What is the minimum pressure a Portable Oxygen Bottle (POB) should not fall below if other oxygen sources are available?

The correct minimum pressure that a Portable Oxygen Bottle (POB) should not fall below, if other oxygen sources are available, is 500 psi. This threshold is critical to ensure that the POB has enough oxygen for any necessary emergency use without risking depletion.

Maintaining the POB above this pressure level ensures that there is a sufficient supply of oxygen readily available, which can be crucial for passenger safety, especially in cases of in-flight emergencies where supplemental oxygen may be needed. If the pressure were to fall below this level, it could indicate an insufficient amount of oxygen, which might render the bottle ineffective for its intended purpose during a critical situation. Therefore, maintaining the POB at or above this minimum pressure is an important safety protocol in inflight services.