Abstract: A self contained breathing apparatus includes a pressure vessel which holds a supply of breathing air. The pressure vessel is in fluid communication through a first stage pressure regulator with a second stage breathing regulator. The breathing regulator is operatively connected to a user face mask. When the pressure available in the supply is at a suitable pressure, the pressure regulator provides pressure to breathing regulator at a first pressure. When the pressure in the supply falls to a value indicative of impending depletion of the air supply, a transfer piston in a step up vale shifts. A change in condition of the step up valve causes a step up piston to increase the output pressure from regulator. This increased pressure moves a sensing piston and causes indicating devices in an alarm circuit to be activated. In alternative embodiments, an electronic alarm module may be used.

Abstract: A breathing apparatus includes a regulator which delivers air to a user wearing a mask. The regulator is connected to the mask through an adaptor. The adaptor includes an exhalation valve which enables the user's breath to pass out of the adaptor to atmosphere. The regulator includes a sensing diaphragm that is movable responsive to pressure in the mask. A main valve delivers air to the mask responsive to opening of a pilot valve. The pilot valve includes a pilot opening. A lever moves in response to the sensing diaphragm to open the pilot opening which causes flow through the main valve. Air from the main valve is also delivered to a positive pressure chamber. Pressure in the positive pressure chamber moves a positive pressure diaphragm which causes a positive pressure spring to biasingly engage the sensing diaphragm. The biasing of the sensing diaphragm causes the regulator to maintain a positive pressure in the mask.

Abstract: A pressure indicating device for self contained breathing apparatus includes a piston arrangement which is responsive to the relative pressures of the supply and the pressure at the outlet of the first stage regulator to assume several different positions in the containment housing. Piston position is recognized by electronic circuitry and an LED display is lighted accordingly to provide a series of unique signals to the user, of the remaining quantity of breathing fluid. In one embodiment of the invention, plural, graduated-size pistons provide a progressive indication of the air supply. In another embodiment, a single, stepped piston effects progressive electrical contact at various positions in the travel of the piston.

Abstract: A pressure demand breathing apparatus having a facemask connected through a pressure demand regulator with a shut-off device that operates automatically to interrupt the supply of air to the mask when the facemask is removed. The device operates with a time delay to permit momentary user-induced high flow rates without interrupting the supply.

Abstract: A pressure demand breathing apparatus having a facemask connected through a pressure demand regulator with a shut-off device that operates automatically to interrupt the supply of air to the mask when the facemask is removed. The device operates with a time delay to permit momentary user-induced high flow rates without interrupting the supply.

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 compatible 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 primary regulator an automatic transfer valve switches on the backup regulator and communicates its slightly higher outlet pressure to the demand regulator.