US 3604416 A
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Description (OCR text may contain errors)
United States Patent  lm entors Joseph A. Petrahai Fairfield; James E. Bellemare, Madison; August .1. Hildenbrandt, Jr., Fairfield, all 01, Conn.  App]. No. 822,853  Filed Apr. 28, 1969  Patented Sept. 14, 1971  Assignee Universal Oil Products Company Des Plaines, ll].
 EMERGENCY OXYGEN SYSTEM 7 Claims, 4 Drawing Figs.
 U.S. C1 l28/l42.3, 206/.7  Int. Cl A62b 25/00 [50} FieldoiSearch 128/1423, 203,142.2,142.6,l220.127.116.11, 202,142.4; 206/.7
 References Cited UNITED STATES PATENTS 1,608,155 11/1926 Bamebey 206/O.7 X
Fo/dab/a Breather Bag 2.586,670 2/1952 Lambertsen 55/387 2,881,758 4/1959 Motsinger 128/1423 3,390,676 7/1968 Warncke et al 128/1422 3,500,827 3/ 1 970 Paine 128/1425 3,502,075 3/1970 Cowley 128/1458 Primary Examiner- Richard A. Gaudet Assistant Examiner-G. F. Dunne Attorneys-James R. Hoatson, Jr. and Philip T. Liggett ABSTRACT: A lightweight, portable oxygen supply system embodying a face-breathing mask and eye protection hood, a foldable breather bag, flexible tubing for connecting the mask and breather bag, flexible tubing for connecting the mask and breather bag, a gaseous oxygen supply pressure container (with special adsorbent therein to increase oxygen storage capacity) which connects through special valve-regulator means to the breather bag, and a gas permeable bed of carbon dioxide absorbent provided between the mask and the breather bag, but preferably adjaCent or partially within the latter, so as to preclude carbon dioxide buildup in the system.
sum 1 [1F 2 Figure IN VE/VTORS Joseph A. Petra/mi James E. Bel/amara Augusl J. Hi/danbrandr ghw/ 69:6 m
A TTOR/VEYS PATENTEU SEP! 41% 36041416.
Joseph A. Pe/raha/ James E. Bel/emare August J Hi/denbrandf A TTOR/VEYS EMERGENCY OXYGEN SYSTEM This invention relates to an improved stowable form of emergency oxygen supply system. More particularly, the invention is directed to a lightweight, portable type, emergency system which can be easily carried and preferably utilizes a mask with two sections, one for breathing and one for eye protection, so that the unit may be well suited for fire fighting.
The presently commercially available forms of oxygen supply kits, or portable oxygen resuscitators, have generally made use of small high-pressure cylinders which supply the oxygen through valving means to a users mask. Usually, the oxygen holding containers have stored the gas at 1,1500 p.s.i.g. or higher in order to be able to store at least about a 15- minute supply of oxygen within a relatively small container. However, is certain areas it has been considered dangerous to use or to store oxygen at this high pressure. For example, where a large number of small portable oxygen supply kits are carried aboard a ship or within an airplane, it may be considered hazardous because of the possibility of a crash situation and/or fire situation in turn giving rise to high-pressure explosion.
There are also various types of oxygen generating kits to provide emergency supplies of oxygen, such as the chlorate candles," which provide a chemical method of oxygen generation. In certain instances, however, the chlorate candles can provide a nonuniform product from nonuniform burning properties and may produce a toxic halogen. Generally, the nonuniform burning characteristics will result from a settling o certain of the insoluble materials used in forming the candle and/or the partial decomposition of the chlorate in the manufactured candle.
In any event, it may be the oxygen a principal object of the present invention to provide a lightweight, portable oxygen supply unit which will store the oxygen at relatively low pressure (generally less than about 600 p.s.i.g.) in a small oxygen storage container or flask containing a nonreactive solid oxygen absorbent material which will permit an increased storage capacity for the oxygen so as to hold at leas about double the quantity of oxygen when it is charged into the filled container as compared with an identical container without the absorbent material.
It is also a feature of the present improved system to use a special breather mask which is connectable through flexible tubing means to flexible and foldable breather bag in an arrangement having the latter receive the oxygen from the supply container.
A still further object of the present invention is to provide a system with a carbon dioxide absorbent material provided in a special gas permeable section and to have such section between the breathing mask and breather bag so that a buildup of carbon dioxide is precluded in the emergency system.
A still further object of the improved oxygen supply system is to utilize a special combination breathing maskeye protecting hood arrangement such that the unit may be carried by an individual and used in emergency fire fighting operations. In other words, a hook or complete face protector is provided in combination with the nose-mouth breathing mask, with the upper face portion of the hood having a transparent eye protecting shield to preclude irritation from smoke and hot gases.
A still further object of the present invention is to utilize a special improved form of oxygen flow regulating means from the oxygen supply container and upstream from the breather bag such that the pressurized supply of oxygen will have a proper regulated flow into the breather bag and permit the supply container to, in effect, meter the oxygen therefrom over a given predetermined period of time of the order of to minutes or longer as desired. A still further feature of the improved system particularly in combination with the gas flow regulator, is to use a removable pin arrangement that releases a shutoff piston or valve in the regulator so as to permit oxygen flow therefrom. Also, means is preferably provided to have the pin pulled along with the unfolding of the mask and breather bag means from a compact stored arrangement.
Briefly, the present invention provides in connection with a portable oxygen supply system which has in combination, a face-breathing mask, a breather bag, flexible tubing means connecting the mask and breather bag, and a gaseous oxygen supply container connecting through regulator means to the breather bag, the improved construction and arrangement in said system which provides a lightweight pressuretight container for the oxygen in turn containing a large surface area absorbent material having the capability of adsorbing oxygen and providing at least about double the quantity of oxygen that can be contained in a given volume at 400 p.s.i.g., and said system further providing a gas permeable bed of carbon dioxide absorbent material contained between the mask and the breather bag, whereby a buildup 0 carbon dioxide is precluded in said system.
As noted briefly hereinbefore, a preferred arrangement for the improved supply system utilizes a special carbon dioxide absorber section in the path between the breathing mask and the breather bag and preferably, the construction is such that the carbon dioxide absorber section is built adjacent to or within the upper portion of the breather bag so as to provide a combination of the two portions. Still further, a preferred design and construction of the absorption section will make use of a solid carbon dioxide absorbing material in a confined unitary section which has screened inlet and outlet means, with the screened gas outlet section toward the breathing mask being positioned and arranged such that it will be in a generally vertical position, or in the top of the unit, so as to preclude the settlement of small particulates or dust against the interior face of the screen and case any clogging thereof.
Various types of carbon dioxide absorbents may be used to advantage in the absorption section, however, a preferred unit would make use of a pill or pellet type of absorbent material which may be packed into the absorption section and be of a type that will minimize dust formation. For example, hard lithium hydroxide pills or pellets have been found to be of particular advantage in being highly efficient in carbon dioxide absorption and when properly prepared in a pill or pellet form will have a minimum of dust formation.
Inasmuch as a preferred embodiment will permit the compact storage of the entire system into a box or other storage container, the breather bag will be flexible and foldable. It is also to be noted that such bag should be of an airtight construction and of a material not readily punctured or easily torn. For example, the bag may be made in multiple layers of a nylon or mylar-type material on the interior thereof and have a protective cover of one or more layers of nylon or nylonpolyurethane type of materials. Of course many other types of materials may be suitable in that they may be readily folded or rolled so as to be in a compact arrangement for storage purposes; however, the aforementioned materials have been found to be of high utility and of lightweight construction.
Reference to the accompanying drawing and the following descriptions thereof will serve to illustrate one embodiment of the improved system as well as point out advantageous features incorporated in various portions thereof.
DESCRIPTION OF THE DRAWING FIG. 1 of the drawing indicates diagrammatically an assembly of the present improved emergency supply system in an unpacked arrangement.
FIG. 2 indicates in a partial sectional view the manner in which the entire emergency system may be stowed within a small box or container.
FIG. 3 indicates, in an isometric-type view, a design suitable for the carbon dioxide absorption section of the system.
FIG. 4 shows in a sectional elevational view one embodiment of the oxygen flow regulator means used to control the pressure container and the use of pull-pin means to block oxygen flow before the system is to be utilized.
Referring now particularly to FIG. 1 of the drawing, there is indicated a small pressuretight oxygen storage container 1, which in this instance is indicated to be of a cylinderlike construction with outlet means 2 adapted to receive a regulator valve means 3 which in turn has outlet port means 4. The latter in turn connects through tube 5 into the interior of the breather bag 6 by means of a passageway or inlet means 7 carrying through an upper carbon dioxide absorption section 8. It is to be noted that the tubing 5 could connect directly with the side portion of the breather bag 6 if it were deemed convenient; however, the illustrated embodiment found it desirable to make all tubular connections to a top plate member 17.
For carrying purposes and in order to provide that the entire system is readily carriable by an individual, the oxygen cylinder 1 is indicated as connecting through linkage means 9 to the upper part of the breather bag unit at plate 17. Also, the upper portion of the cylinder 1 connects through additional linkage means 10 to a support strap 1 1 designed to encompass the shoulder or the neck of a user.
The embodiment of FIG. 1 indicates the preferred type of breather mask and eye-protecting hood and is indicated generally by the numeral 12. However, the hood-mask arrangement really is comprised of two sections, an inner breathing mask portion 13 adapted to fit over the nose and mouth of the user so that the oxygen supply received by way of flexible tubing 14 from the breather bag unit will properly serve the user. Also, the inner mask has a peripheral edge which is flexible and serves to flt the face of any user to seal in the oxygen, carbon dioxide and moisture so that there is a closed system, with no condensate to the eye shield. The upper and large portion of the hood comprises an airtight pliable or resilient cover section 15 to fit over at least the upper face and forehead of the user and shall contain a transparent eye shield section 16. A preferred design has a continuous loop of foam or a soft rubber-type material, such as 15, to provide a fairly tight fit around the users face. For example, the seal loop can go under the users chain, around each side of the face and over the top of the head. As noted hereinbefore, the eye protection, from the seal 15' is of particular value in permitting the present emergency oxygen system to be utilized for fire fighting conditions where smoke and cinders may be present. Also, in accordance with the present improved system, there is a carbon dioxide (CO absorption section, such as 8, provided in the flow between the breather mask 13 and the breather bag 6 such that carbon dioxide may be absorbed and precluded from building up in the enclosed breathing system. The carbon dioxide absorption section can be adjacent the mask, however, inasmuch as it should comprise a section of sufficient size to maintain a carbon dioxide absorbing material it has been found preferable to place such section adjacent to, or in combination with, the breather bag section 6. in the embodiment illustrated, the absorption section 8 has been provided, in effect, as an upper portion to the breather bag section 6 and is encompassed by the latter in a manner having the top portion of the bag 6 connect to the section 8 such that there is an airtight construction.
As best shown in FIG. 3 of the drawing, the carbon dioxide absorption section a may comprise a container box of generally rectangular form that has an intermediate partition 18 with an opening traversed by fine mesh screening 19, as well as a side opening with fine mesh screening 20. There is thus provided a partitioned and screened section adapted to hold a carbon dioxide absorbing packing or filler material 21. The unpacked side section 22, downstream from the partition 18, provides an interior open section adapted to pass oxygen into outlet portion means 23 and thence into the flexible tube means 14 and the breather mask 13 as shown in FIG. 1. There is also indicated, as carrying through the packed section 21 of the carbon dioxide unit, a tubular passageway means 7 which has an outlet end 24 and a tube connection portion 25 adapted to connect with tube means 5 from regulator 3 and the oxygen supply cylinder 1. The tubular passageway means 7 is, of course, arranged to carry entirely through the box section 8 whereby oxygen will be discharged therebelow into the breather bag 6, as best shown in FIG. 1 of the drawing. Also, as shown in FIG. 3, for the present embodiment, there is a spaced wrap-around" continuation for the cover section 17 so that the flexible bag 6 will be held away from the side screen 20 at the side of the carbon dioxide packing 21.
In the operation of the unit and upon the unfolding of the emergency supply kit or system, there is an automatic release mechanism provided by pull-pin means 26 attached to line 27 in turn attached to the support strap means 11. Thus, a pull on strap 11 will result in a release of the oxygen flow from container 1 through regulator valve 3 and into tubing 5 for passage into the breather bag 6. Various means may be provided for using a release pin in combination with the flow regulator valve means from the oxygen container and one embodiment is shown in connection with FlG. 4 of the drawing which will be described more fully hereinafter. After pressure has been released into the breather bag 6, oxygen will pass up to and through the screen means 20 and through the carbon dioxide absorbing material 21 to be discharged into the open mixing section 22 which communicates with flexible tubing 14 so as to be available to the user at the breather mask section 13. As the user breathes in a normal manner, there sill also be an exhaling of carbon dioxide into the tube 14 and a reverse flow through the latter down into section 22 and then laterally into the carbon dioxide absorption bed 21. The latter will effect an absorption removal operation so that primarily only oxygen will carry on back into the breather bag 6 with the exhaling cycle. Again, as the user inhales, there will be the upward flow from breather bag 6 into the tubing 14 and mask 13 as aforedescribed. Of course, inasmuch as there is constant supply of oxygen from cylinder 1 through regulator means 3 into the breather bag, there will be na increase in the quantity of gas in the system and a resulting small pressure buildup. Generally, the breather bag will be sufficiently large to be able to take care of the increased gas volume, although, when desired, various means may be utilized to release this gradual pressure increase in the system and suitable spring-biased poppet valve means may be placed in the unit. For example, there may be a poppet valve 28 provided in combination with the breather mask section 13 as shown in FIG. 1. However, where desired, the pressure release valve means may be in the hose 14 or in combination with the breather bag section 6.
As noted hereinbefore, the entire emergency system is designed for simplicity in opening and making it ready for use as well as for carrying purposes. A loop arrangement is provided by the support strap means 11 and preferably the design is such that upon the pulling of the loop from its stored position, there will be an accompanying pulling of line 27 and an attached pull-pin 26 to turn effect a release of oxygen from the cylinder 1 through a pin-release type of regulator valve at 3. The user may then take the mask portion and pull it over his head to make the system fully operable, with the eyes sealed from outside smoke and the oxygen available at the nosemouth breather section 13.
in order to make the entire system storable in a compact container, the mask and breather bag section 6 shall be of a readily foldable or crushable material whereby they may be arranged to occupy a minimum of space. As best shown in FIG. 2 of the drawing, there is a simple rectangular box or container means 30 with cover means 31 which is adapted to hold the entire assembly and permit a multiplicity of oxygen systems to be stored in a bulk-head manner. Preferably, the stowing will be accomplished so that the bag portion 6 is in the bottom of the container and the carbon dioxide absorption section 8 placed in an intermediate zone while the mask portion 15 is above the storage cylinder 1 and, in turn, topped by the strap means 11 such that the latter is available for being pulled by the user as the initial step of removal. As noted hereinbefore, the initial pulling on strap 11 as the entire system is taken from the storage box 30 will effect the pulling of pin 26 from regulator valve 3 and make the entire unit ready for use.
Attention is called to the particular preferred construction and arrangement of the carbon dioxide absorption section 8 in that the lithium hydroxide, or other carbon dioxide absorbing material, will be held in a compact bed so as to try and prevent movement and breakage of the pills or pelletized solids. Also, it is to be noted that the screen means 19 in partition 18 which communicates with the chamber 22 that in tum passes oxygen into tube 14 and breather mask 13, is in an elevated position whereby clogging with absorbent dust or broken particles will be substantially precluded. In other words, with an outward flow of pressure through an upper or vertically positioned arrangement for the outlet screen means 1Q will insure that dust and particles will be jarred loose from such screen and normally settle to the lower portion of the box 8. The inlet screen section 20 has also been shown to be within the side portion of the unit so that again there is no chance of the screen being clogged with dust or broken particles. Actually, the upward gas flow through screen 20 into the bed 21 will effect a dislodgement of dust and preclude the clogging of such screen.
It is to be further noted that FIG. 1 of the drawing indicates a pressure dial means 29 in the end of the oxygen supply cylinder 1 whereby there may be a visible dial and gauge reading of the oxygen pressure in cylinder 1. Where there has been a long period of storage for the emergency oxygen supply system it may be of advantage to have the gauge means provide a ready check as to the operability of the entire system. Still further for convenience purposes, there may be an arrangement in combination with the storage box 30, as shown in FIG. 2, such that a window section (not shown) in the end of the box 30 will be in alignment with the dial or pressure gauge means 29 whereby there may be a periodic check of the oxygen pressure of each unit without having to remove the system from the stowage box.
Various types of pressure control valves may be used to regulate oxygen flow from the oxygen flask 1, however, preferably the regulator means shall be such as to insure a relatively steady flow over a given period of time, such as for a 10 to 20 minute period that is normally desired for emergency assistance of this nature. In FIG. 4 of the drawing there is indicated one embodiment of a regulator means which will provide for the maintaining of a constant pressure across an internal metering orifice. Generally, the orifice size and storage pressure are coordinated to provide of the order of a minimum of 2.5 liters per minute of pure oxygen from the cylinder 1 into the breather bag 6 so that it will be available for use by the individual.
Referring now particularly to FIG. 4 of the drawing, there is indicated a pressuretight housing 33 having an inlet opening 34 in turn adapted to hold fine mesh screen means 35. Inwardly from the opening 34 is an elongated cylindrical recess 36 adapted to hold spring means 37 which in turn circumscribes a plunger 38 having a conically shaped seat means 39 adapted to closely approach the end or shoulder portion 36 of recess 36 to provide a regulated flow of oxygen therearound into a smaller tubular passageway 40 circumscribing one end of an elongated partially slotted pin or rod portion 41 carrying into and contacting the interior end portion 42 of a hollow cylinder member 42. The latter is adapted to move within a second exterior hollow cylindrical member 43 which has a flanged portion 44 to contact a spring means 45 resting, in turn, on an adjustable threaded bushing member 46. Thus, there can be adjustment of force on an internal bellows 48. The internal cylindrical portion 42 also has a flange section 47 connecting with the compressible and expansible bellows member 48 which joins, at its opposite end, s with a threaded bushing member 49. It will be noted that the threaded bushing 49 is sized to permit the insertion of the entire bellows unit 48 into the large open portion 53 of housing 33, while the small threaded bushing 46 provides for the insertion and adjustment of the spring member 45 against the cylindrical member 43 within the interior of the bellows member 48. A still smaller threaded plug member so with end portion 51 is adapted to contact the exterior end portion of member 43 and effect the adjustment or biasing of the bellows unit 48. Spring member 45 of course effects a continuous inward biasing movement of members 43 and 42 so that there is a resulting adjustment of the seat 39 toprovide a desired-regulated flow of oxygen inwardly through inlet 34 and down through the passageway 40 around rod means 41. Oxygen flow continues from the latter into open space 52 and around the exterior of flange section 47 to carry into the open space 53 which communicates with passageway 54. The latter has communication with passageway means 55 and 56 to a small orifice 56 and the outlet nozzle 4 that is adapted to receive the tube means 5 connecting with the breather bag means of the system, as shown in FIG. 1.
In accordance with the present invention, the present regulator means is designed to have a close-off piston 57 with seal rings 58 and 59 in the respective passageways 54 and 60. Thus, as long as a pull pin 26 extends through the hub portion 61 there will be a blocking of the oxygen flow from passageway 54 into outlet nozzle 4. However, upon the pulling of pin 26 from its cross position there will be pressure from the oxygen flow to cause the piston unit 57 to move forwardly and generally outwardly such that stop means 62 will move into the socket 63 and, at the same time, permit the seal ring 58 to move forwardly into the larger zones 60 to result in oxygen flow from passageway 54 into passageway 55 and outlet nozzle 4. The recess 63 is, in the present embodiment, within a separate threaded bushing 64 whereby there may be a proper adjustment of the seal plug means 57 and, at the same time, an arrangement whereby a removable release pin may be inserted and removed from the end portion 61.
Various modifications in design may, of course, be made within the scope of the present invention; however, it is particularly desirable that the regulator be adjustable and preferably preset so as to given the desired release of oxygen without field adjustment. It is realized that other types of valves or pistons may be used in combination with release pin means; however, it is desirable that there be simplicity in design, with proper gasketing or seal means to preclude any gradual leaking of oxygen from the storage cylinder.
It is also to be realized that various modifications may be made within the scope of the invention with respect to other portions of the entire emergency oxygen supply system, as for example, in the hose arrangements from one section to another, or in particular unit of the system. For instance, the carbon dioxide scrubber or absorption section need not be of a rectangular shape, as indicated in FIG. 3, for various other designs and configurations could be practicable and might well utilize other types of carbon dioxide absorbent materials. However, in each instance a preferred construction will arrange the absorption system and the inlet and outlet means thereto such that irritating dusts or particles will be precluded from clogging outlet screens therefrom being transferred to the breather mask. Although not shown, suitable filter means may be installed in one end of he breather hose 14, such that any dust passing screen 19 will be precluded from reaching the user.
Also, modifications may be made in the foldable breather bag 6 with respect to general shape and design as well as with respect to materials. While lightweight airtight plastic materials or coated fabrics will be generally preferable by reason of availability and capability for folding and storing in a tight container, it is to be realized that other airtight materials might well be used.
With respect to the oxygen container 1, it has been noted that the unit will preferably be one which will contain a nonreactive oxygen absorption material capable of increasing the storage capacity of the container, however, it is to be noted that conventional low pressure substantially empty storage cylinder means may be utilized within the scope of the stowable system being disclosed. Where the cylinder is to have an absorbent which will permit increased capacity of oxygen storage for a given sized container, then the absorbent will preferably be one of the crystalline alumino-silicate materials, i.e., molecular sieves, having pore openings of about 3 to about 15 Angstroms which have been calcined at a temperature in the range of from about 400 C. to about 600 C. Again, while the molecular sieves seem to be of particular advantage, it is not intended to limit the present system to a container with this particular material, inasmuch as other adsorbents may be used to assist in low-pressure storage and may comprise one or more of the materials selected from the group of silica gel, clay, activated alumina, silica-alumina and synthetic and natural zeolites. By way of illustration, it has been found that a canister which will hold of the order of 1,028 cubic centimeters of oxygen at 300 p.s.i.g., when packed with molecular sieves of type A (vibrated into place), would then hold 2,400 cubic centimeters of oxygen at standard temperature and pressure conditions. In a similar instance, where the chamber is provided with type 5A molecular sieves and pressured with oxygen to a 400 p.s.i.g. level there was a storage of 2,920 cubic centimeters of oxygen at S.T.P. conditions as compared with the 1,028 cubic centimeter storage capacity in the event that there were no sieves in the canister.
We claim as our invention:
1. in a portable oxygen supply system for an individual, a foldable face breathing mask, a foldable breather bag, a lightweight gaseous oxygen supply container having regulator means connecting through said breather bag said container having disposed therein a large surface area oxygen absorbent material having the capability of absorbing oxygen that can be contained in a given volume at 400 p.s.i.g., a carbon dioxide absorbent material disposed as a bed between the mask and breather bag whereby a buildup of carbon dioxide is precluded in said system, oxygen flow regulator means disposed adjacent said supply container provided with adjustable metering orifice means thereby to provide substantially constant pressure discharge flow from said supply container, said regulator means including oxygen exit means, a movable valve plug means closure for said exit means, a removable pull-pin means disposed to exert thrust and bear against said valve plug closure means to maintain said plug closure means in closed position to preclude oxygen flow when said system is in storage, a carrying strap for said system, a cord means interconnecting said strap and said pin means, whereby upon pulling of said strap to unfold said breather mask and breather bag said pin means is removed from its position against said plug closure means to thereby positively remove said plug means from said exit means to thereby provide continuous oxygen flow into said breather bag and said supply system 2. The portable oxygen supply system of claim 1 further characterized in that said breather bag is of a multiple layer flexible material comprising an inner layer of airtight nylon- Mylar construction and there is an outer protective cover layer of nylon-polyurethane construction.
3. The portable oxygen supply system of claim 1 further characterized in that the carbon dioxide absorbent material comprises lithium hydroxide in a particulated form.
4. The portable oxygen supply system of claim 1 further characterized in that said carbon dioxide absorbent material is in a confined bed maintained adjacent the breather bag and has inlet and outlet means with fine screen mesh precluding the passage of dust and particulates from said bed.
5. The portable oxygen supply system of claim I further characterized in that the oxygen supply container is provided with a visually readable pressure indicator means connected with the interior of said container whereby there may be a ready observation of the oxygen pressure in the container during storage of the system.
6. The portable oxygen supply system of claim 1 further characterized in that a small storage box is provided for said system, a pressure indicator is provided within said box, and the end portion of said box is provided with a window means at an area to be in alignment with said pressure indicator means on said oxygen cylinder when the latter is packed and stowed in said box with the entire system.
7. The portable oxygen supply system of claim 1 further characterized in that said face-breathing mask is provided as an inner portion to an overall face and head ood means which is adapted to provide a relatively tight seal around the users face and, in addition, said hood is provided with a transparent eye shield whereby the combination hood and breathing mask will be of particular advantage in utilizing the portable system for tire fighting operations.