11.15 - Oxygen Flashcards
What is the percentage of oxygen contained in the atmosphere at sea level?
21% Oxygen
What is the normal way to prevent hypoxia in an aircraft cabin?
Pressurising the cabin so that the oxygen is forced into the bloodstream as it passes through the lungs under normal cabin pressure.
Chemical oxygen generator systems are normally provided for?
Chemical oxygen generator systems are normally provided for passengers.
What is the function of the LP supply valve in the crew oxygen system?
The LP supply valve can be set to allow or isolate the gaseous oxygen supply from the oxygen cylinder to the distribution manifold.
What pressure is oxygen normally stored at on aircraft?
Oxygen on aircraft is stored normally at a pressure of 1800 psi
How is the crew oxygen cylinder protected against overpressure?
the pressure relief valve protects the system in case of overpressure (>175 psi) and the crew oxygen cylinder’s internal pressure (usually 1800 psi) is protected against overpressure by the frangible disk which ruptures releasing oxygen if internal cylinder pressure exceeds 2600 psi
The oxygen flows overboard through the disk and through the green disk on the outside of aircaft.
What happens when the cabin altitude reaches 14000 FT?
A pressure switch closes to complete a circuit, energising the solenoid which opens the passenger oxygen container doors. The ‘‘SYS ON’’ warning light in the cockpit will be illuminated to alert the flight crew.
List the safety precautions when working with oxygen? (5)
- Keep Oxygen away from fire
- Keep oil and grease away from oxygen hoses and fittings
- Wear clean overalls
- Use clean spark-proof tools
- Never mix oxygen with other gases
What are the different ways that the cabin oxygen system can be activated?
- Automatically if the cabin altitude reaches 14000 ft.
- Manually by the flight crew by actuating the guarded switch on the oxygen control panel in the cockpit.
Both methods energise the door latch solenoids opening oxygen container doors
How do you know an oxygen generator has been activated?
A heat sensitive tape on the generator turns black due to the surface temperature increase (can be up to 260^C) once the oxygen generator has been activated.
How do chemical oxygen generators work?
Multiple hoses are fitted to the generator and oxygen masks are connected at the other end of the hose. If a mask is pulled to face level, the activation pin is pulled out by a lanyard which releases the firing pin.
The firing pin strikes the primer which starts a chemical reaction of sodium chlorate and iron in the generator which generates oxygen.
(a) 21%
(c) To pressurise the cabin that the partial oxygen pressure is sufficient
(a) Passengers and cabin crews
(c) To allow or shut off the oxygen flow to the distribution manifold
(b) By a frangible disk
Could be either but as per diagram, the dish is the first line of protection on the actualy cylinder.
Pressure relief valve is more for system pressure
diagram pg 373 11.15
What are the percentages of oxygen and nitrogen in air?
21% Oxygen
78% Nitrogen
What is hypoxia?
It is the pressure of the atmosphere that forces oxygen into the bloodstream as it passes through the lungs.
As the pressure reduces with altitude, less pressure is exerted on the lungs and therefore the bloodstream absorbs less oxygen.
List the safety precautions for oxygen? (5)
- Keep oxygen away from fire
- Keep oil and grease away from oxygen hoses and fittings
- Wear clean overalls
- Use clean spark-proof tools
- Never mix oxygen with other gasses
What is the difference between aviation O2 and medical O2?
Medical Oxygen contains a high moisture content and other contaminants unlike aviation oxygen