CO2 release cabinet or release box consist of two pilot CO2 cylinders or bottles containing CO2 gas inside. It is an effective fire suppression agent applicable to a wide range of fire hazards. This allow passage of CO2 to the pressure operated cylinder valve of main bottle. Due to safety reasons, the CO2 flooding system is manually released from a release cabinet located outside the protected space. Figure below 000000shows two time delay units, one for engine room and the other for purifier room.
Both release cabinets are connected in parallel and non return valves fitted in the lines prevent back flow of CO2. It has a high rate of expansion which allows it to work fast.
For releasing CO2 to the protected space, one of the pilot bottle valve is opened. So it is important to keep the temperature of CO2 bottles low for limiting the pressure inside bottles.
Service chart sample used by marine engineers for CO2 flooding system on ships is shown below. A valve for pressure testing of the system is also connected to the pressure gauge connection as shown in CO2 line diagram.
The pilot CO2 line is connected to all these heads.
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 flooding system or central bank CO2 system is one of the common fixed fire fighting system installed on most of the ships.
Since the master valve is already open before, CO2 from manifold is released to the protected space through distribution pipe lines and nozzles.
After CO2 flooding system is operated efficiently, engine room fire will extinguish by smothering action. It releases carbon dioxide CO2 in bulk quantity to a protected space such as engine room, cargo hold, purifier room, pump room, etc. As temperature increases, pressure also increases.
A pressure gauge is also fitted on the manifold to read any gas pressure inside. Head assembly mainly consist of a cylinder valve, which is operated by a pneumatic actuator and linkages as shown in the figure below.
The pressure of CO2 inside the bottle depends on the temperature of the surroundings. A relief valve is required for two purposes:.
N ormally a by pass valve is also fitted across this time delay unit which can be used in case the unit goes defective. Out of these, two types of time delay unit is commonly used in CO2 flooding system on board ships. Set pressure of relief valve is about 180 bar.
This closes the pressure switch. The micro switch will ensure the activation of CO2 warning alarms and ventilation shut off.