Plain English Meaning

An oxygen system that only releases oxygen when you breathe in, and at very high altitudes pushes the oxygen into your lungs under pressure so your body still gets enough to function.

Full Definition

An oxygen delivery system that supplies oxygen to the user's mask only when the user inhales, and delivers it under positive pressure at higher altitudes so that oxygen is forced into the lungs rather than relying on the user's breathing effort alone. It is used in aircraft operating at altitudes where a continuous-flow or simple demand system cannot maintain adequate blood oxygen levels.

Context Anchor

Seen in high-altitude aircraft oxygen equipment, oxygen regulator descriptions, mask checks, and maintenance procedures.

Derivation

‘Pressure’ refers to the positive pressure used to oxygen into the lungs at . ‘Demand’ means the system only delivers oxygen on inhalation, in to the user’s breathing demand. The combined name describes a demand- system with the added feature of pressurized delivery when needed.