Valve assembly for breathing systems

A control valve for selectively switching from providing a breathable primary gas from a primary gas source to a breathing gas outlet, to providing a breathable secondary gas from a secondary gas source to the outlet, the valve comprising:

• a body including a first inlet, a second inlet and an outlet, the first inlet and the outlet being normally in fluid communication;
• an end fitting removably disposed over the first inlet, the end fitting connected to the primary gas source, the second inlet connected to the secondary gas source;
• a retention device securing the end fitting to the first inlet;
• a flow control device disposed in relation to the secondary gas source for normally preventing a flow of the secondary gas source;
• a poppet adjacent the end fitting;
• a piston fitted within the body;
• a biasing means for biasing the piston into contact with the poppet;
• the piston positioned to one side of the poppet, the piston being maintained in a cocked position by the poppet;
• wherein upon removal of the retention device from the valve, the piston is driven from its cocked position by the biasing means in a direction toward the flow control device so that the piston forces the poppet toward the first inlet for stopping the flow of the primary gas through the first inlet, and by actuating the flow control device to permit the secondary gas to flow from the secondary gas source.

For use in an emergency breathing system including a user-donnable breathing device for supplying breathing oxygen to a user of the breathing device:

• a control for selectively switching from a normal source of the breathing oxygen to a pressurized emergency source of breathing oxygen associated with the device, the control including;
• a normal source inlet, an emergency source inlet, and a delivery outlet for delivery of the breathing oxygen to the user of the breathing device when donned;
• the control including a control element permitting when in a normal position oxygen to flow from the normal source into the control and then out through the delivery outlet;
• a releasable retention device for maintaining the control element in its normal position;
• a shiftable drive element urging the control element against the control element, the control element normally preventing the control element from being driven from normal position by the drive element;
• a seal for normally preventing flow of oxygen from the emergency source until ruptured;
• rupturing means interposed between the control element and the seal for rupturing the seal by being driven by the control element when released from its normal position;
• the retention device being selectively releasable by the user, the retention device when released permitting the control element to move in response to the drive element from the normal control element position to an emergency position which blocks the normal source inlet and drives the control element driven against the rupturing means;
• the seal when ruptured permitting the emergency breathing oxygen to flow through the valve body and then through the delivery outlet for user emergency breathing.