Gas fire-extinguishing systems in machinery spaces
The use of a fire-extinguishing medium which, either by itself or under expected conditions of use, gives off toxic gases in such quantities as to endanger persons is not permitted. New installations that use fire-extinguishing media, which have ozone-depleting properties under the Montreal Protocol, are not permitted.
The necessary pipes for conveying a fire- extinguishing medium into protected spaces are to be provided with control valves which are to be so placed that they will be easily accessible and not readily cut off from use by an outbreak of fire. The control valves are to be so marked as to indicate clearly the spaces to which the pipes are led.
Suitable provision is to be made to prevent inadvertent admission of the medium to any space. Where pipes pass through accommodation spaces they are to be seamless and the number of pipe joints are to be kept to a minimum and made by welding only.
The piping for the distribution of fire-extinguishing medium is to be of adequate size and so arranged, and discharge nozzles so positioned that a uniform distribution of medium is obtained.
All joints are to be made by suitable barrel couplings, cone connections or flanges. Screwed and running couplings are not allowed except that threaded sleeve joints may be allowed where connecting the nozzles to the distribution piping in the protected spaces.
All pipes are to be arranged to be self-draining and where led through any refrigerated spaces, the arrangement will be specially considered. A means whereby the individual pipes to all protected spaces can be tested using compressed air is to be provided. Distribution pipes are to extend at least 50 mm beyond the last nozzle.
Steel pipes fitted in spaces where corrosion is likely to occur are to be galvanized, at least internally. Means are to be provided to close all openings which may admit air into, or allow gas to escape from, a protected space.
Where the volume of free air contained in air receivers in any space is such that, if released in such a space in the event of fire, such release of air within that space would seriously affect the efficiency of the fixed fire-extinguishing system, an additional quantity of fire-extinguishing medium is to be provided.
Means are to be provided for automatically giving audible warning of the release of fire-extinguishing medium into any space in which personnel normally work or to which they have access. The alarm is to operate for a suitable period before the medium is released.
Where pneumatically-operated alarms are fitted which require periodic testing, carbon dioxide is not to be used as an operating medium. Air-operated alarms may be used provided that the air supply is clean and dry.
Where electrically-operated alarms are used, the arrangements are to be such that the electric operating mechanism is located outside the pump room,
The means of control of any fixed gas fire- extinguishing system are to be readily accessible and simple to operate and are to be grouped together in as few locations as possible at positions not likely to be cut off by a fire in a protected space. At each location, there are to be clear instructions relating to the operation of the system having regard to the safety of personnel.
Automatic release of fire-extinguishing medium is not permitted.
Where the quantity of extinguishing medium is required to protect more than one space, the quantity of medium available need not be more than the largest quantity required for any one space so protected.
Means are to be provided for the crew to safely check the quantity of medium in the containers.
Containers for the storage of fire-extinguishing media and associated pressure components are to be designed and tested to Codes of Practice recognized by LR, having regard to their locations and the maximum ambient temperatures expected in service.
The fire-extinguishing medium is to be stored outside a protected space, in a room which is situated in a safe and readily accessible position and effectively ventilated. Any entrance to such a storage room is to preferably be from the open deck and in any case be independent of the protected space.
Access doors are to open outwards, and bulkheads and decks including doors and other means of closing any opening therein, which form the boundaries between such rooms and adjoining enclosed spaces are to be gastight.
In systems where containers discharge into a common manifold, non-return valves are to be provided at the connections of the container discharge pipes to the manifold to allow any container to be disconnected without preventing the use of other containers in the system and to prevent the discharge of extinguishing medium into the container storage room in the event of the system being operated.
Manifolds are to be tested by hydraulic pressure to 1,5 times the design pressure. The design pressure is the maximum gauge pressure to which the system may be subjected and is not to be less than the gauge pressure corresponding to the maximum ambient temperature expected in service. After the hydraulic test, manifolds are to be carefully cleaned and dried before the non-return valves are finally fitted.
For ships on unrestricted service, spare parts for the system are to be stored on board. As a minimum, these are to consist of:
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