Self-contained closed circuit breathing apparatus

Claim 2

A self-contained, closed circuit breathing apparatus comprising an inhalation conduit and an exhalation conduit, a mouth connection communicating with said conduits for making connection with the mouth of the operator, an inhalation check valve and an exhalation check valve on either side of said mouth connection providing unidirectional flow through said inhalation and exhalation conduits respectively, a chemical canister connected across said inhalation and exhalation conduits, a positive pressure reservoir communicating with said exhalation conduit at a point between said chemical canister and said exhalation check valve, and a negative pressure reservoir communicating with said inhalation conduit at a point between said chemical canister and said inhalation check valve, said positive pressure reservoir comprising an expansible container having flexible wall means incorporating resilient means providing a positive pressure loading on the gas within said container when said container is expanded by an exhalation, and said negative pressure reservoir comprising a contractible chamber having flexible wall means incorporating resilient means providing a negative pressure loading on the gas within said chamber when said chamber is contracted By an inhalation.

Claim 3

Breathing apparatus as claimed in claim 1 in which said contractible chamber includes rigid top and bottom walls, means securing said top and bottom walls in a fixed spaced relationship to each other, and flexible side wall means connecting said top and bottom walls and being secured thereto in air tight relationship, said flexible side wall means being formed of elastic sheet material and constituting said resilient means.

Claim 4

Breathing apparatus as claimed in claim 1 in which said expansible container comprises an elongate bag having flexible walls, and in which said resilient means comprises means tensioning said bag in the longitudinal direction to urge said flexible walls toward each other into a small volume position, and providing a resilient loading on said walls when said bag is expanded by said exhalation.

Claim 5

Breathing apparatus as claimed in claim 1 in which said flexible wall means of said expansible container comprises an elastic wall portion, said elastic wall portion also constituting said resilient means.

Claim 6

Breathing apparatus as claimed in claim 1 which includes an oxygen bottle, a regulating valve connected thereto providing a constant supply pressure, a demand regulating valve connected between said negative pressure reservoir and said first-mentioned regulating valve for supplying oxygen to the closed breathing circuit of said breathing apparatus when the difference between the pressure within said negative pressure reservoir and ambient pressure exceed in the negative direction a predetermined negative pressure.

Claim 7

Breathing apparatus as claimed in claim 5 which includes a water tight enclosure surrounding said positive and negative pressure reservoirs to permit immersion of said apparatus, and means for substantially equalizing the ambient air pressure within said enclosure with the water pressure surrounding same.

Claim 8

A self-contained, closed circuit breathing apparatus comprising an inhalation conduit and an exhalation conduit, a mouth connection communicating with said conduits for making connection with the mouth of the operator, an inhalation check valve and an exhalation check valve on either side of said mouth connection providing unidirectional flow through said inhalation and exhalation conduits respectively, a chemical canister connected across said inhalation and exhalation conduits, a positive pressure reservoir communicating with said exhalation conduit at a point between said chemical canister and said exhalation check valve, and a negative pressure reservoir communicating with said inhalation conduit at a point between said chemical canister and said inhalation check valve, said positive and negative pressure reservoirs each comprising a chamber having rigid top and bottom walls in a fixed spaced relationship to each other, and side wall means connecting said top and bottom walls and being secured thereto in air tight relationship, said side wall means being formed of elastic sheet material, the relationship of the volume of said reservoir, the quantity of gas contained in a full exhalation or inhalation, and the elasticity of said side wall means being such that said positive pressure loading will be less than 2.0 inches water gauge, and said negative pressure loading will be not more negative than -2.0 inches water gauge.

Claim 9

A self-contained, closed circuit breathing apparatus comprising an inhalation conduit and an exhalation conduit, a mouth connection communicating with said conduits for making connection with the mouth of the operator, an inhalation check valve and an exhalation check valve on either side of said mouth connection providing unidirectional flow through said inhalation and exhalation conduits respectively, a chemical canister connected across said inhalation and exhalation conduits, a positive pressure reservoir communicating with said exhalation conduit at a point between said chemical canister and said exhalation check valve, and a negative pressure reservoir communicating with said inhalation conduit at a point between said chemical canister and said inhalation check valve, said positive and negative pressure reservoirs each comprising a chamber having rigid top and bottom walls in a fixed spaced relationship to each other, and side wall means connecting said top and bottom walls and being secured thereto in air tight relationship, said side wall means being formed of elastic sheet material, the relationship of the volume of said reservoir, the quantity of gas contained in a full exhalation or inhalation, and the elasticity of said side wall means being such that said positive pressure loading will be less than 2.0 inches water gauge, and said negative pressure loading will be not more negative than -2.0 inches water gauge.

Claim 10

A self-contained, closed circuit breathing apparatus comprising an inhalation conduit and an exhalation conduit, a mouth connection communicating with said conduits for making connection with the mouth of the operator, a chemical canister connected across said inhalation and exhalation conduits, a positive pressure reservoir communicating with said exhalation conduit at a point between said chemical canister and said mouth connection, a negative pressure reservoir communicating with said inhalation conduit at a point between said chemical canister and said mouth connection, said positive pressure reservoir being designed to accommodate a fuLl exhalation with a positive pressure loading, and said negative pressure reservoir being designed to accommodate a full inhalation with a negative pressure loading, an oxygen bottle, a regulating valve connected thereto providing a constant supply pressure, a demand regulating valve connected between said negative pressure reservoir and said first-mentioned regulating valve for supplying oxygen to the closed breathing circuit of said breathing apparatus when the difference between the pressure within said negative pressure reservoir and ambient pressure exceed in the negative direction a predetermined negative pressure, a water tight enclosure surrounding said positive and negative pressure reservoirs to permit immersion of said apparatus, and means for substantially equalizing the ambient air pressure within said enclosure with the water pressure surrounding same, said pressure equalizing means comprising elastic tubes communicating with said enclosure and adapted to surround the chest of the user.

Claim 11

A self-contained, closed circuit breathing apparatus comprising an inhalation conduit and an exhalation conduit, a mouth connection communicating with said conduits for making connection with the mouth of the operator, a chemical canister connected across said inhalation and exhalation conduits, a positive pressure reservoir communicating with said exhalation conduit at a point between said chemical canister and said mouth connection, a negative pressure reservoir communicating with said inhalation conduit at a point between said chemical canister and said mouth connection, said positive pressure reservoir being designed to accommodate a fuLl exhalation with a positive pressure loading, and said negative pressure reservoir being designed to accommodate a full inhalation with a negative pressure loading, an oxygen bottle, a regulating valve connected thereto providing a constant supply pressure, a demand regulating valve connected between said negative pressure reservoir and said first-mentioned regulating valve for supplying oxygen to the closed breathing circuit of said breathing apparatus when the difference between the pressure within said negative pressure reservoir and ambient pressure exceed in the negative direction a predetermined negative pressure, a water tight enclosure surrounding said positive and negative pressure reservoirs to permit immersion of said apparatus, and means for substantially equalizing the ambient air pressure within said enclosure with the water pressure surrounding same, said pressure equalizing means comprising elastic tubes communicating with said enclosure and adapted to surround the chest of the user.