CA.VIII.A.K3aFAA-S-ACS-7B · Nov 2023Knowledge
a. Characteristics, limitations, and applicability of continuous flow, demand, and pres...
Operational factors, including: a. Characteristics, limitations, and applicability of continuous flow, demand, and pressuredemand oxygen systems
Bottom line
Regulators and masks work on continuous flow, diluter demand, or pressure demand systems. Diluter demand and pressure demand systems supply oxygen only when the user inhales through the mask. Pressure demand regulators provide a positive pressure application of oxygen to the mask facepiece, which allows the user's lungs to be pressurized with oxygen.
Key numbers
| Number | What it means |
|---|---|
| Certificated up to 41,000 ft MSL, but requires very careful attention above 25,000 ft MSL | Continuous flow |
| Safe up to 40,000 ft MSL | Demand mask |
| Safe at altitudes above 40,000 ft MSL | Pressure demand |
| Oxygen supplied under pressure at cabin altitudes above 34,000 feet | Pressure delivery |
| Can reduce oxygen needed by 50–85 percent compared to continuous-flow systems | Pulse-demand savings |
FAA references
- AC 61-107, para. 2-9 — AC No: 61-107B
- PHAK ch. 7 (pp. 7-38–7-39) — FAA-H-8083-25C (2023)
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