System to deliver oxygen in an aircraft
The invention relates to a system to deliver a respiratory gas to crew members in a cabin of an aircraft. The system includes at least one respiratory mask, an ambient air inlet for admission of ambient air into the respiratory mask, a source of additional gas, supply lines to transport the additional gas to the respiratory mask, a mixing chamber provided on the supply lines to mix the additional gas with ambient air to supply a respiratory gas corresponding to a mixture of the additional gas and the ambient air to the respiratory mask, regulation system to regulate the additional gas content of the respiratory gas at least partly as a function of the aircraft altitude.
1. A system to deliver a respiratory gas in a normally pressurized cabin of an aircraft to passengers and one or more crew members, said system comprising:
equipment for pressurizing the cabin at a cabin altitude of between approximately 5000-8000 feet for passengers and crew members;
a respiratory mask in the cabin for the crew member,
an ambient air inlet for admission of ambient air into said system,
a source of additional gas,
supply lines to transport said additional gas to said respiratory mask,
mixing chamber provided on said supply lines for feeding said respiratory mask with said respiratory gas corresponding to a mixture of said additional gas and said ambient air, and
a regulation system configured to regulate the additional gas content of said respiratory gas while at the cabin altitude at least partly as a function of the aircraft altitude according to the equation:
F I O 2 =21%+ F PREOX( Z aircraft )
wherein:
F I O 2 =total percentage of additional gas in said respiratory gas, and
Z aircraft =aircraft altitude,
such that, when FPREOX(Z aircraft )>0, FPREOX(Z aircraft ) varies incrementally as Z aircraft varies incrementally.
2. A system according to claim 1 , further comprising a demand regulator provided upstream the respiratory mask, said demand regulator comprising the regulation system and the ambient air inlet, said demand regulator providing the respiratory gas to said respiratory mask.
3. A system to deliver a respiratory gas in a normally pressurized cabin of an aircraft to passengers and one or more crew members, said system comprising:
equipment for pressurizing the cabin at a normal cabin altitude of between approximately 5000-8000 feet for passengers and crew members;
a respiratory mask in the cabin for the crew member,
an ambient air inlet for admission of ambient air into said system,
a source of additional gas,
supply lines to transport said additional gas to said respiratory mask,
mixing chamber provided on said supply lines for feeding said respiratory mask with said respiratory gas corresponding to a mixture of said additional gas and said ambient air, and
a regulation system configured to regulate the additional gas content of said respiratory gas as a non-binary function of aircraft altitude while at the normal cabin altitude.
4. A system to deliver a respiratory gas in a normally pressurized cabin of an aircraft to passengers and one or more crew members, said system comprising:
equipment for pressurizing the cabin at a cabin altitude for passengers and crew members;
a respiratory mask in the cabin for the crew member,
an ambient air inlet for admission of ambient air into said system,
a source of additional gas,
supply lines to transport said additional gas to said respiratory mask,
mixing chamber provided on said supply lines for feeding said respiratory mask with said respiratory gas corresponding to a mixture of said additional gas and said ambient air, and
a regulation system configured to regulate the additional gas content of said respiratory gas as functions of the aircraft altitude and a fixed, guaranteed decompression time of the aircraft.
5. A system to deliver a respiratory gas in a normally pressurized cabin of an aircraft to passengers and one or more crew members, said system comprising:
equipment for pressurizing the cabin at a cabin altitude for passengers and crew members;
a respiratory mask in the cabin for the crew member,
an ambient air inlet for admission of ambient air into said system,
a source of additional gas,
supply lines to transport said additional gas to said respiratory mask,
mixing chamber provided on said supply lines for feeding said respiratory mask with said respiratory gas corresponding to a mixture of said additional gas and said ambient air,
a regulation system to regulate the additional gas content of said respiratory gas at least partly as a function of the aircraft altitude,
wherein the regulation system is configured to regulate the additional gas content of the respiratory gas as a function of aircraft altitude according to the equation:
F I O 2 =21%+ F PREOX( Z aircraft )
wherein:
F I O 2 =total percentage of additional gas in said respiratory gas,
Z aircraft =aircraft altitude, and
FPREOX(Z aircraft )≦FREF(Z aircraft ), with FPREOX(Z aircraft ) a percentage function of Z aircraft ,
FREF(Z aircraft ) being a percentage function of Z aircraft and given by the following table:
Z aircraft (ft)
FREF(Z aircraft )
Z aircraft (ft)
FREF(Z aircraft )
25,000
0
36,000
20
30,000
7
37,000
23
31,000
9
38,000
27
32,000
11
39,000
31
33,000
13
41,000
35
34,000
15
43,000
40
35,000
17
45,000
46.
6. A method of using a system to deliver a respiratory gas to a crew member in a normally pressurized cabin of an aircraft, said system comprising:
a respiratory mask in the cabin for the crew member,
an ambient air inlet for admission of ambient air into said system,
an additional gas source,
supply lines to transport said additional gas to said respiratory mask,
mixing chamber provided on said supply lines for feeding said respiratory mask with said respiratory gas corresponding to a mixture of said additional gas and said ambient air,
said method comprising
pressurizing the cabin to a cabin altitude lower than the aircraft altitude for passengers,
delivering said additional gas to said respiratory mask when worn by a crew member at least as a function of the aircraft altitude, wherein delivering the additional gas is according to the following equation:
F I O 2 =21%+ F PREOX( Z aircraft )
wherein:
F I O 2 =total percentage of additional gas in said respiratory gas,
Z aircraft =aircraft altitude, and
FPREOX(Z aircraft )≦FREF(Z aircraft ), with FPREOX(Z aircraft ) a percentage function of Z aircraft ,
FREF(Z aircraft ) being a percentage function of Z aircraft and given by the following table:
Z aircraft (ft)
FREF(Z aircraft )
Z aircraft (ft)
FREF(Z aircraft )
25,000
0
36,000
20
30,000
7
37,000
23
31,000
9
38,000
27
32,000
11
39,000
31
33,000
13
41,000
35
34,000
15
43,000
40
35,000
17
45,000
46.