CO2 flooding system is discussed in this article in details and we will discuss majorly about how we release it. CO2 flooding fire fighting system is among the common and widely used system on board. CO2 is being used because of its effective smothering action on fire and can be stored onboard in large amount.
Either it can be stored in bottles, or it can be stored in large vessel and the CO2 is cooled constantly in that large vessel. It is called as Low pressure system. But the arrangement of storage in bottle is quite prevalent, and the later one is slowly gaining the momentum.
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CO2 Releasing System Room Regulations
Following are the requirements of CO2 flooding system room in which all the bottles are kept.
1) It should not be kept before the forward collision bulkhead.
2) Room should only used for storing the CO2 cylinders and nothing else than that.
3) This kind of space should be directly being accessible from the deck.
4) If the space is under deck, then there should be access by ladder or other suitable means.
5) It can only be put on deck lower than the open deck and not more deck lower than that.
6) A Mechanical ventilation should be provided at the entrance of the door.
7) The suction of the exhaust duct should be kept at the bottom, as CO2 is a heavy gas as compare to the air.
8) As per the regulation, at least 6 air changes per hour should be done in such room.
For Cargo Space: CO₂ quantity shall be suﬃcient to give a minimum volume of free gas, equal to 30% of gross volume of largest cargo space so protected.
For Machinery Space: CO₂ quantity shall be suﬃcient to give a minimum volume of free gas, equal to 40% of gross volume of machinery space so protected excluding the casing.
By regulation, 85% of the capacity must be able to be released within 2 minutes.
Co2 Flooding Releasing
Co2 releasing is a sequence of events that leads to release of it. Generally it will be released in case all other fire fighting systems are not able to extinguish the fire. Master and Chief Engineer on ship should decide when to release Co2 in a space whether it is cargo hold or machinery spaces.
Releasing arrangement for machinery spaces and cargo hold is different. Generally the Co2 releasing lines for cargo holds are also used for sampling of smoke. So before releasing it, the change of 3 way valves should be change over to release of Co2.
Also for cargo holds, the number of cylinders to be released for each space is different. A larger space will have large batch of bottles that will release in to that cargo hold.
There are two release box provided on ship, one is at the fire station and other is at local location where Co2 room is there.
Following is the process of releasing Co2:
- All the personals in the space where Co2 is to be released should be vacated.
- Make sure all the ventilation and opening to the space are closed. Otherwise there will be no effect of releasing it and all will just go out in the air.
- Stop the main engine.
- As soon as the panel for the Co2 alarm will ring. It is just a warning to the all that now Co2 will be released soon.
- We first going to discuss about releasing in Machinery Spcaes and Then Cargo Hold Spaces
- Machinery Spaces
- Press the lever for Pilot cylinder. Co2 in this pilot cylinder will open certain number of cylinders which are dedicated for the machinery spaces.
- It also opens the master valve which is opened well before the release of the Co2.
- After level is pushed, there is a time delay unit which will release the pilot cylinder gas to open the main bottles. This is just to safeguard people in case there is an accidental release. And they can evacuate. Also it makes sure that master valve is opened before all cylinder release Co2. Otherwise there will be access pressure inside the line and the relief valve will lift. This will make Co2 to get release into the air.
- Check locally that the Co2 have been released from the Co2 Storage Room by feeling the cylinders.
Cargo Hold Spaces
- For releasing Co2 in the cargo spaces, hold into which it should be released must be identified as for holds; there is a grouping for Co2 bottles, depending on the size of such space.
- Change over the 3 way valve for that space from sampling to releasing line.
- This will set the line for discharging gas into that space.
- Now we have to lift the lever for such cargo hold where Co2 is to be released.
This was all from the article on CO2 Flooding System, hope you enjoyed reading it.