Under ESSEX model, when will the PBE run out of oxygen?

• A. When the hood collapses.
• B. The flashing green Service Indicator Light begins flashing red or the hood collapses.
• C. After 30 minutes of use.
• D. The system provides oxygen indefinitely.

Answer: (B)

The PBE provides a finite amount of oxygen through a protective hood, and its status is monitored by a Service Indicator Light. When the oxygen supply is depleted or nearing depletion, the indicator changes from a normal steady state to flashing red, signaling that the usable oxygen has run out. A hood collapse is another condition that stops the supply entirely, indicating the unit can no longer deliver breathable air. Because of these indicators and potential mechanical failure, the correct moment for the PBE to be considered as exhausted is when the flashing red indicator appears or the hood collapses. The idea of an indefinite supply or a fixed, longer duration like thirty minutes isn’t how the ESSEX PBE is designed to operate.