What oxygen flow condition should occur when the oxygen regulator selector is set to emergency?

When the oxygen regulator selector is set to emergency, it initiates a continuous flow of 100% oxygen under positive pressure. This setting is crucial in situations where a rapid supply of oxygen is necessary, such as in cases of hypoxia, and helps ensure that the highest concentration of oxygen is provided to the user.

Under positive pressure, the oxygen can more effectively counteract the physiological effects of altitude and ensure that the oxygen reaches the user's lungs and bloodstream without dilution. This method is particularly important during emergencies, where maintaining adequate oxygen levels is critical for sustaining consciousness and physical performance.

Other conditions, such as intermittent flow or oxygen concentrations lower than 100%, would not provide the necessary support during a critical situation, reducing the effectiveness of the emergency oxygen supply. Continuous flow under negative pressure is also not feasible, as it would not allow for the efficient delivery of oxygen when it is most needed.