What must be true regarding the POB ON/OFF valve during pre-flight?

What must be true regarding the POB ON/OFF valve during pre-flight?

• A. Verify ON/OFF valve is OFF
• B. Valve is ON
• C. Valve is open
• D. Valve is disconnected

Answer: (A)

During preflight, the portable oxygen bottle’s valve should be OFF, meaning the flow path is closed. This keeps oxygen from leaking or being released while the unit is being inspected, secured, and stowed, and it prevents unnecessary oxygen use or pressure changes before the system is needed. Only when the POB is put into service will the valve be opened to allow flow as required. If the valve were ON or the line were open, oxygen could unintentionally discharge or drain the bottle during ground handling, which is not acceptable during preflight. Disconnecting the unit or having it in an open state would also fail the safety check, since the device must be ready and sealed for inspection and transport.

During preflight, the portable oxygen bottle’s valve should be OFF, meaning the flow path is closed. This keeps oxygen from leaking or being released while the unit is being inspected, secured, and stowed, and it prevents unnecessary oxygen use or pressure changes before the system is needed. Only when the POB is put into service will the valve be opened to allow flow as required. If the valve were ON or the line were open, oxygen could unintentionally discharge or drain the bottle during ground handling, which is not acceptable during preflight. Disconnecting the unit or having it in an open state would also fail the safety check, since the device must be ready and sealed for inspection and transport.