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Mechanical Cabin System > oxygen > Flashcards

oxygen Flashcards

1
Q

what is avogadros law

A

equal volume of gases (at same temp and pressure) have same number of molecules, (1 mol = 22.4 L)

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2
Q

why do we need the O2 system

A
  • pressure loss
  • smoke
  • toxic gas
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3
Q

what are system requirements

A
  • indicate loss oxygen pp
  • provide oxygen to pax until get to safe altitude
  • as safe as possible o2 storage
  • portable for crew
  • still communicate
  • redundancy
  • easy to deploy
  • pilot put on with one hand
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4
Q

list some properties of oxygen

A

21% abundant, 50% by mass
very reactive (not combustable but starts combustion)
slightly denser than air
poor conductor of heat of electricity

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5
Q

what are ways to obtain oxygen

A
  • distillation of liquid air
  • pass clean dry air through a zeolite filter to get nitrogen
  • partially permeable ceramic membrane
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6
Q

what is hypoxia, symptoms

A

too little oxygen
quickly fatal
cant tell youre o2 deprived until too late
symptoms: euphoria, tired, vision bad (subjective)
hyperventillate, blue face, down coordination, loc, death (objective)

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7
Q

how does the body use (get oxygen)

A

breathes in oxygen to use for cellular respiration. oxygen dissolved in blood (increased saturation via haemoglobin) and the pressure gradient causes gas exchange at the alveoli.
oxygen dissolved in blood (increased saturation via haemoglobin)
same thing backwards with exhalign c02

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8
Q

what is daltons law

A

total pressure of a gas is the sum of each partial pressure of individual gases

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9
Q

what is time of usefull consciousness? ranges?

A

time between loss of sufficient o2 and ability to initiate counter measures.
18,000ft -> 30 min
40,000 ft -> 15 sec (gets very small

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10
Q

at what altitude do you need full concentratino 02

A

37,000ft

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11
Q

what are 6 ways to classify the oxygen system

A
  • sourse
  • mask
  • regulator type
  • who is using
  • portable vs not
  • reason
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12
Q

explain the different types of oxygen based on the reason for it

A

in non pressurized cabins: normal and emergency oxygen

in pressurized cabins: 
emergency oxygen (decompression), sustenence o2 (after decompression), first aid o2, supplemental o2 (msintain peak condition at higher cabin altitudes)
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13
Q

what were the regulator times on the first aircraft, what were the disadvantages of this

A

no regulators

wasteful (exhaling, no regulation at low altitudes)
potentially no mask

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14
Q

what are the different (5) regulator types

A
  • continuous flow,
  • demand system
  • pressure demand
  • diluter demand
  • pressure demand with dilution at low altitudes
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15
Q

which regulator types are most common in transport aircraft

A

continuous flow pax

diluter demand light crew

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16
Q

discuss the basics of the continuous flow regulator type

A
  • bag (resevoir) in between oxygen pipe and mask
  • three valves:
    1. exhale valve: air out to ambient during exhale
    2. non return: closes between rersevoir and mask (mouth) during exhale to prevent o2 loss
    3. dillution valve: opens to dilute resevoir during inhalation phase
17
Q

+/- of continuous flow regulator type

A

+simple components (3 valves) -> cheap and easy to maintain

  • : only at lower altitudes
  • : cant regulate or stop flow (can waste)
18
Q

basics of demand regulator type

A
  • requires a demand oxygen regulator for eac person
  • slight negative pressure at beginning of inhale opens tube and positive pressure at the end of exhale closes it.
  • max it 100% concentration o2
19
Q

+/- of demand regulator type

A

+saves oxygen

  • : need tight fitting mask
  • : max 37,000 ft
20
Q

basics of pressure demand system

A

has an oxygen pressure regulator and mask which is able to provide positive pressure

21
Q

+/- of pressure demand regulator type

A

allows high altitude

mask fits tight
forceful air into lungs -> overinflates lungs

22
Q

basics of diluter-demand system

A

automatically selects oxygen to air ratio based on altitude
- each mask needs a diluter demand regulator -> can be panel mounted,
three switches on diluter demand oxygen regulator
1. can switch to manual control to get 100% oxygen
2.can get slight positive pressure via emergency switch
3. can switch supply on/off manually
-has diluter-demand regulator valve (see pic)

see pic for diluter demand oxygen regulator
-most common for flight crew

23
Q

+/- of diluter demand

A

+ good up to 37,000 ft (100% o2)
+further saves oxygen while maintaining safe ppo2

-: more complicated and expensive components (not for everyone)

24
Q

what are five types of oxygen masks

A
  • nasal (low alt)
  • oronasal (typical pax)
  • full face
  • quick donning (5 s one hand), microphone
  • smoke hood
25
Q

+/- of gaseous oxygen cylinders

A

+high pressure measn low volume
+consistant

-: very high pressure -> need pressure reducers
-:dangerous (high pressure)
-: short lifetime -> microcracks in metal casing from vibrations
-need to be checked regularly (on pressure gauge)
-

26
Q

+/- LOX

A

+: weight savings -> military operations

  • : has to be kept very cold (boils at -180deg C)
  • : need equipment to turn it from LOX to gas
  • : evaporation loss -> need refilling
27
Q

describe the chemical oxygen generator

A

sodium chlorate (NaClO3) with heat turns to salt and breathable oxygen. Iron used as a heat source so a percentage of oxygen goes to the oxidation of iron
-once the rxn starts it cannot be stopped (starts mechanically or electrically, usually by pulling mask and releasing pin)
width of chamber proportional to flow rate (decreases with time of rxn)
length proportional to length of rxn (15 min) (to descenc)
-oxygen cools quickly
-deployed by lever or automaticlly by a pressure sensor on board
-cylinder has presure relief valve and outlet valve with filter

28
Q

+/- or chemical oxygen generator

A

+ weight and maintenence savings

  • : can’t be stopped (limited time)
  • : cylinder gets hot -> insulate components around it
  • :
29
Q

basic principles of OBOGS

A

-use bleed air for comtinuous supply of o2
-filter which takes out nitrogen
-

30
Q

+/- of OBOGS

A
  • continuous supply

- very heavy system

31
Q

explain pressure reducer principle

A

see pic

-screw sets spring which regulates an area for a constant outflow pressure

32
Q

draw diagram of diluter demand oxygen regulator

A

see pic

Mechanical Cabin System (7 decks)

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