US2314955A - Respirator - Google Patents

Description

March 30, 1943.

I R. L. SLATER RESPIRA'I'OR Filed July 2, 1941, 5 Sheets-Sheet 1 March so, 1943. R, RI I 2,314,955 RESPIRATOR Filed July 2, 194;

Sheets-Sheet 3 mg H III

March 30, 1943.

Filed July 2, 1941 5 Sheets-Sheet 4 wlil" rl' o March so, 1943. I L, SLATER 2,314,955

' RESfIRATOR Filed July 2, 1941 5' Sheets-Sheet 5 fowl $.23 (ya i671- closing of the same.

Another object is to provide a neck collar for Patented Mar. 30, 1943 UNITED STATES PATENT orrlcs mssrmzi ron Robert L Slater, Chicago, in. Application July 2, 1941, Serial No. 30,727

'. 13 Claims.

The invention relates to respirators and has more particularly reference to a light weight,

portable apparatus for treating patients requiring artificial respiration.

The primary object of the invention is to provide a portable respirator which will induce breathing by rhythmic changes of the air pres- In the drawings which illustrat an embodiment of the invention and wherein like reference sure within the respirator chamber; to provide characters are used to designate like parts- Figure lis a side elevationalview of the respirator of the invention showing the location of a patient within the respirator chamber with the neck collar .and rear flexible diaphragm being shown in proper position on the patient; I

Figure 2 is a side elevational view of the respirator shown in Figure 1, illustrating the adjustable standard whereby the apparatus may be supported in tilting position with the head of the patient inclined downwardly;

Figure 3 is a vertical sectional view taken longitudinally through the present respirator showj ing the improved closure means for the respective ends of the respirator chamber and also illustratthe present respirator of soft sponge rubber with improved means for opening the same for appiication to or removal from the neck of thepatient and which may be readily secured to the respirator by novel hinged clamps that ar spring energized to maintain them open unless locked in closed position. a

Another object is to provide a respirator which will confine within the respirator: chamber only the chest and abdomen of the patient and which will thereby have the important advantage of cleanliness as all body functions. can be taken care of outside the apparatus.

Another object is to provide improved diaphragm means for sealing the rear of the respirator chamber around the hips of the patient; to provide a flexible diaphragm which will render possible theopening and closing of the cover by embodying a zipper closure, and a diaphragm which will fit tightly around the hips of the patient when in operative association to prevent the leakage of air. F Another object is to provide bly for the respirator device of the invention that will be'compact and simpl in construction,

a bellows assemmg the construction of the bellows assembly;

Figure 4 is a vertical sectional view. taken transversely through the respirator shown in Fig ure 3, substantially along line 4-4 thereof and looking in the direction of the arrows;

Figure 5 is afront elevational'view showing in particular the hinged clamps for releasably' retaining the neck collar in place;

Figure 6 is a detail sectional view takenvertically through the neck collar and clamping means therefor, substantially along line 6-6 of Figure 5;

Figure 7 is a fragmentary plan view with parts being shown in section to better illustrate the construction of the air inlet and exhaust valves and regulating means therefor;

Figure 8 is a rear elevationalwiew of there'spiratorof the invention illustrating the constructional features of the rear flexible diaphragm for encircling the hips of the patient;

Figure 9 is a fragmentary viewin perspective showing the open end of the rear flexible diaphragm and the zipper closure for makingpos-. sible the opening of the cover to the respirator chamber;

and which will have a volumetric capacity well in excess of that required for producing'normal respiration. 4 V

With these and various other oblects in view,

the invention may .consist of certain novel features of constructionand operation as will be more fully described and particularly pointed out Figure 10 is a detail sectional view showing thezipper closure for the rear flexible diaphragm in closed position; and V Figure 11 is a sectional view ,takensubstan tialhr along line |I,ll of Figure '7 more particularly illustrating the regulating means for the anexhaust valve.

Referring to the dra ings, particularly Figure 1, which illustrates the application of the present apparatus to a. patient. for the purpose of inducing artificial respiration, it will be observed that the present respirator indicated in its entirety by numeral 20 includes a base structure 2| to which-thecover .22 is pivoted and releasably fastened in closed position. The base structure houses the bellows assembly, as will bemore par-- ticularly understood as the description'proceeds,

rear end by a flexible diaphragm 24 having en-.

Said chamber is" closed circling relation with the hips of the patient.

Only thechest and abdomenof the patient is therefore confined within the respirator chamber which has the important advantage of cleanliness as all body functions may be taken care of outside the apparatus. The head rest 25 is pivotally connected with the front wall of the base structure and a rear cushion 26'for supporting the buttocks of the patient has pivotal connection in a similar manner to the rear wall of the base structure. In Figure 1 the respirator is, shown in horizontal position with all four rollers 21 having contact with the floor. Figure 2 illustrates an inclined position of the apparatus which is resorted to in certain types of artificial respiration as drowning and in advance stages of paralysis to facilitate draining of the threat. The tilting is rendered possible by a foot .member 28 extending transverselybeneath the base structure and having pivotal connection at its respective ends with rods 30. When not in use, asin Figure 1, the foot member 23 is supported in an inoperative position by the depending hooks 3| which fltwithin a slot formed in the foot member 28 for the purpose as illustrated in Figure 4.

As best shown in Figures 3 and 4, the base structure includes spaced parallel side walls 32 and 33, a front end wall 34 and a rear wall 35. The four walls at their lower end are each bent inwardly to form flanges 35 reinforced by metal strips 31 and which are additionally reinforced at the corners by brackets 38 suitably secured as by the rivets 39 to the saldwalls. The brackets provide supporting means for the swivel cast ers 40 journalling the rollers 21. Three of the walls-of the base structure, namely, the side walls 32 and 33 and the front wall 34, are also flanged inwardly at their upper end to form a supporting ing from the base structure. as best shown in Figure- 4. The left hand hook depends vertically downward from a plate bracket 48, whereas, the right hand hook member is secured to'and depends from the side wall 33.

The base structure is divided internally by means of a metal diaphragm member 50 having .the' central opening 5| and which diaphragm mernber forms the upper stationary part of the the member 50 is directly supported and also a I lower ledge 55 which is used to suitably fasten the movable diaphragm 53 of the bellows assem-; bly as by means of the ring 51 and bolts 58. An

internal partition'Gll extends upwardly from the lower ledge 55, beingalso suitably secured thereto by bolts 58 and said internal partition at its opposite end connects with the diaphragm 53. The structure thus described, in connection with the rigid center piece 5|, suitably secured around the periphery thereof as at 62 to the movable diaphragm 53, completes the bellows assembly. It will be understood that diaphragm 33 may be formed of any suitable flexible material and by movement of the same in a vertical direction upwardly and downwardly air will alternately be forced from the bellows assembly and drawn into said assembly through opening ll.

manually actuated lever 33 is disclosed, having connection with the rigidcenter piece at 54 by I means of a link 55 pivotally connecting at 33 with the end of the lever located within the base ledge 4| and which ledge is reinforced throughout its extent by the angle piece 42. Wall 35 carries an .additional part which 'extends alongthe upper edge thereof for the purpose of providing, in

conjunction with the cover, suitable fastening means for the rear diaphragm 24. This addition-' al part is clearly shown in section in Figure 3 and includes the transversely extending member- 43 providing the inwardly directed flange 44.

which is disposed in substantially the same plane as the ledge 4|. Said supporti ledge and flange 44, which is substantially a continuation thereof, retains in position a sealing strip 45 that may be Q formed of any soft flexible material and which defines the opening between the base structure and the cover of the respirator. -When the cover is in closed position the samewill have contact withthesealingstrlpliaroundallfouredges thereof seas to effectively seal the interior of the cover from the atmosphere and prevent leakageofairatthesepoints."

The side 18118 are provided with plates 43,.as

bestshowninrigures3and8,whicharelocated relativ close to the rear corner brackets 33. Thus gata each provide a rotatable and adjustable connection '41 adaptedto receive the rods 33 of the foot attachment which permits pivotingof therodsand adJustment-ofthe same a to structure. Said end has a fulcrum connection at 61 and projects outwardly through a rubber covered opening 53 located in the side wall 32.

An adapter 39 is fitted to this projecting end of the lever so as to receive a handle part 10 which projects upwardly and provides a venient reach of' the operator.

The air from opening 5! of the bellows assembfy is caused to travel laterally since a mattress container II is positioned directly over the said opening. Said container, which is of rectangular shape in plan and having upstanding marginal flanges, is suitably supported by brackets 12 and horizontally positioned within theupper portion of the base structure. A mattress or the like, indicated by numeral I3, and shown'in dotted lines in the drawings, Figures 3 and 4, is positioned within the container.

' In order that the air pressure within the respirator chamber may be alternately changed from pressure to vacuum by the action of the bellows, the brackets 12 are provided with a plurality of openings 14 which allow the air to travel to and fro from the bellows upwardly to the respirator chamber. Inother words, the openings I4 provide the necessary communication between opening if of the bellows assembly and the peripheral channel extending aroimd the mattress 13 which leads to the respirator chamber. For inducing artificial respiration relatively slight changes in the air pressure is required and the bellows member is preferablyoperated at. a speed so that said changes take the pressure within the respirator chamber falls length. Twohoobfl mprovidedeaehdependslightly below atmospheric the chest of handle in con-- cured-to this rear end of the cover. The screws I06, employed for securing the member to said cover, also confine between the cover and-a ring This structure is clearly shown in Figure 'I.

' The casing I20 within which the-airvalves are v front wall 34 of the base observed that the inlet conduit The remainder is secured in a similar manner to member 43, similar to member I05 except that the latter, as previously described, is secured to the base structure. It will be observed that ring I01 extends from the hinges on one side of the respirator around the cover to the handles on the opposite side, as-shown in Figure 8. The metal strip I08 which secures the rear diaphragm to member 43 is separate and apart from the cover but likewise extends from the hinges to the clamps so as to complete the circumferential securement of the said diaphragm- 24 to the respirator. The opening in the respirator for receiving the buttocks of the patientis formed of elastic material such as the elastic band H0, shown in Figure 10. Said elastic band is suitably secured to the iaphragm so as to form a continuation thereof and said band as well as the,

diaphragm is slotted so that said rear diaphragm may be separated along a radial line to make possible the opening of the cover 22. The slot extends from the opening'formed by the elastic band H to the circumference of the diaphragm and which is in alignment with the separation between the cover and the base structure. rear diaphragm in open position is clearly shown in Figure 9, wherein it will be observed'that the upper portion is provided with means HI and H2. The lower portion is likewise provided with double fastening means such as H3 and H4. The said fastening means have coaction in pairs to form an exterior zipper closure II 5 and an interior zipper closure H8,- respectively. For' example; the fastening means H I and H3 are joined by the zipper H5. This double closure is provided to form a more eifective seal for preventing leakage of air from the respirator chamber. Although the elastic band H0 will have a relatively close fit around the patient, it may be drawn even tighter if desired by the belt II! which fits around said elastic band and is held in place thereon by loops I I 8. Before opening the cover of the present respirator it will be clearly understood that it is necessary first of all to open the rear diaphragm by releasing the fastening means comprising the zip-.

per closures I I5 and H6 and to also release the belt II I. The next operation requires that the clamps I03 be released in order that the neck collar may be detached from the cover of the respirator. Thereafter the handles 86 are actur ated to unlock the cover, whereupon the same can be swung back upon the hinges 84 and the patient can then be removed. When to place a patient within the respirator the operations above described are just reversed. The

rod'H9, suitably supported by means extending from the rear wall 35 and substantially arcuate in form, is designed to limit the movement of the rear diaphragm 24 particularly in an Outward direction during operation of the respirator.

Operation of the bellows assemblies will alternately increase the air pressure within the respirator chamber and then produce a slight vacuum within the chamber. The deg'ree of pressure and vacuum may be adjusted in accordance with the present invention by regulating means applied to the exhaust and inlet valves,.-respective1y, and which regulating means-are under the control of an operator.

The

double fastening same. During the creation of a reduced pressure within the respirator chamber air will tend to flow into the chamber through the inlet conduit I22 and this action will cause valve I26 to open. The extent of opening is controlled by cam 82% fixed to the actuating rod I21 and having the knob I28 suitably fastened to the portion of said rod projecting outwardly of the casing I20. When a pressure is created within the respirator chamber the action of the air is reversed and the same tends to flow from the chamber through the exhaust conduit I23. Flow in this direction will cause the valve I25 to open and the extent of opening is controlled by cam member I30 suitably actuated by knob I 3i. When valve I25 is open the valve I 24 automatically closes and when air tends to flow into the chamber valve I25 will automatically close and valve I24 will open. As shown in Figure 11, the cams I26 and I30 are elliptical in shape and the degree of opening of the. valves depends on the positioning of the cams. In fact, the cams are so designed that the valves can be held closed or allowed to completely open, in which case the conduits would be fully operative for conducting air to the chamber and exhausting the same therefrom. The casing I20 is closed on three sides but the bottom is open so that the conduits have communication with the atmosphere. The end of the conduits within the respirator chamber is protected by an'interior guard I32 which is open at its respective ends and it is desired Y the'desired pressure changes in this manner communication is maintained with the respirator chamber. The construction, however, sufiiciently shields valve mechanism I24 and I25 to prevent damage thereto either by the oprespirator or erator located on the outside of the by the patient within. The air pressure gauge I33 is positioned centrally of easing I20 and I serves to indicate the degree of pressure and vacuum within the respirator so that the operator may independently adjust the valves to produce for the particular patient undergoing treatment. The gauge is in communication with the respirator chamber by the conduit I34 which passes through the front wall 34, having an air-tight connection therewith, and terminates within the interior guard I32. I The invention is not to be limited to or by de--. tails of construction of the particular embodl- 'ment thereof illustrated :by the drawings as varions other forms of the device will of course be cross section having a hinged connectionalong one longitudinal side thereof with one side wall 7 2,314,955 patient rises and air enters the lungs. The air pressure within the chamber then returns to normal or slightly above atmospheric and the patient breathes air out of hislungs. ,A surprisingly slight change of pressure is required to duplicate normal breathing. Y

The head rest is supported by the pivoted table 15 from the front wall'34 of the base structure. 'The toggle links I6. have connection with the table ,at its'outer end and, with the front wall of the'base structure, serve to support the .table inhorizontal position when the links are in alignment, The rear cushion support 26 for the hips or buttocks of the patient is likewise horizontally positioned by a table 11 having pivotal connection with the rear wall 35. The links 18 connect the end of the table with the bottom portion of the rear wall of the base structure and when said links are aligned the table and rear support is located horizontally as disclosed in the drawings. Since the present respirator is portable it is preferably that the same make as compact a unit as possible during transportation.-

For this purposethe tables are constructed so that they can be collapsed by actuation of the supporting links therefor and in collapsed position it will be understood that the tables depend from their pivots and are located relatively close to the respective walls of the base structure.

As previously described, the cover 22 forms ap-- proximately the entire respirator chamber and accordingly, to provide the necessary space the cover is arcuate in form or more particularly semi-circular in cross section. Within this chamber the chest and abdomen of the patient are located for inducing breathing by rhythmic Y changes of air pressure. The cover 22 is shown as consisting principally of a single sheet of metal having an inwardly directed flange 80 providingthe front wall of the cover and which, as shown in Figure 4, is formed with a U-shaped opening 8| extending to the base of the cover.

Along the longitudinal sides of the cover at the base thereof the metal is also flanged inwardly and then bent upon itself to provide the portions 82 and 83, the former being located along the side of the cover having the handles fixed thereto, and the portion 83 being located adjacent the side having the hinges 84. Said portions and thus'the base perimeter of the cover are suitably reinforced by the-angle piece 85. The portions are located over and are adapted to have contact with the sealing strip 45, which, as previously described, is suitably supported by inturned ledges and flanges provided by the base structure. With the cover in closed position, as shown in the drawings, the sealing strip 45 is confined between the parts just described so as to maintain an air-tight joint. The handles 86 are pivotally fastened to the cover and said handles are designed to" have locking relation with the latch members 81 secured to the base structure. When the handles are released the cover may be shown in said figure. When the respirator is in operation it is of course necessary to seal the slot formed by the separable edges 90. so as to prevent leakage of air from the respirator chamber. This is accomplished as shown in Figure 6 by a canvass or other flexible cloth covering 9| glued or otherwise secured as at 92 to the upper portion of the neck collar and having overlapping relation with the'separable edges 90. A second cloth covering 93 is glued or otherwise secured as at 94 to the lower portion of the neck collar and by the provision of fastening means 95 on the adjacent edges of cloth covering 9| and 92- the same may be releasably closed in overlapping relation with slot 90. The upper and lower edges of the neck collar forming said slot are retained in proper alignment with each other by means of guiding strips 96, a strip being located on each side of the neck collar and being preferably se--' to permit location of the collar around the neck.

of the patient or removal therefrom.

The neck collar is completely detachable from the front wall 80 of the cover. Therefore before a patientis placed within the respirator the neck collar is located on the patient and the flexible cloth covering is closed by zipper 95 as above described to prevent the escape of air. through the separable edges formed-by the slot 90. It will be understood, of course, that the circular opening 88 is substantially closed by the neck of the patient. When the cover is closed it is only necessary, therefore, to clamp the neck collar to the cover. For this purpose four clamps are provided adapted to have coaction with the four sides respectively of said collar. Each clampincludes a base portion-98 fixedto the wall 80 of the cover and a hinge portion Ifldpivotally secured to 98 by the rod IOI. Said rod provides retaining means for the coil springs I02 which are so designed as to apply spring tension to the hinge portions I00 in order to maintain the portions in open position. Therefore the portions automatically assume an open position when the clamps I03 are released. It will be clearly understood that with the hinge portions in open position a substantially square area is provided on wall 80 for receiving the neck collar 23 and when in position thereon the opening 8| in the cover will be closed thereby. To releasably secure the neck collar to the cover it is only necessary to actuate clamps I03 whereby the hinge portions I00 will be caused to close against the neck collar swung open with they pivoting taking place on the hinges 84. To permit this action of the cover the neck-collar 23 and the rear diaphragm 24 are each provided with zipper closures, the construction of which will now be described.

.The neck collar 23, Figure 5, is preferably formed of soft sponge rubber substantially square inshape having an opening 88 of an average size to accommodate the neck of the patient. To facilitate application of the collar the same is severed as at 90, the separation extending from the opening 88 radially to the right hand edge as and securely fasten the same in place. The construction of the hinge portions, which are spring energized to maintain them in open position, and the clamps therefor have the advantage of speed in placing a patient within the respirator and fastening of the collar in desired position.

The rear diaphragm 24 has also been designed to make, possible the greatest amount of speed in placing a patient within the respirator.and operation of the same to induce breathing. The outer periphery of the diaphragm 24 is located over an upstanding flange I04 provided by the substantially U-shaped member I05.which is seof the base structure, handle members on the opposite longitudinal side of the cover for releasably fastening the cover to the other side wall of the base structure, said cover having an openthe front wall of the base structure and having an I exterior position adjacent one of said'diaphragms, and a rear support having connection with the rear wall of the base structure and exteriorly located adjacent the other diaphragm.

2. In a respirator, in combination, a base struc ture including spaced side walls, a front wall and a rear wall, a bellows assembly positioned within the base structure and supported by said walls, a cover substantially semi-circular in transverse cross section having a hinged connection along one longitudinal side thereof with one side wall of the base structure, handle members on the opposite longitudinal side of the cover for releasably fastening the cover to the other side wall of the base structure, said cover having an opening at each end thereof, a diaphragm member for each said opening, one of said diaphragm members having securement for a portion of its circumference to the cover and being secured for the remainder of its circumference to the base structure, the other diaphragm member having releasable securement to the cover and to the base structure, a head rest pivotally supported from the front wall of the base structure, anda rear support having pivotal connection with the rear wall of the base structure.

3. In a respirator, in combination, a base structure, a bellows assembly positioned within the base structure and supported thereby, a cover substantially semi-circular in transverse cross section having a hinged connection along one longitudinal side thereof with the base structure and forming therewith a respirator chamber located above and in communication with the bellows assembly, said cover having an opening in the front end thereof and the rear of said cover also being open, a rear diaphragm member for said rear opening having securement for a portion of its circumference to the cover and bein secured for the remainder of its circumference to the base structure, a diaphragm member forthe front opening in the cover, and said rear diaphragm member being separable along a radial line extending to the circumference thereof and in substantial alignment with the separation between the cover and the base structure, whereby the cover may have pivotal movement into an open position on said hinged connection as an axis.

4. In a respirator, in combination, a base structure, a bellows assembly positioned within the base structure and supported thereby, a cover substantially semi-circular in transverse cross section having a hinged connection along one longitudinal side thereof with the base structure and forming therewith a respiratorchamber located above and in communication with the bellows assembly, .said cover having an opening in the front end thereof and the rear of said cover also being open, -a rear diaphragm member. for said rear opening having securement for a portion of its circumference to the cover and beingsecured for the re- .-mainder of its circumference to the base struc-.

ture, a diaphragm member for the front opening in the cover, each said diaphragm member having an opening therein located substantially centrally of the member, each diaphragm member being separable along a radial line from the opening therein to its circumference, and fastening means on each diaphragm member for releasably joining the edges of the member formed by said radially extending separation therein. v

5. In a respirator, in combination, a base structure, a bellows assembly positioned within the base structure and supported thereby,,a cover substantially semi-circular in transverse cross section having ahinged connection along one longitudinal side thereof with the base structure and forming therewith a respirator chamber located above and in communication with the bellows assembly, said cover having an opening in the front end thereof and the rear of said cover also being open, a diaphragm member for the front opening in the cover, a rear diaphragm member for said rearopening having securement fora portion of its circumference to the cover and being secured for the remainder of its circumference to he base .structure, and said rear diaphragm member having a central opening therein formed by an elastic band secured to the inner periphery of the member.

6. In a respirator, in-combina'tion, a base structure,- a bellows assembly positioned within the base structure and supported thereby, a cover substantially semi-circular in transverse cross section having a hinged connection along one longitudinal side thereof with the base structure and forming therewith a respirator chamber located above and in communication with the bellows assembly, said cover having an opening in the front end thereof and the rear of said cover also being open, a diaphragm member for the front opening in the cover, a rear diaphragm member for said rear opening having securement for a portion of its circumference to the cover a and being secured for the remainder of its circumference to the base structure, retaining means for the first mentioned diaphragm member pivotally connecting with the cover, and resilient means in associated relation with said retaining means the front opening in the cover, a rear diaphragm member for said rear opening having securement for a portion of its circumference to the cover and being secured for the remainder of its circumference to the base structure, retaining means for the first mentioned diaphragm member pivotally connecting with the cover, coil springs in associated relation with the retaining means for yieldingly biasing the latter into an open position, and clamps for releasably holding the retaining means in closed position on the diaphragm member to secure the same to the cover.

8.v In a respirator, in combination, a base structure, a bellows assembly positioned within the base structure and supported thereby, a cover substantially semi-circular in transverse cross section having a hingedconnection' along one longitudinal side thereof with the base structure and forming therewith a respirator -chamber locatedlabo've and in communication with the bellows assembly, said cover having an "opening in-the front end thereof and the rear of said cover also being open, a diaphragm member for the front opening in thecover, a rear diaphragm member for said rear-opening having securement .for aportion of its'circumference to the cover and being secured for the remainder of its circumference to the base structure, said rear diaphragm member having a central opening therein defined byan'elastic band secured to 'the inner circumference of the member, retain-,

ing-means for releasably securing the first mentioned diaphragm member to-thecover including portions having pivotal connection therewith, and

clamps for releasably holding the portions in" closed position on said member.

9. In a respirator, in combination, a base struc- "ture including spaced parallel side walls, a front wall and a rear wall, a container within the base structure for supporting a mattress, a cover substantially semicircular'in cross section having a hinged connection along, one longitudinal side thereof with one side wall of the base structure,

said cover having an opening at each end-thereof, a diaphragm member for each said opening having associated relation with thevcover and base structure respectively, and a bellows assembly supported by the base structure below said container and including a stationary top wall and Y located so that the upper surface thereof is on a'plane approximately coinciding with the separation between the cover and base structure, a bellows assembly within the base structure below the container and in supported relation with the walls thereof, said assembly including a stationary top wall and a movable bottom wall, and said stationary top wall having an opening therein-communicating with the respirator chamber.

II. In a respirator, in combination, a base structure including spaced side walls, a front wall and a rear wall, a cover having a hinged connection with said base structure to close the open top end thereof whereby to form a respirator chamber with thebase structure, means within. and secured to the basestructure providing a support for a mattress adapted to accommodate the body of the patient, a head rest located exteriorly of the base structure and supported thereby in a horizontal plane substantially aligned with the said mattress supporting means, a bellows assembly within the base structure below the said mattress supporting means and substantially closingthe open bottom end of said base structure, said assembly including a stationary top wall secured to the base structure and a movable bottom wall, means having connection with the bottom wall for moving said bottom wall, and said stationary top' wall having an opening therein communicating with the respirator chamber.

12. In a respirator, in combination, a base structure including spaced side walls, a connecting front wall and a connecting rear wall, a bellows assembly positioned within the base structure and supported by said walls, said assembly' including a stationary top wall and a movable bottom wall, a cover substantially semicircular in transverse cross section having a hinged connection along one longitudinal side thereof with one side wall of the base structure and forming therewith a respirator -chamber located above and in communication with the bellows assembly, said cover'having an opening in the front end and the rear end of said cover also being open, a diaphragm member for the rear opening having associated relation with the cover at said end thereof, and a diaphragm mem-. ber for the opening in the front end of the cover having releasable securement to the cover andalso to the base structure,

13. In a respirator, in combination, a base structure including spaced side walls, a connecting front wall and a connecting rear wall, a bellows assembly supported by the base structure and closing the open bottom thereof, said assembly including a stationary top wall and a movable bottom wall, a cover for closing the open top of the base structure and having a hinged connection along one longitudinal side thereof with one side wall of the base structure, said cover forming a respirator chamber with the base structure located above and communicat- .ing with the bellows assembly through an opening in the top wall of the same, said cover having an opening at each end thereof, a diaphragm member for each said opening, one of said diaphragm members having securement fora por tion of its circumference'to the cover and being secured for the remainder of its circumference to the base structure, the other diaphragm member being releasably secured to the cover and base structure respectively.

ROBERT L. SLATER.

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