Respirator

A respirator canister provided with openings for flow of air therethrough is filled with a chemical that removes water vapor and carbon dioxide from the air and liberates oxygen into it. A breathing tube communicates with one of the canister openings, and an expandable breathing bag or equivalent has an opening communicating with the other canister opening. A spring or the like resists expansion of the bag during exhalation through the breathing tube and canister in order to maintain the air in the respirator under positive pressure to prevent toxic air from leaking into the respirator.

With closed circuit breathing apparatus of the known kinds, whether of the 
circulatory or rhythmic type, there always is the possibility that toxic 
ambient air may leak into the system, due to a leak in the apparatus or to 
a poor seal between the breathing mask and the face of the wearer. 
It is among the objects of this invention to provide breathing apparatus, 
in which a positive pressure is maintained to prevent inhaling of ambient 
air through leaks in the system.

Referring to FIG. 1 of the drawings, a chemical canister 1 is provided at 
its upper end with an inlet opening 2 to which one end of an exhalation 
tube 3 is connected. The other end is connected to a conventional 
mouthpiece 4 or the like by means of a valve 5. The lower end of the 
canister has an outlet, such as a perforated bottom 6, that communicates 
with an inhalation tube 7 and also with an opening 8 into an expandable 
chamber, such as a breathing bag from This communication preferably is 
provided by mounting the canister in a housing 11, from the walls of which 
the canister is spaced. The space between the canister and housing is 
connected at the top by a conduit 12 to the bag opening. Also, it is 
desirable, but not absolutely necessary, to position another breathing bag 
13 at the opposite side of the canister, with the bag opening likewise 
connected by a conduit 14 to the upper part of the canister housing. The 
canister is filled with a chemical 15, such as potassium superoxide, which 
will remove carbon dioxide and water vapor from the exhaled air flowing 
through the canister and will also liberate oxygen into that air. The 
liberated oxygen and the exhaled air inflate the expandable bags. During 
inhalation through breathing tube 7, air is withdrawn directly from the 
bags so that their volume decreases. 
It is a feature of this invention that the air in the respirator system is 
maintained under positive pressure, meaning a pressure greater than 
atmospheric, so that if there is any leakage, it will be out of the 
respirator and not into it. A preferred way of accomplishing this is to 
make the bags in the general form of bellows, with rigid lower ends that 
engage coil springs 17 compressed between those ends and suitable 
supports. A preferred type of support is a casing 18 that encloses and 
protects the bags and the canister. The springs then can be compressed 
between the bottoms of the bags and the bottom of the casing. 
During exhalation, as explained above, the exhaled air and liberated oxygen 
leaving the chemical canister will enter the breathing bags and expand 
them. However, such expansion is resisted by the coil springs which must 
be compressed by the bags in order for the bags to expand, so the user of 
the respirator must exhale with enough force to cause the bags to compress 
the springs. This will place the air in the respirator under positive 
pressure so that if there are any leaks in the apparatus or in the seal 
around the face, leaking of air will be out of the apparatus, not into it, 
thereby preventing inhalation of the ambient atmosphere. During 
inhalation, positive pressure in the respirator will be maintained 
because, as the user inhales and the bags start to collapse, the springs 
will expand and continue to exert pressure on them, thereby mantaining 
positive air pressure in the system. Preferably, the excess air pressure 
while the bags are relaxed is about 2 imbar. 
The positive pressure in the system can be maintained when the respirator 
is set aside while not in use, if valve 5 is such that it can close off 
the inhalation and exhalation tubes when desired. Thus, the valve may 
include a closed end cylinder 20 that is rotatable in a cylindrical 
housing 21 by means of a projection 22 at the outer end of the valve 
cylinder. The cylinder and housing are provided with openings that 
normally register with the two tubes, but when the cylinder is turned 
90.degree. this communication with the tubes is shut off and no flow 
through the tubes can occur. 
Although a circulatory breathing system has been illustrated, it will be 
understood that this invention also applies to rhythmical or pendulum 
breathing, in which a single breathing tube is used for both inhalation 
and exhalation and no valves are required. Also, instead of using springs 
to create a back pressure, the bags themselves can be made wholly or 
partly of elastic material that will have to stretch during exhalation, 
thereby resisting entrance of air into the bags. 
As shown in the modification illustrated in FIG. 2, cylinders 25 are 
substituted for the breathing bags, and pistons 26 are disposed in their 
lower ends. The pistons rest on coil springs 27 supported by a casing 28 
that also contains the chemical canister 29. During exhalation, the 
pressure created in the cylinders will force the pistons downwardly 
against the resistance of the springs, whereby the air in the respirator 
will be under positive pressure. The positive pressure will continue 
during inhalation because the springs will force the pistons upwardly in 
the cylinders to maintain the air in the system compressed. 
According to the provisions of the patent statutes, I have explained the 
principle of my invention and have illustrated and described what I now 
consider to represent its best embodiment. However, I desire to have it 
understood that, within the scope of the appended claims, the invention 
may be practiced otherwise than as specifically illustrated and described.