ATA 35 – OXYGEN
3 Separate Oxygen Systems
1. Flight Crew Oxygen System
- High-pressure safety outlet is a frangible disk type.
- Low-pressure safety outlet is a pressure relief valve.
- Overboard green discharge indicator is connected to the high-pressure safety outlet and to the low-pressure safety outlet.
- Rupture of the frangible disk is set at a cylinder pressure of 2500 to 2775 psig.
- The pressure relief valve sets the limit of the low-pressure oxygen supply to 175 psig.
- The pressure regulator regulates the low pressure at 65 to 94 psig.
- REGUL LO PR on ECAM/DOOR/OXY page – Pressure switch operates when the oxygen supply pressure decreases to 50 plus or minus 5 psig
- OXY CYL – 1850 psig
- capacity of 77 cubic feet – An amber half-frame comes into view when the oxygen pressure is less than 1500 psig.
- capacity of 115 cubic feet – An amber half-frame comes into view when the oxygen pressure is less than 1000 psig.
- Each crew station has a quick-donning mask with a “demand regulator” installed.
- Oxygen is supplied from a high-pressure oxygen cylinder to the masks.
- Stowage box – for Quick Donning Mask.
- Reset/Test – control
- When Mask is removed – Oxy Sys automatically ON.
- Microphone is installed in the mask.
- Oxygen supply solenoid valve (LP Valve) – controlled by p/b switch in cockpit.
- Pressure indication on – ECAM door/oxy page.
- Overboard discharge indicator – Green blowout disc
- After blowout – Show a yellow indicator
- Follow precautions for oxygen servicing. (we directly replace the cylinder).
- Oxygen flow is indicated by the blinker showing yellow and an OXY ON flag, which appears on the left door when closed.
- The mask regulator provides either normal or pure oxygen by means of a Normal/100% selector. In the Normal position, the user breathes a mixture of cabin air and oxygen. When the selector is in the 100% position, the user will breathe pure oxygen. When the emergency rotation knob is rotated, the mask regulator supplies 100% of oxygen at a permanent positive pressure, independent of the position of the normal/100% selector. To take the mask off, the harness has to be inflated. This is done by operating the red clips.
- Proper stowing of the mask is essential – At the end of the restowing operation, do the: IN SITU TESTING.
2. Passenger Oxygen System
- The emergency oxygen for the passengers and the cabin attendants is supplied from emergency oxygen containers.
- The emergency oxygen containers are installed:
- Above the passenger seats
- In the lavatories
- At the cabin attendant stations
- In the galley working areas
- Each container has a chemical oxygen generator and two or more continuous-flow oxygen masks, each with a flexible supply hose.
- No. of masks depends on location. Most containers have 4 masks.
- Oxygen generator is a sodium chlorate core installed in stainless steel housing.
- Chemical oxygen generators will supply a flow of low pressure oxygen for a minimum time of 13 minutes.
- Demonstration oxygen masks are used to show the passengers how to use the emergency oxygen.
- Manual release tools for the mechanic use – to manually open oxy containers.
3. Portable Oxygen System
- Flight-crew portable device is a Protective Breathing Equipment (PBE).
- Cabin-Attendants Portable Devices
- HP oxygen cylinder with the continuous-flow masks
- The HP oxygen cylinders with the continuous-flow masks supply first-aid oxygen to the passengers. If necessary, they can also supply oxygen to the cabin attendants. It is held in place by quick release clamps.
- The oxygen cylinder will give a 15 min supply of oxygen at 20 liter/min.
- The primary use of the PBE is to supply oxygen to the crew if there is a fire or an emission of smoke and/or poisonous gas. It permits them to move freely to extinguish the fire.
- Oxygen cylinders or oxygen chemical generators are classified as dangerous material.