System and method for an oxygen system alarm

A system for determining safe operation for a user of an oxygen system on an aircraft, comprising:

• a computer in communication with an oxygen concentration sensor, a flow meter, and an altimeter;
• wherein the computer is programmed to:
• receive a present oxygen concentration value from the oxygen concentration sensor;
• receive a present altitude value from the altimeter;
• compute an alarm flow rate as a function of the received present oxygen concentration value and the received present altitude value, the alarm flow rate corresponding to a flow of breathing gas sufficient to prevent hypoxia in the user at the present oxygen concentration value and the present altitude value;
• receive a present flow value from the flow meter, the present flow value representing a rate of flow of breathing gas to the user from the oxygen system;
• and
• compare the calculated alarm flow rate to the received present flow value, to determine a safe operation status;
• wherein the function is Ax2+Bx+C, where x is the received present oxygen concentration value, and A, B, and C are functions of the received present altitude value.

An oxygen system for an aircraft, the aircraft having an altimeter, comprising:

• a processor;
• an oxygen generator for providing a flow of breathing gas to a user, the oxygen generator being in communication with the processor, the oxygen generator having a selectively variable breathing gas flow rate and a selectively variable oxygen concentration;
• an oxygen concentration sensor in electrical communication with the processor, the oxygen concentration sensor configured to measure a concentration of oxygen in the flow of breathing gas;
• a flow meter in electrical communication with the processor, the flow meter configured to measure the rate of the flow of breathing gas;
• and
• wherein the processor is programmed to:
• receive a present oxygen concentration value from the oxygen concentration sensor;
• receive a present altitude value from the altimeter;
• compute an alarm flow rate as a function of the received present oxygen concentration value and the received present altitude value, the alarm flow rate corresponding to a flow of breathing gas sufficient to prevent hypoxia in the user at the present oxygen concentration value and the present altitude value;
• receive a present flow value from the flow meter;
• and
• compare the calculated alarm flow rate to the received present flow value, to determine a safe operation status;
• wherein the function is Ax2+Bx+C, where x is the received present oxygen concentration value, and A, B, and C are functions of the received present altitude value.