- With reference to the use of a CO2 flooding system:
(a) list the precautions that should be taken before releasing CO2 into the machinery spaces of a vessel;(4)
(b) state the length of time that should be allowed to elapse before re-entry into the machinery spaces can be considered, following release of CO₂;(2)
(c) state the precautions that should be taken before the machinery space can be safely re-entered, following release of CO₂. (4)
What is a CO2 flooding system?
A CO2 flooding system is a type of fixed fire extinguishing system that uses carbon dioxide (CO2) gas to suppress fires, primarily in enclosed spaces like machinery rooms, pump rooms, cargo holds, and other areas where water or other extinguishing agents might be impractical or damaging.
1. Carbon dioxide (CO2) flooding system – Wärtsilä
How it works:
- CO2 Storage: The system stores liquid CO2 under high pressure in cylinders or bulk tanks. 1. What is a Carbon Dioxide (CO2) Fire Suppression System? | CO2Meter.com www.co2meter.com
- Discharge: When activated (manually or automatically), CO2 is released rapidly into the protected space through a network of pipes and nozzles. 1. Carbon dioxide (CO2) flooding system – Wärtsilä www.wartsila.com
- Fire Suppression: The CO2 displaces oxygen, reducing the oxygen concentration in the air to a level that cannot support combustion. This effectively suffocates the fire. 1. What is a CO2 Fire Suppression System and How Does It Work? blog.koorsen.com2. CO2 Flooding and Water Sprinkler System by the Means of Double Routing System – IJRASET www.ijraset.com
- Cooling Effect: The rapid expansion of CO2 as it is released also has a cooling effect, helping to reduce the temperature in the affected area.
Advantages:
- Effective: CO2 is a highly effective fire extinguishing agent, especially for Class B (flammable liquid) and Class C (electrical) fires. 1. 5 types of fire extinguishers: A guide to using the right class www.ifsecglobal.com
- Clean: CO2 leaves no residue after discharge, minimizing cleanup and damage to equipment.
- Non-conductive: CO2 is electrically non-conductive, making it safe for use in areas with electrical equipment. 1. Carbon Dioxide Systems | Lafayette, IN – Official Website lafayette.in.gov
- Penetrates Spaces: CO2 can penetrate hard-to-reach areas due to its gaseous nature. 1. Co2 Gas Flooding System, Fire Extinguishing System, Mumbai, India – Fire Knock www.fireknock.com
Disadvantages:
- Danger to Personnel: CO2 is an asphyxiant, meaning it displaces oxygen and can cause suffocation. It’s critical to evacuate all personnel from the area before activation. 1. HIB 06-05-96 – Potential Carbon Dioxide (CO2) Asphyxiation Hazard When Filling Stationary Low Pressure CO2 Supply Systems – English | Occupational Safety and Health Administration www.osha.gov
- Limited Visibility: The discharge of CO2 creates a dense fog, reducing visibility and making evacuation more difficult.
- Not Suitable for All Fires: CO2 is not effective on Class A (ordinary combustibles) fires, as it doesn’t cool the fuel sufficiently to prevent re-ignition.
- Environmental Impact: Although CO2 is a naturally occurring gas, large discharges can contribute to greenhouse gas emissions.
Safety Precautions:
- Warning Systems: CO2 flooding systems must have audible and visual alarms to warn personnel before discharge. 1. Carbon dioxide (CO2) flooding system – Wärtsilä www.wartsila.com
- Time Delay: A time delay is built into the system to allow for safe evacuation before CO2 release. 1. Carbon Dioxide as a Fire Suppressant: Examining the Risks | US EPA www.epa.gov
- Ventilation: The protected space should be adequately ventilated after discharge to remove CO2 and ensure safe re-entry.
- Training: Crew members should be trained in the operation and safety procedures of the CO2 system.
Conclusion:
CO2 flooding systems are a powerful tool for fire suppression in enclosed spaces on ships. However, due to their potential dangers, they must be used with caution and only after ensuring the safety of all personnel.
Precautions should be taken before releasing CO2 into the machinery spaces of a vesse
Releasing CO2 into machinery spaces is a drastic measure to combat fire, but it poses significant risks to personnel due to its asphyxiating properties. Therefore, several critical precautions must be taken before activation:
1. Evacuation and Headcount:
- Sound Alarms: Activate the CO2 alarm to alert everyone in the affected area.
- Evacuate Personnel: Ensure ALL personnel have evacuated the machinery spaces. Conduct a thorough headcount and search to confirm no one remains.
- Secure the Space: Close all access doors, hatches, ventilation flaps, and other openings to create an airtight seal, preventing CO2 leakage and maximizing its effectiveness.
2. Machinery and Systems:
- Stop Non-Essential Machinery: Shut down any non-essential machinery and equipment to prevent damage and minimize the risk of reignition after CO2 discharge.
- Close Fuel and Oil Valves: Operate remote quick-closing valves to shut off fuel and oil supplies to machinery, further reducing fire risks.
- Secure Ventilation: Ensure all ventilation fans are stopped and their dampers are closed to prevent CO2 from escaping and maintain its concentration in the affected space.
3. Communication and Coordination:
- Notify Bridge: Inform the bridge team about the imminent CO2 release and confirm the evacuation of personnel from the engine room.
- Alert Nearby Vessels: If in close proximity to other vessels, inform them about the CO2 release to avoid accidental entry into the affected area.
- External Communication: In some cases, it might be necessary to inform relevant authorities or shore-based support about the situation.
4. Safety Checks and Precautions:
- Verify CO2 System Readiness: Conduct a final check of the CO2 system to ensure it’s fully operational and ready for discharge.
- Assign Responsible Personnel: Designate a competent and responsible person to oversee the CO2 release and ensure all safety procedures are followed.
- PPE for Entry Team: If an entry team is required for rescue or other purposes after CO2 discharge, they must wear appropriate personal protective equipment, including self-contained breathing apparatus (SCBA), and follow strict safety protocols.
5. Post-Discharge Actions:
- Ventilation Delay: Maintain the space sealed for a specified period (typically several hours) to allow the CO2 to fully extinguish the fire.
- Re-entry Precautions: Before re-entering the space, conduct thorough ventilation and atmospheric testing to ensure safe oxygen levels and the absence of toxic gases.
- Investigation and Repairs: Once safe, investigate the cause of the fire and initiate necessary repairs to prevent recurrence.
Key Takeaways:
- Human Safety is Paramount: The priority is to evacuate all personnel and prevent any casualties during CO2 release.
- Strict Adherence to Procedures: Follow the ship’s specific CO2 system operating procedures and any additional guidelines or regulations from the flag state and classification society.
- Training and Drills: Regular training and drills on CO2 system operation and emergency procedures are crucial for ensuring preparedness and effective response in case of a fire.
Remember, releasing CO2 into machinery spaces is a serious action with potential risks to human life. Meticulous adherence to safety precautions and procedures is crucial for a successful fire suppression operation and the well-being of all personnel onboard.
Length of time that should be allowed to elapse before re-entry into the machinery spaces can be considered, following release of CO₂
Generally, a minimum of 15 minutes should be allowed to elapse after the release of CO2 before considering re-entry into machinery spaces. This is to ensure that the CO2 concentration has sufficiently reduced to a safe level for human respiration.
However, it’s important to note that this is a minimum timeframe, and the actual time required may vary depending on several factors:
- Size of the Space: Larger machinery spaces will take longer for the CO2 to dissipate.
- Ventilation: The effectiveness of ventilation in removing the CO2 will affect the re-entry time.
- Atmospheric Testing: Before re-entry, the atmosphere MUST be tested with appropriate gas detection equipment to confirm safe oxygen levels (typically at least 21%) and the absence of any residual CO2.
Additional Precautions for Re-entry:
- Self-Contained Breathing Apparatus (SCBA): Personnel entering the space should wear SCBA until the atmosphere is confirmed safe.
- Buddy System: Never enter the space alone. Always have at least one person outside to monitor and assist in case of an emergency.
- Communication: Maintain constant communication between those inside and outside the space.
- Continuous Monitoring: Continue to monitor the atmosphere during re-entry in case of any unexpected changes.
Caution:
- CO2 is a silent killer. It’s odorless and colorless, so it’s important to rely on proper atmospheric testing, not just the perceived passage of time. 1. Carbon monoxide – the silent killer – UK Health Security Agency ukhsa.blog.gov.uk2. Carbon Dioxide | Wisconsin Department of Health Services www.dhs.wisconsin.gov
- Re-flash: In some fire scenarios, there’s a risk of re-flash if the fire wasn’t fully extinguished and oxygen is reintroduced.
Always follow the specific procedures and safety guidelines outlined in your vessel’s safety management system and any relevant regulations or instructions from authorities.
Precautions that should be taken before the machinery space can be safely re-entered, following release of CO₂
After a CO2 release in the machinery space, several crucial precautions must be taken before allowing re-entry to ensure the safety of personnel.
1. EK-General : 2019/MAR/08 – DieselShip UK
- Ventilation:
- Thorough Ventilation: The space should be ventilated for an extended period, typically several hours, to remove any residual CO2 and replenish the oxygen levels. This can be achieved by opening ventilation flaps and running exhaust fans.
- Natural Ventilation: If possible, utilize natural ventilation by opening hatches and doors to enhance airflow and accelerate CO2 dissipation.
- Atmospheric Testing:
- Gas Detection: Use calibrated gas detection equipment to monitor the atmosphere within the machinery space before and during re-entry. Verify that the oxygen level has returned to a safe level (at least 21%) and that the CO2 concentration is within permissible limits. 1. Safe working on CO2 systems – SAFETY4SEA safety4sea.com
- Continuous Monitoring: Maintain continuous monitoring of the atmosphere during re-entry, especially in poorly ventilated areas or if there’s a risk of CO2 pockets.
- Entry Team and PPE:
- Authorized Personnel Only: Only trained and authorized personnel wearing appropriate personal protective equipment (PPE) should enter the space.
- Breathing Apparatus: Personnel should wear self-contained breathing apparatus (SCBA) until the atmosphere is confirmed safe for breathing without respiratory protection.
- Other PPE: Additional PPE, such as protective clothing, gloves, and safety footwear, may be required depending on the specific hazards within the space.
- Communication and Safety:
- Buddy System: Implement a buddy system, ensuring that no one enters the space alone. A designated person outside should maintain constant communication and be ready to assist in case of an emergency.
- Communication Equipment: Provide reliable communication equipment, such as intrinsically safe radios or hand signals, to ensure continuous contact between the entry team and those outside.
- Emergency Procedures: Ensure everyone involved is familiar with the emergency procedures, including evacuation plans and rescue protocols, in case of unforeseen incidents during re-entry.
- Additional Precautions:
- Fire Re-flash: Assess the risk of fire re-flash, especially if the fire was not completely extinguished before CO2 release. Take necessary precautions, such as having firefighting equipment readily available.
- Machinery Status: Before restarting any machinery, conduct a thorough inspection to ensure no damage occurred during the fire or CO2 release.
- Logbook Entry: Record the details of the CO2 release, ventilation, atmospheric testing, and re-entry in the engine room logbook.
Remember: Re-entry into a machinery space after CO2 release should not be rushed. Prioritizing safety and adhering to proper procedures are crucial to prevent any further accidents or injuries.