US2710003A

US2710003A - Breathing apparatus dump valve

Info

Publication number: US2710003A
Authority: US
Inventors: William C Hamilton; Bub Frank
Original assignee: Mine Safety Appliances Co
Current assignee: MSA Safety Inc
Priority date: 1952-03-19
Filing date: 1953-12-09
Publication date: 1955-06-07
Anticipated expiration: 1972-06-07

Description

W. C- HAMILTON ETAL BREATHING APPARATUS DUMP VALVE June 7, 1955 Original Filed March 19, 1952 WEI/ l Tr /epsys 2 Sheets-Sheet 1 June 7, 1955 vy. c. HAMILTON ETAL BREATHING APPARATUS DUMP VALVE Original Filed March 19, 1952 2 Sheets-Sheet 2 l w W i 1 fl 2 W uwh haq z m a $0 "-\W\\ |v MT a P UI :1: v. 5 Ma a M J AHHKA 4 m Z w W. I J L a Fri a IN V EN TORI w 0 M w #m m 30M M m H m C m M nited States Patent BREATHING APPARATUS DUMP VALVE William C. Hamilton and Frank Bub, Pittsburgh, Pa.,

assignors to Mine Safety Appliances Company, Pittsburgh, Pa., a corporation of Pennsylvania Original application March 19, 1952, Serial No. 277,408,

now Patent No. 2,679,844, dated June 1, 1954. Divided and this application December 9, 1953, Serial No. 397,091

6 Claims. (Cl. 128-191) This invention relates to valves, and more particularly to valves used in self-contained breathing apparatus provided with removable air-purifying canisters of the type that not only remove carbon dioxide from the exhaled breath, but also generate oxygen and introduce it into the breathing cycle. This application is a division of our copending application Serial Number 277,408, filed March 19, 1952.

The valve disclosed herein is for use in the general type of breathing apparatus shown in Jackson et al. Patent No. 2,403,981, where exhaled air flows through a slide valve and then through a removable air-purifying canister and then back through the valve to a breathing bag that is connected with the inlet of a face-piece.

It is among the objects of this invention to provide a valve for such apparatus which relieves undesirable gas pressure in the breathing circuit, which helps to control the volume of oxygen generated in the canister, which does not release pure oxygen from the circuit and which will not be opened if the wearer exhales with more pressure than normally.

In accordance with this invention, a valve casing is provided with an inlet port adapted to be connected to the exhalation tube of a face-piece, and with an outlet port adapted to be connected to a breathing bag inlet. There are means in the casing for connecting its inlet port with the inlet port of an air-purifying canister and for connecting the canister outlet port with. the casing outlet port. A dump valve housing is provided with a normally closed passage from the inlet end of the casing to the atmosphere. There are gas pressure operated means in the housing for opening the passage and. a conduit connects the outlet end of the casing with the housing in order tosubject the gas pressure operated means to the air pressure at the outlet of the case. When that pressure exceeds a predetermined value, the gas pressure operated means are operated to open the passage from the casing inlet to the atmosphere.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. 1 is a fragmentary front view of self-contained breathing apparatus showing our slide valve in vertical section; Fig. 2 is a similar view of the valve alone, but with parts in the positions they occupy when the canister is removed; Fig. 3 is a horizontal section through the valve taken on the line Ill-III of Fig. 2; and Fig. 4 is a horizontal section taken on the line IV-IV of Fig. 2.

There is shown in Fig. 1 of the drawings the lower portion of a face-piece 1 which fits over at least the mouth and nose of the wearer. The center of the lower part of: the face-piece is provided with a breathing opening, to'

which is connected a rigid horizontal breathing tube 2 that terminates in two downwardly extending flexible tubes 3 and 4. Exhalation takes place through only tube 4 because a check valve 6 mounted in the opposite end of rigid tube 2 prevents air from passing out through the inhalation tube 3. A check valve 7 at theother end of the rigid tube prevents inhalation through the exhala-' 2,710,003 Patented June 7, 1955 ice tion tube. The inhalation tube is connected to an outlet 8 in the back of one side of a flexible breathing bag 9 of well known bifurcated design. The lower end of the exhalation tube is connected to the inlet of a slide valve 11 that has an outlet connected to the inlet 12 of the breathing bag at the side of the apparatus opposite to breathing bag outlet 8. The lower part of the slide valve communicates with the top of a removable air-purifying canister 13 in which carbon dioxide is absorbed and oxygen is liberated by a chemical 14 in a well known manner. Exhaled air entering the slide valve from the exhalation tube passes through the canister where it is purified and receives oxygen and then enters the breathing bag through inlet 12. The purified air and oxygen in the bag are drawn through inhalation tube 3 to the face-piece. A closed breathing cycle thus is formed. When the canister is removed, exhaled air flows through the slide valve directly from exhalation tube 4 to bag inlet 12, as will now be explained.

Before a canister is applied to the apparatus, either initially or after a used canister has been removed, the movable parts of the slide valve 11 appear in the positions shown in Fig. 2. The casing of the valve is formed in two parts, an upper inverted cup-like member 16 and a lower ring 17 bolted to the lower flange of the upper member and projecting a short distance up into it to form a lower annular valve seat 18 between the ends of the casing. The top of the casing is provided with a central inlet port 19, from which an integral neck 21 extends upward. The upper end of this neck is threaded for connection to the lower end of exhalation tube 4. Encircling the lower end of the inlet port is a valve seat 22 facing lower seat 18. The side of the casing is provided between the two seats with an outlet port 23, from which a screw threaded integral neck 24 extends laterally for connection to inlet 12 of the breathing bag.

The lower valve seat 18 normally is engaged by a closure member formed from a sealing gasket 26 fastened to the bottom of a flange 27 projecting radially from the lower end of a sleeve 23. This sleeve is slidably mounted on the upper part of a hollow cylinder 29 spaced radially inward from the lower valve seat and extending above and below it. The cylinder is supported by a few spokes 31 from the encircling ring 17, with which it preferably is integral and concentric. Gasket 26 is pressed down against seat 18 by a heavy coil spring 32 encircling the sleeve and compressed between the top of flange 27 and the top of the casing. The upper end of the sleeve projects above cylinder 29 and is provided inside with a radial flange 33, on the upper and lower surfaces of which there are sealing gaskets 34 and 35, respectively. The upper end of the sleeve normally is spaced a short distance from the top of the casing so that air can flow across the upper valve seat, as shown in Fig. 2. if the sleeve is moved upward on the cylinder, the lower seat will first be uncovered and then the upper gasket 34 will engage the upper seat, as shown in Fig. 1. I

To close the passage through sleeve 28 and cylinder 29 when the sleeve is in its lower position (Fig. 2) a valve disc 37 inside the sleeve is pressed against the inner gasket 35 by means of a coil spring 38 that is weaker than the other spring. The center of this disc is provided with a stem 39 that is slidably mounted in a boss 41 projecting down into the casing from integral spokes 42 connecting it with the wall of inlet port 19. The lower end of spring 38 presses against the upper end of a rigid coupling tube 43 slidably mounted in the reduced lower part of cylinder 29. Downward movement of the tube in the cylinder is limited by a snap ring 44 clamped on the upper part of the tube.

This valve is designed for use with an air-purifying canister 13 of'the type which has concentric inlet and outlet ports at its upper end. The outlet port is formed between a neck 46 on the canister and a metal tube 47 in the center of the neck extending down to a point near the bottom of the canister and below the surround ing carbon dioxide-removing and oxygen-generating chemical 14 therein. The flared upper end of the tube forms the canister inlet port. Exhaled air entering the upper end of the tube flows down through it and leaves its lower end from which the air spreads out in the lower part of the canister and then passes up through the chemical and out through the space between the upper end of the tube and the encircling neck. Mounted on the upper end of the neck is a sealing gasket 48, and before the canister is put into use, the top of the neck is sealed by the usual thin metal sealing disc (not shown).

In order to provide air tight communication between the slide valve and the canister, the upper part of a tubular coupling 50 is slidably mounted in valve casing ring 17. This coupling preferably is flared out some distance below the ring to form a skirt adapted to receive and engage the sealing gasket 48 on the neck of the canister. The coupling or skirt normally is held in its lower position by an encircling rubber-like ring 51, which has its upper end mounted in a groove 52 around casing ring 17 and its lower end secured to a flange 53 around the bottom of the skirt. The resilient ring also prevents air from entering the valve casing between the coupling and ring 17. When the sealing gasket on a canister is inserted in the skirt and the canister is raised, the coupling is pushed upward in the valve casing. This causes a perforated point 54 on the coupling tube to pierce the thin sealing disc on the neck of the canister so that the point can project into the upper end of canister tube 4-7 in sealing engagement with it. Spring 38 allows the coupling tube to be pushed upward in cylinder 29 by canister tube 47 until valve sleeve 28 reaches its upper limit of movement. The canister is locked in its upper position by any suitable means, as is well known in this art. To prevent coupling tube 43 from being pushed upward too far in case the sealing disc on the canister is not readily pierced, a snap ring 55 is mounted on the tube below cylinder 29. This ring will limit the distance that the coupling tube can be moved upward, when necessary.

The upper or inner end of skirt coupling 50 is provided with openings, preferably formed by cutting circumferentially spaced recesses 56 in the upper end. The upper ends of the portions of the coupling between these recesses are turned inward at 57 and normally are spaced a short distance below lower gasket 26 of the sleeve valve, as shown in Fig. 2. This spacing assures the canister neck gasket firmly engaging the skirt before the upper end of coupling 50 engages the gasket and starts to push it away from lower seat 18. Therefore, no outside air can leak past the lower seat before the skirt and canister gasket are in sealing engagement with each other. Continued upward movement of the canister causes the coupling to move the upper sleeve gasket 34 into engagement with valve seat 22. at the top of the casing, as shown in Fig. 1. This shuts on direct communication between inlet port 19 and outlet port 23 of the valve casing. At the same time it connects the inlet port with coupling tube 43, because the valve disc 37 inside of sleeve 28 can only rise with it a short distance before being stopped by the lower end of boss 41. Further upward movement of the sleeve therefore opens the passage downward through the sleeve and cylinder 29.

It is a feature of this invention that slide valve 11 is provided with means for relieving gas pressure in the breathing circuit when that becomes necessary, and for controlling the volume of oxygen generated in the canister. This is accomplished by a dump valve 69 that is located on the inlet side of the slide valve, hub is controlled by air pressure at the outlet side of the slide Cir tit)

valve. As shown in Fig. 3, the dump valve includes a cup-like housing 61 provided with a neck 62 that is screwed into a tubular boss 63 integral with the top of casing 16 and its inlet neck 21. The passage through this boss opens into the side of neck 21. The dump valve housing 61 has its outer end closed by a flanged cap 64 that is clamped in place by a ring 66 screwed on the housing. The cap clamps a flexible diaphragm 67 against a shoulder in the housing, and has a central opening connected by a small metal tube 68 with a boss 69 on the side of outlet neck 24 of the slide valve, so that the diaphragm is subject to the air pressure at the outlet side of the slide valve. Diaphragm 67 engages a head 70 on the outer end of a horizontal valve stem 71 that is slidably mounted in a spider 72 in the passage through housing neck 62. The inner end of this neck serves as a valve seat, and a valve disc 73 mounted on the inner end of stem 71 is held against this seat by a coil spring 74 compressed between the spider and the head of the stem. Whenever the air pressure in outlet neck 24 increases sufliciently to overcome the resistance of dump valve spring 74, diaphragm 67 will be flexed inward and thereby will cause stem 71 to push valve disc 73 off its seat. This will connect the inlet of the slide valve with the atmosphere, through holes 75 in the dump valve housing around its neck 62, and relieve the fluid pressure in the breathing apparatus. The end of tube 68 that extends through boss 69 has a tightly fitting gasket 76 on it between a washer 77 and a shoulder in the boss. This is pressed tightly against the shoulder by a fitting 78 encircling the tube and screwed into the boss and against the washer. By unscrewing this fitting and ring 66, access can be gained to the inside of the dump valve.

An important advantage of this dump valve is that, while it is controlled by the air pressure in the bag, it dumps at the inlet side of the slide valve. This serves a three-fold purpose. First, it controls bag pressure at a comfortable level without actually dumping from the breathing bag pure oxygen supplied by canister 13, because it is the exhaled air that is dumped before it can pass through the slide valve. Second, by dumping the exhaled air directly, some of the moisture in the breath is expelled from the apparatus before it can reach the canister. This reduction of moisture in the breathing circuit reduces the generation of oxygen in the canister at a time when less oxygen is desired. Finally, since the dump valve is operated by the gas pressure in the bag, it will not be opened toward the end of a period of use when it may become necessary for the wearer to exhale with more pressure in order to overcome increasing breathing resistanse in the canister. If the valve opened under such conditions, the canister would generate less oxygen and the breathing bag would collapse.

According to the provisions of the patent statutes, we have explained the principle of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we 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.

We claim:

1. A breathing apparatus valve for connecting both an exhalation tube and a breathing bag inlet with the inlet and outlet ports respectively of an air-purifying canister, said valve comprising a casing provided with an inlet port adapted to be connected to the exhalation tube and with an outlet port adapted to be connected to the bag inlet, means in said casing for connecting its inlet port with the inlet port of the canister and for connecting the canister outlet port with the casing outlet port, and a dump valve communicating with the casing inlet port, said dump valve including a housing provided with a normally closed passage from the inlet end of the casing to the atmosphere, fluid pressure operated means in the housing for openingsaid passage, and a conduit connecting the outlet end of the casing with said housing to subject said fluid pressure operated means to the air pressure at the outlet of the casing, whereby to operate said fluid pressure operated means when said air pressure exceeds a predetermined value.

2. A breathing apparatus valve for connecting both an exhalation tube and a breathing bag inlet with the inlet and outlet ports respectively of an air-purifying canister, said valve comprising a casing provided with an inlet port adapted to be connected to the exhalation tube and with an outlet port adapted to be connected to the bag inlet, means in said casing for connecting its inlet port with the inlet port of the canister and for connecting the canister outlet port with the casing outlet port, and a dump valve communicating with the casing inlet port, said dump valve including a housing provided with a passage from said casing inlet port to the atmosphere, a movable valve member normally seated in said passage for closing it, a conduit connecting said casing outlet port with said housing, and a fluid pressure responsive member in the housing between said conduit and passage for unseating said valve member in response to air pressure of a predetermined minimum value at the casing outlet.

3. A breathing apparatus valve as defined in claim 2, wherein said pressure responsive member is a flexible diaphragm.

4. A breathing apparatus valve for connecting both an exhalation tube and a breathing bag inlet with the inlet and outlet ports respectively of an air-purifying canister, said valve comprising a casing provided with an inlet port adapted to be connected to the exhalation tube and with an outlet port adapted to be connected to the bag inlet, means in said casing for connecting its inlet port with the inlet port of the canister and for connecting the canister outlet port with the casing outlet port, a cup-like housing provided centrally of its base with an opening surrounded by holes having their outer ends exposed to the atmosphere,

means connecting the outer end of said opening with the inlet end of the casing, a movable valve member normally closing said opening, a conduit, means connecting one end of the conduit with the open side of said housing opposite to its base, a flexible diaphragm between said conduit and opening, means connecting the opposite end of the conduit with said casing outlet port, and means in said housing and actuated by said diaphragm for moving said valve member away from said opening.

5. A breathing apparatus valve for connecting both an exhalation tube and a breathing bag inlet with the inlet and outlet ports respectively of an air-purifying canister, said valve comprising a casing provided with an inlet port adapted to be connected to the exhalation tube and with an outlet port adapted to be connected to the bag inlet, means in said casing for connecting its inlet port with the inlet port of the canister and for connecting the canister outlet port with the casing outlet port, a cup-like housing provided centrally of its base with an opening surrounded by holes having their outer ends exposed to the atmosphere, means connecting the outer end of said opening with the inlet end of the casing, a movable valve member normally closing said opening, a conduit, a flanged cap secured to one end of the conduit and projecting into said housing, a flexible diaphragm clamped between said housing and cap flange, means connecting the opposite end of the conduit with said casing outlet port, and means in said housing and actuated by said diaphragm for moving said valve member away from said opening.

6. A breathing apparatus valve in accordance with claim 1, in which the side wall of said casing outlet port is provided with an opening slidably receiving said conduit and encircled outside by an interiorly threaded boss, and including a removable sealing ring encircling the conduit in said boss, and a fitting rotatably mounted on the conduit and screwed'into said boss to compress the sealing ring.

No references cited.