Federal Aviation Administration, DOT

Section 25.1443

any outward leakage causing significant increase in the oxygen content of
the local ambient atmosphere. If a demand oxygen system is used, a supply
of 300 liters of free oxygen at 70 SectionF. and
760 mm. Hg. pressure is considered to
be of 15-minute duration at the prescribed altitude and minute volume. If
a continuous flow open circuit protective breathing system is used, a flow
rate of 60 liters per minute at 8,000 feet
(45 liters per minute at sea level) and a
supply of 600 liters of free oxygen at 70
SectionF. and 760 mm. Hg. pressure is considered to be of 15-minute duration at the
prescribed altitude and minute volume.
Continuous flow systems must not increase the ambient oxygen content of
the local atmosphere above that of demand systems. BTPD refers to body
temperature conditions (that is, 37 SectionC.,
at ambient pressure, dry).
(6) The equipment must meet the requirements of Section 25.1441.
[Doc. No. FAA-2002-13859, 69 FR 40528, July 2,
2004]

spaschal on DSK3GDR082PROD with CFR

Section 25.1441 Oxygen equipment and supply.
(a) If certification with supplemental
oxygen equipment is requested, the
equipment must meet the requirements
of this section and SectionSection 25.1443 through
25.1453.
(b) The oxygen system must be free
from hazards in itself, in its method of
operation, and in its effect upon other
components.
(c) There must be a means to allow
the crew to readily determine, during
flight, the quantity of oxygen available
in each source of supply.
(d) The oxygen flow rate and the oxygen equipment for airplanes for which
certification for operation above 40,000
feet is requested must be approved.
Section 25.1443 Minimum mass flow of supplemental oxygen.
(a) If continuous flow equipment is
installed for use by flight crewmembers, the minimum mass flow of
supplemental oxygen required for each
crewmember may not be less than the
flow required to maintain, during inspiration, a mean tracheal oxygen partial pressure of 149 mm. Hg. when
breathing 15 liters per minute, BTPS,
and with a maximum tidal volume of

700 cc. with a constant time interval
between respirations.
(b) If demand equipment is installed
for use by flight crewmembers, the
minimum mass flow of supplemental
oxygen required for each crewmember
may not be less than the flow required
to maintain, during inspiration, a
mean tracheal oxygen partial pressure
of 122 mm. Hg., up to and including a
cabin pressure altitude of 35,000 feet,
and 95 percent oxygen between cabin
pressure altitudes of 35,000 and 40,000
feet, when breathing 20 liters per
minute BTPS. In addition, there must
be means to allow the crew to use undiluted oxygen at their discretion.
(c) For passengers and cabin attendants, the minimum mass flow of supplemental oxygen required for each
person at various cabin pressure altitudes may not be less than the flow required to maintain, during inspiration
and while using the oxygen equipment
(including masks) provided, the following mean tracheal oxygen partial
pressures:
(1) At cabin pressure altitudes above
10,000 feet up to and including 18,500
feet, a mean tracheal oxygen partial
pressure of 100 mm. Hg. when breathing
15 liters per minute, BTPS, and with a
tidal volume of 700 cc. with a constant
time interval between respirations.
(2) At cabin pressure altitudes above
18,500 feet up to and including 40,000
feet, a mean tracheal oxygen partial
pressure of 83.8 mm. Hg. when breathing 30 liters per minute, BTPS, and
with a tidal volume of 1,100 cc. with a
constant time interval between respirations.
(d) If first-aid oxygen equipment is
installed, the minimum mass flow of
oxygen to each user may not be less
than four liters per minute, STPD.
However, there may be a means to decrease this flow to not less than two liters per minute, STPD, at any cabin altitude. The quantity of oxygen required is based upon an average flow
rate of three liters per minute per person for whom first-aid oxygen is required.
(e) If portable oxygen equipment is
installed for use by crewmembers, the
minimum mass flow of supplemental

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