Safety

Fixed Fire Fighting - Water

Water Fixed Fire fighting systems

Capacity of fire pumps

The capacity of the fire pumps is calculated as a product of the breadth, depth and length of the vessel but need not exceed 25m3 per hour

Fire pumps

For cargo ships of 150 gross tons or more, a minimum of one fixed power pump and one portable pump are to be provided.
For cargo ships of less than 150 gross tons, one portable pump or alternative , is to be provided. which meets the criteria listed later
For fishing vessels, not less than one fixed power pump is to be provided.
Sanitary, ballast, bilge or general service pumps may be accepted as fire pumps, 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 arrangements are fitted.
In cargo ships and fishing vessels classed for navigation in ice, the fire pump sea inlet valves are to be provided with ice clearing arrangements .
Relief valves are to be provided in conjunction with any fire pump if the pump is capable of developing a pressure exceeding the design pressure of the water service pipes, hydrants and hoses. These valves are to be so placed and adjusted as to prevent excessive pressure in any part of the fire main system.

Portable Pumps


Except for electric pumps, which will be specially considered, portable fire pumps are to comply with the following:

If it is not possible to comply with the requirements of the above, an additional fixed fire pump will be required, which is to comply with the following:

Means to illuminate the stowage area of the portable pump and its necessary areas of operation are to be provided from the emergency source of electrical power.

Fire main

The diameter of the fire main is to be based on the required capacity of the fixed main fire pump(s) and the diameter of the water service pipes are to be sufficient to ensure an adequate supply of water for the operation of at least one fire hose.
The wash deck line may be used as a fire main provided that the requirements of this sub-Section are satisfied.
All exposed water pipes for fire-extinguishing are to be provided with drain valves for use in frosty weather. The valves are to be located where they will not be damaged by cargo.

When the fixed main fire pump is delivering the quantity of water required , or the fire pump described as the alternative the portable pump , through the fire main, fire hoses and nozzles, the pressure maintained at any hydrant is to be sufficient to produce a jet throw at any nozzle of not less than 12 m.

Number and position of hydrants

The number and position of the hydrants are to be such that at least one jet of water may reach any part normally accessible to the crew while the cargo ship or fishing vessel is being navigated and any part of any cargo space when empty. Furthermore, such hydrants are to be positioned near the accesses to the protected spaces. At least one hydrant is to be provided in each Category 'A' machinery space.

Pipes and hydrants

Materials readily rendered ineffective by heat are not to be used for fire mains. Where steel pipes are used, they are to be galvanized internally and externally. Cast iron pipes are not acceptable. The pipes and hydrants are to be so placed that the fire-hoses may be easily coupled to them. The arrangement of pipes and hydrants are to be such as to avoid the possibility of freezing. In ships where deck cargo may be carried, the positions of the hydrants are to be such that they are always readily accessible and the pipes are to be arranged, as far as practicable, to avoid risk of damage by such cargo. Unless one hose and nozzle is provided for each hydrant in the ship, there is to be complete interchangeability of hose couplings and nozzles.
A valve is to be fitted at each fire hydrant so that any fire-hose may be removed while the fire pump is at work.

Where an additional fixed fire pump is fitted in as an alternative to the portable pump:

Fire Hoses

Fire-hoses are to be of approved non-perishable material. The hoses are to be sufficient in length to project a jet of water to any of the spaces in which they may be required to be used. Their length, in general, is not to exceed 18 m. Each hose is to be provided with a nozzle and the necessary couplings. Fire-hoses, together with any necessary fittings and tools, are to be kept ready for use in conspicuous positions near the water service hydrants or connections.
The number of fire-hoses to be provided, each complete with couplings and nozzles, is to be one for each 15 m length of the cargo ship or fishing vessel but in no case is there to be less than three. These numbers do not include any hoses required in any engine room. If necessary, the number of hoses is to be increased so as to ensure that hoses in sufficient number are available and accessible at all times.

Nozzles

For the purpose of this Chapter, standard nozzle sizes are to be 12 mm, 16 mm or 19 mm, or as near thereto as possible, so as to make full use of the maximum discharge capacity of the fire pump(s).
For accommodation and service spaces, the nozzle size need not exceed 12 mm.

The size of nozzles intended for use in conjunction with a portable fire pump need not exceed 12 mm.
All nozzles are to be of an approved dual purpose type (i.e. spray/jet type) incorporating a shut-off.

Typical system



Shown above is a typical system which may be found on most vessel. Of note are the large number of fire main isolator valves. The system may be so arranged as to split the supply between port and stbd sides over all deck levels. Thereby in the event of damage on one side of the vessel a nearby supply of water is ensured. In addition to the required main and emergency fire pumps, on this vessel a standy by pump capable of serving the fire main as well as the ballast and emergency bilge suction systems is available. ( note that a special arrangement must be made to ensure that bilge water is not delivered through the fire main.


Sprinkler systems

Must be fitted to passenger ships carrying less than 36 passengers in the accommodation spaces and other areas considered necessary be the administration. For passenger ships carrying greater than 36 passengers it must be fitted to accommodation spaces, corridors, stairwells and to control stations ( the latter may be served by an alternative system to prevent damage). The system must be of an approved type. See below for full requirements.
Generally takes the form of a wet pipe (line continuously flooded) on to which are connected a number of sprinkler head. These heads consist of a valve held shut by a high expansion fluid filled quartzoid bulb.A small air space is incorporated.


When a fire occurs in an adjacent area to this bulb the fluid expands until the air space is filled, increasing internal pressure causes the bulb to fracture. The size of the air gap determines the temperature at which this failure occurs. The valve plug falls out and a jet of water exits , striking the spray generator where it is then distributed evenly over the surrounding area. In acting this way only the area of the fire is deluged and damage is minimised


Water is supplied from an air pressurised water tank ( thus the system functions without electrical power), this water is fresh water to minimise damage. The tank is half filled with water and the rest is compressed air at pressure sufficient to ensure that all the water is delivered to the highest sprinkler at sprinkler head working pressure. Once this source of water is exhausted, falling main pressure is detected by a pressure switch. This activates a sea water supply pump. A valve is fitted on the system to allow proper testing of this function. After sea water has entered the system proper flushing with fresh water is required to prevent corrosion

A shore connection may be connected to the system to allow function during dry-dock

High Pressure Water spray system

A similar but essentially different system exists for the supply of water under pressure to dry pipes onto which sprinkler heads are fitted. These sprinkler heads do not have the bulb and valve arrangement. Instead when an area is to be served a relevant isolation valves is opened. The fundamental difference between this and the sprinkler system is that human intervention is required, whereas the sprinkler system is required to be fully automated. Commonly a cross connection vai a non-return valve exists able to deliver to the water from the high pressure spray system to the sprinkler system


When an isolation valve is opened pressure in the line falls and the sea water pump is started. The air vessel is there to prevent cycling of the pump due to slight water leakage. The fresh water pump is there for flushing and initial filling of wet pipe only.

Regulations

Taken from SOLAS 1974 Regualtion II/2A

Regulation 12 Automatic sprinkler, fire detection and fire alarm systems

1.1 Any required automatic sprinkler, fire detection and fire alarm system shall be capable of immediate operation at all times and no action by the crew shall be necessary to set it in operation. It shall be of the wet pipe type but small exposed sections may be of the dry pipe type where in the opinion of the Administration this is a necessary precaution. Any parts of the system which may be subjected to freezing temperatures in service shall be suitably protected against freezing. It shall be kept charged at the necessary pressure and shall have provision for a continuous supply of water as required in this regulation.

1.2 Each section of sprinklers shall include means for giving a visual and audible alarm signal automatically at one or more indicating units whenever any sprinkler comes into operation. Such alarm systems shall be such as to indicate if any fault occurs in the system. Such units shall indicate in which section served by the system fire has occurred and shall be centralized on the navigation bridge and in addition, visible and audible alarms from the unit shall be located in a position other than on the navigation bridge, so as to ensure that the indication of fire is immediately received by the crew.

2.1 Sprinklers shall be grouped into separate sections, each of which shall contain not more than 200 sprinklers. In passenger ships any section of sprinklers shall not serve more than two decks and shall not be situated in more than one main vertical zone. However, the Administration may permit such a section of sprinklers to serve more than two decks or be situated in more than one main vertical zone, if it is satisfied that the protection of the ship against fire will not thereby be reduced.

2.2 Each section of sprinklers shall be capable of being isolated by one stop valve only. The stop valve in each section shall be readily accessible and its location shall be clearly and permanently indicated. Means shall be provided to prevent the operation of the stop valves by any unauthorized person.

2.3 A gauge indicating the pressure in the system shall be provided at each section stop valve and at a central station.

2.4 The sprinklers shall be resistant to corrosion by marine atmosphere. In accommodation and service spaces the sprinklers shall come into operation within the temperature range from 68АC to 79АC, except that in locations such as drying rooms, where high ambient temperatures might be expected, the operating temperature may be increased by not more than 30АC above the maximum deckhead temperature.

2.5 A list or plan shall be displayed at each indicating unit showing the spaces covered and the location of the zone in respect of each section. Suitable instructions for testing and maintenance shall be available.

3 Sprinklers shall be placed in an overhead position and spaced in a suitable pattern to maintain an average application rate of not less than 5 l/m2/min over the nominal area covered by the sprinklers. However, the Administration may permit the use of sprinklers providing such an alternative amount of water suitably distributed as has been shown to the satisfaction of the Administration to be not less effective.

4.1 A pressure tank having a volume equal to at least twice that of the charge of water specified in this subparagraph shall be provided. The tank shall contain a standing charge of fresh water, equivalent to the amount of water which would be discharged in one minute by the pump referred to in paragraph 5.2, and the arrangements shall provide for maintaining an air pressure in the tank such as to ensure that where the standing charge of fresh water in the tank has been used the pressure will be not less than the working pressure of the sprinkler, plus the pressure exerted by a head of water measured from the bottom of the tank to the highest sprinkler in the system. Suitable means of replenishing the air under pressure and of replenishing the fresh water charge in the tank shall be provided. A glass gauge shall be provided to indicate the correct level of the water in the tank.

4.2 Means shall be provided to prevent the passage of seawater into the tank.

5.1 An independent power pump shall be provided solely for the purpose of continuing automatically the discharge of water from the sprinklers. The pump shall be brought into action automatically by the pressure drop in the system before the standing fresh water charge in the pressure tank is completely exhausted.

5.2 The pump and the piping system shall be capable of maintaining the necessary pressure at the level of the highest sprinkler to ensure a continuous output of water sufficient for the simultaneous coverage of a minimum area of 280 m2 at the application rate specified in paragraph 3.

5.3 The pump shall have fitted on the delivery side a test valve with a short open-ended discharge pipe. The effective area through the valve and pipe shall be adequate to permit the release of the required pump output while maintaining the pressure in the system specified in paragraph 4.1.

5.4 The sea inlet to the pump shall wherever possible be in the space containing the pump and shall be so arranged that when the ship is afloat it will not be necessary to shut off the supply of seawater to the pump for any purpose other than the inspection or repair of the pump.

6 The sprinkler pump and tank shall be situated in a position reasonably remote from any machinery space of category A and shall not be situated in any space required to be protected by the sprinkler system.

7.1 In passenger ships there shall be not less than two sources of power supply for the seawater pump and automatic alarm and detection system. Where the sources of power for the pump are electrical, these shall be a main generator and an emergency source of power. One supply for the pump shall be taken from the main switchboard, and one from the emergency switchboard by separate feeders reserved solely for that purpose. The feeders shall be so arranged as to avoid galleys, machinery spaces and other enclosed spaces of high fire risk except in so far as it is necessary to reach the appropriate switchboards, and shall be run to an automatic change-over switch situated near the sprinkler pump. This switch shall permit the supply of power from the main switchboard so long as a supply is available therefrom, and be so designed that upon failure of that supply it will automatically change over to the supply from the emergency switchboard. The switches on the main switchboard and the emergency switchboard shall be clearly labelled and normally kept closed. No other switch shall be permitted in the feeders concerned. One of the sources of power supply for the alarm and detection system shall be an emergency source. Where one of the sources of power for the pump is an internal combustion engine it shall, in addition to complying with the provisions of paragraph 6, be so situated that a fire in any protected space will not affect the air supply to the machinery.

7.2 In cargo ships there shall not be less than two sources of power supply for the seawater pump and automatic alarm and detection system. If the pump is electrically driven it shall be connected to the main source of electrical power, which shall be capable of being supplied by at least two generators. The feeders shall be so arranged as to avoid galleys, machinery spaces and other enclosed spaces of high fire risk except in so far as it is necessary to reach the appropriate switchboards. One of the sources of power supply for the alarm and detection system shall be an emergency source. Where one of the sources of power for the pump is an internal combustion engine it shall, in addition to complying with the provisions of paragraph 6, be so situated that a fire in any protected space will not affect the air supply to the machinery.

8 The sprinkler system shall have a connection from the ship's fire main by way of a lockable screw-down non-return valve at the connection which will prevent a backflow from the sprinkler system to the fire main.

9.1 A test valve shall be provided for testing the automatic alarm for each section of sprinklers by a discharge of water equivalent to the operation of one sprinkler. The test valve for each section shall be situated near the stop valve for that section.

9.2 Means shall be provided for testing the automatic operation of the pump on reduction of pressure in the system.

9.3 Switches shall be provided at one of the indicating positions referred to in paragraph 1.2 which will enable the alarm and the indicators for each section of sprinklers to be tested.

10 Spare sprinkler heads shall be provided for each section of sprinklers to the satisfaction of the Administration.