Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Patent
1988-11-10
1990-10-02
Burr, Edgar S.
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
12820524, 12820512, A62B 702, A62B 710, A62B 902
Patent
active
049601202
DESCRIPTION:
BRIEF SUMMARY
The invention relates to breathing apparatus, and especially to self-rescue breathing apparatus, that is to say, to a small, compact breathing apparatus that can be carried by, for example, a miner, as part of his normal equipment and can be brought into use in an emergency to enable the wearer to escape from or through regions of suffocating or poisonous gas or water.
Because self-rescue breathing apparatus is worn by ordinary workers, who may not be highly trained and who will seldom actually use the apparatus, and because when the apparatus is used it may have to be brought into use quickly and reliably under emergency conditions, it is desirable that the procedure for starting to use the apparatus should be as simple as possible.
In the past, however, forms of self-rescue breathing apparatus have been proposed that require a variety of procedures for starting to use them, some being quite elaborate.
It is an object of the invention to provide a breathing apparatus that a user can start to use as simply as possible, and that is tolerant of being subjected to more elaborate start up procedures such as have previously been proposed.
The invention provides closed-circuit breathing apparatus arranged when brought into use to operate initially with an open circuit and then to change automatically to closed-circuit operation.
The subsequent operation of the apparatus depends to a large extent on the condition of the apparatus at the moment when it changes over from open-circuit to closed-circuit operation, which can be determined by the means that effects the changeover, and can thus be less subject than in previously proposed forms of apparatus to the initial actions of the user.
The apparatus may comprise means responsive to the breathing of a user to cause the change to closed-circuit operation. That can virtually ensure that the user has in fact started to use the apparatus properly, and is especially advantageous with apparatus in which oxygen is supplied from a reservoir under pressure higher than ambient pressure, because if one complete exhalation is allowed between the user's beginning to breathe with the apparatus and the apparatus's changing to closed-circuit operation a high proportion of the nitrogen in the user's lungs and in the apparatus will be expelled, which is in general advantageous with that sort of apparatus.
The apparatus may comprise a demand valve for supplying oxygen to a user and in operation a common pressure-responsive means then advantageously both operates the demand valve and causes the change to closed-circuit operation. The pressure-responsive means preferably comprises a diaphragm that in use is exposed on one face to ambient pressure and on the other to a gas pressure within the breathing apparatus.
The apparatus may comprise a member movably mounted and resiliently urged to move, a plurality of stops, and a latch reciprocable between positions in which it can so engage different ones of the said stops as to prevent movement of the movably mounted member, the arrangement being such that the breathing of a user can cause the latch to reciprocate and to engage and pass each said stop in turn, and that after the latch passes the last stop the movably mounted member is free to move to cause or permit the apparatus to change to closed circuit operation. The reciprocating latch then in effect counts a predetermined number of inhalations and exhalations before permitting the change to closed-circuit operation. The movably mounted member is advantageously rotatably mounted and then preferably bears the reciprocable latch on a radially outer portion of it, the stops then being on an adjacent fixed member of the apparatus.
The rotatably mounted member may be rotatable in a plane that lies parallel to a diaphragm that is arranged to cause reciprocation of the reciprocable latch, and the rotatably mounted member then preferably sweeps out as it rotates a region of that plane that lies substantially face-to-face with the diaphragm.
The apparatus may be arranged to change to closed-circ
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Asher Kimberly L.
Burr Edgar S.
Siebe Gorman & Company Limited
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