Cessna 182 1973 - Oxygen Duration Calculation; Oxygen System Servicing

OXYGEN
DURATION CALCULATION.
The
Oxygen
Duration
Chart
(figure 7-2)
should
be used
in
determin-
ing
the usable duration
(in
hours)
of
the
oxygen
supply
in
your
airplane.
The
following
procedure
outlines the method
of
finding
the duration
from
the
chart.
(1)
Note
the
available
oxygen
pressure
shown
on
the
pressure
gage.
(2)
Locate
this
pressure
on
the
scale
on
the
left
side
of
the
chart,
then
go
across
the
chart
horizontally
to the
right
until
you
intersect
the
line
representing
the number
of
persons
making
the
flight.
After
intersecting
the
line, drop
down
vertically
to
the bottom
of
the
chart
and
read
the
duration
in
hours
given
on
the
scale.
(3)
As
an example
of
the above
procedure,
1400
psi
of
pressure
will
safely
sustain
the
pilot
only
for
nearly
6
hours and
15
minutes.
The
same
pressure
will
sustain
the
pilot
and
three
passengers
for
approx-
imately
2
hours
and
30
minutes.
NOTE
The
Oxygen
Duration
Chart
is
based
on a
standard
con-
figuration
oxygen
system
having
one
orange
color-coded
hose
assembly
for
the
pilot
and
green
color-coded hoses
for
the
passengers.
If
orange
color-coded
hoses
are
provided
for
pilot
and
passengers,
it
will
be
necessary
to
compute new
oxygen
duration
figures
due
to
the
greater
consumption
of
oxygen
with
these
hoses.
This is
accom-
plished
by
computing
the
total
duration
available
to
the
pilot
only
(from
"PILOT
ONLY"
line
on
chart),
then
di-
viding
this
duration
by
the
number
of
persons
(pilot
and
passengers)
using
oxygen.
OXYGEN
SYSTEM
SERVICING.
The
oxygen
cylinder,
when
fully
charged,
contains
approximately
48
cubic
feet
of
oxygen,
under
a
pressure
of
1800
psi
at
70°F.
Filling
pressures
will
vary,
however,
due
to the
ambient
temperature
in
the
filling
area,
and
because
of
the
temperature
rise
resulting
from
com-
pression
of
the
oxygen.
Because
of
this, merely
filling
to
1800
psi
will
not
result
in
a
properly
filled
cylinder.
Fill
to the
pressures
indicated
in
the
table
on
the
following
page
for
ambient
temperature.
7-9