Extinguishing Agent
FIRE FIGHTING
EXTINGUISHING AGENT
Water and High Fog
The HI - FOG marine sprinkler system is an alternative to conventional sprinkler systems and is approved by all amjor marine authorities ang classification societies. The high fog sprinkler system protects the accomodation ang machinery spaces on board.
The HI - FOG marine sprinkler system comprises a number of HI - FOG sprinkler connected by fresh water filled stainless steel small bore tubing to a pump unit via section valves.
Water is the most common cooling agent. This is largely because water possesses very good heat absorbing qualities and is available in ample quantities at terminals and on ships.
A water jet, although excellent for fighting fires involving combustible materials, should not be used on burning oil, or on burning cooking oil or fat in galleys, because of the danger of spreading the fire.
Owing to the danger of electrical shock, water should not be directed towards any electrical equipment. A wetting agent may be added to water when it is to be used on tightly packed combustible materials. This has the effect of lowering its surface tension and thus increasing its effective penetration.
High fog is a fixed system fitted in the owners interior - it is a pressurized system that when the glass bulb in the detector head is broken - a fine fresh water mist is emitted - smothering the fire.
Smothering Agent
1. Foam
Foam is an aggregation of small bubbles, of lower specific gravity than oil or water, which flows across the surface of a burning liquid and forms a coherent smothering blanket. it will also reduce the surface temperature of the liquid by the absorption of some heat.
Foam applicators should be directed away from liquid petroleum fires until any water in the system has been flushed clear.
Foam should not come into contact with any electrical equipment.
Foam concentrates may deteriorate with time depending on the storage conditions. Storage at high temperatures and in contact with air will cause sludge and sediment to form. This may affect the extinguishing ability of the expanded foam. Sample of the foam concentrate should therefore be returened periodecally to the manufacturer for testing and evaluation.
2. Carbon Dioxide
Carbon dioxide is an excellent smothering agent for extinguishing fires, when used in conditions where it will not be widely diffused. carbon dioxide is therfore effective in enclosed areas such as machinery spaces, pump rooms and electrical switch rooms where it can penetrate into places that cannot be reached by other means. on an open deck or jetty area carbon dioxide is comparatively ineffective. Carbon dioxide does not damage delicate machinery or instruments and, being a non - conductor, can be used safely on or around electrical equipment.
Due to the possibility of static electricity generation, carbon dioxide should not be injected into any space containing a flammable atmosphere that is not on fire. Carbon dioxide is asphyxiating and cannot be detected by sight or smell. No one should enter confined or partially confined spaces when carbon dioxide must be fully ventilated before entry without breathing apparatus.
3. Steam
Steam is inefficient as a smothering agent because of the substantial delay that may occur before sufficient air is displaced to render the atmosphere incapable of supporting combustion. Steam should not be injected into any space containing an un-ignited flammable atmosphere due to the possibility of static electricity generation.
4. Sand
Sand is relatively in effective as an extinguishing agent and is only useful on small fires on hard surfaces. Its basic use is to absorb small spills.
Flame Inhibitors
Flame inhibitors are materials that interfere chemically with the combustion process, and thereby extinguish the flames. However cooling or removal of fuel is necessary if re-ignition is to be prevented.
Dry Chemical Powders
Dry chemical powder is discharged from an extinguisher as a free flowing cloud. It is most effective in dealing initially with a fire resulting from an oil spill on a jetty or on the deck of a tanker but can also be used in confined spaces. It is especially useful on burning liquids escaping from leaking pipelines and joints. It is a non-conductor and thereforesuitable for dealing with electrical fires. It must be directed into the flames.
Dry chemical powder has a negligible cooling effect and affords no protection against re-ignition, arishing, for example, from the presence of hot metal surfaces.
Certain types of dry chemical powder can cause a breakdown of a foam blanket and only those labeled 'foam compatible' should be used in conjunction with foam.
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