Chapter 16 Cabin Environmental Control Systems...........16-1 Physiology of Flight.....................................................16-1 Composition of the Atmosphere...............................16-1 Human Respiration and Circulation .........................16-2 Oxygen and Hypoxia ............................................16-2  Hyperventilation ..................................................16-3 Carbon Monoxide Poisoning ................................16-3 Aircraft Oxygen Systems.............................................16-3 Forms of Oxygen and Characteristics ......................16-4 Gaseous Oxygen ...................................................16-4 Liquid Oxygen ......................................................16-4 Chemical or Solid Oxygen....................................16-5 Onboard Oxygen Generating Systems  (OBOGS) ..............................................................16-5 Oxygen Systems and Components ...........................16-6 Gaseous Oxygen Systems.....................................16-6 Chemical Oxygen Systems .................................16-16 LOX Systems......................................................16-17 Oxygen System Servicing ......................................16-17 Servicing Gaseous Oxygen.................................16-17 Filling LOX Systems ..........................................16-19 Inspection of Masks and Hoses ..........................16-20 Replacing Tubing, Valves, and Fittings .............16-20 Prevention of Oxygen Fires or Explosions.............16-21 Oxygen System Inspection and Maintenance.....16-21 Aircraft Pressurization Systems.................................16-21 Pressure of the Atmosphere....................................16-21 Temperature and Altitude.......................................16-22 Pressurization Terms ..............................................16-23 Pressurization Issues...............................................16-23 Sources of Pressurized Air .....................................16-24 Reciprocating Engine Aircraft............................16-25 Turbine Engine Aircraft......................................16-26 Control of Cabin Pressure ......................................16-28 Pressurization Modes..........................................16-28 Cabin Pressure Controller...................................16-29 Cabin Air Pressure Regulator and Outflow  Valve...................................................................16-31 Cabin Air Pressure Safety Valve Operation .......16-31 Pressurization Gauges.........................................16-33 Pressurization Operation.....................................16-33 Air Distribution...................................................16-34 Cabin Pressurization Troubleshooting................16-35 Air Conditioning Systems..........................................16-35 Air Cycle Air Conditioning....................................16-35 System Operation................................................16-35 Pneumatic System Supply ..................................16-35 Component Operation.........................................16-37 Water Separator ..................................................16-40 Cabin Temperature Control System ...................16-43 Vapor Cycle Air Conditioning ...............................16-43 Theory of Refrigeration ......................................16-43 Vapor Cycle Air Conditioning System  Components ........................................................16-46 Vapor Cycle Air Conditioning Servicing  Equipment...........................................................16-52 System Servicing ................................................16-55 Technician Certification .....................................16-59 Aircraft Heaters..........................................................16-59 Bleed Air Systems ..................................................16-59 Electric Heating Systems........................................16-59 Exhaust Shroud Heaters .........................................16-59 Combustion Heaters ...............................................16-60 Combustion Air System......................................16-61 Ventilating Air System .......................................16-61 Ignition System...................................................16-62 Controls...............................................................16-62 Safety Features....................................................16-62 Maintenance and Inspection ...............................16-63 Chapter 17 Fire Protection Systems ...................................17-1 Introduction..................................................................17-1 Classes of Fires.........................................................17-2 Requirements for Overheat and Fire Protection  Systems.....................................................................17-2 Fire Detection/Overheat Systems ................................17-2 Thermal Switch System............................................17-2 Thermocouple System..............................................17-3 Continuous-Loop Systems .......................................17-4 Fenwal System......................................................17-4 Kidde System........................................................17-4 Pressure Type Sensor Responder Systems...............17-6 Pneumatic Continuous-Loop Systems..................17-7 Fire Zones.................................................................17-8 Smoke, Flame, and Carbon Monoxide Detection  Systems ........................................................................17-8 Smoke Detectors.......................................................17-8 Light Refraction Type...........................................17-8 Ionization Type.....................................................17-8 Flame Detectors........................................................17-9 Carbon Monoxide Detectors ....................................17-9 Extinguishing Agents and Portable Fire  Extinguishers..............................................................17-10 Halogenated Hydrocarbons ....................................17-10 Inert Cold Gases .....................................................17-10 Dry Powders ...........................................................17-10 XXI