What is the correct sequence to turn off the POB?

• A. Remove mask first, then turn off the POB
• B. Turn off the POB first, then remove the mask
• C. Turn off POB while mask remains on
• D. Remove mask and leave POB on

Answer: (A)

When handling a portable oxygen bottle and its mask, you want oxygen to be controlled smoothly as you remove the equipment from your face. The safest sequence is to take the mask off first, then turn off the POB. Removing the mask while the oxygen supply is still active avoids pulling on a live line and lets you detach the mask with the hose freed, reducing the chance of struggle or leaks. Once the mask is off, turning off the POB stops the oxygen flow and lets you safely stow both items. Turning off the POB first can make mask removal awkward or awkwardly timed, and leaving the POB on while you remove the mask keeps the system active longer than necessary.