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Oxygen Flow Rates
The following graph illustrates the relative rates of oxygen delivery for the various OPC operating modes. (Fig. 23).
ON Mode
•
Oxygen is only delivered above the 8,000 ft pressure altitude (PA) threshold.
•
Oxygen delivery is suspended when the altitude drops below 8,000 ft PA.
•
Above 8,000 ft PA, more oxygen is delivered as altitude increases (altitude compensating).
F20 Mode
•
Oxygen is delivered at all altitudes.
•
A fixed amount of oxygen is delivered at all altitudes below 8,000 ft PA.
•
Above 8,000 ft PA, more oxygen is delivered as altitude increases (altitude compensating).
•
The amount of oxygen delivered at any altitude is greater than what would otherwise be provided in
the ON mode (enriched flow).
R/M Mode
•
Oxygen is delivered at all altitudes.
•
A fixed amount of oxygen is delivered at all altitudes up to ~ 32,000 ft PA.
•
The fixed amount of oxygen delivered in the lower altitude range is significantly greater than what
would otherwise be provided in either ON or F20 mode (extremely enriched flow).
•
The amount of oxygen delivered above ~32,000 ft PA is the same as provided in ON mode, and
likewise, more oxygen is delivered as altitude increases (altitude compensating).
Notes:
•
At any altitude, ON mode will always provide the best efficiency and greatest oxygen duration.
•
F20 mode will always provide more oxygen than ON mode.
•
At lower altitudes, R/M mode will provide the most oxygen (by far).
•
The OPC will continue to operate above 32,000 ft PA, although at such high altitudes physiological
factors begin to compromise the effectiveness of an SBA (Supplemental Breathing Apparatus)
system such as the OPC.
Figure 23
15
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