US2160317A - Respirator - Google Patents
Respirator Download PDFInfo
- Publication number
- US2160317A US2160317A US116456A US11645636A US2160317A US 2160317 A US2160317 A US 2160317A US 116456 A US116456 A US 116456A US 11645636 A US11645636 A US 11645636A US 2160317 A US2160317 A US 2160317A
- Authority
- US
- United States
- Prior art keywords
- face
- respirator
- wall
- filter
- piece
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- A—HUMAN NECESSITIES
- A62—LIFE-SAVING; FIRE-FIGHTING
- A62B—DEVICES, APPARATUS OR METHODS FOR LIFE-SAVING
- A62B18/00—Breathing masks or helmets, e.g. affording protection against chemical agents or for use at high altitudes or incorporating a pump or compressor for reducing the inhalation effort
- A62B18/02—Masks
- A62B18/025—Halfmasks
Definitions
- This invention relates to filter type respirators adapted to cover the nose and mouth of the wearer for the purpose of protection against dust, fumes and gases and is a modification of my Letters Patent 2,035,097 and my copending applications Serial No. 110,557, filed November 13, 1936, and Serial No. 113,323, filedNovember 30, 1936.
- the invention broadly aims to provide a filter type respirator of minimum size and weight while afiording a maximum area of filtration and also to facilitate the replacement of filter material and also minimize the reinhalation of exhaled air and also to provide a neutralizer for acid or similar dangerous fumes and also to provide pressure means at the nose' section of the face piece of' the respirator to hold said face piece in air tight contact with the face of the wearer.
- the invention resides in the 20 emplacement of filter units at the sides of the respirator face piece and there connecting them by means of registering holes and eyelets and placing deformable metal strips into the eyelet lock or other place, which metal strips are di- 25 rected towards the nose section of the face piece of the respirator, namely to each side of the said nose section for the purpose of supplying needed pressure at the said point in order to obtain an air tight contact between the face'piece 30 and the face of the wearer.
- Another feature is to raise the filter fabric at the point of marginal attachment by means of an angular deviation at the marginal area of the wall .of the .filter casing, for the purpose of 35 obtaining immediate filtration at the marginal attachment of the said filter fabric, and also providing supporting strips for the said filter material.
- Another feature is the provision of a neu- 40 tralizing separator unit located in the outlet area of the filter casing.
- Figure 1 is perspective view of the improved 50 respirator in applied position.
- Figure 2 is a section of line 2-2 of Figure 1.
- Figure 3 is a section of line 33 of Figure 2.
- Figure 4 is a section of line 4-4 of Figure 3, showing supporting strip attached to eyelet con- 55 nection.
- Figure 5 is a perspective view of sponge'sep'arator pad, prior to emplacement of the sponge into the grit gauze fold. The sponge and its folder is apart.
- Figure 6 is a perspective of the sponge and 5 its fold container assembled. and forming a separator pad.
- Figure 7 is an enlarged section of connecting bolt for separator pad and wall of filter unit.
- Figure 8 is a modified form of the supporting strip for the nose section of the body of the respirator.
- the supporting strip is illustrated here as being attached to the rear side of the casing wall.
- Figure 9 shows the filter material supporting 15 strip.
- A' designates the face piece of the respirator
- B designates the filter unit
- 0 designates the valve
- D the head band
- E the sponge separator pad
- the face piece A of the respiratoris prefer ably constructed of molded rubber or its equivalent and is adapted to engage the face of the 1 wearer and secured thereto by head bands D.
- the face piece A has a horizontal set back 5 below the nose line which set back 5 has a depending boss 6' which boss is in surrounding relation with a hole! in the said set back 5.
- An exhalation valve C is connected to the body of the respirator at the said horizontal section 5.
- the said exhalation valve C has a metal tube 8 inserted at its inlet 9, for the purpose of providing a constant potency at such inlet 9.
- the inlet end 9 of the valve C is inserted into the interior of the boss 6 and by means of cement is attached thereat.
- the valve 0 is made of molded elastic rubber and is the army type regulation exhalation valve.
- the filter unit B in this respirator has a rear 40 wall l0 and has a. marginal rim l I at the edge of the said rear wall l0 and at the edge of the marginal rim an intumed flange I2 is provided, which fiange removably secures a filter fabric I3.
- the rim II is outwardly directed and forms an obtuse angle with relationto the wall Ill;
- the said angular arrangement provides an advantageous juncture for correctly securing the said filter fabric. It is required that the said filter fabric be held in spaced relation with its supporting Wall Ill.
- the said filter fabric I 3 is impingingly held against said wall by the inturned fiange l2, and due to the outward direction of the rim and also due to the elevations at the inner side of the rear wall III, the said filter fabric l3 obtains an immediate partin from its attachment.
- filter units one on each side of the face piece A and the connection is made by means of registering holes 15 contained in the rear wall In of the filter unit and in the lateral parts of the face piece A.
- the said holes I5 are joined by eyelets I6.
- the rear wall In of the casing of the filter unit has a set back I1.
- the said set back [1 surrounds the outlet hole I 5 and is concentric therewith.
- the said set back II is covered by the sponge separator pad E, and the pad Eis secured thereat by means of bolts I 4.
- the object of the separator paid E is to purify the exhaled air from its carbon dioxide contents.
- an air space I8 is formed between the filter fabric l3 and the rear wall l0, and another comparatively small air space I9 is formed behind the sponge pad E.
- the sponge pad E is moistened with a dilute solution of sodium hydrate and thereby the exhaled air is purified of its carbon dioxide contents. Therefore, the reinhalation of impure exhaled air is minimized and is only equal to the small air space area l9, and thereby continued use of the respirator is made possible without the production of headache and tiredness to the wearer, which headache and tiredness is caused by the carbon dioxide of the reinhaled air.
- the said alkaline sodium hydrate solution is also useful when the respirator is used for protection against acid fumes, in which instance the acid fume is neutralized by the alkaline solution.
- the sponge pad separator E is secured to the wall ID by means of bolts H, which bolt is illustrated in Figure 7, the head 20 of the bolt is located at the rear side of the wall Ill.
- is threaded and a nut 22 is secured thereat.
- a rubber washer 23 is emplaced between the head 20 and the wall Ill, for the purpose of making the connection air tight.
- a rubber washer 23a is emplaced between the nut 22 and the grit gauze folder 24 of the sponge pad E.
- the rubber washer 23a is cut larger than usual and it is thus used for an additional purpose, namely to cover over the nut 22. It is folded and cemented to each other at a point outside of the nut 22. This arrangement is useful because the filter fabric is apt to be damaged by the nut 22 contact. Rubber contact is safer.
- the sponge pad E is illustrated in Figures 5 and 6. It has a grit gauze folder 24 wherein is enclosed a sponge separator element 25.
- Filter fabrics that are useful for filter type respirators are varied in texture and some are soft and flexible.
- the soft variety need extra support so that they do not sag and contact the wall In. If they would contact the wall ill the filtration area would diminish and thereby the breathing resistance would increase, which must be avoided. Therefore, additional support for the fabric is required and it is supplied by means of a metal supporting strip 26 which is substantially rigid and is placed behind the filter fabric at the greatest diameter of the marginal rim H.
- a metal supporting strip 26 which is substantially rigid and is placed behind the filter fabric at the greatest diameter of the marginal rim H.
- one metal strip is suflicient, and only one is'shown in the drawing, however when required two such metal strips may be inserted and preferably at right angle to one another.
- metal strips 21 are shown. These metal strips are preferably deformable and are locked into the eyelet joint I6. There are two such strips provided, one at each side of the face. These strips are bent to provide rearward pressure at the lateral nasal portion of the face-piece of the respirator, whereby the said face-piece portion is caused to engage the face of the wearer at the said part compressingly and thus a leak proof juncture is assured thereat. That is, the said strips 21 engage the face-piece of the respirator and press upon the said face-piece at the lateral nasal portion thereof, causing thereby a tight leak proof engagement betwen the face of the wearer and the said face-piece.
- Figure 8 there is shown a similar deformable metal supporting strip 21a.
- the strip 21 is for the same purpose as the strip 21. But, here the strip is shown to be attached to the rear of the casing wall I0 and attached to the said wall by means of the bolt M. It engages the face-piece of the respirator at the lateral nasal portion providing rearward pressure thereat to assure a leak proof joint between the said face-piece and the face of the wearer.
- a respirator having a hollow mask body of molded elastic material which body is adapted to engage the face of the wearer and the said body has lateral sides and filter units which filter units are connected to the said body at the said lateral sides and the said connections have attachably included deformable supporting elements which elements are directed towards the body of the respirator and pressingly engage the lateral nasal areas of the said body and thereby cause an air tight juncture of the body of the respirator and the face of the wearer at the said nasal areas.
- a respirator having a hollow mask body of molded elastic material which body is adapted to engage the face of the wearer and the said body has lateral sides and filter units which filter units are connected to the said body at the said lateral sides and the said filter units have substantially rigid inner side walls which walls have attached thereto deformable supporting elements which elements are directed towards the body of the respirator and pressingly engage the lateral nasal areas of the said body and thereby cause an air tight juncture of the body of the respirator and the face of the wearer at the said nasal areas.
- a respirator having a hollow mask body connected with a filter unit which filter unit has at least one wall and filter material removably secured at the margin of said wall and the said wall has an inwardly directed recess which recess unit including a substantially rigid wall with an outlet port and a marginal rim, and supported filter material, and the periphery of said rim has an intumed flange which removably secures the said filter material at the edges thereof and the said filter material confronts the said wall in spaced relation therewith, and the said outlet port connects with the said intake port whereby communication is provided-between the said filter unit and the said body, and means provided adjacent the said connection at the outer portion thereof whereby pressure is exerted to the lateral nasal portion of the said body to maintain a leak proof engagement of the said 'body and the face of the wearer at the said nasal portion.
- a face piece adapted to en-' gage the face of the wearer and made of semiflexible material having lateral sides, connecting with a filter unit having a substantially stiff wall, and means, the said wall being located in adjatween the said wall and the said face piece lateral side whereby pressure is brought to bear against the said lateral side and a leak proof engagement e 3 cent relation with the said face piece at its lat- 'eral side and the said means is positioned be is provided between the face of the wearer and the face piece of the respirator.
- a face piece adapted to enage the face of the wearer and made of semifiexible material having lateral sides, a filter unit having a stiff wall connected to the said face piece and located adjacent thereto, and means, the said means abutting the said wall and the NATHAN SCHWARTZ.
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Zoology (AREA)
- Pulmonology (AREA)
- General Health & Medical Sciences (AREA)
- Business, Economics & Management (AREA)
- Emergency Management (AREA)
- Respiratory Apparatuses And Protective Means (AREA)
Description
N. SCHWARTZ May 30, 1939.
RESPIRATOR Filed Dec. 18, 1936 INVENTOR Patented May 30, 1939 HNETE green? I ansrma'roa Nathan Schwartz, New York, N. )Y.
Application December 18, 1936, Serial No. 116,456
6 Claims.
This invention relates to filter type respirators adapted to cover the nose and mouth of the wearer for the purpose of protection against dust, fumes and gases and is a modification of my Letters Patent 2,035,097 and my copending applications Serial No. 110,557, filed November 13, 1936, and Serial No. 113,323, filedNovember 30, 1936.
The invention broadly aims to provide a filter type respirator of minimum size and weight while afiording a maximum area of filtration and also to facilitate the replacement of filter material and also minimize the reinhalation of exhaled air and also to provide a neutralizer for acid or similar dangerous fumes and also to provide pressure means at the nose' section of the face piece of' the respirator to hold said face piece in air tight contact with the face of the wearer.
More particularly the invention resides in the 20 emplacement of filter units at the sides of the respirator face piece and there connecting them by means of registering holes and eyelets and placing deformable metal strips into the eyelet lock or other place, which metal strips are di- 25 rected towards the nose section of the face piece of the respirator, namely to each side of the said nose section for the purpose of supplying needed pressure at the said point in order to obtain an air tight contact between the face'piece 30 and the face of the wearer.
Another feature is to raise the filter fabric at the point of marginal attachment by means of an angular deviation at the marginal area of the wall .of the .filter casing, for the purpose of 35 obtaining immediate filtration at the marginal attachment of the said filter fabric, and also providing supporting strips for the said filter material.
Another feature is the provision of a neu- 40 tralizing separator unit located in the outlet area of the filter casing.
With the above recited and other objects in view reference is had to the following description and accompanying drawing in which there 45 is exhibited one example or embodiment of the invention, while the claims define the actual scope of the same.
In the drawing:
. Figure 1 is perspective view of the improved 50 respirator in applied position.
Figure 2 is a section of line 2-2 of Figure 1.
Figure 3 is a section of line 33 of Figure 2.
Figure 4 is a section of line 4-4 of Figure 3, showing supporting strip attached to eyelet con- 55 nection.
Figure 5 is a perspective view of sponge'sep'arator pad, prior to emplacement of the sponge into the grit gauze fold. The sponge and its folder is apart.
Figure 6 is a perspective of the sponge and 5 its fold container assembled. and forming a separator pad.
Figure 7 is an enlarged section of connecting bolt for separator pad and wall of filter unit.
Figure 8 is a modified form of the supporting strip for the nose section of the body of the respirator. The supporting strip is illustrated here as being attached to the rear side of the casing wall. I
Figure 9 shows the filter material supporting 15 strip.
Referring to the drawing by character refer-' ence, A'designates the face piece of the respirator, B designates the filter unit, 0 designates the valve, D the head band and E the sponge separator pad.
The face piece A of the respiratoris prefer ably constructed of molded rubber or its equivalent and is adapted to engage the face of the 1 wearer and secured thereto by head bands D.
The face piece A has a horizontal set back 5 below the nose line which set back 5 has a depending boss 6' which boss is in surrounding relation with a hole! in the said set back 5. An exhalation valve C is connected to the body of the respirator at the said horizontal section 5. The said exhalation valve C has a metal tube 8 inserted at its inlet 9, for the purpose of providing a constant potency at such inlet 9. The inlet end 9 of the valve C is inserted into the interior of the boss 6 and by means of cement is attached thereat. The valve 0 is made of molded elastic rubber and is the army type regulation exhalation valve.
The filter unit B in this respirator has a rear 40 wall l0 and has a. marginal rim l I at the edge of the said rear wall l0 and at the edge of the marginal rim an intumed flange I2 is provided, which fiange removably secures a filter fabric I3. It is to be noticed that the rim II is outwardly directed and forms an obtuse angle with relationto the wall Ill; The said angular arrangement provides an advantageous juncture for correctly securing the said filter fabric. It is required that the said filter fabric be held in spaced relation with its supporting Wall Ill. This is accomplished by the bolts 14, which bolts extend outwardly from the wall Ill and also by the separator E which separator E is connected to the said wall I!) by the bolts M. It is also requir'ed that the said filter fabric obtain immediate filtration 'at the inner point of its marginal attachment. The reason for this is that a large filter area is needed in order to reduce resistance to breathing. The obtuse angle formation of the rim with relation to its base provides proper and immediate separation of the filter fabric from its attaching wall, which in this instance is the obtuse rim II. The said filter fabric I 3 is impingingly held against said wall by the inturned fiange l2, and due to the outward direction of the rim and also due to the elevations at the inner side of the rear wall III, the said filter fabric l3 obtains an immediate partin from its attachment.
In this improved respirator there are provided two. filter units, one on each side of the face piece A and the connection is made by means of registering holes 15 contained in the rear wall In of the filter unit and in the lateral parts of the face piece A. The said holes I5 are joined by eyelets I6.
The rear wall In of the casing of the filter unit has a set back I1. The said set back [1 surrounds the outlet hole I 5 and is concentric therewith. The said set back II is covered by the sponge separator pad E, and the pad Eis secured thereat by means of bolts I 4. The object of the separator paid E is to purify the exhaled air from its carbon dioxide contents.
It is to be noticed that an air space I8 is formed between the filter fabric l3 and the rear wall l0, and another comparatively small air space I9 is formed behind the sponge pad E. In practise the sponge pad E is moistened with a dilute solution of sodium hydrate and thereby the exhaled air is purified of its carbon dioxide contents. Therefore, the reinhalation of impure exhaled air is minimized and is only equal to the small air space area l9, and thereby continued use of the respirator is made possible without the production of headache and tiredness to the wearer, which headache and tiredness is caused by the carbon dioxide of the reinhaled air. The said alkaline sodium hydrate solution is also useful when the respirator is used for protection against acid fumes, in which instance the acid fume is neutralized by the alkaline solution.
The sponge pad separator E is secured to the wall ID by means of bolts H, which bolt is illustrated in Figure 7, the head 20 of the bolt is located at the rear side of the wall Ill. The
. shank 2| is threaded and a nut 22 is secured thereat. A rubber washer 23 is emplaced between the head 20 and the wall Ill, for the purpose of making the connection air tight. Also a rubber washer 23a is emplaced between the nut 22 and the grit gauze folder 24 of the sponge pad E. The rubber washer 23a is cut larger than usual and it is thus used for an additional purpose, namely to cover over the nut 22. It is folded and cemented to each other at a point outside of the nut 22. This arrangement is useful because the filter fabric is apt to be damaged by the nut 22 contact. Rubber contact is safer.
The sponge pad E is illustrated in Figures 5 and 6. It has a grit gauze folder 24 wherein is enclosed a sponge separator element 25.
Filter fabrics that are useful for filter type respirators are varied in texture and some are soft and flexible. The soft variety need extra support so that they do not sag and contact the wall In. If they would contact the wall ill the filtration area would diminish and thereby the breathing resistance would increase, which must be avoided. Therefore, additional support for the fabric is required and it is supplied by means of a metal supporting strip 26 which is substantially rigid and is placed behind the filter fabric at the greatest diameter of the marginal rim H. Usually one metal strip is suflicient, and only one is'shown in the drawing, however when required two such metal strips may be inserted and preferably at right angle to one another.
In Figures 3 and 4 are shown metal strips 21. These metal strips are preferably deformable and are locked into the eyelet joint I6. There are two such strips provided, one at each side of the face. These strips are bent to provide rearward pressure at the lateral nasal portion of the face-piece of the respirator, whereby the said face-piece portion is caused to engage the face of the wearer at the said part compressingly and thus a leak proof juncture is assured thereat. That is, the said strips 21 engage the face-piece of the respirator and press upon the said face-piece at the lateral nasal portion thereof, causing thereby a tight leak proof engagement betwen the face of the wearer and the said face-piece. In Figure 8 there is shown a similar deformable metal supporting strip 21a. This is for the same purpose as the strip 21. But, here the strip is shown to be attached to the rear of the casing wall I0 and attached to the said wall by means of the bolt M. It engages the face-piece of the respirator at the lateral nasal portion providing rearward pressure thereat to assure a leak proof joint between the said face-piece and the face of the wearer.
Having thus described my invention I claim as new and desire to secure by Letters Patent as follows:-
l. A respirator having a hollow mask body of molded elastic material which body is adapted to engage the face of the wearer and the said body has lateral sides and filter units which filter units are connected to the said body at the said lateral sides and the said connections have attachably included deformable supporting elements which elements are directed towards the body of the respirator and pressingly engage the lateral nasal areas of the said body and thereby cause an air tight juncture of the body of the respirator and the face of the wearer at the said nasal areas.
2. A respirator having a hollow mask body of molded elastic material which body is adapted to engage the face of the wearer and the said body has lateral sides and filter units which filter units are connected to the said body at the said lateral sides and the said filter units have substantially rigid inner side walls which walls have attached thereto deformable supporting elements which elements are directed towards the body of the respirator and pressingly engage the lateral nasal areas of the said body and thereby cause an air tight juncture of the body of the respirator and the face of the wearer at the said nasal areas.
3. A respirator having a hollow mask body connected with a filter unit which filter unit has at least one wall and filter material removably secured at the margin of said wall and the said wall has an inwardly directed recess which recess unit including a substantially rigid wall with an outlet port and a marginal rim, and supported filter material, and the periphery of said rim has an intumed flange which removably secures the said filter material at the edges thereof and the said filter material confronts the said wall in spaced relation therewith, and the said outlet port connects with the said intake port whereby communication is provided-between the said filter unit and the said body, and means provided adjacent the said connection at the outer portion thereof whereby pressure is exerted to the lateral nasal portion of the said body to maintain a leak proof engagement of the said 'body and the face of the wearer at the said nasal portion.
5. In a respirator a face piece adapted to en-' gage the face of the wearer and made of semiflexible material having lateral sides, connecting with a filter unit having a substantially stiff wall, and means, the said wall being located in adjatween the said wall and the said face piece lateral side whereby pressure is brought to bear against the said lateral side and a leak proof engagement e 3 cent relation with the said face piece at its lat- 'eral side and the said means is positioned be is provided between the face of the wearer and the face piece of the respirator.
' 6. Ina respirator, a face piece adapted to enage the face of the wearer and made of semifiexible material having lateral sides, a filter unit having a stiff wall connected to the said face piece and located adjacent thereto, and means, the said means abutting the said wall and the NATHAN SCHWARTZ. o
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US116456A US2160317A (en) | 1936-12-18 | 1936-12-18 | Respirator |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US116456A US2160317A (en) | 1936-12-18 | 1936-12-18 | Respirator |
Publications (1)
Publication Number | Publication Date |
---|---|
US2160317A true US2160317A (en) | 1939-05-30 |
Family
ID=22367305
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US116456A Expired - Lifetime US2160317A (en) | 1936-12-18 | 1936-12-18 | Respirator |
Country Status (1)
Country | Link |
---|---|
US (1) | US2160317A (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2640481A (en) * | 1950-02-14 | 1953-06-02 | American Optical Corp | Exhalation valve |
US2664887A (en) * | 1952-02-05 | 1954-01-05 | Mine Safety Appliances Co | Gas mask |
US3249106A (en) * | 1963-07-29 | 1966-05-03 | Armard V Motsinger | Rifleman's gas mask |
US4583535A (en) * | 1980-08-07 | 1986-04-22 | Saffo John J | Protection mask |
US4974586A (en) * | 1986-11-06 | 1990-12-04 | Moldex/Metric Products, Inc. | Breathing mask |
US20010029952A1 (en) * | 1999-10-19 | 2001-10-18 | Curran Desmond T. | Manner of attaching component elements to filtration material such as may be utilized in respiratory masks |
USD980410S1 (en) * | 2020-07-10 | 2023-03-07 | Lg Electronics Inc. | Filter housing for mask type air purifier |
-
1936
- 1936-12-18 US US116456A patent/US2160317A/en not_active Expired - Lifetime
Cited By (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2640481A (en) * | 1950-02-14 | 1953-06-02 | American Optical Corp | Exhalation valve |
US2664887A (en) * | 1952-02-05 | 1954-01-05 | Mine Safety Appliances Co | Gas mask |
US3249106A (en) * | 1963-07-29 | 1966-05-03 | Armard V Motsinger | Rifleman's gas mask |
US4583535A (en) * | 1980-08-07 | 1986-04-22 | Saffo John J | Protection mask |
US4974586A (en) * | 1986-11-06 | 1990-12-04 | Moldex/Metric Products, Inc. | Breathing mask |
US20010029952A1 (en) * | 1999-10-19 | 2001-10-18 | Curran Desmond T. | Manner of attaching component elements to filtration material such as may be utilized in respiratory masks |
US6959709B2 (en) * | 1999-10-19 | 2005-11-01 | 3M Innovative Properties Company | Manner of attaching component elements to filtration material such as may be utilized in respiratory masks |
US20050252839A1 (en) * | 1999-10-19 | 2005-11-17 | 3M Innovative Properties Company | Method of making a filtering face mask that has an exhalation valve attached thereto |
US7007695B2 (en) * | 1999-10-19 | 2006-03-07 | 3M Innovative Properties Company | Manner of attaching component elements to filtration material such as may be utilized in respiratory masks |
US7069931B2 (en) | 1999-10-19 | 2006-07-04 | 3M Innovative Properties Company | Method of making a filtering face mask that has an exhalation valve attached thereto |
USD980410S1 (en) * | 2020-07-10 | 2023-03-07 | Lg Electronics Inc. | Filter housing for mask type air purifier |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US2228218A (en) | Respirator | |
US2130555A (en) | Respirator filter | |
US2893387A (en) | Respirator | |
US2895472A (en) | Respirator | |
US2744525A (en) | Respirator | |
US6698427B1 (en) | Comfort ring for patient medical mask | |
US1710160A (en) | Respirator | |
US2067026A (en) | Respirator | |
US2290885A (en) | Respirator and method of making the same | |
US2529106A (en) | Combined hood and respirator | |
CN108136237A (en) | Filter mask retainer | |
US3750665A (en) | Flexible respirator with inflatable frame | |
BRPI0517361B1 (en) | personal respiratory protection device | |
US1837591A (en) | Respirator | |
US2160317A (en) | Respirator | |
US2295119A (en) | Respirator | |
US3736928A (en) | Collapsible face mask | |
US1946334A (en) | Respirator | |
US3266490A (en) | Pocket respirator | |
US2065775A (en) | Respirator | |
US2199230A (en) | Respirator | |
US2114358A (en) | Filter type respirator | |
US2112213A (en) | Filter type respirator | |
US2199231A (en) | Respirator | |
US2019928A (en) | Respirator |