What is the size of the Oxygen Cylinder?

• A. 50 Cubic Feet
• B. 60 Cubic Feet
• C. 77 Cubic Feet
• D. 100 Cubic Feet

Answer: (C)

Oxygen cylinder size refers to how much gas is stored to feed the masks during depressurization. For the CRJ-550’s onboard oxygen system, the cylinder used is rated at 77 cubic feet. That size is chosen to provide enough oxygen across the mask lines for the duration needed during a descent when cabin pressure is lost, balancing enough supply with reasonable weight. Seventy-seven cubic feet translates to about 2,180 liters of gas at standard conditions, which supports the typical flow rates of multiple masks for the required emergency period. The system’s actual delivered flow depends on the regulator and mask, but the capacity tells you how much gas is available overall. Other cylinder sizes like 50, 60, or 100 cubic feet aren’t the standard configuration for this aircraft’s oxygen setup, so 77 cubic feet is the correct specification.