TM 55-1510-221-10
Table 2-5. Oxygen Duration In Minutes 140 Cubic Foot System
TWO MAN
3 1,000
100%
8.4
CREW
25,000
100%
11.8
20,000
100%
15.2
20,000
NORMAL
7.4
15,000
100%
19.0
15,000
NORMAL
10.2
10,000
100%
23.8
CABIN
CREW
TOTAL
PRESSURE
MASK
FLOW
ALTITUDE
CONDITION
LPM-NTPD
TWO MAN
CREW PLUS
ONE PASS
10,000
3 1,000
25,000
20,000
20,000
15,000
15,000
10,000
10,000
(1) For 100% capacity of useable oxygen, 3,226 L.
NORMAL
100%
100%
100%
NORMAL
100%
NORMAL
100%
NORMAL
13.8
233.7
12.1
266.6
15.5
208.1
18.9
170.0
10.9
295.9
22.7
142.1
13.9
232.1
27.5
117.3
17.5
184.3
DURATION
IN
MINUTES (1)
384.0
273.3
212.2
448.0
169.7
316.2
135.5
2-61. OXYGEN DURATION EXAMPLE PROBLEM
WANTED
Duration in minutes of oxygen at 100% capac-
ity.
KNOWN
Two man crew plus one passenger, cabin pres-
sure altitude = 15,000 feet, crew masks, normal,
100% capacity.
METHOD
Find “two man crew plus one pass” line, move
right then down to 15,000 - “normal” read “232.1”
minutes.
WANTED
Duration of oxygen for previous example data at
84% of capacity.
KNOWN
232.1 minutes duration at l00%, 84% capacity,
total aircraft flow = 13.9 LPM.
METHOD
Multiply 232.1 X 0.84 = 194.9 minutes. or Mul-
tiply 3,226 X 0.84 = 2709.8, divide by 13.9 LPM =
194.9 minutes.
WANTED
Duration of oxygen for complement at other
cabin pressure altitude, at less than 100% capacity.
KNOWN
Cylinder at 84% capacity, 100% capacity =
3,226 L, cabin pressure altitude = 21,000 feet.
1 crew mask = 7.2 LPM ( 100%) 1 passenger
mask = 3.7 LPM
METHOD
Multiply 3,226 L X 0.84 = 2.709.8 L, multiply
2 crew X 7.2 LPM = 14.4 LPM, multiply 1 passen-
ger X 3.7 LPM, add 14.4 LPM crew plus 3.7 LPM
passenger = 18.1 LPM. Divide 3,226 L by 18.1
LPM = 178.2 minutes.
2-62. OXYGEN CYLINDER CAPACITY EXAMPLE
PROBLEM
WANTED
a.
Percent of capacity at known pressure and
temperature.
b.
Pressure when temperature decreases.
2-49
