I I1. If desired, the spaced relationship of the upper end of the guard strip I23 and the rear wall of the depression H8 may plate H5 is pressurally retained therebetween to assist in securing the valve plate inoperative position. I

In the use of the respirator with the parts asplaced on the wearer's face, as indicated by the dotted outline in Fig. 3, and the head strap 40. adjusted to hold the mask tightly against the wearers face. As before explainedthe inner sur'face'3l ofthe face mold is shapedtocom form to the facial contour of the wearer and as l the mask 'is drawn tightly against'the face by the .head strap, the material of the 'face-.mold;is

ginal edges I01 and I08 of the sheet 41 are confined between the upper edges ofv the side walls capable of being deformed in a direction nor! malto'fthe contacting surfacetocompensate for 7 -any irregularities in the features of the wearer,

and although the face-engaging surface is preformed, the compressionof the body of the material allows it to adapt itself to conform to the contour of the face, thus providing an efllcient air-excluding seal between the face-engaging surface 3| of the mold and the wearers face. This compression of the material of the mold, as distinguished from the face-engaging cushions of the prior art which depend upon elasticity of the material to adapt the cushions: to various facial contours, provides a more eflicient seal for all types of faces and is much" more comfortable for the wearer. The hook portions 23 may be bent laterally toward or away from each other, effecting a decrease or increase in the width of the nose bridging portion 34 to adapt the mold to various nose contours.

The shape of the mask l2 having the nose covering portion conforming generally to the contour of the wearer's nose and extending only slightly above the nostrils of the wearer so that the forward nose-engaging portion of the face mold extends only over the lower portion of the nose, permits the wearer to have a normal unobstructed vision, not only straight ahead but also at a sharply downward angle, as indicated by the dotted line I of Fig. 3. Likewise, this feature permits the wearer to continue to wear spectacles which may be necessary to his vision, or permits the use of protective goggles which are essential in various kinds of factory and mine work without interference with the'efliciency of the mask and without discomfort to the wearer.

With the respirator in position, air is drawn into the mask by inhalations of the wearer through the perforations forced to fiow through the sheet of filtering material 41 before entering the interior of the mask. The air is thus purified and cleaned of smoke, dust particles, or the like, before being breathed by the wearer. It will be seen that the manner in which the filter spreading member holds the sheet of filtering material provides four surfaces of the filtering material exposed to direct contact with the air flowing through the perforations, each of the surfaces being substantially equal in area to the greatest cross-sectional area of the cover. Likewise, the space between the side walls 90 of the cover and the adjacent surface of the sheet'of filtering material is an important feature in that the air flowing through the perforations is not forced to flow directly through the filtering material but may circulate after passing through the perforations so that the entire surface of the filtering material adjacent the perforations is effective to filter and purify the air. Thus, a thicker, finer mesh filter fabric may be employed without increasing the breathing effort of the wearer to a noticeable degree. This results in a more efficient filtering action, an easier inhalation by the wearer, and an economy in the utilization of the filtering material. 4

When it is desired to change the filtering material, it is merely necessary to press the latch members 94 and to withdraw the cover, whereupon a fresh sheet of filtering material may be disposed around the surfaces 85 and 86 of the 'legs 6| and 62 andthe cover repositioned. The

pressural engagement of the marginal edges of the filter sheet between the W-shaped surfaces 85 and 86Jo'f the filter spreader. and the W- shaped surfaces formed by the end portions 98 of the side walls 90, the bottom wall 92 and the side H0 and H2 and iswalls llll of the wedge I00, serves to effectively prevent any air from flowing around the marginal edges of the filter sheet.

When air is expelled fromthe lungs of the wearer, the lower edge of the outlet valve H5 is forced from contact with the wall H6 uncovering the opening to allow the escape of exhaled air and upon subsequent inhalation by the wearer is caused to engage the wall H6 in sealing engagement therewith, effectively preventing entrance of unpurified air through the opening I 11. The valve Plate H5 is preferably extremely flexible, being formed of comparatively thin soft rubber, Cellophane, or the like, so that undue pressure is not required to force the valve outwardly and normal inhalations of air by the wearer effectively serve to draw the valve plate tightly against the wall H6.

The guard strip I23 serves both to limit the outward movement of the valve plate H5 and to protectthe material of the valve during use from sprayed materials or solids in the air which would otherwise destroy its flexibility and usefulness. The guard strip is easily detached for replacement or adjustment of thevalve plate.

Although I have disclosed and described only one complete embodiment of my invention, it should be understood that various structural features thereof might be changed, and various modifications of the inventive combination might be devised by those skilled in the art without departing from the invention the scope of which should be interpreted by the appended claims.

I claim as my invention: I

1. In a respirator of the character described, the combination of: a mask having a rim adapted to extend around the mouth and nostrils of a wearer and having a nostril covering portion conforming substantially to the shape of the lower portion of the nose and extending less forwardly of the nose than the line of vision of the wearer; an air filtering inlet in said mask; a valved outlet in said mask; a pair of forwardly projecting hook portions formed on said rim adjacent said nostril covering portion; and a face mold formed of compressible material and providing a face-engaging surface conforming generally to the facial contour of said wearer, said mold having walls forming 'a groove for receiving said rim and pockets in said groove engaging said hook portions for retaining said mold on said rim, said material of said mold being deformable normal to said face-engaging surface whereby an air-excluding seal is formed between said face-engaging surface and the wearers face.

2. In a respirator of the character described, of combination of: a mask having a rim adapted to extend around the mouth and nostrils of a wear and having a nostril covering portion conforming substantially to the shape of the lower portion of the'nose and extending only slightly beyond the nose so that normal vision is not obstructed; an air filtering inlet in said mask; a valved outlet in said mask; a pair of forwardly projecting hook portions formed on said rim adjacent said nostril covering portion; and a face mold formed of compressible material and comprising a continuous strip, one edge of which is adapted to be stretched around and extend over said rim, said strip having walls forming pockets engaging said hook portions for retaining said mold on said rim, and the thick-' I the inner surface thereof conforms substantially to the contours of the chin, cheeks, and nose of said wearer, said material of'said strip being de-' a forming substantially to the facial contour of said wearer; a valved outlet in said mask; walls forming an inlet opening insaid mask; filter means comprising acap secured to said mask and communicating with'said inlet, a perforated cover having releasable latch means securing said cover to said'cap, a sheet of filtering material, and' an inner filter spreading member formed to hold said filtering material in a position exposing a greater area thereof to direct surface contact with air entering said perforations than-the combined area of said perforations.

4. In a respirator 'of the character described, the combination of: a mask adapted to cover the mouth and nostrils of a wearer and comprising a rigid shell having-secured theretoa face mold formed of compressible material conforming substantially to the facial contour of said wearer; a valved outlet in said mask; walls forming-an inlet opening in'said mask; and a filter means comprising a cap secured to said shell and communicating therewith through said opening, a perforated cover detachably secured to said cap, a sheet of filtering material, and a filter spreading member. supported by said cap adapted to hold said filtering material in a position exposing a plurality of spaced faces thereof to direct surface contact with air entering said perforations and each of said faces having-an area substantially equal to the greatest cross-sectional area of said cover.

5. Ina respirator, the combination of: a mask adapted for air-excluding contact with a wearers face to cover the mouth and'nost'rils, said mask h ving a suitable air outlet and an air inlet; a d' a filter means comprising a cap secured to said mask to communicate with said air inlet, a perforated cover detachably secured to said cap, a sheet of filtering material, and an inner filter spreading member supported by said cap and formed to hold said sheet in a position exposing a plurality of spaced faces thereof to direct surface contact with air entering said perforations and each of said faces having an area substantially equal to the greatest crosssectional area of said cover, said cover and said filter spreading member having opposed sur- .prising a strip of flexible rubber secured to the outer surface of said mask and having a portion covering said opening; and a guard strip detachably secured to said 'mask and covering said strip in spaced relation therewith to allow out ward movement of said flexible strip, the upper 8 edge of said strip'o! flexible rubber being (118-, posed between and in clamped relationship with boththe upper edge of said guard strip and theouter surface of said mask.

7. In a respirator of the character described. the combination of: a mask adapted for airexcluding contact with a wearers face to cover the mouth and nostrils, said mask having a suitable air filtering inlet, the frontwall of said mask being formed with a rearwardly extending recess having generally vertical re-entrant end:

walls, a re-entrant rear wall connecting said end walls and inclined rearwardly and inwardly from the top of said recess, a reentrant bottom wall connecting said end walls and extending from the lower edge of said rear wall to the front lower edge. of said recess, said rear wall having formed therein an air outlet opening; a thin flexible rubber fiap valve secured at its upper edge in said recess across the outside of said opening and with its lower portion free to move outwardly from said opening; and a guard strip detachably secured to said mask across said 'recess and substantially in the plane of the slightly beyond the nose so that normal vision is not obstructed; a pair offorwardly projectinghook portions formed on said rim adjacent said nostril covering portion; a face mold formed of compressible material and providinga faceengaging surface conforming generally to the facial contour of said wearer, said mold having walls forming a groove for receiving said rim and pockets in said groove engaging said hook portions for retaining said mold on said rim, said material of said mold being deformable normal to said face-engaging surface whereby an air-excluding seal is formed between said face-engaging surface and said wearers face; a

valved outlet in said mask; walls forming an air inlet insaid mask; and a filter means comprising a cap secured to said mask to communicate with said air inlet, a perforated cover detachably secured to said cap, a sheet of filtering material, and an inner filter spreading member supported by said cap and'formed to hold said sheet in a position exposing four spaced faces thereof to direct surface contact with air entering said perforations and each of said faces having an area substantially equal to the greatest crosssectional area of said cover, said cover and said filter spreading member having opposed surfaces gripping the entire marginal edge of said sheet of filtering material in sealing engagement therewith. v

9. In a respirator of the character described, the combination of: a mask having a rim adapted to extend around the mouth and nostrils of a wearer and having a nostril covering portion conforming substantially to the shape of the lower portion of the nose and extending only slightly beyond the nose so that normal vision is not obstructed; a pair of forwardly projecting hook portions formed on said rim adjacent said, nostril covering portion; a face mold formed of compressible material and providing a face-engaging surface conforming generally to the facial contour of said wearer, said mold having walls forming a groove for receiving said rim and pockets in said groove engaging said hook portions for retaining said mold on said rim, said material of said mold being deformable normal to said face-engaging surface whereby an air-excluding seal is formed between said face-engaging surf-ace and said wearer's face; an air filtering inlet in said mask; walls forming an air outlet opening in said mask; a valve comprising a flexible plate secured to the outer surface of said mask and having a portion covering said opening; and a guard strip detachably secured to said mask and covering said plate in spaced relation therewith to allow outward movement of said flexible plate.

10. In a respirator of the character described, the combination of: a mask having a rim adapted to cover the mouth and nostrils of a wearer; said mask having an air filtering inlet and a suitable valved outlet; and a face mold secured to said rim, the material of which between its inner and outer edges is out of contact with the face of the wearer and is of a flexible character to permit bodily movement of its outer portions,

said face mold having a relatively thin stretchable and flexible front portion to fit over the nose of the wearer and being formed at two portions of its outer face-engaging edge with thickened marginal solid enlargements having the qualities of sponge rubber, said enlargements being adapted to fit within the lateral nose hollows of the wearer, said mold being also formed with a continuous face engaging bead of lesser cross-sectionalsize than said enlargements and extending from one of said enlargements to the other, said bead being adapted to fit the cheeks and undersurface of the chin of the wearer, said enlargements and bead being capable of being compressed normally of the plane of the adjacent portions of the mold upon contact with the face of the wearer.

11. In a respirator of the character described, the combination of: a mask having a rim adapted to extend around the mouth and nostrils of a wearer and having 'a nostril covering portion conforming substantially to the shape of the lower portion of the nose; an air filtering inlet in said mask, a valved outlet in said mask; a pair of forwardly projecting hook portions formed on said rim adjacent said nostril covering portion and adjacent the sides of the bridge of the nose 'of the wearer, said hook portions being adapted to be bent toward or from each other to adapt the mask to various nose contours; and a face mold formed of flexible material secured to said rim and hook portions in air-excluding relationship therewith and adapted to conform to the face of the wearer in airexcluding relationship therewith.

fllterelement shaped to receive the sheet on its external surfaces in convoluted form, said sheet being unsupported vertically by said form; a detachable cover for said filter element provided with contact surfaces adapted to mate with said external surfaces on the filter form and grip and vertically support the filter element therebetween when said cover is in closed position; and means independent of said cover for securing said form to said bottom wall in rigid relation thereto.

13. In a respirator of the character described, the combination of: a mask adapted to cover the mouth and nostrils of the wearer, comprising a rigid shell and a face mold secured thereto formed of flexible material adapted to fit the face of the wearer in air-excluding relationship therewith; a valved outlet in said mask; walls forming an inlet opening in said mask; a boxlike filter shell secured to said mask, said filter' shell being formed with two perforated side walls and a perforated bottom wall; a filter element;-

and a frame for said element mounted within the shell and formed to hold the filter element with two first portions substantially parallel to and normally spaced from and within'said side walls, and with at least two other portions between said first two portions and separated from each other to afford a chamber therebetween in communication with the perforations in said bottom wall of said shell.

14. In a respirator of the character described, the combination of: a mask having a rim adapted to extend around the mouth and nostrils of a wearer and (having a portion covering the lower portion of the nose); an air filtering inlet in said mask; a valved outlet in said mask; a pair of hook portions projecting forwardly of the face of the wearer formed on said rim adjacent said nose covering portion and adjacent the sides of the bridge of the nose of the wearer, said hook portions being adapted to be bent toward or from each other to adapt the mask to various nose contours; and a face mold formed of flexible material secured to said rim and hook portions in air-excluding relationship therewith and adapted to conform to the face of the wearer in air-excluding relationship therewith.

15. In a respirator of the character described, the combination of: a mask having a rim adapted to extend around the mouth and nostrils of a wearer and having a portion covering the lower portion of the nose; an air filtering inlet in said mask; a valved outlet in said mask; a pair of hook portions projecting forwardly of the face of the wearer formed at symmetrically related points on the two sides of said rim respectively,

said hook portions being adapted to be bent toward or from each other to adapt the mask to various facial contours; and a face mold formed of flexible material secured to said rim and hook portions therewith and adapted to conform to the face of the wearer in air-excluding relationship therewith. I

' HOWARD B. LEWIS.

in air-excluding relationship' I CERTIFICATE OF'CORRECTION. Petent No. 2,220,57h. j Novemberf5, 19140.

nowmo e. LEWIS. It is hereby certified that erronp'pears in the printed specification of theabove'numbered patent requiring'correction as follows: Page h, sec- 1v 0nd column line 60, claim 2, for theword "weer" read -wearerpage fi, first colwqh, line'Zl, claim 10, strike out thesemicolon and-insert in-' stead a comma; li efi'l, same claim, after, "crosseeo tizonalfl strike out-the hy ahen'; same page, secongi-colm nn, lixies 55 3116. 56, claim 114., str -ike out the parenthesis marks before 'heving and. after "no se"; end that the said Letters Patent shoiillfibe read with this co i'rection therein: that the same may conform to the recoz d of the oaeein the Patent Office. I

signed f l his 17th day of: December, A'.' 1;. 91m,

Hem-y- Airedale;

(Seal) Acting comiestoner of Patents;

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