Aircraft Systems

Figure 7-45. Continuous flow mask and rebreather bag. breathing cycle because oxygen is only delivered during inhalation. Compared to continuous-flow systems, the pulse- Figure 7-46. EDS-011 portable pulse-demand oxygen system. demand method of oxygen delivery can reduce the amount of oxygen needed by 50–85 percent. Most pulse-demand systems are to be serviced. Oxygen system servicing should oxygen systems also incorporate an internal barometer be accomplished only when the aircraft is located outside that automatically compensates for changes in altitude by of the hangars. Personal cleanliness and good housekeeping increasing the amount of oxygen delivered for each pulse as are imperative when working with oxygen. Oxygen under altitude is increased. [Figure 7-46] pressure creates spontaneous results when brought in contact with petroleum products. Service people should be certain to Pulse Oximeters wash dirt, oil, and grease (including lip salves and hair oil) A pulse oximeter is a device that measures the amount of from their hands before working around oxygen equipment. It oxygen in an individual’s blood, in addition to heart rate. is also essential that clothing and tools are free of oil, grease, 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. [Figure 7-47] Servicing of Oxygen Systems Before servicing any aircraft with oxygen, consult the specific aircraft service manual to determine the type of Figure 7-47. Onyx pulse oximeter. equipment required and procedures to be used. Certain precautions should be observed whenever aircraft oxygen 7-39