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Shetland School of Nautical Studies

Firefighting Fire Prevention And Sources Of Ignition On ShipsFire is a danger that never rests and one that is often due to carelessness.The basis of fire prevention is the elimination of the hazard. A determined effort to reduce flammable material can go a long way towards this aim. Cleanliness and tidiness are the best protection against fire.Loose cotton material left lying about instead of being stowed away provides kindling to carelessly discarded matches or cigarette ends.Areas of the no cigarette smoking rule must be strictly adhered to.Oily waste should not be allowed to accumulate. Accumulation of oil bilges should not be tolerated. Tank tops and bilges should be kept clear and oil free.There are certain prime sources of heat from which combustible material must be kept separate:

Boilers, Internal Combustion or steam driven machinery. Steam pipes Radiators Galley ranger and ovens Hot water boilers Boiler uptakes and Funnel casings Galley uptakes and exhaust pipes Workshop welding area

Rags, waste, clothing or anything that will burn should not be stowed near these items. The machinery may be cool initially but when brought on line may cause a fire. Carelessly carried out maintenance often gives rise to a source of heat which is undetected may cause a fire. Examples are:

Poor insulation on wandering electrical leads Glands in rotating spindles too tight. Badly adjusted brush gear in electric motors causing sparking. Badly fitted bearings, insufficient lubrication and similar neglect by maintenance staff. Damaged electrical insulation of multicore cables fitted to portable equipment,

allowing leads to become exposed, resulting in short circuiting. Heavily painted Main Engine parts which connect directly to a source of high

temperature.Electrical FiresWith few exceptions, fires of electrical origin occur due to a lack of reasonable care in the maintenance and use of electrical equipment. The power which drives electric motors and provides heat and light is capable of igniting its insulation or any combustible material near by. All electrical equipment should be properly installed, maintained and operated.The most common causes of electrical fires are:

Failure of insulation causing short circuits or discharge to earth. Overheating of cable or equipment due to overloading, lack of ventilation or local

overheating. Ignition of flammable substances by electrostatic discharges. Misuse of electrical equipment which in itself is not actually defective. Switchboard fires due to loose connections, faulty contactors or loose bus-bar

retaining bolts.Safeguards are:

All equipment should be installed correctly and only used for specific function that it is designed for.

Regular electrical and mechanical maintenance should be carried out including insulation readings and cleanliness.

All overload devices should be tested regularly. Switchboard chattering contactors to be repaired or replaced. Regular inspection of the switchboard internal connections to be carried out.

WRHunter 1 Underpinning Knowledge


FirefightingSpontaneous CombustionSpontaneous combustion can occur when packed cargoes such as coal, hemp, copra, grain etc. are carried especially if these are in a damp condition when loaded. In the centre of these cargoes there is very little ventilation to supply a cooling effect and the natural heat generated can build up to such a degree that it causes combustion of the material. Due to the restriction of oxygen supply this will just smoulder for a considerable time until part of the cargo is removed. Then by admitting additional air the cargo will burst into flames. Stowage of engine room stores is important since materials such as cleaning rags, cotton waste, sawdust etc. can all give rise to spontaneous combustion especially if they are stored next to the various chemicals now carried on board ships. Unattended oil leakage dripping on to hot pipes can ignite and cause fires.The disposal of used dry cell batteries must be carried out in a careful manner.Causes Of Ignition On Board ShipFire and explosion cannot occur unless a source of ignition is applied to a fuel in the presence of oxygen. The potential fire hazard on board any ship varies as the type of ship and the cargo carried. Though all are covered by the same regulations, the observance of these regulations may be stricter and vary slightly from one ship to another.SmokingSmoking on board ship can be dangerous but smoking in prohibited places endangers all lives on board. In some ports the local authorities prohibit smoking anywhere on board particularly with vessels carrying flammable cargoes. More usually one smoking area is allocated, nominated either by company regulations or by the Master. Smoking in bed is a perpetual hazard especially after the consumption of alcohol. Numerous deaths have resulted from this habit due to people falling asleep with lighted cigarettes and setting the bedding on fire. This offence often leads to dismissal.Cigarette lighters are banned on some vessels due to their ability to operate when dropped therefore they should never be carried in a pocket. Many companies provide safety matches TorchesAll electric torches on board should be of an approved type and are usually provided on the vessel. Unless the type of torch has been approved by the appropriate certification authority there is a danger of sparking when the switch makes and breaks. Also the possibility of an ignition source if the torch should be accidentally dropped breaking the bulb. This would be particularly dangerous in a gas filled atmosphere. There are a wide variety of approved torches available which range from being gas tight, explosion proof to being classified as intrinsically safe.or use on board.Domestic EquipmentElectric shavers, radios and galley appliances can all produce sparks of sufficient intensity to ignite flammable vapour and material. Probably the most common source of fire in galley equipment is the thermostatically controlled fryer. If the high temperature cut-out fails to operate and if the unit is not "fail-safe" then the fat or oil in the unit can overheat and burst into flames. When installing domestic electrical equipment on board ship it is advisable to consider all safety features of the unit as the most important factor. Regular inspection and maintenance must be carried out.Any build up fat residues must be avoided, especially underneath the cooking hobs on the galley range.

Oil FiresOils and vapours given off from all hydrocarbon oils contain the combustible elements of hydrogen and carbon which if temperature and pressure conditions are correct will ignite in the presence of oxygen.Steam heating coils are fitted to some oil tanks to assist in the separation of water and also serve to keep the oil in a preheated condition and reduce its viscosity for easier pumping and



Firefightingatomisation. The temperature is kept between 38.5 - 43.5C and the maximum temperature permitted is 53.5C. This limit is necessary because of the fire risk due to formation of oil vapour during heating. The minimum closed flashpoint for oil under storage is 66.5C.Great caution is required when filling any settling or other oil tank to prevent overflowing, especially in machinery spaces where exhaust pipes or other hot surfaces are directly belowParticular care should be taken when filling tanks which have their sounding pipes in the machinery space to ensure that weighted cocks are closed. Under no circumstances should a weighted cock on a fuel tank or lubricating oil tank sounding pipe or on a fuel, lubricating or hydraulic oil tank gauge be secured in the open position.All Main Engine high pressure pipes to be secure with no leakage. Fire has occurred, when the paint on a recently fitted Air Start Valve caught fire, and came in contact with a leaking Fuel Pump connection.

Precautions Against Fire And Explosion While Welding

Before welding, flamecutting or other hot work, a check should be made that there are no combustible solids, liquids or gases present or adjacent to the area of hot work. Welding or other hot work should never be undertaken on items covered with grease, oil or other flammable materials.

The vessel should have a permit to work system in force, this will include a “Hot Work Permit”, prior to starting any hot work on board, a responsible person is to complete and sign a “Hot Work Permit”, inspected and signed by the Master of the vessel. The permit is to be kept at hand at the place of work.

When welding is to be carried out in the vicinity of open hatches, suitable screens should be erected to prevent sparks dropping down the holds. Where necessary combustible materials and dunnage should be moved to a safe distance before commencing operations. Port holes and other openings through which sparks may fall should be closed where practicable.

Where work is being carried out close to or at bulkheads, decks or deckheads, the remote sides of the divisions should be checked for materials and substances which may ignite and for cables, pipelines or other services which may be affected by the heat. Particular attention should be taken when proposing to weld onto bulkheads or tank tops for temporary securing purposes. Familiarisation of the structure of the ship and the exact location of all fuel and ballast tanks is important in order that the aforementioned welding does not take place on fuel tank bulkheads. This is particularly relevant in respect of steel tank tops where there will inevitably be vapour on the lower side of the tank top.

Cargo, fuel tanks, cargo holds or other tanks should be certified as gas free before any repair work is commenced. The testing should include the testing of adjacent spaces, double bottoms, cofferdams, etc. Further tests should be carried out at regular intervals and before hot work is recommenced following any suspension of the work. When preparing tankers or similar ships, all tanks, cargo pumps and pipelines should be thoroughly cleaned with particular attention paid to the draining and cleaning of pipelines that cannot be directly flushed using the ships pumps.

Welding and burning operations should be properly supervised and kept under regular observation. Suitable fire extinguishers should be kept at hand ready for use during the welding operation. A second person should be standing by with a fire extinguisher in order to sight any potential fire hazard.



FirefightingDue to the risk of delayed fires due to the use of welding operations, appropriate and frequent checks should be made for at least two hours after the cessation of a major welding operation.

Relevant codes of safe working practice and company regulations should be adhered to.

ANYONE WHO HAS EXPERIENCED A MAJOR FIRE AT SEA WILL TELL YOU THAT ANY TIME OR EFFORT EXPENDED IN PREVENTING FIRE HAS BEEN WELL SPENT.

Fire Prevention And Precautions

Cleanliness, vigilance and common sense are the principal weapons with which to prevent fire.

Tank tops should be kept clean and well lighted, it is recommended that tank tops should be painted white so that any oil leakages from drip trays, pipes, joints, filters and valves may be detected easily and dealt with promptly. Bilges must be kept clean. Bilge pumps and strainers to be maintained in good order.

The testing of all fire and safety equipment to be logged in a critical equipment log.

All fire fighting appliances must be kept in good working order and tested regularly. Emergency pump and fan stops, collapsible bridge oil valves, watertight doors etc. should all be tested frequently and kept in good operative order. All fire detection devices should be regularly tested and any faults rectified. Not only is this good shipboard practice but it is necessary to ensure updating of the vessels Safety Certificate.

All engine room personnel should be fully aware of the recognised procedure for dealing with a fire aboard ship and should know the location and method of operating all fire fighting equipment.

What ever the cargo carried, reference should be made to the International Maritime Dangerous Goods Code or the International Chamber of Shipping regulations for oil, chemicals or gas cargo (the red, blue and green books) which will be carried onboard. Apparently harmless cargo may well present unexpected hazards and loss of life has resulted from cargo as mundane as scrap iron, grain and coal. Personnel should also be thoroughly familiar with the problems associated with any special cargo the vessel may be carrying e.g. LPG, LNG and chemicals.

Change over cocks and their safety devices associated with duplex filters in oil systems should be designed and maintained so as to ensure that the working filter cannot be opened up inadvertently.



Firefighting

Overflow Arrangements

The air vent and overflow pipes for all tanks should be arranged so that oil cannot overflow into a machinery space where there is a risk of fire. The overflow from one tank should be to another tank containing the same grade of oil, finally leading to an overflow tank. The air and overflow pipes from this tank should be led to the open deck and fitted with wire gauze diaphragms flame arrestor at the open ends. The overflow tank should be fitted with a level alarm which operates when the tank is about one quarter full. Air pipes from oil tanks should also be led to the open deck and fitted with wire gauze diaphragms flame arrestor at the open ends.

Drain pipes fitted to the oil tight flats should preferably be open pipes but readily accessible cocks would be acceptable and may be necessary if interflooding of separate watertight compartments could occur through the drains. The heights of coamings around such flats should be arranged so that a small adverse list would prevent effective drainage and cause an overflow. Regulations governing the above points are promulgated by flag state governments and Classification Societies. The vessel will have been built in accordance with these regulations and care should be taken that no modifications are made which could place the vessel out of Class.

Sounding Arrangements

Sounding Arrangements and oil level indicators should be of types which will not permit the escape of oil if they are damaged. Nor should oil escape if the tank is overfilled. The use of gauges which require the lower part of the tank to be pierced are not allowed in passenger vessel's and it is preferred that their use is also avoided on cargo ships. On the latter, neither round or flat gauge glasses should be used for fuel oil tanks. However, suitably protected gauges having flat glass of substantial thickness and self closing fittings at each tank connection may be fitted to lubricating oil tanks. (See note above regarding Class regulaThermometer Fitting

Where thermometers are required to measure the temperature in oil pipes etc. they should be placed in suitable permanent pockets as that damage to the thermometer or its removal does not allow oil to escape.

Due to the number of fires caused by the inadvertent opening or failure of vent plugs and cocks and failure of pressure gauge lines the elimination of these items should be considered whenever possible. When installation cannot be avoided they should be positioned so that they are clear of sources of ignition. Hydraulic power packs or other hydraulic machinery should not be located in spaces containing machinery which has a hot exhaust system or other heated surfaces which may ignite the hydraulic oil. tions.)

Oil Units, Pumps And Fittings

Oil units, pumps and fittings present the same hazards as pipes conveying oil and the following precautions should be taken:

1. Suitable screens should be erected to prevent any oil which might escape from any oil pump, filter or heater from coming into contact with boilers or other heated surfaces.



Firefighting2. Save-alls or gutters should be provided under the oil pumps, heaters or strainers to

catch any oil which may be spilled when any door or cover is removed. Similar arrangements should be made at the furnace fronts to intercept any oil which may escape from the burners. In the case of top fired boilers special care should be taken in arranging the save-alls and coamings to prevent the spread of any oil spillage.

3. Any relief valve fitted to prevent overpressure in the oil fuel heater should be in a closed circuit.

4. Master oil valves at the furnace fronts should be of the quick closing type and fitted in conspicuous and readily accessible positions. It is recommended that they are painted bright red to aid identification in an emergency.

5. Provision should be made to:

i. prevent the supply of oil to any burner unless it has been correctly coupled to the oil supply line and

ii. prevent the removal of the burner before the oil supply is shut off. 6. A suitable mounted plan of the oil piping arrangements should be provided for the

guidance of the engineers.

Much of the above relates to the vessel's construction and as such could be considered as outside the control of the ships staff, however it is the function of the ships staff to understand the importance of these items and to maintain them in working condition.

In many cases the ships main engine and auxiliary engine are supplied by a single fuel supply or booster pump. Thus if there is a leakage the watchkeeper from his position in the machinery control room must stop all machinery when attempting to stop further leakage on the defective machine. Although advice may be given that the best course of action may be to stop all machinery, there will be occasions when promptly stopping the machine on which the leak has developed and isolating its fuel supply will suffice. Therefore in multi engine installations supplied from the same fuel supply consideration should be given to fitting means of isolating the fuel supply to individual machines from the control room

Heated surfaces particularly the exhaust systems of main and auxiliary diesel engines should be effectively insulated so that the surface temperature is below the auto-ignition temperature of any oil which may come in contact. It should be noted that different grades of hydrocarbon fuel and lubricating oil have different auto ignition temperatures which can vary from 250C - 600C. This insulation should be provided with readily removable sections around joints, flanges and couplings to allow access for normal maintenance.

Electrical Cables

It is essential electrical cables must be carried in trays attached to the deckhead over the engines. Because of limited headroom in the machinery spaces special attention must be paid to the need to protect them from adjacent fires. The effect of any fire protection arrangements on cable ratings and heat dissipation requirements will have to be considered.



Firefighting

Operation

1. Several fires have been caused by pipe connections and fittings working loose. It is recommended that fuel, lubricating and hydraulic oil pipes, their fittings, connections and securing arrangements should be routinely checked at the same frequency as crankcase inspections of main and auxiliary engines. Care should be taken not to overtighten fittings during these checks.

2. When maintenance or repair to the main or auxiliary engines has been carried out a check should be made to ensure that the insulation covering the heated surfaces has been properly replaced. A regular check of the engines should be made to confirm that the insulation is in place.

3. Any fuel, lubricating or hydraulic oil leakages should be dealt with promptly. The double containment screening arrangements and pipe securing devices should be kept in good order.

4. It is essential to avoid the most dangerous situation in which a small fire could spread to waste oil in the bilges or on tank tops where it could rapidly spread out of control. Cleanliness is essential for safety and a high standard must be maintained.

5. No combustible material should be stored near any part of the oil installations. Bituminous or similar flammable compounds which give off noxious fumes on combustion should not be used in machinery and boiler spaces. Drums of lubricating oil, cleaning chemicals, detergents, etc, should not be stored in engine rooms.

6. When repairs, however temporary, are carried out to the oil lines special attention must be paid to fire risks. Reports have been received of the repair to oil pressure lines with plastic hose and "Jubilee" type clips. Such repairs place the vessel outside Classification and may reduce Underwriters liability. Although repairs using small lengths of piping inserted by means of compression type couplings may be justifiable in an emergency the general use of this method for permanent repairs is not recommended where high vibration levels are experienced. Subsequent failure of such repairs has led to fires causing fatality. All repairs should be adequate to prevent any danger of leakage and should be to a standard which would stand exposure to fire. If there is evidence that the failure was caused by work hardening of the pipe material the complete pipe should be replaced.

7. If fire breaks out then immediate alarm should be raised. It is impossible to offer advice to meet all circumstances but early decisions should be taken about the usefulness of remaining in the space or leaving to fight the fire remotely. Watchkeepers should try to isolate the cause and consider attempting to fight the fire. However if the fire is developing rapidly they should vacate the engine room quickly. Unless everyone is accounted for the use of the fixed fire fighting installation will be delayed. Time lost searching for missing persons may allow the fire to spread and endanger other lives.

8. All crew members and particularly those who work in machinery spaces should ensure that they are familiar with all means of escape including emergency exits which are not in normal day to day use, also the fixed fire fighting installation activation alarm.



Firefighting

Examples Of Incidents Which Have Caused Fire Onboard Ships

a. The auxiliary engines on a ship had just been started and the electrical load transferred from the shaft AC generators when the watchkeeper was alerted to a serious fuel leakage on one of the auxiliary engines when the second fuel supply pump started automatically.Whilst attempts were being made to start the standby auxiliary engine a serious fire broke out in the auxiliary engine room. Fortunately the fire was contained within the machinery spaces by prompt use of the fixed fire fighting installation, but the ship was disabled because of extensive damage to electrical equipment. The fire was caused by a fitting in the fuel return line to one of the auxiliary engines becoming loosened.

b. Whilst crew were boarding and the cargo was being loaded a fire suddenly broke out in the auxiliary engine room. The fire was extinguished using the ships fixed fire fighting installation but there was extensive damage to electrical equipment. Also, one of the engineer officers working in the space at the time had difficulty making his escape. The fire was caused by hydraulic oil spraying from a filter. Two of the set screws which retained the cover were found to be stripped, allowing the oil to escape.

c. A ship was completely disabled because of the fracture of a small bore copper pipe which transmitted the fuel pressure from the main engines to a pressure gauge in the machinery control room. The fire was contained within the machinery spaces by the use of the fixed fire fighting installation even though one third of the CO2 bottles failed to discharge. There was extensive damage to electrical equipment. The pipe had been repaired on a number of occasions, being shortened in the process resulting in the imposition of additional stresses on the remaining lengths.

d. A Ship was completely disabled when lubricating oil sprayed from the displaced cover of the filters on one engine on to the heated surface of the other. The watchkeepers shut down the engine on which the fire appeared not realising that the other engine was the cause of the fire. Even though the remaining engine stopped automatically when the lubricating oil pressure was lowered an electrically driven standby pump continued to run and feed lubricating oil to the fire until the lubricating oil drain tank was empty. Unfortunately the watchkeepers had difficulty escaping and the use of the fixed fire fighting installation was delayed but the fire was contained within the machinery spaces. The cover of the lubricating oil filter was displaced when two studs fractured. The filter had been subjected to frequent cleaning and considerable pressure variations due to the means of regulating the main engine lub oil pressure.



Firefighting

Unit 1 - Firefighting: Fire Prevention And Sources Of Ignition On Ships

QUESTIONS

1. Give some examples from your own experience of the ways in which carelessly carried out maintenance may cause a fire?

2. What are the safeguards against common causes of electrical fires?

3. What causes spontaneous combustion?

4. a) State where information can be obtained with regard to the safe carriage of hazardous substances as cargoes.

b) For a hazardous substance of your choice discuss EACH of the following:

i. Storage and transportii. Propertiesiii. Fire fighting techniquesiv. Medical effects and treatment after physical contact with the substance.(If

your ship does not carry a hazardous cargo then consider a substance on board which would be considered to be hazardous and answer the question accordingly.)

5. Describe an example on board your ship of a welding operation and explain in detail the precautions taken against fire and explosion.

6. Describe the fuel tank overflow arrangements on your vessel with particular reference to location and safety design features.



Firefighting

Inert Gas Generator

This was originally developed to supplement CO2 flooding systems. Since if a fire occurred on board a ship at sea and the fire was extinguished through using all the CO2 available and a further outbreak occurred then a backup was available.

In a compartment wherein there is an outbreak of fire the minimum percentage of oxygen in the atmosphere in the compartment which will allow combustion to proceed varies with different materials. Between 12 to 16 percent approximately. Hence if the oxygen content of the compartment can be reduced below 12 percent then insufficient oxygen would be present to allow combustion to continue. This reduction in oxygen content can be achieved by employing a generator which will supply inert gas which is heavier than air so displacing the atmosphere in the compartment.

The generator consists of a horizontally arranged brick lined furnace cylindrically shaped and surrounded by a water jacket. This is connected to a vertical combustion chamber in which water spray units and lessing rings (Cylinders of galvanised metal arranged to baffle the gas flow) are fitted. A water cooled diesel engine usually fitted alongside the generator drives a fuel pump, a constant volume air blower and an electric generator. The electric generator supplies current to an electric motor which in turn drives the cooling water pump. Motor and pump are usually situated at the forward end of the shaft tunnel. By fitting the cooling water pump in the tunnel and having it connected to the washdeck line this pump can also be used as an emergency fire pump. Cooling water for the gas generator can also be supplied by the ballast and general service pumps. The amount of water required is approx. 545 litres per hour for every 27.7 m3 of inert gas produced.

The oil fuel burner is initially lighted by means of high tension electrodes, the electrical supply being through a small transformer. A constant pressure regulator is fitted to the oil supply line to the burner along with a control valve.

A control panel for the gas generator incorporates a CO2 recorder, water and oil fuel alarms and pressure gauges. In the gas piping system leading from the combustion chamber condensate traps and drains are fitted.

The following is an approximate analysis of the as generated:Oxygen : 0-1 %Carbon monoxide : NilCarbon dioxide : 14-15%Nitrogen : 85%Remainder, unburnt hydrocarbons and oxides of Nitrogen.



Firefighting

Inert Gas Installation For Tankers

The following diagram shows a system of inert gas supply for the cargo tanks of an oil tanker. Gas from boiler uptakes passes through the pneumatically operated, remote controlled, high temperature valves. It then passes through a scrubber into which sea water is sprayed for cooling the gases to about 3.5c above water temperature and scrubbing out soot particles and most of the sulphur oxides. The gas then passes through a plastic demister which can be cleaned by back flushing.

After scrubbing the gas analyses would be about 13% carbon dioxide, 4% oxygen, 0.3% sulphur dioxide, remainder nitrogen and water vapour.

Two centrifugal blowers are provided, only one would normally be operated with the other being on standby.

The supply of cleaned dry inert gas at a pressure of 1.2-6.0 kn/m2 pressure is regulated by the automatically controlled bypass valve which is linked to the main supply valve. When the main valve starts to close the bypass begins to open.

The main purpose of the aforementioned system is to ensure that all cargo tanks are inert at all times i.e. during loading, discharging, ballasting and tank cleaning operations.



Firefighting

System Requirements For Classification Society

1. Sufficient gas can be obtained from main or auxiliary boiler to ensure effective inerting of the tanks in particular the rate of production must be at least 125% of the maximum rated capacity of the cargo pumps.

2. That the oxygen content of the gas does not exceed 5% by volume, thus automatic combustion control of the boilers becomes mandatory.

3. At least two blowers are fitted.

4. A scrubber is fitted.

5. The system must be fitted with an automatically closing valve in the inert gas line in case of water failure. Two non return devices must be fitted on the weather deck.

6. The system must be fitted with pressure-vacuum breaking device to operate at 0.235 bar pressure and 0.058 bar vacuum.

7. Audible and visible alarms are to operate

when the oxygen content of the gas supplied reaches 8% by volume. at high gas temperature. at low gas pressure. at loss of water pressure in the scrubber and/or deck seal. in case of power supply failure to the control system.

8. Blowers must stop automatically at high gas temperature and/or loss of water to the scrubber or deck seal.

9. Fixed or portable oxygen analysers must be provided.



Firefighting

Definitions

Fire And Explosion

Two of the greatest hazards on board any vessel is the possibility of FIRE and EXPLOSION.

Flammable

Means capable of being set on fire. A mixture which can be set on fire is a flammable mixture.

Flammable Limits

It is possible to have an air oil mixture containing so little or too much flammable vapour that it cannot burn. Mixtures which are within these limits are said to be in the "Flammable Range".

Flash Point

This is the temperature at which an oil, in a closed container will ignite when exposed to an ignition source.

Auto Ignition Point

This is the temperature at which an oil will ignite spontaneously without the introduction of an ignition source.

Flammable Range

From the following diagram it can be seen that there is a flammable range which at 21% oxygen has an upper limit of approx 10.5% air/oil vapour and a lower limit of approx 1%. Within these limits the vapour may ignite if supplied with a source of ignition.

As the level of oxygen is reduced the flammable range becomes narrower. Ignition can not take place when the oxygen content is reduced to about 10%. For this reason the cargo tanks of oil tankers are inerted, that is the atmosphere is filled with a gas containing low levels of oxygen to eliminate the possibility of ignition.



Firefighting

Fire

Fire can only occur if three conditions are present simultaneously:

1. Material has reached a sufficiently high temperature to produce vapour.2. A source of ignition is applied.3. There is sufficient oxygen to support combustion.

Explosion

Most substances expand when heated. Evaporation caused rapid expansion. Burning of the vapour causes heating and even greater expansion and if the expansion is confined, pressure may increase still further, RESULT - EXPLOSION.

Heat

The conditions required for fire and explosion may be represented by a triangle with the sides representing the 3 requirements of combustion - fuel - oxygen - heat. Providing all of these conditions remain the fire will continue to burn. If one of these conditions is removed the triangle will collapse and the fire will be extinguished.

Fire Fighting

The method of fighting fires is to remove one or more of the conditions supporting combustion: cooling - removing the source of fuel - removing the oxygen by smothering.



FirefightingClassification of fires

The new British Standard which now incorporates a European Standard, Classifies fires as being in four groups:

Class "A"

Fires involving solid materials of an organic nature, in which combustion normally takes place with the formation of glowing embers e.g. wood, paper, textiles, etc.

Class "B"

Fires involving liquids or liquefiable solids e.g. oil, paint, fat, grease, etc.

Class "C"

Fires involving gases e.g. propane, butane, etc.

Class "D"

Fires involving metals e.g. magnesium, sodium, titanium, etc.

It will be noted that these is no classification for "Electrical Fires" as such since these are only fires in materials where electricity is present. Such fires can thus be classified in any of the four definitions given.

However electrical fires require special mention due to increased frequency with which they are occurring at sea. Electrical demands are increasing with the further development of each new class of vessel, increasing the fire risk on much more heavily loaded cables and switchboards. When fighting electrical fires it is imperative that water based extinguishers are never used unless it can be fully ascertained that all electrical power has been removed. The Carbon Tetrachloride extinguisher used many years ago on electrical fires has now been superseded by the "Dry Powder" type. The CTCextinguisher type was found to release a toxic gas - "Phosgene" - when exposed to heat.



Firefighting

Fire Extinguishers (Foam)

A 9 litre portable foam extinguisher of the inverting type is shown in fig.1. The inner and outer containers are made of lead or zinc coated steel. The outer container being of riveted construction. Cap and nozzle are made of brass and the loosely fitting lead valve may be situated at the top of the inner container to provide a seal. The brass cap has a series of small radial holes drilled through it which communicate the inside of the extinguisher with the atmosphere when the cap is being unscrewed, hence these holes act as a vent if the nozzle is blocked. This type of extinguisher has now been largely superseded by the mechanical type foam extinguisher.

Some flag states stipulate specific colours for different extinguisher types. It is important that you are aware of the colour code for each ship you sail on.

The inner container is filled with a solution of Aluminium Sulphate and the annular space formed by the inner and outer containers is filled up to the level indicator with a solution of Sodium Bicarbonate and foam stabiliser. Proportions of solution approx. 1:3 inner and outer containers respectively.

Performance: 9 litre foam extinguisher generates approx. 72 litres of foam at a working pressure of 7 bar.

Fig 1. 9 Litre Portable Foam Fire Extinguisher

136-litre Foam Fire Extinguisher



FirefightingThis extinguisher is similar to the 9 litre unit apart from the screw down valve, hose and frame.

To operate, the hose is uncoiled, valve opened, stop pin removed and the extinguisher is pivoted until it rests on the crossbar. This causes the two solutions to mix and generate foam.

The performance figures are: Foam generated 1000 litres, working pressure 15 bar, testing pressure 25 bar, length of jet 18 metres and duration of discharge 15 minutes approximately.

Portable Mechanical Foam Fire Extinguisher

When the plunger is depressed it pierces the tin copper seal releasing CO2 which ruptures the plastic bag and forces out the liquid foam concentrate into the water, where rapid mixing takes place. The foam solution is then driven up the steel dip tube, through the hose to the nozzle. At this point it is aerated into good quality fire smothering air foam.

Performance: The 9 litre of solution produces approx. 72 litres of foam, length of jet approx. 7 metres, duration of discharge about 50 seconds and the body is pressure tested to 25 bar. This type of extinguisher can be rapidly re-loaded, all that is required is to fill the body with water to the required level, drop in a new charge container and replace head assembly.

Fig 3. Portable Mechanical Foam Fire Extinguisher



Firefighting

CO2 Portable Fire Extinguisher

A 4.5kg portable CO2 extinguisher is shown below. The body is made of solid drawn steel which is hydraulically tested to 227 bar and is coated internally and externally with zinc. The external surface being painted.

A solid brass pressing forms the head assembly and this is screwed into the neck of the steel bottle. The head assembly incorporates a lever-operated valve, copper dip tube, bursting disc and a discharge horn made of non conducting material that can be swivelled in one plane only into the desired position.

The extinguisher contains 4.5 kg of liquid CO2 at a pressure of 53 bar approx.

Operation of the extinguisher is carried out by removing the safety pin, then operating the valve lever. The liquid CO2 will pass into the discharge horn and emerge as a cloud of CO2 gas. The discharge results in some components becoming extremely cold.

Contact with Horn can cause severe burns.

The extinguisher has a range of 3-4 metres in still air, duration of discharge about 20 secs. and about 2.5 cub. met. of gas is produced.

Note: CO2 extinguishes by smothering but has very little cooling effect. The gas has the advantage that it can get into inaccessible places. The contents should be checked regularly by weighting.

Fig 4. CO2 Fire Extinguisher



FirefightingFire Extinguishers (Water)

Soda-Acid Type:

Riveted mild steel, lead coated internally and externally is used for the body of the extinguisher. A screwed brass neck ring is riveted to the top dome which incorporates plunger and acid bottle carrying cage. The head assembly joint is either acid resistant rubber or greased leather. The nozzle is made of brass and delivery tube with loose gauze filter generally copper.

The extinguisher contains 9 litres of Sodium Bicarbonate solution and the glass bottle contains Sulphuric Acid.

When the plunger is depressed the acid bottle breaks and the sulphuric acid mixes with the main solution producing CO2 the pressure builds up in the casing and drives the water solution out through the dip tube and nozzle.

It produces a jet length of 9 metres, working pressure 2.7 bar and duration of discharge 1.5 minutes.

CO2 Water Type:

In this case the CO2 used to discharge the extinguisher is contained within a pressure charged container and is released by bursting the disc. The CO2 then drives the water out through the dip tube and hose.

It produces a jet length of 10.6 metres and has a duration of discharge of approx. 60 seconds.

Dry Powder Fire Extinguisher

Dry powder acts to smother a fire in a similar way to a blanket. Owing to the great shielding properties of the powder cloud the operator can approach quite close to the fire.

The Sodium Bicarbonate powder will, due to the heat from the fire produce CO2 which should further assist in smothering the fire.

The body contains approx. 4.5 kg of dry powder, this powder charge is principally Sodium Bicarbonate with some Magnesium Stearate added to prevent the powder from caking. The CO2 bottle contains about 60mg of CO2.

When the plunger is depressed it pierces the CO2 bottle seal. CO2 then blows out the powder charge.

Range is about 3-4 metres and duration of discharge about 15 seconds.



FirefightingUnit 1 - Fire Fighting: Inert Gas And Extinguishers

QUESTIONS:

1. Sketch and describe an inert gas installation for an oil tanker and detail what safety features and alarms are fitted to the system.

2. Which fire fighting media would you use on the following types of fire, explain why you chose that particular media and detail the fire fighting procedure:

a. Small oil fire in the machinery space.b. Bedding fire in the accommodation.c. Galley fryer has been left switched on, the thermostat has failed and the oil

has burst into flames. 3. Sketch and describe the following portable fire extinguishers:

a. Portable foamb. Dry powder.

4. Define: Flammable limits



FirefightingCO2 Flooding System

CO2 cylinders are constructed from manganese steel and the working pressure in each cylinder is generally about 52 bar, although the pressure at any time is a function of temperature. The CO2 cylinders should be stored at a temperature less than 55°C. The sealing/bursting disc fitted in each cylinder is designed to rupture spontaneously at 177 bar and this pressure would be produced in the cylinder if the temperature of the contents reached approximately 63°C

CO2 gas is approximately one and a half times as dense as air the density at 1 bar and 21°C being 1.8 kg/m3 and this is the figure normally used to calculate the mass of CO2 required to flood any particular space.

The installation consists of a predetermined number of CO2 storage cylinders (30% of free gas of volume of engine room) or (40% of volume to 1 metre above engine room or boiler room which ever is the greater). The cylinder bank can be divided into two categories, slave and master cylinders. The master cylinders are manually operated by means of a pull handle installed within the control box in the engineers alleyway discharge of gas from master cylinders is routed by means of 15mm diameter HP piping to a CO2 operating ram. The piston of the ram is connected by stainless steel cable to the operating lever of each slave cylinder valve mechanism. Discharge of liquid CO2 is routed by way of flexible loop connections from the cylinders to a high pressure steel manifold incorporating a non-return valve at each inlet orifice. From the manifold CO2 is distributed by means of a fixed system of high pressure piping to discharge nozzles installed in strategic positions and specially designed to promote uniform discharge of gas without freezing of the nozzle apertures. The control box also contains a pull handle wire connected to an isolating valve which interrupts the main discharge to distribution piping. A premature release valve on the master cylinder manifold prevents accidental discharge of slave cylinders. The locked control box access door is fitted with a micro-switch which is actuated when the door is opened to sound alarm bells or klaxons.

CO2 cylinders should be recharged if there is a 10% weight loss. It is a requirement that 85% of CO2 gas must be released into machinery space within two minutes and since such systems are one shot systems it is essential that all skylights and ventilators are closed and fans stopped before the gas is released.

After CO2 flooding and fire extinguishing the machinery space must be well ventilated before entry, for damage survey/inspection, since CO2 gas is heavier than air there is a danger of gas pockets under plates, in corners and in any area in which air circulation may be difficult.



FirefightingBulk Carbon Dioxide System

A bulk CO2 fire extinguishing system consists essentially of one or more pressure tanks, refrigerating machinery and the appropriate network of pipes for distributing the gas around the machinery spaces.

The pressure vessels are normally arranged as cylindrical tanks fabricated to class 1 construction. Low temperature steels fully tested and stress relieved are used and the vessels are mounted on supports capable of withstanding collision shocks. The tank is heavily insulated and covered with metal cladding, the working temperature and pressure being - 20°c and 21 bar.

Internal cooling coils are connected to dual refrigerating units, the latter being controlled automatically by pressure switches. One unit is sufficient to deal with the heat ingress into the CO2 and is rated to operated for more than 18 hours per 24 hours when the ambient temperature is +38½C. The other unit is standby. Either water or air cooling, can be arranged. The duty from main to standby unit can be reversed to equalise running hours. The instrument panel contains tank contents gauge, pressure gauge and alarms to indicate high or low liquid level, high or low CO2 pressure and the refrigerator controls.

To ensure a dangerous high pressure condition does not exist if a serious refrigeration fault develops, pressure relief valves are fitted, discharging directly to atmosphere. The valves are mounted on a changeover valve and are set to discharge CO2 gas if the pressure in the vessel rises above the design pressure of 23.8 bar. Each valve in turn can be isolated for removal and periodic testing.



FirefightingThe vessels are fitted with a capacitance type continuous indicator, together with a standby liquid level indicator which ensures that the CO2 liquid level can always be checked approximately by opening the standby liquid level indicator valve which will flood the pipe to the same level as the pressure vessel. A frost line appears due to the low temperature of the liquid CO2. Closing the valve will cause the CO2 to vaporise back into the pressure vessel.

The filling and balance lines are normally run to the main deck port and starboard sides for hose connections to be made to a road tanker. The balance line is used to equalise pressure with the road tanker during the filling operation.

The liquid CO2 discharge is through a 150mm bore pipe fitted with an isolating valve but the quantity of CO2 discharged into the various spaces is controlled by timed opening of a discharge valve. A relief valve is fitted which will relieve excess pressure in the discharge pipe should the isolating valve be closed with liquid CO2 trapped in the discharge. Automatic or remote operation can be achieved by utilising CO2 gas pressure from the top of the tank as the operating medium.

Due to the considerably reduced amount of steel, the storage tank compared with cylinders gives and approximate 50% weight saving and because low pressure CO2 has a greater density than CO2 at ambient temperature, the volume it occupies is considerably less in terms of deck space. Also, low pressure CO2 usually costs considerably less than CO2 supplied in cylinders.

Apart from the incorporated alarm systems the tank and its instrument panel along with the refrigeration units should be examined regularly. Contents gauges should be checked to ensure no leakage has taken place since the last inspection. The tightness of the relief valves are usually checked by means of rubber balloons secured over the ends of waste pipes, any inflation of balloons telling its own story. Two sets of relief valves are fitted, the LP set at 24.1 bar and HP set at 26.5 bar. These valves are designed especially for use with CO2.

Automatic Sprinkler System

The sprinkler system is an automatic fire detecting, alarm and extinguishing system that is constantly 'on guard' to deal quickly and effectively with any out break of fire that may occur in accommodation or any other spaces.

Sprinkler heads are grouped into sections with not more than 150 heads per section and each section has an alarm system. Each sprinkler head is made up of a steel cage fitted with a water deflector, a quartzoid bulb, which contains a highly expansible liquid, is retained by the cage. The upper end of the bulb presses against a valve assembly which incorporates a soft metal seal.

When the quartzoid bulbs are manufactured, a small gas space is left inside the bulb so that if the bulb is subject to heat, the liquid expands and the gas space diminishes. This will generate pressure inside the bulb and the bulb will shatter once a predetermined temperature (and hence pressure) is reached. Generally the operating temperature range permitted for these bulbs is 68½C to 93½C but the upper limit of temperature can be increased. This would depend upon the position where the sprinkler head or heads are to be sited. Quartzoid bulbs are manufactured in different colours, the colour indicates the temperature rating for the bulb:e.g.: Rating colour: 68½C - Red; 80½C - Yellow; 93½C - Green.



FirefightingOnce the bulb is shattered the valve assembly falls permitting water to be discharged from the head, which strikes the deflector plate and sprays over a considerable area.

When a head comes into operation the non-return alarm valve for the section opens and water flows to the sprinkler head. This non-return valve also uncovers the small bore alarm pipe lead and water passes through this small bore alarm pipe to a rubber diaphragm. The water pressure acts upon the diaphragm and this operates a switch which causes a break in the continuously live circuit. Alarms, both visible and audible, fitted in engine room, bridge and crew space are then automatically operated.

Automatic Sprinkler System

Stop valves, A and B are locked open and if either of these valves are inadvertently closed a switch will be operated that brings the alarms into operation. The alarm system can be tested by opening valve C which allows a delivery of water similar to that of one sprinkler head to flow to drain.

An electrically operated pump with a direct suction to the sea comes into operation when the fresh water charge in the pressure tank has been used up. This is arranged to operate automatically through the pressure relay.

A hose connection is also provided so that water can be supplied to the system from shore when the vessel is in dry dock.



FirefightingHigh Pressure Water Spray System

This can be a completely separate system or it can be interconnected with the sprinkler system that is available for fire extinguishing in accommodation spaces (usually the latter).

The system incorporates an air vessel, fresh water pump and salt water pump all connected to piping which is let to sections, each section having its own shut-off valve and sprayer heads, which unlike the sprinkler system have no quartzoid bulbs or valves but are open.

With all section valves closed the system is full of fresh water under pressure from the compressed air in the air vessel. When a section valve is opened, water will be discharged immediately from the open sprayer heads in that section. Pressure drop in the system automatically starts the salt water pump which will continue to deliver water to the sprayers until the section valve is closed.

After use the system should be flushed out and recharged with clean fresh water.

The air vessel is incorporated into the system to prevent the pump cutting in if there is a slight leakage of water from the system.

To test: This should be carried out at weekly intervals: Open A, close B, open C; the pump should automatically start and discharge from A. This avoids having to refill the system with fresh water.

High Pressure Water Spray System



FirefightingEmergency Fire Pump

This independent pump with its own prime mover, generally a diesel engine with own low flash point fuel supply, must be situated outside of the engine room and connected into the fire main.

In the event of fire in the engine room and subsequent evacuation and sealing, the emergency fire pump must be started and the engine room isolating valve in the fire main closed.

The diagram shows a completely independent emergency fire pump system. The centrifugal fire pump and hydraulic motor would be completely submersible and irrespective of the height and draught of the vessel the pump would not require a priming device as it would be below the water level. Such an arrangement may also be used as a booster/priming device for a main fire pump situated on deck.

Emergency Fire Pump

Foam Compound Injection System

The diagram shows diagrammatically the compound injection system often found on tankers. Foam is drawn from the tank, air enters as the compound is drawn off as the atmospheric and compound valves are linked. Delivery of the compound is automatically to the regulator unit. The regulator controls the water to foam compound ratio for a wide range of foam spreaders. A fire pump delivers the solution to the foam monitors so that foam can reach any part of the deck, or be delivered to the engine room spreaders. After use the system must be thoroughly flushed and recharged.



FirefightingIn chemical foam installations the principal disadvantages is the deterioration of the chemicals and chemical solution, hence regular checking is necessary to ensure the system is at all times capable of effective operation. However, with the chemical foam system good quality uniform foam is capable of being produced.

With mechanical foam systems, storage and deterioration of the foam compound presents no difficulty, which is one of the reasons why this particular type of system is generally preferable.

High Expansion Foam System

This recently introduced foam system has been recognised by the DTp as an alternative fire extinguishing medium for boiler and engine room compartments.

The generators are large scale bubble blowers which are connected by large section trunking to the compartments.

High Expansion Foam System

A 1.5m long, 1m square generator could produce about 15 m3/min of foam which would completely fill the average engine room in about 15 minutes. One litre of synthetic detergent foam concentrate combines with 30 to 60 litres of water (supplied from the sea) to give 30,000 to 60,000 litres of foam.



Firefighting

Advantages:

(1) Economic(2) Can be rapidly produced(3) Could be used with existing ventilation system(4) Personnel can actually walk through the foam with little ill effect.

Disadvantages:

(1) Persistent, could take up to 48 hours to die down in an enclosed compartment(2) Large trunking required(3) Should be trunked to bottom of compartment to stop convection currents carrying it away.

Foam Spreading Installations

When fitted, permanently piped foam spreading installation, operated external to boiler or machinery space, which supply foam to boiler and/or engine room tank tops, must have sufficient capacity to give a depth of foam of a least 152mm over the whole tank top.

Fire Patrols

These are not normally carried out on a regular basis upon most vessels but they should be conducted (1) immediately prior to, or upon sailing. A thorough inspection of the vessel being made especially in hold compartments, stores, engine and boiler rooms, etc. (2) when the



Firefightingvessel has been vacated by shipyard personnel whilst the vessel is in port undergoing repair. Someone may have been using oxy-acetylene burning or welding equipment on one side of a bulkhead totally unaware that the beginnings of a fire were being created on the other side of the bulkhead.

Every one on board should, in addition to looking for fire, assess and correct any possible dangerous situations, e.g. loose oil or paint drums, incorrectly stored chemicals, etc.

Fire Alarm Circuits

These consist of an alarm panel, situated outside of the machinery spaces, which gives indication of the fire zone. Zone circuits, audible alarms and auxiliary power supply

Circuits

When the contacts in a detector head close (open under normal conditions) they short the circuit and cause operation of the audible fire alarm. The lines in the circuit and cause operation of the audible fire alarm. The lines in the circuit are continuously monitored through 1 to 2 and 3 to 4, hence any fault which develops, e.g. damaged insulation, break in the cable, causes the system failure alarm to sound.

Fire Alarm Circuit



Firefighting

Power Failure

In the event of failure of mains supply power, automatic auxiliary power is supplied from fully charged stand-by batteries for up to 6 hours. Most systems operate on 24V, DC, however, for those operating at mains supply of 22V, Ac an inverter converts the 24V, DC to 220V, AC.

Audible Alarms

The fiFire Detector Heads

Various types are available for fitting into an alarm circuit. Choice is dependent upon fire risk, position, area to be covered, volume and height of compartment, atmosphere in the space, etc. To economise and simplify, standard bases are generally used in the circuit into which different types of detectors can be fitted.

Heat Sensors

These may be fixed temperature detectors, rate of rise detectors or a combination. Rate of rise detectors do not respond and give alarm if the temperature gradually increases, e.g. moving into tropical regions or heating switched on.

Fire Detectors

re alarm is usually an intermittent audible signal whereas, fault and manual test are normally a continuous audible signal.



FirefightingBi-metal Coil type:Two bi-metal coils attached to a vertical support bracket are encased in a protective metal cap. When the temperature increases, A will move to close gap C at a faster rate than B moves to maintain the gap. This is due to B being better insulated from the heat than A. If the rate of rise of temperature is sufficient, gap C will be closed and alarm given. At a predetermined temperature, gap D, then gap C will be closed, giving alarm.

Quartzoid bulbs of the type fitted into a sprinkler system are fixed temperature detectors used for spaces other than engine and boiler rooms.

Ionisation Type Detectors

If the potential is low not all the ionised particles reach the electrodes, some will combine with electrons and thus be neutralised.

When the potential reaches a predetermined value all the ions formed reach the electrodes giving saturation. Beyond this, the current will remain approximately constant irrespective of any further increase in potential. In this way the reference chamber has a constant resistance.

If combustion particles, visible or invisible, pass through the open detecting chamber the current will drop since the combustion products are made of larger and heavier particles than normal gas molecules. When ionised, the particles are less mobile than ionised air particles and because of increased bulk and lack of mobility, can readily combine with particles of opposite charge and hence be neutralised. The effect is to greatly increase the resistance of the detecting chamber, this change in resistance produces a substantial change in the potential at the centre point B.

Normal voltage A to C is 220, A to B 130 Volts, B to C 90 Volts. When voltage shift, due to increasing resistance in the detecting chamber, reaches 1 Volt across BC this is sufficient to trigger a discharge in the valve from 2 to 3, the capacitor then unloads itself across 2 to 3



Firefightingencouraging a discharge from 1 to 3, by-passing the chamber and causing heavy current flow through the alarm relay and the alarm to sound.

It can be tested by cigarette smoke or the use of butane gas delivered from an aerosol container. It is a very sensitive fire alarm and a time delay circuit may be incorporated to minimise the incidence of false alarms.

Smoke Detector - Light Scatter

Relevant Points

Smoke may be present without much heat or any flame, hence this detector could give early warning of fire. Photo-cells and light sources are vulnerable to vibration and dirt. Testing can be done with smoke from a cigarette.

The light obscuration type is used in oil mist detectors for diesel engine crank case protection and the obscuration/scatter type is to be found in the detecting cabinet of the carbon dioxide flooding system.

Standard Bases

The standard bases shown in the diagrams for the various detector heads have a neon light incorporated which flashes to indicate which detector head has operated. Detector heads can be simply unplugged from the base and tested in a portable test unit which has an adjustable time delay, audible alarm and battery.



FirefightingCombustion Gas Detector

A circuit diagram of a combustion gas detector is shown . Two ionisation chambers connected in series contain some radioactive material which emits a continuous supply of ionising particles.

The detecting chamber is open, the reference chamber closed and operating at a constant current since it contains air which is being ionised and the applied potential ensures that saturation point is passed. Current strength is dependent upon the applied

Relevant Points

Sensitivity: a typical response curve for a rate of rise detector is shown in Fig.3. The greater the heat release rate from the fire the poorer the ventilation and the more confined the space, the quicker will be the response of the detector and the sooner an alarm sounds. Fixed temperature setting depends upon whether the detector is in accommodation or machinery spaces and can vary from 55½C to 70½C. The detector is useful for dusty atmospheres as it is completely sealed but it does not give as early a warning of fire as other types of detectors. It can be tested by a portable electric hot air blower or muff.

Infrared Flame Detector

Flame has a characteristic flicker frequency of about 25 Hz and use is made of this fact to trigger an alarm. Flickering radiation from flames reaches the detector lens/filter unit, which only allows infra-red rays to pass and be focused upon the cell. The signal from the cell goes into the selective amplified, which is tuned to 25 Hz, then into a time delay unit (to minimise incidence of false alarms, fire has to be present for a predetermined period), trigger and alarm circuits.



FirefightingRelevant Points

Very early warning of fire is possible, with this type of detector which makes it suitable for areas where fire risk is high, that is machinery spaces. It should not be used in boiler rooms where naked flame torches are to be used for igniting oil. Reflected radiation can be a problem in boiler rooms as can flickering fluorescent lights. Obscuration by smoke renders it inoperative. It can be tested by means of a naked flame.

Photo-Electric Cell Smoke Detectors

Three types are in use, those that operate by light scatter, those that operate by light obscuration and a type which combines scatter and obscuration.

Light Scatter Type

A photo-cell separated by a barrier from a semi-conductor intermittently flashing light source is housed in an enclosure whose containment allows smoke but not light inside. When smoke is present in the container, light is scattered around the barrier on to the photo-cell and an alarm is triggered.



Firefighting

Unit 1 - Fire Fighting: CO2, Sprinkler Systems And Detection

QUESTIONS:

1. What are the advantages and disadvantages of each of the following fixed fire fighting systems:

a. Carbon Dioxide flooding systemb. Water spray systemsc. High expansion foam system

2. Describe with the aid of sketches the fixed fire fighting system for the machinery spaces on board your vessel.

3. Describe the type, location and operation of the emergency fire pump installed on your vessel. Explain how the aforementioned pump fulfils the Classification requirements.

4. Write a short note on each of the following fire detection methods:

a. Fire patrolsb. Heat sensorsc. Infra red flame sensorsd. Photo-electric smoke detectors.

5. Explain how the aforementioned detectors are tested in situ.



Firefighting

Classification Regulations For Fire Fighting

All ships are classified according to type of vessel and nature of voyage. There are several different classes from small yachts on short coastal voyages up to large foreign going passenger ships. Two classes are considered in the following notes for guidance. It is important that you identify which Class of vessel you are sailing on.

Class 1 Ships

These are Passenger ships engaged on long international voyages and registered in Britain. The survey of its fire appliances forms part of the general survey of the vessel for purposes of its passenger certificate, which is valid for one year.

Note: - A "Passenger" ship is defined as, "a vessel which can carry more than twelve fare-paying passengers".

Class 7 Ships

These are Cargo vessels engaged on long international voyages and registered in Britain. The survey of its fire fighting equipment forms part of the general survey of all life saving, and other appliances, for purposes of its safety certificate, which is valid for periods up to two years.

Regulations For Class 1 Ships

1. Fire Patrol, Alarm and Detection

An efficient patrol must be maintained at all times so that outbreak of fire can be quickly detected and manual fire alarms operated to give immediate alarm to the navigating bridge or fire control station.

A Fire detection system incorporating an automatic alarm must be fitted so that those parts which are inaccessible to the patrol can be protected at all times.

2. Fire Pumps, fire main, water service pipes, hydrants, hoses and nozzles

(a) Appliances must be provided so that at least two powerful jets of water can be rapidly and simultaneously directed into any part of the ship normally accessible to the Passengers or Crew while the ship is being navigated and any store room and any part of any cargo space when empty.

(b) Every ship of 4000 tons or over must have at least three power operated fire pumps and every ship under 4000 tons must have at least two such pumps, to supply the required jets of water. Each such pump shall be capable of delivering at least one jet simultaneously from each of any tow hydrants, hoses and nozzles.

The total capacity of these pumps (excluding any emergency fire pump), must not be less than ⅔ of the capacity of the pumps provided for bilge pumping.



FirefightingThe capacity of each pump must not be less than 80 per cent of the total capacity divided by the number of pumps.

The pumps must be operated by means other than the main engines, and they may be "dual purpose", i.e. used also for sanitary, ballast, bilge or general service, provided they are not normally used for pumping oil. Any centrifugal pump connected to the fire main must be fitted with a non-return valve.

(c) In vessels of 1000 tons or over, the arrangement of the sea connections, pumps and the sources of power for operating them, must be such that a fire occurring in any one compartment will not put all the fire pumps out of action.

In vessels below 1000 tons, if a fire in any one compartment could put all the fire pumps out of action, then an independently driven power operated emergency fire pump must be provided in a position outside the machinery space. It must have its own power source and sea connection and be capable of producing at least two jets of water from any two, hydrants, hoses and nozzles, while maintaining a pressure of at least 30 psi at any hydrant in the ship.

(d) The diameters, of the fire main and the service pipes supplying the hydrants, must be sufficient to effectively distribute the maximum discharge:(1) from the two pumps in the case of vessels below 4000 tons(2) from the two largest pumps in the case of vessels of 4000 tons or over.

(e) When the pumps are discharging the required quantity of water through adjacent hydrants, in any part of the ship, the minimum pressure any hydrant must be:45 psi in vessels of 4000 tons or over40 psi in vessels between 1000 tons and 4000 tons35 psi in vessels under 1000 tons.

(f) All ships of class 1 fitted with oil fired boilers or internal combustion main machinery must have in each boiler or engine room, at least two hydrants, one port the other starboard. A shaft tunnel which provides access to the machinery space must also have a hydrant fitted close to the access point. Nozzles suitable for creating water spray or "fog" must be provided for every fire hose at each hydrant fitted in such spaces.

(g) The pumps, firemain, service pipes, hydrants, hose and nozzles must be so arranged that the closing of all watertight and other doors in bulkheads does not affect the supply of water or its pressure.

(h) The fire main must have no other connections than those for fire fighting and washing down. It must not be constructed from any materials easily made ineffective by heat, nor, of cast iron. If the fire main is constructed of iron or steel it must be galvanized. The system must be capable of being drained to avoid damage by freezing.

(i) Fire hoses must not exceed 60 ft in length in vessels whose moulded breadth is less than 90 ft. The length must not exceed 90 ft where the moulded breadth is 90 ft or more.

The hose must be made of closely woven flax canvas or other suitable material, provided with all necessary fittings and couplings including a plain nozzle, in addition to any spray nozzle. The diameter of the plain nozzle need not be greater than ¾ inch for machinery



Firefightingspaces and other exterior spaces, except for accommodation and service spaced where it need not be greater than ½ inch.

(j) Every ship of 1000 tons or over, must carry at least one "international" connection which will allow water to be supplied to the ships fire main from another ship or from the shore. Permanent provision must be made to enable the connection to be used on the port or starboard side of the ship.

3. Accommodation and service spaces

Sufficient portable fire extinguishers must be provided so that at least two of these will be readily available for use in every accommodation and service space between watertight bulkheads.

In enclosed accommodation and service spaces above the bulkhead deck at least one portable extinguisher must be provided on each side of the ship.

At least one portable fire extinguisher and an asbestos blanket must be provided for every galley, and where the superficial deck area of the galley exceeds 500 sq. fit. two such extinguishers and blankets must be provided.

At least one portable extinguisher must be provided at each fire control station.

4. Cargo Spaces

Every Ship over tons must have a fixed fire smothering gas installation which must be so arranged that protection is provided in every cargo space.

5. Machinery spaces containing oil fired boilers or oil burning equipment

(a) Any space, which contains any oil fired boiler, oil fuel settling tank, or oil fuel unit, must be protected by at least one of the following fixed fire extinguishing installations:(i) a pressure water spraying system(ii) a smothering gas installation(iii) a foam system.Note: The combined engine and boiler room spaces must be regarded as a single space if they are not completely separated from each other by a bulkhead or if fuel oil can drain from one space to the other.

In addition to the requirement of paragraph (a), there must be provided:

(1) In each boiler room one or more foam fire extinguishers each of at least 30 gallons capacity or carbon dioxide extinguishers each of at least 100 lb capacity. These extinguishers must be sited so as to be readily accessible in case of fire and they must be sufficient in number to enable foam or CO2 to be directed on to any part of the boiler room and spaces containing any part of the oil fuel installation.

(2) In each firing space and in each space which contains any part of any oil fuel installation at least two portable fire extinguishers suitable for extinguishing oil fires.



Firefighting(3) In each firing space a receptacle containing at least 10 cubic feet of sand or other dry material suitable for quenching oil fires, together with a scoop for its distribution, oralternatively an additional portable fire extinguisher suitable for extinguishing oil fires.

6. Machinery spaces containing internal combustion type machinery

(a) Any space containing internal combustion type machinery, for main propulsion, or having an aggregate total power or not less than 1000 BHP for auxiliary purposes, must have at least one of the fixed fire fighting systems as required in section 5 Para (a).

(b) In addition to the requirement of Para (a), there must be provided in any such space:1. One foam fire extinguisher of at least 10 gallons capacity or a CO2 extinguisher of at least 35 lb capacity.2. One portable fire extinguisher suitable for extinguishing oil fires for each 1000 BHP or part thereof of such machinery but in no event less than two and they need not exceed six.

7. Machinery spaces containing steam engines

(a) Any space containing steam turbines or enclosed pressure lubricated steam reciprocating engines, used either for main propulsion or having an aggregate total power of not less than 1000 BHP for auxiliary purposes, must have provided:

1. Foam fire extinguishers each of at least 35lb capacity sited and of sufficient number so that foam or CO2 can be directed on to any part of the pressure lubrication system and on to any part of the casings which enclose pressure lubricated parts of the turbine, engines or gearing provided that such extinguishers shall not be required if equivalent protection is provided in such spaces by a fixed fire fighting installation in accordance with section 5 Para (a) or section 6 Para (a).

2. One portable fire extinguisher for each 1000 BHP or part thereof of such machinery, suitable for extinguishing oil fires but in no event less than two and they need not exceed six provided that such extinguishers shall not be additional to appliances carried in accordance with section 6 Para (b) 1, 2.

8. Firemen's Outfits

(a) One fireman's outfit must be carried for each 100 ft (or part 100 ft) of registered length of ship but in no case must there be less than two such outfits. The outfits must be kept in widely separated positions where they are easily reached and not exposed unduly to fire risk. Each outfit must consist of:

(1) A safety lamp: This is a gas tight lamp operated by an electric battery with minimum life of three hours.(2) A breathing apparatus: This can be a self-contained compressed air set or a smoke helmet or mark of the "air hose" type.(3) A fireman's axe.

Note: At least two of the outfits carried must include breathing apparatus of the air hose type.

(b) A breathing apparatus of the "air hose" type must use an air pump or bellows to supply air from the outside atmosphere. The hose must be non-collapsible and of sufficient length to enable the air pump or bellows to be on the open deck in clean air well clear of hatches or



Firefightingdoorways while the wearer of the helmet or mask is in any part of the accommodation. Efficient coupling must be provided if two or more lengths of hose have to be used.

The air inlet to the pump or bellows must not be able to be obstructed.

Note: No vessel is permitted to carry only breathing apparatus of the air hose type if it would be necessary to use an air supply hose exceeding 120 ft at least two self contained compressed air sets must be carried in addition.

(c) Self contained breathing apparatus must be of the open circuit compressed air type.

The storage capacity of the compressed air cylinder or cylinders attached to the apparatus and carried by the wearer must be at least 1200 litres (42 cu ft) of free air.

The cylinders must be constructed of suitable material which will withstand (with an adequate safety factor) any internal air pressure to which it may be subjected and also a hydraulic test pressure of a value in excess of the maximum working pressure.

Automatic regulation of the air supply from the cylinder to the wearer must be provided according to breathing requirements and should be able to deal with any volume of free air up to 85 litres (3 cu ft) per minute at any time when the pressure in the cylinder is over 150 psi. A bye-pass valve must be provided which can over-ride the automatic air supply valve. A pressure gauge must be fitted into the high pressure side of the system to enable the wearer to see directly and easily the internal pressure of the supply cylinder. The gauge must incorporate an anti-bursting orifice. An audible warning device must be fitted to indicate to the wearer when 80 per cent of the usable capacity of the apparatus has been consumed. The maximum weight of any such apparatus must not be more than 35 lb excluding any lifeline, safety belt or harness.

Fully charged spare cylinders must be provided so that each set has a reserve capacity of at least 2400 litres (84 cu ft) except that:

1. If the ship is carrying 5 or more sets, the reserve capacity need not exceed 9.600 litres (336 cu.ft.)or

2. If the ship has means for recharging air cylinders to full pressure with air free from contamination, the storage capacity of fully charged spare cylinders of each set shall be at least 1200 litres (42 cu ft) of free air. They need not exceed 4800 litres (168 cu ft).

(d) Every breathing apparatus must be clearly marked with the name of the manufacturer and the operating instructions. A servicing and instruction manual must be kept with each set.

(e) The materials from which the breathing apparatus is constructed must possess adequate mechanical strength, durability and resistance to deterioration by heat or by contact with water and be resistant to shrinkage. Metal parts of the apparatus, harness or other fittings, which are exposed, should as far as is practicable, be resistant to frictional sparking.

The breathing circuit must not be able to be penetrated by smoke or chemical fumes.

(f) Each set of breathing apparatus must be provided with:



Firefighting(i)A fire proof life and signalling line which is at least 100 ft longer than is required to reach to any part of the accommodation, service spaces, cargo or machinery spaces from a position on the open deck in clean air. Its breaking strength must be at least 1120 lb and must be overlaid with hemp or other covering to provide a firm grip even when wet.

(ii)An adjustable safety belt or harness to which the life line can be securely attached by means of a snap hook.

(iii)Plates of non-inflammable material bearing a clearly legible code of signals to be used between the user and his assistant. One must be attached to the harness, the other to the free end of the line.

(iv)A lightweight safety helmet with a lining and adjustable headband (for all apparatus other than a smoke helmet).

Regulations For Class 7 Ships Of 500 Tons Or Over

1. Fire Patrol

A Patrol is not specifically required, bur, an efficient fire "watch" must be maintained at all times.

2. Fire pumps, fire main, water service pipes, hydrants, hoses and nozzles

(a) Two jets of water as in class 1 ships.

(b) Ships of 1000 tons or over must have at least two fire pumps operated by power and each such pump must be capable of delivering at least one jet from each of any two fire hydrants, hoses and nozzles.

Ships of 500 tons or over but under 1000 tons must have at least two fire pumps operated by power and each such pump must be capable of delivering at least one jet from any fire hydrant, hose and nozzle. The total capacity of these pumps (excluding any emergency fire pump) must not be less than that given by:

tons of water per hour = Cd2

where C = 5 for vessels with more than one pump (excluding any emergency pump)or C = 2.5 for vessels with one pumpand d = 1 + L (b + D)2,500where L = length of ship in feet at summer load lineB = greatest moulded breadths of ship in feetD = moulded depths of the ships in feet, measured to the bulkhead deck amidships.Provided that in any ship the total capacity need not exceed 180 tons per hour.

Note: The value of d is calculated to the nearest ¼.

The capacity of any pump must not be less than 80 per cent of the total capacity divided by the number of pumps. The pumps must be operated by means other than the main engine and they may be "dual purpose", provided they are not normally used for pumping oil. Centrifugal pumps connected to the fire main must be fitted with a non-return valve.



Firefighting(c) If a fire in any one compartment could put all the fire pumps out of action, there must be, in a position outside the machinery spaces, an independently driven, power operated emergency fire pump with its own source of power and its connection to the sea, provided that in any vessel under 1000 tons, this emergency pump may be manually operated.

In vessels of 1000 tons or over the emergency fire pump must be capable of producing at least two jets of water from any of the hydrants, hoses and nozzles and simultaneously maintain a pressure of at least 30 psi at any hydrant in the ship.

In vessels over 500 tons but under 1000 tons the emergency fire pump must be able to produce from any of the hydrants and hoses, a jet of water from a nozzle and the jet must have a "throw" of not less than 40 ft.

(d) The diameters of the fire main and the service pipes supplying the hydrants must be sufficient to effectively distribute the maximum discharge:(1) from that pump, where only one is required,(2) from both pumps operating simultaneously where two are required.

Provided that the diameters of fire main and service pipes need not exceed that required for a discharge of 140 tons per hour.

(e) When the pumps are discharging the required quantity of water through adjacent hydrants in any part of the ship, the minimum pressure at any hydrant must be:40 psi in vessels of 6000 tons or over,37 psi in vessels between 1000 tons and 6000 tons and30 psi in vessels under 1000 tons.

(f) Hydrants, hoses and "fog" nozzles must be provided for boiler rooms, engine room and tunnel access, as in Class 1 Ships.

(g) No specific regulation is given regarding the closing of bulkhead doors and its effect on water supply and pressure because, in general, cargo vessels have no need for access through watertight bulkheads.

(h) Materials etc., for the fire main, as for Class 1 Ships.

(i) All ships of 1000 tons or over must have, in addition to any hoses provided, for the machinery spaces, at least one fire hose for each 100 ft of the ship's length, but in no case must they be less than five and they must have a total length of at least 60% of the ship's length. In addition to these hoses, there must be one spare hose.

Ships between 500 and 1000 tons must have at least two fire hoses having a total length of at least 60 per cent of the ship's length, plus one spare hose (and these must be in addition to any hoses provided for the machinery spaces).

The materials for hoses and nozzles, as for Class l Ships.

3. Accommodation and Service Spaces

Sufficient portable fire extinguishers must be carried to ensure that at least one such extinguisher will be available for use in any part of the accommodation or service spaces.



FirefightingThe number of such extinguishers must not be less than 5 vessels of 1000 tons or over and must not be less than 3 in ships between 500 and 1000 tons.

4. Cargo Spaces

Every ship of 2000 tons or over must have a fixed fire smothering gas installation, which must be so arranged that protection is provided in every cargo space.

Steam smothering may be used instead of fire smothering gas if the system conforms to the regulations governing fixed installations and providing the compartments in which steam smothering is to be used, do not contain "dangerous goods" such as explosive or reactive chemicals.

In those instances when "dangerous goods" are carried, the compartments containing them and every adjacent compartment must have, either, a fire detection system which will automatically indicate the increase of temperature, or, a smoke detection system with automatic detection of smoke.

In any tanker a fixed foam installation may be used instead of fire smothering gas, provided that the foam can discharge externally and through suitable mobile sprayers internally to the liquid cargo tanks.

Any ship, other than a tanker, may be exempted from the requirements for a fixed fire fighting installation, if,(a) the holds are provided with steel hatch covers and there is effective means of closing all ventilators and other openings leading to the holds,or(b) the ship is constructed for, and solely engaged in, the transport of ore, coal or grain.

5. Machinery Spaces Containing Oil-Fired Boilers or Oil Burning Equipment

(a) A fixed fire fighting installation as in Class 1 Ships.Note: Class 7 Ships over 500 tons but under 1000 tons are permitted to use a steam smothering installation as an alternative to the systems specified in Para (a).

(b) In addition to the requirements of Para (a) there must be provided:

1. In each boiler room one foam fire extinguisher of at least 10 gallons capacity, or a carbon dioxide extinguisher of at least 35 lb capacity, if the number of burners is five or more. If the number of burners is less than five, there must be one portable fire extinguisher, suitable for fighting oil fires, provided for each burner.

2. In each firing space, and in each space which contains any part of any oil fuel installation, there must be at least two portable fire extinguishers suitable for fighting oil fires, in addition to any carried in compliance with Para (6)(1).

3. In each firing space a receptacle containing 10 cu ft. in ships over 1000 tons, or 5 cu ft in vessels over 500 tons, of sand or other dry material suitable for fighting oil fires, with a scoop for its distribution, or, alternatively an additional portable fire extinguisher suitable for fighting oil fires.



Firefighting4.If, in any ship between 500 and 1000 tons a fixed steam smothering installation is fitted in accordance with Para (a) and the steam is supplied by water tube boilers, there must be provided an additional foam fire extinguisher of at least 30 gallons capacity (or a carbon dioxide extinguisher of at least 100 lb capacity), for the protection of the boiler room and the spaces containing the oil fuel installation.

6. Machinery Spaces Containing Internal Combustion Type Machinery

(a) Fixed installation must be provided as in Class 1 Ships.Note: Class 7 Ships over 500 tons but under 1000 tons are permitted to use steam smothering as analternative.

(b) In addition to the requirements of Para (a), there must be provided in any such space:(1) Non-portable foam (or CO2) as in Class 1 Ships(2) Portable extinguishers as in Class 1 Ships.

7. Machinery Spaces Containing Steam Engines

Para (a) (1) and (2): Protection provided as in Class 1 Ships.

8. Firemen's Outfits

(a) Firemen's outfits must be carried in accordance with the following scale:500 tons but under 2500 tons - 1 outfit2500 tons but under 5000 tons - 2 outfits4000 tons and over - 3 outfits.

The outfits must consist of safety lamp, breathing apparatus and axe, as in Class 1 Ships and at least one outfit carried in any ship must include a breathing apparatus of the air hose type.

(b), (c), (d), (e) and (f) as for Class 1 Ships.

Fire Precautions In Tankers

1. Airpipes from tanks to masthead, with flame arrestor gauze in end of pipe2. Care must be taken to prevent sparking at funnel

3. No smoking on deck

4. Tank cleaning gear of special materials to avoid sparks

5. Bronze tools for working on tanks and fittings

6. Only torches and hand lamps of approved patterns may be carried on board

7. Electric cables must be armoured near tanks

8. Fuses of special safety type



Firefighting9. Lamp fittings of safety pattern, no unnecessary wiring in pump room

10. When pumping cargo, centrifugal pumps must be stopped as soon as they cease to discharge

11. Power to pumps often supplied by means of shafts through bulkhead

12. Earth connection fitted with charging or discharging

13. Steam smothering connections fitted in all tanks and pump rooms

14. Provision made for the safe venting and cleaning of tanks.

Fire Fighting In Port

Chief Causes

1. Gas cutting and gas and electric welding 2. Smoking 3. Electrical faults

Precautions to be Observed

1. Decks and wharves to be kept clear 2. Hydrants should be protected from frost and their position known 3. All doors, ports, hatches, etc., to be kept closed where possible 4. Inflammable material aboard should be kept to a minimum (timber, paint, cork, etc) 5. The shore Fire Brigade should be warned of any special risks 6. All parts of passenger ships should be patrolled every hour and a check made on

patrols who should operate from a control centre 7. Burning and welding operations should be performed with great care. Check:

i. other side of bulkhead ii. fall of sparks iii. storage of gas bottles iv. all sites after work has been completed (also the patrol should be warned of

possible danger). 8. Temporary electrical wiring should:

i. be removed as soon as possible ii. not be overloaded iii. be protected against chaffing

9. Unofficial radiators and boilers should not be permitted 10. Smoking rules must be observed (usually during meals only and in safe places) 11. Portable rivet forges should be provided with steel plates and ash boxes 12. Alarm systems to be maintained (gongs, klaxons, telephones, etc) 13. At least two gangways 14. All fire-fighting gear to be kept in ready condition if possible, if not, temporary mains

or hoses from shore hydrants 15. Wire ropes laid out bow and stern for moving ships. 16. Vessels which carry flammable cargos: No hot work during cargo operations. Any

other times, as allowed by the terminal.



FirefightingResponsibility

In the case of new ships under construction, the responsibility for all fire precautions rests with the shipbuilder.

In other cases the responsibility, unless delegated, remains with the shipowner. For this reason it is advisable to see if a written agreement can be prepared, stating the degree to which each party is responsible in case of fire. The agreement should include a clause stating who accepts the responsibility for cessation of pumping when stability of the ship is endangered, although this responsibility usually falls on the senior fire brigade officer present.

Unit 1 - Fire Fighting: Classification Regulations

QUESTIONS

1. With reference to a water sprinkler fixed fire fighting system suitable for accommodation spaces:(a) Sketch such a system and explain its method of operation(b) Discuss the advantages and disadvantages of such a system.

2. (a) Sketch a bulk Carbon Dioxide fixed fire fighting system suitable for machinery spaces and for the cargo spaces of a dry cargo ship.(b) i) Describe the system you have sketched and its method of operation ii) State the advantage this system has over the multi-bottle Carbon Dioxide system.

3. (a) Compile a list of various means by which explosive gas may be ignited inadvertently by electrical machinery(b) State how the probability of the ignition of explosive gas by electrical machinery may be reduced.

4. Ask the Chief Engineer what an International Fire Connection is. How and when would it be used and where is it stored on your ship. Make a sketch of the aforementioned connection and indicate it's dimensions.
