HỆ THỐNG CỨU HỎA CO2 VÀ HALON TRÊN TÀU HÀNG (FIXED CO2 AND HALON ON BOARD)

In the majority of the ships the fixed fire extinguishing system to the Engine Room is CO2/Halons.. Prior to the release of any fixed gas based extinguishing medium in an enclosed space,

Fixed CO2 & HALON Installation for cargo ships

The use of fixed installations must be carefully considered at an early stage especially in the case of a cargo ships engine room fire In particular Carbon Dioxide/Halons are to be used before there is a build up of temperature causing severe convection

In the case of a serious fire, to effectively use CO2/Halons, the time factor is probably in the order of 10-12 minutes from the time that the fire situation is deemed to be beyond the

capability of first aid fire fighting equipment Proper closing down of the space is essential before the system is operated, and therefore the Chief Engineer Officer must make the necessary preparations during the first aid fire fighting stage in accordance with the vessel’s Ventilation Shut-down Plan

In the majority of the ships the fixed fire extinguishing system to the Engine Room is

CO2/Halons This is a "once off" shot and to have maximum effect all ventilation fans must be stopped and the fire flaps closed Several minutes may be required before all necessary

preparations have been completed and the CO2/Halons can be released

Fig:CO2 total flooding system

As total loss of power may result from flooding the Engine Room with CO2/Halons the Chief Engineer Officer must consult with the Master before releasing the CO2/Halons

Once this course of action is decided upon the Senior Officer in charge of the Emergency Party must act to release the CO2/Halons

Prior to the release of any fixed gas based extinguishing medium in an enclosed space, and to ensure that no personnel are present in that space positive verification is to be made by

mustering all the vessels crew

After flooding with the extinguishing gas, a careful watch is to be made on the space

temperature On no account is the space to be ventilated or opened up until the temperature has fallen to a safe level Failure to do this will result in the fire restarting with no further means to control or extinguish it Regardless of system fitted onboard, a description of the system is to be included within the shipspecific Fire Training Manual

Fig:CO2 total flooding system for engine room

Precautions Using Fixed C02 Systems

Once the system has been fully released and the fire extinguished, no personnel are to enter the space until the main supply valve has been shut The space must of course be well ventilated prior to entry in order to remove all traces of CO2 and ensure sufficient air has been introduced

to make the space safe It can take a considerable amount of time for the fire to be completely extinguished and for the space to cool down (in excess of 24 hours) Procedures for entry into enclosed spaces are to be followed in such cases

Halons 1301

Unlike CO2, Halons 1301 does not smother a fire Instead it interferes with the combustion cycle that occurs in a fire, arresting the heat producing reactions

Whilst Halons is not toxic at normal temperatures at temperatures above 800C toxic vapours may be given off Therefore personnel must immediately evacuate a space where Halons has been released into

There are some environmental concerns over the use of Halons and as a result this type of fire-fighting medium is being phased out

Maintenance of Carbon Dioxide and Halons Systems

The onboard planned maintenance system should include all maintenance requirements of the fixed fire fighting system as outlined by the system manufacturers and the flag administration including:

1 Maintenance and inspection procedures and instructions;

2 Required schedules for periodic maintenance and inspections;

3 Listing of recommended spare parts; and

4 Records of inspections and maintenance, including corrective actions taken to maintain the system in operable condition

The PMP should clearly indicate which parts of the recommended inspections and maintenance schedule should be completed by competent trained personnel Whenever fixed

fire-extinguishing systems are subjected to inspection or maintenance, care must be taken that the system is not accidentally triggered off Prior to performing any work, a risk assessment should

be developed

Extreme care is also to be taken when inspecting the room where the extinguishing medium is stored Ventilation must be continuously running to eliminate any chances of asphyxiation which may result from CO2 leaks

In addition to the recommendations of the manufacturers, and in accordance with IMO

MSC.1/Circ.1318, the following items should be included within the PMS

Monthly Inspections: CO2 / Halons alarms are to be tested monthly Note, where CO2 / Halons

alarms automatically shut down ventilation and machinery on opening of control boxes,

appropriate precautions are to be taken to avoid shut down of machinery Such tests shall be made only with the Chief Engineer’s approval after consultation with the Master

At least every 30 days a general visual inspection should be made of the overall system condition for obvious signs of damage, and should include verification that:

 all stop valves are in the closed position;

 all release controls are in the proper position and readily accessible for immediate use;

 all discharge piping and pneumatic tubing is intact and has not been damaged;

 all high pressure cylinders are in place and properly secured; and

 the alarm devices are in place and do not appear damaged

In addition, on low pressure systems, the inspections should verify that:

 the pressure gauge is reading in the normal range;

 the liquid level indicator is reading within the proper level;

 the manually operated storage tank main service valve is secure din the open position; and

 the vapour supply line valve is secured in the open position

Annual Inspections: The boundaries of the protected space should be visually inspected to

confirm that no modifications have been made to the enclosure that have created uncloseable openings that would render the system ineffective

All storage containers should be visually inspected for any signs of damage, rust or loose

mounting hardware Cylinders that are leaking, corroded, dented or bulging should be

hydrostatically retested or replaced

System piping should be visually inspected to check for damage, loose supports and corrosion Nozzles should be inspected to ensure they have not been obstructed by the storage of spare parts

or a new installation of structure or machinery

The manifold should be inspected to verify that all flexible discharge hoses and fittings are properly tightened

All entrance doors to the protected space should close properly and should have warning signs, which indicate that the space is protected by a fixed carbon dioxide system and that personnel should evacuate immediately if the alarms sound All remote releasing controls should be

checked for clear operating instructions and indication as to the space served

The bottle levels are also to be tested on an annual basis by ship’s staff using the testing

equipment supplied

Inspections at each intermediate, periodical or renewal survey: All high pressure cylinders

and pilot cylinders should be weighed or have their contents verified by other reliable means to confirm that the available charge in each is above 905 of the nominal charge Cylinders

containing less than 90% of the nominal charge should be refilled The liquid level of low

pressure storage tanks should be checked to verify that the required amount of carbon dioxide to protect the largest hazard is available

The hydrostatic test date of all storage containers should be checked High pressure cylinders should be subjected to periodical tests at intervals not exceeding 10 years At the 10-year

inspection, at least 10% of the total number provided should be subjected to an internal

inspection and hydrostatic test If one or more cylinders fail, a total of 50% of the onboard

cylinders should be tested If further cylinders fail, all cylinders should be tested Flexible hoses should be replaced at the intervals recommended by the manufacturer and not exceeding every

10 years

The discharge piping and nozzles should be tested to verify that they are no blocked The test should be performed by isolating the discharge piping from the system and flowing dry air or nitrogen from test cylinders or suitable means through the piping

Halons initiators must be replaced by a service engineer every three years Inspections at Each Renewal Survey by a Competent Authority

Where possible, all activating heads should be removed from the cylinder valves and tested for correct functioning by applying full working pressure through the pilot lines In cases where this

is not possible, pilot lines should be disconnected from the cylinder valves and blanked off or connected together and tested with full working pressure from the release station and checked for leakage In both cases, this should be carried out from one or more release stations when

installed If manual pull cables operate the remote release controls, they should be checked to verify the cables and corner pulleys are in good condition and freely move and do not require an excessive amount of travel to activate the system

All cable components should be cleaned and adjusted as necessary and the cable connectors should be properly tightened If the remote release controls are operated by pneumatic pressure, the tubing should be checked for leakage and the proper charge of the remote releasing station pilot gas cylinders should be verified All controls and warning devices should function normally and the time ideally, if fitted, should prevent the discharge of gas for the required time period After completion of the work, the system should be returned to service All releasing controls should be verified in the proper position and connected to the correct control valves All pressure switch interlocks should be rest and returned to service All stop valves should be in the closed position Masters are to refer to the regulations laid down by the Flag Administration / Class for the requirements to hydraulically pressure test gas cylinders of fixed systems

Fixed Dry Powder System

Fixed Dry Powder systems are to be checked monthly to ensure that valves are set correctly, guns operate freely and nitrogen bottles are at the correct pressure Every four months all pipe work is to be blown through with compressed air