CA1104457A

CA1104457A - Breathing apparatus

Info

Publication number: CA1104457A
Application number: CA301,581A
Authority: CA
Inventors: John W. Henneman; Michael Flood
Original assignee: BREATHING SYSTEMS Inc
Current assignee: BREATHING SYSTEMS Inc
Priority date: 1977-04-21
Filing date: 1978-04-20
Publication date: 1981-07-07
Also published as: IT7822508A0; DE2817561A1; FR2387667B1; JPS53132197A; IT1108997B; GB1581218A; US4186735A; FR2387667A1; JPS6224107B2

Abstract

BREATHING APPARATUS
Abstract of the Disclosure A portable breathing apparatus for use in a noxious atmo-sphere includes a helmet that is closed except for a bottom opening that is provided with a neck seal to permit the helmet to be slipped over the head of the wearer while sealing the open bottom of the helmet to provide an airtight enclosure about the wearer's head. A backpack includes a high pressure oxygen cylin-der, that is connected to a regulator valve through a pressure reducer; and a carbon dioxide scrubber, that receives expiration gas from the helmet through an exhaust breathing line which connects to a flexible reservoir which collects the majority of expired gases and which is provided with a relief valve to protect the bag and limit expiration resistance. The outlet of the reservoir is connected to the inlet of the scrubber and the outlet of the scrubber being connected to a second inlet in the regulator valve by a line that includes a heat exchanger asso-ciated with the oxygen cylinder so that the oxygen cylinder removes heat from the recirculating gas from the carbon dioxide scrubber. The regulator valve has an outlet chamber connected to the helmet interior through an inlet breathing line and the regulator valve includes an on-off-type valve that delivers oxygen from the oxygen supply to the chamber through an injection nozzle only when inhalation by the wearer causes a pressure drop in the chamber that acts on a diaphragm to open the valve, The gas from the scrubber enters the chamber in a reduced pressure zone adjacent the nozzle outlet, the reduced pressure helping to pull scrubbed gases from the carbon dioxide scrubber.

Description

11~4~57 This invention relates to a breathing apparatus and more particularly to a self-contained portable breathiny apparatus for temporary use by a wearer in a noxious atmosphere, such as is worn by fire fighters when exposed to smoke or noxious gases.
Such portable breathing apparatuses are generally either of the open loop or the closed loop type. In the open loop system, compressed air is delivered to the wearer and the expired gases are vented to the atmosphere. Such systems are relatively simple and have the advantage of providing cool breathing gas and a minimum of breathing resistance. However, since the gas is not reused, a system of reasonable weight has a relatively short duration of breathing supply, while being relatively heavy. In a closed loop system, the exhaled gases are directed through a device that generates oxygen or at least removes the carbon dioxide ! from the gas, which is recycled to the wearer, and although some high pressure gas is normally supplied, the gas tank is relatively small and lighweight, so that the breathing system provides a relatively long duration of air supply while being relatively lightweight. ~owever, such systems have the disadvantage of a relatively high breathing resist-ance, a moisture buildup in the system, and a heat buildup in the recycled gas, so that the wearer is breathing rela-tively warm gas.
Typically, prior systems have featured a face mask that is uncomfortable and cumbersome for the wearer, and while some of the more modern systems have utilized a helmet, it has still been necessary to provide a face seal with its attendant disadvantages.
According to the present invention, there is ~ ~.
~ provided a portable breathing apparatus for use by a wearer ....

-2~
~ .

. -1l~,24~S.~

having a respiratory system. The apparatus includes a pack adapted to be carried on the wearer and including an exhaust breathing line, an inlet breathing line, a pressurized oxygen supply container with a first connecting means operatively connecting the oxygen supply container to the inlet breathing line for delivering oxygen from the container to the breathing line at a reduced pressure.
An exhaust gas scrubbing means is provided which ~as an outlet and is operatively connected to and is adapted to remove carbon dioxide from gas removed from the exhaust breathing line to the outlet. The gas having received heat from the respiratory system of the wearer. Second connecting means operatively connects the outlet to the inlet breathing line and include heat exchanger means operatively closely surrounding a substantial portion of the oxygen supply container for transferring heat from the gas in the second1connecting means to the container.
Means is provided for connecting the inlet and exhaust breathing lines to the respiratory system of the wearer.

11~445~

Brief Description of the Drawings .
Fig. ] is a som~what schematic vie~7 of the breathing system in use b~ a wearer.
Fig. 2 is an er~araed, somewhat sche~tic section throuqh the regulator valve.
Fiq. 3 is a side elevation view of the he~ets installed on the wearer, with portions of the helmet broken away to show the interior construction.
Fig. 4 is a front view of the helrnet.
Description of the Preferred Emkodiment The invention is embcdied in a portable breathing apparatus that includes a hel~et, indicated in its entirety by the nurneral 10, and a backpack, indicated in its entirety by the numeral 12, the hel~et being adapted for rnounting over the head of the user or wearer 14 while the backpack is supported on the back of the ~earer by means of shoulder s-traps 15. The helmet 10 includes a rigid hood or shel] 16 that is molded from strong and rigid ~lastic, such as used by pilots or astronauts, and has a bottom openin~ 18 adapted to receive the head of 'he wearer and a relatively large face openinq 20 that substantially spans the width of the front of the helmet and exte~ds approximately from the wearer's mouth to his hair line to afford a relatively wide ran~e of vision. The helmet includes a liner 22 of insulating, shock-absorbing material and a strap-type head sup~ort 24, all of the above beina of more or less known construction. The face opening 20 is closable by a door 26 that includcs a somewhat rectan~ular frame 28 which holds a transparent window 29. The door frare 28 is slightly larger than the outline of the face o~ening 20 and has a seal 30 on its inner side around its entire ~eriphery, the seal 30 seating aaainst the exterior of the helmet shell 16 ad~acent the face openin~ 20 when the door is in a closed condition. The door is mo~mted on a hinge 32 at one side of the face mb/J O ~ 4 ~

opening and is s~ingable thereon between a closed condition, as shown in Figs. 3 and 4, and an opened position wherein it extends outwardly from the wearer. A latch 34 is pro-vided on the opposite side of the door from the hinge to tightly clamp the door against the helmet shell when the door is closed.
An annular, flexible neck seal 36 has a central neck opening 38 and is mounted around the bottom opening 18. The neck opening 38 is smaller than the neck size of any potential user, and flexes and stretches sufficiently to pass over the wearer's head when the helmet is put on, the edge of the neck seal opening 38 tightly seating against the neck of the wearer and the outer portion of the neck seal seating against the bottom of the helmet to seal the helmet interior and consequently the wearer's respiratory system from the ambient atmosphere when the door 26 is in its closed condition. -l~eck seals for helmets such as described above are known and have been used by astronauts in the space program.
The helmet includes an inlet port 40 on the right side of the helmet below the door 26, and the inlet port 40 is connected to an inlet breathing line 41 by means of a quick disconnect device 42 of conventional construction.
An inlet check valve 43, also of conventional construction, is disposed in the inlet port 40 to permit movement of gas only into the helmet interior. An exhaust port 44 is disposed on the opposite side of the helmet from the inlet port 40 immediatel~ below the door and is connected to an exhaust breathing line 46 by means of a quick disconnect device 48.
The exhaust port is provided with a check valve 50 that permits movement of gas only from the helmet interior.
The backpack 12 includes a rigid housing 52 that is -5 ~

~ 4~S~ :

preferably made of rigid plastic or the like to protect the backpack contents. Mounted in the housing is a carbon dioxide scrubbing ~' 3 ~
,- ~,c~
-5a- -device indicatecl in its entirety by the numeral 54. Such scrubbinq devices are~ well kno~n an~l are provided with a pack of carbon dioxide-c~bsorbing ~teria], indicated by the numeral 56. Various carbon dioxide-absorbing materials are well known and readily available at rclatively inexpensive prices. Plternately, a material cou]d be provided that chemically converts carbon dioxide to oxygen to generate oxygen, such as potassium superoxide, althouqh such materials are not as readily available and are more expensive. A
breathing bag or exhaust gas reservoir 58 is disposed in the scrubbing device 54 between the carbon dioxide-absorbing material 56 and the exh~ust breathin~ line 46 to supply exhaust gas to the scrubbina device when the breathing apparatus operates, the breathing bag beinq flexible and filling with gas as the ~7earer exhales in the ~ell-kno~7n manner. A relief valve 60 is provided in the exhaust breathin~ line 46 at the inlet of the hreathina baq 58 and vents gas to the atm~sphere when the exhaust aas exceeds the capacity of the scrubbing device and results in a back ~ressure in the exhaust breathing line. ~he scrubbed ~as is delivered to an outlet line 62 at the bottom of the scrubbing device 54.
An oxygen cylinder 64 is unted in the housing 52 adjacent the scru~bing device and is inverted so that its outlet is adjacent the bottom of the housing. A pressure reducer 66 is mounted on the oxygen cylinder outle~, and is schematica]ly illustrated since it is of well-known construction, the reducer siqnificantly reducing the outlet pressure of the o~yqen supply. An on-off valve is associated with the pressure reducer 66 and is controlled by a control kllob 67 exten~ing through the bottom of the housing 52.
Also associated with the pressure reducer is a fill port 68 for rechargina the oxyaen cylinder and a pressure aauae 70 that is disposed on the exterior of the housin~ and is connected to the oxygen cylinder by a line 71, ~ereby the wearer by observing the ~auge can deter~ine the amount of oxygen in the oxysen supply mb/). - 6 -11~4~ 7 cylinder. A ~ressure ~s~itch 72 havincJ an associated battery is mounted in the li.ne 71 so that the s~7itch closes when the pressure in the gauge line fall.s helow a predetermin~d value, the switch being connecte~ by an electric lead 74 to a warning light 75 that is disposed in the helmet interior in a location visible to the wearer. The electric lead 74 is provic7ed with a disconnect device 76 so that the helmet can be removed fr.o~ the rest of the system by disconnecti,ng the electric lead and the inlet and exhaust breathing lines. As is apparent, the ~larning lic,lht directs the attention of the user to the fact that his oxya,en supply is running low when it goes on.
A bypass line 78 extends bet~A7een the pressure reducer and the breathing line 41, and a bypass valve 80 controls the flc~
through the line 78, the valve being actuated by a knob on the exterior of the housing so that the ~learer can selectively open the valve to permit oxygen flow directly from the r~gulator to the breathin~ line in the event that a malfunction obstructs the normal flow to the breathing line.
A regulator valve 82 is mounted in the housing adjacent the upper end of the oxy,a,en cylinder 64 and is described and sc~ewhat schematically shown in greater detail in Fig. 2. The re~ulator valve 82 inclucles a valve body 83 having an oxygen supply inlet 84 that is connected to the outlet of the pressure reclucer 66 by an oxygen su~ply line 85. The regulator valve has a second inlet 86 that is connected to an inlet line 87 that is in turn connected to the outlet line 62 of the scrubbing device 54 through a heat exchanger 88. The heat exchan~er in the illustrated embodiment is simply a jacket that encom~asses substantially the entire len~th of the oxygen cylinder 64, the jacket bein~ sealed at the top and the bottom and having a relatively small annular air passaa,e 90 between the jacket and the cylinder, the outlet line 62 being connected to the bottom of the jacket while the line 87 to the mb/~)~ ~ 7 S~

r~ulator valve is connected to the to~? of the jacket so that air ~oving from the scrubbina, device to the regulator valve 82 passes in intimate contact with the oxycren cylinder 64 for cooling thereby.
A]ternately, the out]et line could be ~und tightly around the oxyaen cylinder to transfer heat thereto before it is connectecl to the regu]ator valve. As is well known, the flow of high pressure gas from the cylinder causes a cooling of the cylinder.
The reclulator valve also includes an outlet chamber 92 that is connected to the hreathin~ line 41. Forming a part of the outlet chamber 92 is a low pressure chamker 94 that is disposed within the valve bocly and is connected to the outer port;on of the cha~b~r 92 by a tubular orifice 95.
At the opposite end of the body is a cavity 95 having a flexible diaphragm 98 that spans the cavity to divide the cavity into outer and inner chambers 99 ar~ 100 respectively. The outer cha~ber 99 is connected to the atmosphere hy means of a vent 101, while the inner or diaphraa~ cha~ber 100 is connected to the outlet chamber 92 by a sensing line 102. A poppet-type valve 104 is biased against its valve seat 106 by a relatively light spring 108 and is disposecl between a passa~e 110 connected to the oxygen inlet 84 and a passaa,e 112. A valve plun~er 114 is connected to the valve ln4 and extends throu~h a bushing 116 into the inner chamber portion 100 and engages the inside of the diaphragm 98. The diaphra~m is biased acrainst the pluna,er 11~ by a diaphra~m spring 117, an~ when the pressure drops in the chamker 92 as a result of inhalation by the user, the sensing line 102 causes a corresponding drop in ~ressure in the chamber 100 which causes the diaphragm 98 to flex upwardly moving the valve 104 to an open condition, whereby oxygen flows through the passage 110, the valve 104 and into the passage 112. ~n injector nozzle 118 at the end of the passage 112 extends into the chamber 94, so that oxygen rn~ving through the valve 104 is discharged into the cha~er 94 throu~h the injector rnb/J G - 8 -nozz]e. ~ relatively iligh velocity discharge of the gas from the nozzle 1]8 crea~es an area of lc~ pressure in the cha~ber 94 adjacent to the nozzle by the well-known venturi effect.
A valve 120 seats against an annular valve seat 122 between the scrubbed aas inlet 86 and the chamber 94, and a relatively light spring ]24 biases the valve 120 tcward an open condition. r~hen the pressure drops in the chamber 94 as a result of the inhalation of the gas and the venturi action of the gas flowing from the nozzle 118, the reduced pressure with the aid of the spring 124 causes the valve 120 to open so that the aas is pulled from the ~ort 86 into the chamher 94, where the oxygen escaping from the nozzle 118 is 7~Lxed with the recirculated gas from the scrubbing device.
In operation, when it is desired to use the breathing apparatus, the backpack 12 is first strapped onto the back of the user and the helmet is then moun-ted on the head of the user with the door 26 in an open position. m e ~uick disconnects 42 and 48 for the breathing lines are then connected and the disconnect 76 for the electric lead is also connected. ~ith the ~oor open, the operator can reach into the interior of the helmet and manipulate the nek seal 36 so that it properly seats against his neck to provide a comfortable and secure seal.
To initiate use, the operator merely has to turn on the on-of valve via the knob 67 and close the helmet door 26. O~yaen then flows through t7ne line 85 to the regulator valve inlet 84.
As soon as the user inhales, the pressure in the cha7~ber 92 and consequently the cha7nber 100 lowers so that the diaphraqm 98 opens the valve 104, whereupon oxygen fl~h7s through the valve and out through the nozzle 118 as previously described. m e flow continues until the wearer stops inhaling to allow the pressure in the chamber 92 to build up to a point t7nat the diaphragm returns to the position as shown in Fig. 2, wherein it permits the valve 104 to close, ~hich shuts off the flow of oxygen through the nozzle 118.

~b~ 9 _ 5~
As the user exhales, the check valve 43 prevents the return of air into the breathin~ line 41 so that the exhalecl gas passes through the line ~6 into the breathin~ baa, 58. From the hreathing bag a constant flow of air moves through the carbon dioxide-absorbing material 56 and the scrubbed air is returned to the regulator valve through the line 62, the head exchanger 88 and the line 87, the scrubbed air enterina the valve inlet 86. As long as the user is exhaling, the valve 120 would normally re~ain closed due to a pressure drop across the scrubbing device, but on inhalation, the oxygen flow through the nozzle is started again to reduce the pressure in the chamber 94, which causes the valve 120 to open, pulling the scrubbed gas through the valve 120 where it is mixed with the oxygen in the ch~mber 94. A~s previously described, the heat exchanger ~8 cools the recycled ~as passinq through the scrubbina device 54 to aid in the comfort of the user.
As is apparent, ~le oxygen flows only when the user is inhaling, and the on-off characteristic of the ox~gen flow optimizes the use of the oxygen. The use of the venturi action through the nozzle 118 helps to pull air through the gas scrubbing device 54 to reduce the breathing effort. As is also apparent, the user is not encumbered by a face mask which would recluce his vision and encumber his operation, while the helmet lO provides the necessary protection. When the user is free of the noxious atmosphere, he can breathe ambient air by simply opening the helmet door while shutting off the on-off valve via the valve knob 67.
IE a carbon dioxide scrubber is utilized which ~roduces oxygen as a by-product of absorbing the carbon dioxide, then compressed air rather than oxygen could be used in the cylinder 64 because the oxya,en produced by the scrubber ~uld more than equal the metabolic oxygen consumed by the body. For the purposes of the invention and the claims herein, the term "oxygen supply" is used generically to include both a supply of pure oxygen or co~pressed air, which contains other qases in addition to oxygen.

mh/J~ - 10 -

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A portable breathing apparatus for use by a wearer having a respiratory system and comprising: a pack adapted to be carried by the wearer and including an exhaust breathing line, an inlet breathing line, a pressurized oxygen supply container, a first connecting means opera-tively connecting the oxygen supply container to the inlet breathing line for delivering oxygen from the container to the breathing line at a reduced pressure, an exhaust gas scrubbing means having an outlet and operatively connected to and adapted to remove carbon dioxide from gas moving from the exhaust breathing line to the outlet, said gas having received heat from the respiratory system of the wearer, and second connecting means operatively connecting said outlet to the inlet breathing line and including heat ex-changer means operatively closely surrounding a substantial portion of the oxygen supply container for transferring heat from the gas in said second connecting means to the container; and means for connecting the inlet and exhaust breathing lines to the respiratory system of the wearer.

2. The invention defined in claim 1 wherein the means for connecting the breathing lines to the respiratory system of the wearer comprises a helmet having a bottom opening adapted to slip over the head of the wearer as the helmet is put on, a flexible neck seal in the bottom opening and including means having a neck opening adapted to expand to slip over the head of the wearer and contract to seal around the neck of the wearer when the helmet is worn, the neck seal sealing the helmet bottom opening to form a sub-stantially airtight enclosure about the head of the wearer, the helmet including an inlet and an outlet respectively connected to the inlet and exhaust breathing lines.

3. The invention defined in claim 1 wherein the first connecting means includes a regulator valve having a first valve means shiftable between open or closed conditions to respectively connect or disconnect the oxygen container from the inlet breathing line, and pressure responsive actuating means operatively connected to the first valve means and the inlet breathing line to shift the first valve means to its open condition when pressure in the inlet breathing line falls below a predetermined value and to its closed condition when said pressure exceeds said predeter-mined value.

4. The invention defined in claim 3 wherein the regulator valve includes an outlet chamber connected to the inlet breathing line and an injection nozzle between the first valve means and the outlet chamber, the second con-necting means being connected to the outlet chamber adjacent to the nozzle so that a pressure reduction adjacent the nozzle as a result of gas moving therethrough tends to pull gas from the second connecting means.

5. A portable breathing apparatus for use by a wearer and comprising: a helmet having a bottom opening adapted to slip over the head of the wearer as it is put on, an annular, flexible neck seal means mounted in the bottom opening and having a neck opening adapted to expand to slip over the head of the wearer as the helmet is mounted and to contract to seat against the neck of the wearer when the helmet is worn, the neck seal sealing the helmet bottom opening to form a substantially airtight enclosure about the head of the wearer, and a door having a transparent portion opposite the eyes of the wearer and swingably mounted on the helmet for swinging between an open condition, wherein it permits exposure of the helmet interior to ambient atmosphere and provides manual access for adjust-ment of the neck seal, and a closed condition wherein it seals the helmet interior from the ambient atmosphere;
a breathing line means connecting an air supply to the interior of the helmet; and exhaust means operatively con-nected to the helmet for permitting the exhaust of gas from the helmet interior; a portable pack adapted to be carried by the wearer and including an oxygen tank, an air scrubber means connection to and adapted to receive exhaust gas from the helmet exhaust means and remove carbon dioxide therefrom, said scrubber means having an outlet and regulator valve means operatively connected to the outlet of said air scrubber means and to the oxygen tank by first conduit means for mixing oxygen at a reduced pressure from the oxygen tank with gas from the air scrubbing means said regulator valve means being connected by second conduit means to the breathing line for delivering the mixed gas to the breathing line; and said first conduit means including heat exchanger conduit means connecting the air scrubber means to the regulator valve means and closely surrounding a substantial portion of the oxygen tank exterior in a heat exchanging relationship therewith to transfer heat from the gas in said conduit to the oxygen tank.

6. The invention defined in claim 5 wherein the helmet includes a warning light visible to the wearer, and including a source of electric power and a pressure switch means operatively associated with the air supply for connecting the warning light to the source of electric power when the pressure in the air supply falls below a certain value.
7. A portable breathing apparatus for use by a

Claim 7 cont'd wearer having a respiratory system and comprising: an inlet breathing line; an exhaust breathing line; means for con-necting the inlet and exhaust breathing lines to the respiratory system of the wearer; a pack adapted to be carried by the wearer and including an oxygen supply; an exhaust gas scrubbing means having an inlet connected to the exhaust breathing line, an outlet, and means for removing carbon dioxide from exhaust gas moving from the inlet to the outlet; and a regulator valve means including a housing having a first inlet, means connecting the first inlet to the oxygen supply for delivering oxygen at a reduced pressure, a second inlet, means connecting the second inlet to the scrubbing means outlet, an outlet chamber connected to the inlet breathing line, an injector nozzle opening into the outlet chamber, a first valve means operative to connect the first inlet to the injector nozzle when it is in an open condition, spring means operatively biasing said first valve means in a normally closed position, a diaphragm chamber, means connecting the diaphragm chamber to the outlet chamber to equalize the pressure in said chambers, a diaphragm at one end of the diaphragm chamber and shiftable in response to changes of pressure therein, means connecting the diaphragm to the first valve means to open the valve means when the pressure created by inhalation in the diaphragm chamber falls below a predetermined value to cause oxygen flow through the injector nozzle to the outlet chamber and means operative to connect the second inlet to the outlet chamber, so that gas from the gas scrubbing means is mixed with oxygen flowing through the nozzle, the means connecting the second inlet to the outlet chamber including a second valve means responsive to the pressure in the outlet chamber adjacent to the nozzle and operative to move between an open condition to connect the second inlet to the outlet chamber when the pressure in the chamber is reduced adjacent the nozzle as a result of gas flowing through the nozzle and a closed condition wherein it disconnects the second inlet from the outlet chamber, the means connecting the second inlet to the scrubbing means outlet including heat exchanger conduit means closely surrounding a substantial portion of the oxygen supply to transfer heat from the gas moving from the scrubbing means to the oxygen supply.

8. The invention defined in claim 7 wherein the means connecting the breathing lines to the respiratory system of the wearer comprises a helmet having a bottom opening adapted to slip over the head of the wearer as the helmet is put on, a flexible neck seal in the bottom open-ing and including means having a neck opening adapted to expand to slip over the head of the wearer and contract to seat around the neck of the wearer when the helmet is worn, the neck seal sealing the helmet bottom opening to form a substantially airtight enclosure about the head of the wearer, the helmet including an inlet and an outlet respec-tively connected to the inlet and exhaust breathing lines.

9. The invention defined in claim 7 wherein the exhaust breathing line includes an expansible exhaust gas reservoir adjacent the scrubbing means inlet for temporarily storing gas expired by the wearer in excess of the immediate capacity of the scrubbing means to treat said gas.