Oxygen Systems Flashcards
Cannula
A cannula is an ergonomic piece of plastic tubing that runs
under the nose to administer oxygen to the user. [Figure 7-44]
Cannulas are typically more comfortable than masks, but
may not provide an adequate flow of oxygen as reliably as masks when operating at higher altitudes. Airplanes certified to older regulations had cannulas installed with an on-board oxygen system. However, current regulations require aircraft with oxygen systems installed and certified for operations
above 18,000 feet to be equipped with oxygen masks instead
of cannulas. Many cannulas have a flow meter in the oxygen
supply line. If equipped, a periodic check of the green flow
detector should be a part of the pilot’s regular scan.
Pressure-Demand Oxygen Systems
Pressure-demand oxygen systems are similar to diluter
demand oxygen equipment, except that oxygen is supplied to
the mask under pressure at cabin altitudes above 34,000 feet.
Pressure-demand regulators create airtight and oxygen-tight
seals, but they also provide a positive pressure application of
oxygen to the mask face piece that allows the user’s lungs
to be pressurized with oxygen. This feature makes pressure
demand regulators safe at altitudes above 40,000 feet. Some
systems may have a pressure demand mask with the regulator
attached directly to the mask, rather than mounted on the
instrument panel or other area within the flight deck. The
mask-mounted regulator eliminates the problem of a long
hose that must be purged of air before 100 percent oxygen
begins flowing into the mask.
Continuous-Flow Oxygen System
Continuous-flow oxygen systems are usually provided for
passengers. The passenger mask typically has a reservoir
bag that collects oxygen from the continuous-flow oxygen
system during the time when the mask user is exhaling.
The oxygen collected in the reservoir bag allows a higher
aspiratory flow rate during the inhalation cycle, which
reduces the amount of air dilution. Ambient air is added to
the supplied oxygen during inhalation after the reservoir bag
oxygen supply is depleted. The exhaled air is released to the
cabin.
Electrical Pulse-Demand Oxygen System
Portable electrical pulse-demand oxygen systems deliver
oxygen by detecting an individual’s inhalation effort and
provide oxygen flow during the initial portion of inhalation. Pulse demand
systems do not waste oxygen during the breathing cycle because oxygen is only delivered during inhalation. Compared to continuous-flow systems, the pulse demand method of oxygen delivery can reduce the amount of oxygen needed by 50–85 percent. Most pulse-demand oxygen systems also incorporate an internal barometer that automatically compensates for changes in altitude by increasing the amount of oxygen delivered for each pulse as altitude is increased.
Pulse Oximeters
A pulse oximeter is a device that measures the amount of
oxygen in an individual’s blood, in addition to heart rate.
This non-invasive device measures the color changes that
red blood cells undergo when they become saturated with
oxygen. By transmitting a special light beam through a
fingertip to evaluate the color of the red cells, a pulse
oximeter can calculate the degree of oxygen saturation
within one percent of directly measured blood oxygen.
Because of their portability and speed, pulse oximeters are
very useful for pilots operating in nonpressurized aircraft
above 12,500 feet where supplemental oxygen is required.
A pulse oximeter permits crewmembers and passengers of
an aircraft to evaluate their actual need for supplemental
oxygen.
> 12,500’ to 14,000’
No Person may operate an aircraft
*At cabin pressure unless the required minimal flight crew is provided with and uses supplemental oxygen for more than 30 minutes at these altitudes
> 14,000’
No Person may operate an aircraft
*Unless the required minimal flight crew is provided and uses supplemental oxygen during the entire flight time at these altitudes
> 15,000’
No Person may operate an aircraft
*Unless each occupant of the aircraft is provided with supplemental oxygen
_>FL 250
No Person may operate an aircraft
*10 minute supply of oxygen for use in the event of cabin depressurization and rapid descent is needed
> FL 350
No Person may operate an aircraft
*Whenever the cabin pressure exceeds 14,000ft MSL, one person at the controls needs to wear an oxygen mask at all times.
Below FL 410, Above FL 350
If there are two pilots and you are in between these altitudes, each pilot can have access to a quick donning mask. However if one pilot gets up to use the restroom, the pilot at controls needs to wear a mask at all time till the next pilot comes back.
FL 410
Each pilot must be on oxygen at all times
FAR AIM for Oxygen Requirements
FAR 135.157
FAR 91.211
