A self-contained breathing apparatus with automatic redundant fluid pressure controls and a facemask mounted low pressure whistle alarm is described. The first stage of the system includes pair of pressure regulators connected in parallel with different outlet pressures, both of which reduce the pressure of the stored supply gas to pressures compatible with the second stage breathing demand regulator. A primary regulator in the first stage delivers a low output pressure to the demand regulator. In the event of a failure closed condition of the primary regulator an automatic transfer valve switches on the backup regulator. A warning that the supply pressure has been depleted is also provided by a supply pressure actuated transfer valve which transfers the output of the first stage pressure regulators from the primary to the backup regulator. The alarm is activated in either the failure closed condition or if the supply pressure is reduced to a dangerously low level

Giorgini, E. A.

Simmonds, M. R.

Sullivan, J. L.

English

NASA Technical Reports Server

United States Patent (191 
Fletcher et al. 
1 1  1 I 3,957,044 
[451 May 18, 1976 
[ 541 SELF-CONTAINED BREATHING 
APPARATUS 
Inventors: James C. Fletcher, Administrator of 
the National Aeronautics and Space 
Administration, with respect to an 
invention of John L. Sullivan, Fort 
Erie, Canada; Eugene A. Giorgini, 
Cheektowaga; Milo R. Simmonds, 
Williamsville, both of N.Y. 
[ 761 
2221 Filed: Nov. 11, 1974 
[21] Appl. No.: 522,971 
[52] U.S. C1 .............................. 128/142.2; 128/203; 
[ 5 1 1  Int. CL2 ............................................ A62B 7/04 
[ 5 8 ]  Field of Search .............. 128/142.2, 142, 142.3, 
137/DIG. 9; 137/110 
128/142.4, 145.8, 145.5, 145.6, 146.4, 188, 
203, 191 R, DIG. 17; 137/110, DIG. 9 
mi References Cited 
UNITED STATES PATENTS 
2,854,001 9/1958 Humblet .......................... 128/142.2 
3,190,287 6/1965 Miller, J r  ....................... 137/DIG. 9 
3,481,356 12/1969 McQueen ........................... 137/1 10 
3,508,542 4/1970 Browner .......................... 128/142.2 
3,742,972 7/1973 Hughes ............................... 137/1 10 
Primary Examiner-Robert W. Michell 
Assistant Examiner-Henry J. Recla 
Attorney, Agent, or Firm-Marvin J. Marnock; John 
R. Manning; Marvin F. Matthews 
[571 ABSTRACT 
A Self-contained Breathing Apparatus with automatic 
redundant fluid pressure controls and a facemask 
mounted low pressure warning device. The apparatus 
utilizes two stages of pressure regulation wherein the 
final stage is the demand regulator that delivers the 
breathing gas to the wearer. The first state includes a 
pair of pressure regulators connected in parallel with 
different outlet pressures, both of which reduce the 
pressure of the stored supply gas to pressures compati- 
ble with the second stage breathing demand regulator. 
A primary regulator in the first stage delivers a low 
output pressure to the second stage demand regulator. 
In the event of a “failure closed” condition of the pri- 
mary regulator an automatic transfer valve switches 
on the backup regulator and communicates its slightly 
higher outlet pressure to the demand regulator. A 
warning that the supply pressure has been depleted to 
a predetermined low level is also provided by a supply 
pressure actuated transfer valve which transfers the 
output of the first stage pressure regulators from the 
primary to the backup regulator thereby activating a 
whistle alarm device in the facemask to which the de- 
mand regulator is also mounted. The whistle is acti- 
vated by the higher outlet pressure from the backup 
regulator during the inhalation phase of each breath in 
either of the two events of a “failure closed” condition 
of the primary regulator or the depletion of the supply 
pressure to a dangerously low level. 
3 Claims, 1 Drawing Figure 
CYLINDER B VALVE ASSY. 
5 
BACKUP PRESSURE 
REDUCER (125 PSI) 
AUTOMATIC TRANSFER VALVE 33 
LOW CYLINDER PRESSURE TRANSFER VALVE 
https://ntrs.nasa.gov/search.jsp?R=19760017812 2020-03-20T02:17:53+00:00Z
U S .  Patent May is, 1976 
In 
3,95 7,044 
3,957,044 
2 
BRIEF DESCRIPTION OF DRAWING 
1 
SELF-CONTAINED BREATHING APPARATUS 
The single FIGURE of the drawing is a schematic 
diagram of a preferred embodiment of the invention. 
DESCRIPTION OF PREFERRED EMBODIMENT 
In the drawing, a preferred embodiment of the self- 
contained breathing apparatus 10 of this invention is 
.^  disclosed. The apparatus is supplied with a breathing 
ORIGIN OF THE INVENTION 
The invention described herein was made in the per- 
formance of work under a NASA contract and is sub- 
ject to the provisions of Section 305 of the National 
Aeronautics and Space Act of 1958, Public Law 
85-568 (72 Stat. 435; 45 U.S.C. 2457). ’” gas such as air or oxygen from a pressure vessel 11 
which is preferably a lightweight filament wound com- BACKGROUND OF THE INVENTION - -  - 
In self-contained breathing apparatus, used for respi- posite pressure vessel and which initially supplies a 
ratory protection in hazardous atmospheres and which fluid Pressure of approximately 4500 p.s.i.g. The outlet 
include a supply of air or oxygen, hand operated valves of the gas supply cylinder is connectable to a conduit 
are frequently used to provide the extra margin of l 5  12 through a conventional coupling 13. When the out- 
safety against failure of the breathing gas supply. Such let valve 14 of the Supply container is opened, the SUP- 
failures might be “failure closed” of the supply regula- Ply Pressure is COmmunicated through the high Pres- 
tor valves or “failure open” that would lead to prema- sure conduit 12 and branch conduit 1% to a primary 
ture loss of the breathing gas. In order for the hand 2o pressure The Pri- 
valves to be effective as a backup system, it is essential mary Pressure regu1ator 2o a constant low 
that the user be properly trained in their use, that he Outlet Pressure Of 90 Psi to a conduit 22 which is in 
not panic as a result of the primary malfunction, and fluid communication with a conventional demand regu- 
that his hands are free to operate the valves. lator 24 attached to the facemask respirator 25. 
2o Of 
In the previously mentioned breathing apparatus a 25 A backup pressure regu1ator 30 is connected to 
the high pressure conduit l2  through the conduit 
branch 12b. The backup pressure regulator delivers a 
warning system is usually provided to warn when the 
breathing gas has been depleted to a pre-established 
level. In most of these systems, a depleted pressure 
supply causes the operation of an electrical signal de- 
vice or a fluid-actuated alarm device such as a whistle 30 
or bell wherein the fluid which operates the alarm is 
wastefully exhausted to the outside atmosphere. 
SUMMARY OF THE INVENTION 
apparatus with a facemask respirator used for respira- 
tory protection during entry into and escape from haz- 
ardous atmospheres. The system is provided with auto- 
redundant fluid pressure controls for delivering 
the breathing gas to the wearer of the apparatus. A pair 40 
of first stage pressure regulators connected in parallel 
between the gas supply container and the second stage 
breathing demand regulator which delivers the breath- 
ing gas to the wearer serve to reduce the pressure of the 45 
stored gas to outlet pressures compatible with the 
breathing regulator. One of the first stage regulators is 
a primary regulator which Provides a low output Pres- In the event of a failure of the primary regulator 20 
sure to the breathing regulator. The other first stage which would close off its fluid communication with the 
regu1ator is a backup regu1ator which Provides an Out- 5 0  breathing regulator and facemask respirator, the trans- 
let Pressure higher than the low outlet Pressure of the fer valve 33 is opened by the action of the 125 psi fluid 
Primary regulator but is normally closed from fluid in the conduit 31 and the difference in opposing forces 
communication with the breathing regulator. In the acting on the valve element 3sa to communicate the 
event of a failure closed condition Of the primary EgU- fluid from the backup pressure regulator 30 to the 
lator, an automatic transfer valve Operates to switch On 55 breathing regulator. A check valve 35 located in the 
the backup regulator to communicate its higher outlet conduit 22 between the junctions with the conduits 31 
pressure to the breathing regulator. A pressure aCtU- and 34 and which permits fluid flow in the direction 
ated transfer valve also serves to transfer the outlet towards the demand regulator, serves to prevent com- 
pressure of the backup regulator to the breathing regu- munication of the backup regulator outlet pressure 
lator when the supply pressure has been depleted to a 6 0  with the conduit 34 and a consequent intermittent or 
predetermined dangerously low level. A fluid actuated oscillatory operation of the transfer valve 33. It will 
whistle alarm mounted in the facemask operates during therefore be seen that a redundant pressure regulated 
the inhalation phase of each breath whenever the outlet supply line of breathing gas to the demand regulator is 
pressure of the backup regulator is communicated to provided which is operative to supply breathing gas to 
the respirator. The alarm is activated during inhalations 65 the wearer in the event the primary regulator should 
in either of the two events of a failure closed condition become clogged or otherwise rendered inoperative in a 
of the primary regulator or a depletion of the supply of condition that would close off its outlet to the breathing 
breathing gas to a dangerously low level. regulator. 
‘Onstant Outlet pressure Of psi to a conduit 319 
coupled at one end to the outlet of the regulator 30 and 
at its other end to the conduit 22. An automatic trans- 
fer valve 33 is coupled in fluid communication with the 
conduit 31 and to the conduit 22 by means of a conduit 
34. The conduit 34 connects with the conduit 22 at a 
junction between the primary regulator 20 and the 
This invention relates to a self-contained breathing 35 
I ,  
junction of the conduits 31 and 22. 
The transfer valve 33 normally closes off the conduit 
31 from fluid communication1 with the conduit 22. A 
slide valve element 33a in the valve 33 is biased in the 
position which closes off the conduit 31 by the applica- 
tion of the 90 psi pressure from the primary regulator 
to a surface area of the valve element 33a which is 
larger than the surface area on which the 125 psi pres- 
sure is applied. A coil spring biasing means (not shown) 
might also be employed in combination with the 90 psi 
to overcome the 125 psi. However, any conventional 
valves actuated by a pressure differential might be 
emdoved. 
3,957,044 
3 4 
An alarm device in the form of a whistle 40 is the whistle 40 by means of an annular recess 49 about 
mounted in the facemask and is responsive to the deliv- the valve element positioned to communicate the spray 
ery of the 125 psi outlet pressure from the backup nozzle passage 48 with the whistle. The sound is gener- 
regulator to the breathing regulator to provide an audi- ated only on inhalation and the gas passing through the 
ble signal during inhalations of the wearer whenever 5 whistle is available to the wearer rather than being 
the backup regulator is providing the breathing gas. wastefully exhausted to the ambient environment. 
The whistle alarm also serves as a warning device to In a preferred embodiment, the gas supply cylinder 
signal that the supply to breathing gas has been de- and the pressure reducer assembly are carried on a 
pleted to a dangerously low level. The operation of the frame and harness assembly whereby the greater part 
alarm system is hereinafter described. 10 of the weight of the apparatus is carried on the hips. A 
When the supply of breathing gas is dcpleted to a very lightweight self-contained breathing apparatus is 
relatively low pressure level as, for example, 800 psi, a therefore represented by this invention which marks a 
pressure transfer valve 41 is actuated to switch the significant improvement over the known prior art sys- 
pressure output to the breathing regulator from the tems. The audible signal from the whistle is preferably 
primary to the backup regulator. The transfer valve 41 15 at a signal intensity of 70 to 90 db at the ear of the user, 
is coupled to the conduit 31 by a conduit 426 and is with a frequency range of 500 to 4000 cps. By changing 
coupled to the high pressure conduit 12 by a conduit the cadence of his breathing, the wearcr can differenti- 
branch 12c. The conduit 42a joins the conduit 31 inter- ate between his warning and that of others who may be 
mediate the outlet end of the regulator 30 and the nearby. The warning sound is emitted when the gas 
transfer valve 33. The conduit 42b couples the transfer 20 supply is seriously depleted or if there is a failure of the 
valve 41 to the conduit 31 at a point between the trans- primary reducer. In either case, the wearer is warned to 
fer valve 33 and the breathing regulator. proceed to a “safe” area. 
Although the application of the 125 psi outlet pres- What is claimed is: 
sure of the backup regulator acts on a larger surface 1. A breathing apparatus with automatic redundant 
area of the moveable valve element 43 of the valve 41 25 fluid pressure controls and a low pressure warning 
than does the high pressure from the breathing gas device. said apparatus comprising: - .  - I
supply, the transfer valve element is normally biased to 
the position which closes off communication between 
the conduits 42a and 42b. However, when the supply 
pressure drops below 800 psi, the 125 psi outlet pres- 30 
sure from the backup regulator which acts on the valve 
element 43 is sufficient to overcome the force acting on 
the valve element from the supply conduit 12c and the 
valve element is moved to open communication be- 
tween the conduits 42a and 42b. In this occurrence, the 35 
125 psi outlet pressure of the backup regulator is deliv- 
ered to the breathing regulator on the facemask respi- 
rator. The check valve 35 in the conduit 22 prevents 
the 125 psi pressure being applied to the outlet of the 
primary regulator 20 and to the conduit 34 as this 40 
would likely cause a sporadic operation of the transfer 
valve 33. 
The breathing regulator 24 is of a conventional type 
which delivers breathing gas to the wearer only during 
his inhalations. In the preferred embodiment, the 45 
breathing regulator is connected to the facemask by a 
quarter turn “quick-disconnect,’’ which is utilized for 
convenience in donning and doffing the apparatus. A 
spray bar made up of a small duct with a plurality of 
small holes (not shown) is coupled to the outlet 46 of 50 
the breathing regulator for spraying the breathing gas 
onto the visor or eyepiece for the prevention of fogging 
on the visor of the facemask. As customary, the control 
element of the breathing regulator is arranged to sense 
and control the facemask cavity pressure. Exhaust from 55  
the facemask is through a flapper-type exhalation valve 
47 mounted on the facemask in conventional manner. 
In the preferred embodiment, the flow for the sound 
generator is obtained from the flow to the spray nozzle 
as the whistle is coupled in a flow passage 48 communi- 60 
cating with the spray nozzle. A slide valve element 45 is 
disposed in a cylinder communicatng with the conduit 
22 in a position biased by the action of a coil spring 56 
which normally closes off fluid flow to the whistle. 
However. when either of the transfer valves 33 or 41 65 
first and se‘cbnd conduii means, said first conduit 
means being adapted to be connected to a source 
supply of high fluid pressure; 
a facemask respirator connected in fluid communica- 
tion with said second conduit means; 
first pressure reducer means interconnecting said 
first and second conduit means for delivering fluid 
at a first low pressure to said second conduit means 
and said respirator means; 
third conduit means connected with said second con- 
duit means; 
second pressure reducer means interconnecting said 
first and third conduit means and operable to de- 
liver fluid at an intermediate pressure higher than 
said first low pressure to said third conduit means; 
first pressure transfer means normally closing said 
third conduit means and responsive to failure of 
said first pressure reducer means and a drop in 
pressure in said second conduit means to a prede- 
termined level below said first low pressure to open 
said third conduit means and communicate fluid at 
the intermediate pressure to said second conduit 
means; 
second pressure transfer means connected in fluid 
communication with said first and third conduit 
means and responsive to a pressure drop of said 
supply source below a predetermined dangerously 
low level of pressure to communicate fluid at said 
intermediate fluid pressure to said second conduit 
means; and 
fluid actuated alarm means mounted in said face- 
mask respirator and responsive to delivery of fluid 
at said intermediate pressure to the respirator upon 
actuation of said first or second pressure transfer 
means to thereby signal an alarm and indicate a 
failure of said first pressure reducer means or the 
depletion of the gas supply to a dangerously low 
level. 
2. A breathing apparatus as described in claim 1, - .. 
operate to supply 125 psi fluid pressure to the breath- 
ing regulator, the slide valve is shifted against the bias- 
ing action of the spring 56 to open communication with 
wherein the facemask respirator includes a breathing 
demand regulator connected in fluid communication 
with the second conduit means and said alarm means is 
3,957,044 
6 
said first pressure regulator means to communicate 
said low output pressure; 
second pressure transfer means responsive to a dif- 
ference in pressure levels between said fluid pres- 
sure source and said intermediate outlet pressure 
which is less than a predetermined difference to 
thereby fluidly communicate said intermediate 
pressure to the breathing regulator in the event of 
depletion of the gas in said gas supply container to 
a predetermined low level; 
a facemask respirator means, said breathing regula- 
tor being mounted in said facemask respirator 
means and providing breathing gas to the facemask 
respirator in response to inhalations of a wearer of 
the facemask respirator; and 
a fluid actuated signal device responsive to applica- 
tion of said intermediate pressure to the breathing 
regulator upon operation of either of said pressure 
transfer means to provide a warning during inhala- 
tions of the wearer in the event of failure of said 
first pressure regulator means or the depletion of 
gas in said gas supply container to a dangerously 
low pressure, said signal device being mounted 
within the facemask whereby the actuating fluid for 
said signal device is supplied as breathing gas to the 
wearer of the facemask respirator. 
5 
fluid actuated to signal an alarm only during the inhala- 
tions of a wearer of the facemask respirator. 
3. A self-contained breathing apparatus with auto- 
matic redundant fluid pressure controls, said apparatus 
comprising: 5 
a pair of first-stage pressure regulators; 
a second-stage breathing regulator, 
said pair of first-stage pressure regulators including a 
first pressure regulator means and a backup regula- 10 
tor means connected in fluid communication with 
said second-stage breathing regulator and connect- 
able in parallel between a gas supply container and 
the second-stage breathing regulator to reduce the 
pressure of the stored gas to pressures compatible 15 
with the second-stage breathing regulator, 
said first pressure regulator means producing a low 
output pressure and said backup regulator means 
producing an intermediate output pressure when 
connected to said gas supply; 
first pressure transfer means responsive to a differ- 
ence in pressures between said low and intermedi- 
ate outlet pressures which is greater than a prede- 
termined difference to thereby fluidly communi- 25 
cate said intermediate pressure to said second- 
20 
stage breathing regulator in the event of failure of * * * * *  
30 
35 
40 
45 
50 
55 
60 
65 


Self-contained breathing apparatus

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