THE FIRE MAIN LINE IS USED TO FIGHT FIRE ONBOARD SHIP
FIRE MAIN LINE
General Principles
-The fire main is a system consisting of sea water inlet(s), suction piping, fire pumps and a distributed Piping system supplying fire hydrants, hoses and nozzles located throughout the vessel.
-Its purpose is to provide a readily available source of water to any point throughout the vessel which can be used to combat a fire and is considered the backbone of the fire fighting systems onboard a vessel.
-Through the fire main system, the firefighter is provided with a reliable and versatile system capable of providing a number of different methods with which to engage a fire.
-Water can be supplied as a straight stream for combating deep seated fires, as a spray for combating combustible liquid fires where cooling and minimum agitation is desired or as a means to
protect personnel where cooling is the primary effect desired.
Extinguishing Capabilities of Water
Water primarily extinguishes a fire by the removal of heat. It absorbs heat more effectively than any other commonly used extinguishing agent due to its good thermal conductivity and its high latent heat of vaporization. it is most effective when it absorbs enough heat to raise its temperature to 100°C (212°F). Water absorbs additional heat as it goes through the transition from a liquid to vapor (i.e., steam). In the process of heating the water from normal temperatures, up through its conversion into
team, water absorbs approximately 2.6 kilo-joules of heat per gram(1117 BTU/lb) of water, which As a much higher heat absorption value than any other agent.This absorption of heat reduces the temperature of the burning vapors and also reduces the amount of vapor being generated by the cooling of the fuel surface
With adequate cooling, there is insufficient heat to maintain the self-supporting combustion process and the fire goes out .Water also has an important secondary effect. When it turns to steam, it expands about 1600 times in volume at atmospheric pressure. As a result, one cubic meter (cubic foot) of water can generate
p to 1600 cubic meters (cubic feet) of steam vapor.This great cloud of steam surrounds the fire, displacing the air that supplies oxygen for the Combustion process.
SOLAS REGULATION FOR FIRE PUMP
Sanitary,ballast, bilge GS pump may be accepted as fire pump provided that they are not normally used for pumping oil and that if they are subject to occasional Duty for the transfer or pumping of fuel oil suitable changeover arrangement are fitted.IN MY SHIP WE HAD 2 FIRE PUMP ,-FIRE AND GS PUMP &- FIRE AND BILGE PUMP with changeover arrangement.FOR BALLAST, 2 BALLAST PUMP AND 2 SEA WATER PUMP.
- Ship shall be provided with independently driven fire pump as follows
= cargo ship 1000 GRT and upwards at least 2
less than 10000 GRT at least two power driven pump
one which shall be independently driven.
- Arrangement of connection fire pump and their sources of power shall be as to ensure that if a fire is in any one Compartment would put all the pump out of action there shall be an alternative means consisting of an emergency fire pump with its source of power and connection located outside the space where the main fire pump for their source of Power located. Location of space containing emergency fire pump the space emergency fire pump shall not be contiguous to the boundaries of the machinery space of category A or other space containing main fire pump no Direct Access shall be permitted between machinery space and space containing the emergency fire pump and its source of power ,when this is impracticable the administration accept and arrangement where the access is by means of an air lock with the door of the machinery space being A60 class and other door being at least Steel gasket self closing and without any hold back arrangement ventilation arrangement to went if any smoke possibility
- Additional pump for cargo ship in addition in cargo ship where the other pump such as general service, bilge and ballast etc are fitted to ensure to provide 2.7 bar of pressure to the main fire at least by one pump .
-Capacity of fire pump at a pressure of 2.7 Bar by all fire pump. Each cell have a capacity not less than 80% of the total required capacity by the minimum number of required fire pump but in any case not less than 25 metre cube per hour and each from shall in any event be capable of supplying the Fireman with two required Jets of water .
Diameter of fire main- self sufficient for the effectiveness distribution of maximum required discharge from the two fire pump operating simultaneously or diameter need only to be sufficient for the discharge of 140 metre cube per hour .
Isolating valve and relief valve
-ISOLATING VALVE to separate section of fire main within the machinery spaces containing the main fire pump or pump from rest of the fire means. It be fitted in an easily accessible and runable position outside the machinery space.
- The main fire shall be so arranged that when the isolating valves are shut, all the hydrant on ship except those in machinery space can be supplied with water by another pump'
- For emergency fire pump the emergency fire pump at sea water inlet and suction and delivery pipe shall be located outside the machinery spaces.
- A valve shall be fitted to serve each fire hydrant so that any fire hose may be removed while the fire pump are in Operation. It is a screw down isolating valve.
- RELIEF VALVE shall be provided in conjunction with fire pump pump are capable of developing a pressure exceeding the design pressure of water service pipes hydrants and hoses. This valves are so placed and arranged adjusted as to prevent excessive pressure in any part of the Fire main system. Fire line is fitted with relief valve to prevent the damage of pipe in case the valve is fighting fire with the help of shore in dry Dock.
EMERGENCY FIRE PUMP REGULATION
Apart from Main Fire Pump, an Emergency Fire Pump is also provided on board a ship, that can be
Used in case of an emergency like CO2 flooding or when Main fire pumps are disfunctional
-Capacity being 40% of the total capacity of the Main Fire pumps, but in any case not less than 25m3/h for passenger ships of less than 1,000 gross tonnage and for cargo ships of 2,000 gross
tonnage and upwards; and 15m3/h for cargo ships of less than 2,000 gross tonnages
-The emergency fire pump has its own independent means of power source, which can be used to take over in case of main power failure.
-it has attached priming unit and should be capable of overcoming the suction head in the lightest segoing draft the vessel may encounter and in any condition of list and trim.
-if suction pining is passing through the space to be protected must be additionally reinforced with fire retarted material so that damage take place and supply of water ensured at all time.
-the regulation required that if motor emergency gen can be met by a self contained CI engine driven unit or a hydraulic driven unit.
-emergency fire pump with its source of power and connection located outside the space where the main fire pump for their source of Power located.
Location of space containing emergency fire pump the space containing emergency fire pump shall not be contiguous to the boundaries of the machinery space of category A or other space containing main fire pump no Direct Access shall be permitted between machinery space and space containing the emergency fire pump and its source of power ,when this is impracticable the administration accept and arrangement where the access is by means of an air lock with the door of the machinery space being A60 class and other door being at least Steel gasket self closing and without any hold back arrangement ventilation arrangement to went if any smoke possibility
-Such units, their sea suctions, means of priming, sources of power supply, switchboards, electric Cables and hydraulic piping as appropriate, must not be in the compartment containing the main
ire pumps, but in a position not likely to be cut off by fire or smoke in that compartment and be at all times ,Such that the supply of water is ensured venting of Emergency fire pump room should be as far as possible from M/C space to avoid any smoke from M/C space fire entering into that space.
-The pumps can be started from remote locations also.Though sea water is the best mode of fighting fire, the main emergency fire fighting system can only be used on fires of Type A. However, in case of class B fires, if all modes for extinguishing fire fails,sea water from main emergency system can be used fire main system is also be used for boundary cooling.
-Performance criteria = 12 meter jets from 2 hydrants located farthest from each other.
All the hydrant outlets are provided with an isolating valve so as to isolate those valves which are Not in use.The fire hydrants are also provided with standard size flanges in order to attach hoses which have Nozzles attached to them. All hoses are provided with snap in connectors for easy and quick Engaging and disengaging operation.The nozzles attached to the hoses can be operated in two modes jet and spray, depending on The type of discharge required for extinguishing the fire.The nozzles can be adjusted according to the type of spray and flow required, which could be used Over the fire to cool it without spreading.The pumps are connected with the main sea water connection, having appropriate head to prevent
any type of suction problem.
HYDRANT
=Shall be such that atleast two jets of water not emanating from same hydrant -one of which shall be from a single length of hose ,may reach any part of the shape normally accessible to crew -or in which latter case the to two jet shall reach any part of the space is from a single length of hose.
=Further more such hydrant shall be positioned and near the eccess to the protected space.At least two fire hose nozzle can be fitted in a fire hydrant.
=In machinery space two hydrant shall be provided but near to entrance to that machinery space.
=above 6000GRT the min pressure is 2.7 bar. The max pressure at any hydrant shall not exceed that at which the effective control of a fire hose can be demonstrated.
=Fire Main System must have at least two independently driven fire pumps that can each deliver water at a continuous pitot tube pressure of at least 3.5 kilograms per square centimeter approximately 50 pounds per square inch) at least two fire hose nozzles that are connected to the highest two fire hydrants on the unit.Alternative designs that meet the pressure requirement of this paragraph will be considered for column stabilized and self-elevating units. pressure @ hydrant:
or passenger ships:
4,000 gross tonnage and upwards 0.40 N/m
less than 4,000 gross tonnage 0.30 N/m
or cargo ships
6,000 gross tonnage and upwards 0.27 N/m
less than 6,000 gross tonnage 0.25 N/m
the maximum pressure at any hydrant shall not exceed that at which the effective control of a fire hose can be demonstrated.
Fire Hoses and Nozzles
Fire Hoses:
=These are made from synthetic woven textiles, lined with rubber and PVC coated.
=They are strong and are not affected by oils, chemicals, extreme climates and mildew.
=These are generally 18 meter long and 64mm diameter and provided with couplings and Nozzle.
15 m for M/C space
20 m other space and open deck
25 m open deck with a max breadth in excess of 30 m
=They are conspicuously kept at designated positions near the hydrants, either rolled or flaked, in a Fire Hose Box.
=Testing annually @ 50% above working pressure, damaged and suspect hose must be removed.
=Working pressure 17 bar and testing pressure 24 bar.
Nozzles
=They should be of approved dual purpose type, i.e. spray and jet, also incorporating a shut-off. They Are kept with hoses in the Fire Hose Box.
=Nozzles shall be fitted above the bilges, tank tops and other areas over which oil fuel is liable to Spread and also above other specific fire hazards in the machinery spaces. Precautions shall be taken to prevent the nozzles from becoming clogged by impurities in the water by corrosion.
=The number and arrangement of the nozzles shall be to the satisfaction of the Administrator and Shall be such as to ensure an effective average distribution of water at least 5 litre/m2 /min in the Spaces to be protected
=Where increased application rates are considered necessary, these shall be to the satisfaction of the Administrator.
Size are 12 mm, 16 mm, 19 mm
For accommodation only 12 mm use
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