9.5.1 The equipment should
be capable of producing inert gas with an oxygen content at no time
greater than 5% by volume subject to the special requirements of chapter 17. A continuous-reading oxygen content
meter should be fitted to the inert gas supply from the equipment
and should be fitted with an alarm set at a maximum of 5% oxygen content
by volume subject to the requirements of chapter
17. Additionally, where inert gas is made by an on-board process
of fractional distillation of air which involves the storage of the
cryogenic liquefied nitrogen for subsequent release, the liquefied
gas entering the storage vessel should be monitored for traces of
oxygen to avoid possible initial high oxygen enrichment of the gas
when released for inerting purposes.
9.5.2 An inert gas system should
have pressure controls and monitoring arrangements appropriate to
the cargo containment system. A means acceptable to the Administration,
located in the cargo area, of preventing the backflow of cargo gas
should be provided.
9.5.3 Spaces containing inert
gas generating plants should have no direct access to accommodation
spaces, service spaces or control stations, but may be located in
machinery spaces. If such plants are located in machinery spaces or
other spaces outside the cargo area, two non-return valves, or equivalent
devices should be fitted in the inert gas main in the cargo area as
required in 9.5.2. Inert gas piping
should not pass through accommodation spaces, service spaces or control
stations. When not in use, the inert gas system should be made separate
from the cargo system in the cargo area except for connections to
the hold spaces or interbarrier spaces.
9.5.4 Flame burning equipment
for generating inert gas should not be located within the cargo area.
Special consideration may be given to the location of inert gas generating
equipment using the catalytic combustion process.