US2910979A - Canisterless gas mask - Google Patents

Description

Nov. 3, 1959 F. SHANTY EI'AL CANISTERLESS GAS MASK Fi led May 6, 1958 v! R E 7 9 d N 5 N f W v4w 34 r r 6 M m i. I a. h m 3 5 M u 9 U "x .m r 4 .H R F v, 3 B 4 CANISTERLESS GAS MASK Frank Shanty, Baltimore, and Richard S. Brumfield, Edgewood, Md., assignors to the United States of America as represented by the Secretary of the Army Application May 6, 1958, Serial No. 733,460

6 Claims. (Cl. 128-141) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a canisterless gas mask. Instead of the conventional bulky, external canister this mask utilizes compact filtration-adsorption units mounted within the facepiece. It is an improvement on the mask shown and claimed in the application of Eugene Sovinsky, Serial No. 421,458, filed April 6, 1954.

In the drawings:

Fig. 1 is a perspective view of the mask with portions cut away to show the interior structure.

Fig. 2 is a view generally in section on the line 22, Fig. 1, but showing parts in elevation.

Fig. 3 is a view of the air inlet, partially in elevation and partially in section on the line 33, Fig. 1.

Conventional gas masks, for combat and industrial use comprise impermeable facepieces and metallic canisters which contain filtering material and/ or activated carbon, oxidation catalysts, chemical reactants, etc. Those intended for combat use commonly include fibrous filters for removing aerosols, and activated carbon, usually imp'regnated with metallic oxides, for adsorbing high molecular weight gases and vapors. Such masks are very effective so far as protection is concerned and while they have a high first cost, they are capable of repeated-use, since the canisters can be readily replaced. They also include refinements which prevent, or at .least greatly lessen, fogging of the lenses. They are however, quite cumbersome and interfere with the activity of the wearer. The canister either requires a carrier and hose connection or hangs from the facepiece, usually on one side, where it causes considerable discomfort because of the unbalanced weight, and also interferes with many activities, e.g. the use of the rifle.

In the last few years so-called gas-aerosol filter materials have been developed. They consist of intermingled fibrous material and finely divided activated char coal. These materials provide, in a single sheet, protection against both gases (by adsorption) and aerosols (by filtration). Masks have been constructed in which the facepiece itself is formed in part of these gas-aerosol filter materials, e.g. the masks shown in Patent 2,741,246 to G. R. Litchfield and Patent No. 2,775,967 to E. Sovinsky, Such masks initially offer good protection and are light and comfortable to wear.

bines theadvantages of the two types of maskalready United States Patent I 2,910,919 Patented Nov. 3, 1959 "Ice mentioned. That mask includes a permanent impermeable facepiece very similar to that of conventional masks. The canister is, however, replaced by an air purifying unit which is formed of two layers of gasaerosol filter material sealed together at their edges and held apart by a spacer to form an interior space. This unit lies against the outside of the facepiece, with the layers of filter material parallel to the surface of the facepiece, which is more or less enveloped. Conduits communicating with the interior space pass through the walls of the facepiece. Inhaled air flows into the interior space through the filter material and then through the conduitinto the facepiece. These masks are lighter and better balanced than conventional canister masks, yet offer the advantages of replaceable purifying elements. They can therefore be of sturdy construction and incorporate refinements for, e.g., preventing foggingof the lenses which are not practical in throwaway masks.

We have now further improved the mask shown in application Serial No. 421,458. Instead of putting the air purifying units outside the facepiece, we provide pockets within the facepiece in which the units are housed and protected from the weather. The conduit to they interior space of a unit communicates with an air inlet on the outside of the facepiece. Air thus flows into the interior space through the conduit then out through th Patent No. 2,800,901, granted July 30, 1957 and in ap- However, the filter element is not replaceable and these masks are therefore of the use with the hood, since it has.

plication Serial No. 492,809, filed March 7, 1955, now Patent 2,821,192, by Randolph C. Monro. The mask of Serial No. 421,458 is not suited to use with such a hood, since the air inlet must, of course, be outside the hood. The present mask, on the other hand, is well adapted for.

fit through in the hood. 7 a

The present mask can be readily checked for leak tight fit since the two inlet ports, which are the only intakes for air, can be readily sealed 01f with the palms of the hands. 1 j V The gas-aerosol filter elements are completely pro tected against the weather and against contamination on their outer surfaces. All toxic agents are collected on the interior of the elements, making the partly expended ele-' 'ments safe to handle.

Air flow problems are simplified. The fit of the mask is improved since the filter elements have only onepoint attachment to the face piece and can be made to conform more readily to the shape of thefacepiece. The total' thickness of the facepiece-filter combination is reduced.

One sizefilter unit can be used with several sizes of," Replacement filters can be packaged in much j masks.

more compact form.

Referring to the drawing, the mask includes a facepiece indicated generally at 1 whichis formed of an impermeable material such as molded rubber. The upper portion 3 of thefacepiece is formed of a single layer and includes conventlonal lenses 5. (Whil'ewe have shown separate lenses for each eye it will be understood that a single 1 ,lens extending across the entire front of the maskmay be two air inlets which may employed if'desired.) Below the lenses the facepiece is divided into two Walls. An inner wall7 is continuous with upper portion 3 and forms therewith a face-fitting inner mask. A head harness formed of straps '9 is attached to upper portion 3 and inner wall 7 to hold the inner mask in sealing relationship with the face of the wearer. An outer wall 11 joins the inner wall beneath the lenses and at the front and rear of the mask. Over the rest of its area it is spaced from the inner wall 7, forming a pocket 13 on each side of the facepiece, which pockets are joined by a passage 15 beneath the chin. The inner wall 7 is provided with an opening 17 beneath each lens 5, which openings form air outlet openings for pockets 13.

Within the facepiece is a conventional nosecup 19, having one-way inlet valves 21. The nosecup serves in a well known manner to prevent contact between the moist exhaled air and the lenses.

At the front of the mask, outer wall 11, inner wall 7, and nosecup 19 are all joined to a rigid, usually metallic, fixture which comprises a conventional speech transmitter 23 and an outlet tube 25, the latter carrying a conventional one-way outlet valve 27. An elastic rubber valve cover 29 having outlet ports 31 fits over the fixture.

Within each of the pockets 13 is an air purifying filter unit 33. This unit is formed of two sheets 35, 37 of filter material which are held apart by spacer 39, formed of corrugated wire or plastic screen. The sheets 35, 37 are sealed together at their edges, eg by rubber seal 41. The shape of units 33 is shown in dotted lines in Fig. 2.

An air inlet conduit 43 is mounted on, and passes through, sheet 35 of unit 33. It communicates with the interior space formed between sheets 35 and 37 and seal 41." Conduit 43 passes-through an opening in outer wall 11 and is tightly embraced by the elastic walls of the opening. It terminates in a flange 45 which carries an air inlet member 47. This air inlet member is preferably formed of stiff but resilient material and snaps over flange 45. The air inlet member 47 carries a series of downwardly and outwardly inclined baffles 49 and, behind the baffles, a one-way inlet valve 51.

The inner Wall 7 is provided with a flap 53, equipped with snap fasteners or the like, which provides access to.

pockets 13 for the removal and replacement of air purifying units 33.

To replace one of the air purifying units 33, air inlet member 47 is snapped off flange 45. Flap 53 is then opened and the unit 33 removed, the facepiece being sufficiently elastic to allow flange 45 to be pulled through the opening in the outer wall which embraces conduit 43. A unit is then inserted and air inlet .47 is replaced.

The presently preferred material for sheets 35, 37 is that designated by the Chemical Corps, United States Army, as Gas Aerosol Filter Material E 17, Type III.

As acceptable embodiment of this material will now be described. It consists of a plurality plies or core layers of intermingled carbon, glass fibers and organic fibers between two boundary sheets of carbon-free material formed of the same fibers and treated with a waterrepellant composition. It has the following composition and properties:

Glass fibers 1b./sq. yd 0.33 Organic fibers do 0.74 Charcoal do 2.95 Total density do 4.02 Thickness in 0.26

(2) 52-42% polyacrylonitrile fibers, 3 denier, 2 in. staple, tacky temperature 455 F.

The charcoal is the type known as ASC whetlerite, i.e. activated charcoal impregnated with the oxides of silver, copper and chromium, conforming to the U.S. Government specification MIL-C-13724A, through 40 mesh sieve, 92l00% retained mesh sieve.

The material is formed by an air-forming process and thenhot pressed. The thermoplastic polyvinyl chlorideacetate fibers act as an adhesive to stabilize the other fibers and the charcoal. The gas-aerosol material per se and the methods of making it are not our invention.

it will be understood, of course, that other gas-aerosol filter materials, such as those described in Patent No. 2,741,246, granted April 10, 1956 to George R. Litchfield and Patent No. 2,775,967, granted January 1, 1957 to Eugene Sovinsky, may also be used.

Furthermore, filter materials of different types may be employed for specialized purposes. For example, if the mask is to be used in a situation where very efiicient protection against aerosols is desired but the problem of removal of toxic gases or vapors is not present, a highly efficient aerosol filter formed of the fibrous materials listed above, but omitting the charcoal, may be employed.

Operation In Fig. 1 the path of the inhaled air is shown by short arrows and that of the exhaled air by long arrows. When the wearer inhales, air flows in through bafiies 49, inlet valves 51, and conduits 43 into the interior spaces of purifying units 33. It then flows out through filter sheets 35, 37, which remove aerosols and high molecular weight gases, into pockets 13. From pockets 13 it flows out through openings 17, across lenses 5 and through inlet valves 21, into nosecup 19 and thence to the wearers lungs.

Exhaled air flows out of nosecup 19 through valve 27, being kept away from lenses 5 by the nosecup 19 and its associated inlet valves 21.

While we have described one embodiment of the invention, it will be obvious that various changes are possible. We therefore wish our invention to be limited solely by the scope of the appended claims.

We claim:

1. A gas mask comprising a facepiece having a substantially impermeable outer wall, at least one transparent lens member in said facepiece, an air outlet in said facepiece comprising a one-way outlet valve, an inner wall within said facepiece joined to said outer wall so as to form at least one pocket having an outlet opening within said facepiece adjacent said lens member, an air inlet on said outer wall, a filter unit within said pocket, said filter unit comprising two sheets of filter material, spacing means holding said sheets of filter material apart to form an interior space, and an air inlet conduit passing through one of said sheets of filter material and communicating with said interior space, said conduit being connected to said air inlet, and means sealing the edges of said sheets of filter material together in air-tight relationship, whereby when the wearer of said mask inhales air will flow into said inner space through said air inlet conduit, then through said sheets of filter material into said pocket, and then through said outlet opening and across said lens member.

2. A gas mask as defined in claim- 1, wherein said inner wall comprises a flap adapted to be opened for access to said pocket and said air inlet conduit is removably connected to said air inlet, whereby said air purifying unit may be inserted in and removed from said pocket.

3. A gas mask as defined in claim 2, wherein said filter material is a gas-aerosol filter material formed of inter.- mingled fibers and finely divided activated carbon 4. A gas mask comprising a facepiece having a sub-- stantially impermeable outer wall, a nose cup within said facepiece adapted to fit closely over the mouth and nose of the 'wearer, one-way inlet valves in said nosecup communicating with the interior of said facepiece, an outlet tube communicating with the interior of said nosecup and the exterior of said facepiece, a one-way outlet valve in said outlet tube, two transparent lenses in said facepiece, said facepiece comprising, below said lenses, an inner wall and an outer wall so joined together as to form two pockets, one on each side of said facepiece, two air inlets on said outer wall, one being on each side of said facepiece and communicating with each of said pockets, an air outlet in each of said pockets, each being adjacent to one of saidlcnses, an air purifying unit within each of said pockets, each unit comprising two sheets of filter material, spacing 'means holding said sheets of filter material apart to form an interior space, sealing means joining said sheets at their edges in air tight relationship, an air inlet conduit passing through one sheet of filter material and communicating with said interior space,the air inlet conduit of each unit communicating with the corresponding air inlet on said outer wall, whereby, when the 20 wearer inhales air will flow in through said inlet conduits into said interior space of each unit, through said sheets 6 of filter material, through said air outlets, across said lenses and into said nosecup.

5. A gas mask as defined in claim 4 wherein said inner wall comprises a flap on each side of said facepiece adapted to be opened for access to said pockets and each said inlet conduit is removably connected to one of said air inlet means, whereby said air purifying units may be inserted in and removed from said pockets.

6. A gas mask as defined in claim 5 wherein each of said air inlet conduits extends through said outer wall and said air inlet means comprises a cap fitting over the outer end of said conduit, a plurality of downwardly and outwardly inclined baflies on said cap, and a one-way inle valve mounted on said cap behind said baflles.

References Cited in the file of this patent UNITED STATES PATENTS 2,775,967 Sovinsky Jan. 1, 1957

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