CO2 SYSTEM and fixed fire fighting system.pptx

fire

1. ADVANCE FIRE FIGHTING 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. FUNCTION

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. FUNCTION

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. WHY Co2 IS USED ?

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 ADVANTAGE

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. DISADVANTAGE

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 EXPLANATION OF Co2 FLOODING SYSTEM

8. SYSTEM DRAWING

9. 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. WORKING

10. 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. WORKING-2

11. 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’ WORKING-3

12. 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 WORKING-4

13. 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 WORKING-5