Which component is encountered immediately after the inhalation hose in the O2 path?

• A. carbon dioxide scrubber canister
• B. breathing bag
• C. demand valve
• D. exhalation hose

Answer: (D)

In a closed-circuit oxygen rebreather, gas moves through two hoses that connect the mouth to the breathing loop: an inhalation hose that delivers gas to you and an exhalation hose that carries your breath back into the loop. When you inhale, you draw fresh gas from the loop through the inhalation hose. When you exhale, the gas leaves your mouth and enters the exhalation hose, which is the immediate next path back toward the rest of the loop. From there, the gas goes toward the counterlung/breathing bag and on to the CO2 scrubber and other components to be reused. So the exhalation hose is the first component encountered after the inhalation hose in the O2 path because it carries the breath back into the loop.