Which type of oxygen system supplies oxygen under pressure?

Pressure Demand systems are designed to supply oxygen under pressure, which is critical for high-altitude flight where the atmospheric pressure is significantly lower. This system operates by maintaining a positive pressure in the mask, ensuring that the pilot receives an adequate supply of oxygen even during circumstances where the external air pressure might not allow for normal inhalation of oxygen.

With a pressure demand system, the oxygen is delivered directly from a pressurized source, allowing for a steady flow that compensates for changes in breathing patterns and altitude. This is particularly important during high-stress situations or rapid climbs where the pilot's oxygen needs may fluctuate significantly. The pressure also helps prevent the inhalation of any outside contaminants, providing not just oxygen but a consistent and safe flow to the user.

Other systems, such as Diluter Demand or Continuous Flow Demand, may not provide oxygen under pressure in the same way, relying more on the ambient airflow and user effort to draw in oxygen. Therefore, the pressure demand design is essential for ensuring that oxygen is available in sufficient quantities and at the right pressure for safe operation at high altitudes.