The CO2 flooding system releases carbon dioxide into protected spaces on ships to extinguish fires. CO2 cylinders located in a separate room contain liquid CO2 that is directed through pipes to nozzles in protected spaces when manually activated. CO2 displaces oxygen in the air which prevents combustion from occurring, smothering the fire. It is effective on various fire types and leaves no residue, but is also highly asphyxiating to humans if inhaled in high concentrations.

1. Co 2 SYSTEM

2.  CO2 flooding system or central bank CO2
system is one of the common fixed fire
fighting system installed on most of the
ships. It releases carbon dioxide (CO2) in
bulk quantity to a protected space (such as
engine room, cargo hold, purifier room,
pump room, etc.) under fire. Smothering
action of CO2 extinguishes the fire thereby
preventing spreading of fire to other parts of
the ship. It consist of several CO2 cylinders
located in a separate room, called CO2 room.

3.  These bottles contain CO2 in liquid state.
When the fire in a protected space goes out
of control or in a situation when the fire is
not able to extinguish by local fire fighting
media, CO2 flooding system comes into
picture. CO2 from the bottles directed via
common manifold, main valve and
distribution pipe lines to nozzles through
which it is released to the protected space for
fire extinction. Due to safety reasons, the
CO2 flooding system is manually released
from a release cabinet located outside the
protected space.

4.  Carbon dioxide is the fire extinguishing
medium used in CO2 flooding system. It is an
effective fire suppression agent applicable to
a wide range of fire hazards. It has a high rate
of expansion which allows it to work fast.
When applied to a fire, CO2 provides a heavy
blanket of gas that reduces the oxygen level
to a point where combustion cannot occur.
Since carbon dioxide is a gas, there is no
clean up associated with a system discharge.
Low and high pressure CO2 is used for the
fire protection of machinery spaces, pump
rooms, cargo holds, paint stores and galley
exhaust ventilation ducts on board ships.

5.  Density is 1.5 times higher than air. So CO2
settles down and displaces air.
 It can be easily liquefied and bottled.
 20% – 30% CO2 concentration extinguishes
fire by smothering
 Non-corrosive
 Non- conductor of electricity
 No residues left after application
 No deterioration with age

6.  CO2 is highly asphyxiating. 9% concentration
causes unconsciousness within minutes
 Very little cooling effect. So there is danger of
re-ignition.
 When discharged, solid CO2 particles present
and generate sufficient static electricity to
produce spark.

7.  As mentioned earlier CO2 flooding
system floods the protected space
under fire with carbon dioxide, which
displaces air, thereby removing one
leg of fire triangle for the extinction of
fire. CO2 flooding system consist of
main CO2 bottles, common manifold,
master valve or distribution valve and
distribution pipe lines with nozzles

10.  Main CO2 bottles contain carbon dioxide in
liquid state with a pressure of 56 bar at 20
degree Celsius. Pressure of CO2 at 25 and
30 degree Celsius are 64 bar and 71 bar
respectively. So it is important to keep the
temperature of CO2 bottles low for limiting
the pressure inside bottles. CO2 from the
main bottle is released by a ‘CO2 release
cabinet’ as shown in the figure.

11.  As soon as the release cabinet door is
opened, a micro switch is activated. The
micro switch will ensure the activation of CO2
warning alarms and ventilation shut off. CO2
release cabinet or release box consist of two
pilot CO2 cylinders or bottles containing CO2
gas inside. The pressure of CO2 inside these
pilot bottles is same as that of main CO2
bottles. Only quantity of gas is different.

12.  For releasing CO2 to the protected space, one
of the pilot bottle valve is opened. Now CO2
reaches two valves marked 1 and 2. First
valve 1 is to be opened. Then CO2 passes
through a non return valve and opens
pneumatically operated master valve. Now
master valve is opened. Next, open valve 2 in
the release cabinet, which supply CO2 to
main CO2 bottle head assembly through a
non return valve and ‘time delay unit’

13.  Head assembly consist of a pressure operated
cylinder valve. This pressure operated
cylinder valve prevents CO2 from bottle
coming to the common manifold. As CO2
reaches the head assembly from pilot bottle,
pneumatic actuator in the head moves and
opens the pressure operated cylinder valve.
Then CO2 from main bottle escapes to the
common manifold via non return valve

14.  Each of the main CO2 cylinder have a head
assembly and non return valve. The pilot CO2
line is connected to all these heads. All the
CO2 from the main bottles now release to
common manifold. Since the master valve is
already open before, CO2 from manifold is
released to the protected space through
distribution pipe lines and nozzles