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12DE1004 Saiesh
1005 Brembley
1006 Russell
1007 Mukesh
THE FIRE TRIANGLE
Three components required for combustion
Fuel – to vaporize and burnOxygen – to combine with fuel vapourHeat – to raise the temperature of the fuel
vapour to its ignition temperature.
Two important factors to remember in
preventing and extinguishing a fire:
i) If any of the three components are missing, then a fire
cannot start.
ii) If any of the three components are removed, then the
fire will go out.
THE FIRE TETRAHEDRON
solid figure with four triangular faces
shows the chain reaction and each face touches the
other three faces.
The basic difference - illustrates how flaming combustion
is supported and sustained through the chain reaction of
the oxidation process.
VARIOUS SYSTEMS USED ONBOARD FOR
FIGHTING FIRE
HIGH EXPANSION FOAM SYSTEM
CO2 SYSTEM
SPRINKLER & SPRAYER SYSTEM
HALON SYSTEM
WHAT IS FOAM ? combination of three materials:
• Water
• Air
• Foam making agent
formed by mixing the foam-making agent with water to
create a foam solution.
foam bubbles created by introducing air into the foam
solution through aerating devices.
Two most common concentrations are 3% and 6%
foams.
HOW IS FOAM GENERATED ?
A constant amount of foam concentrate is added to water
by means of a proportioner.
The resulting mixture of water/foam concentrate is
expanded with air in the foam generator.
FOAM CONCENTRATOR
SEA WATER EDUCTOR
AIR IN
FAN SPRAY NOZZLE
TO ENGINE ROOM
NYLON MESH
THE INDUCTION RATE
specifies the percentage ratio of foam concentrate added
to water.
At 3% induction rate, for example, 3 parts of foam
concentrate are mixed with 97 parts of water.
FILM FORMATION
The foam produces a very thin aqueous film on non polar
liquids
This film floats ahead of the foam and provides for its
excellent flowing, extinguishing and re-ignition inhibiting
properties.
Aqueous film
(AFFF effect)
• produced by the polymer film formers contained in the
foam when extinguishing polar hydrocarbons (e.g
alcohols, ketones, ester).
• The film floats as an insulating protective layer between
the foam destroying alcohol and the foam cover above.
Polymer film
HOW FOAM EXTINGUISHES FIRE ?
o Separating effect
The closed foam cover separates the combustion zone from the ambient air.
o Cooling effect
The flammable material is cooled down by the water/ foam solution discharged by the foam.
o Cover effect
The closed foam cover stops any further gas evaporation
from burning materials, i.e. flammable gases
foam forms a blanket on the surface of flaming liquids
o Repression effect
Flooding spaces, channels, plant parts, etc. with high or
medium expansion foam represses the atmospheric oxygen
and flammable gases necessary for the combustion
process.
o Insulation effect
foam insulates flammable material which has not yet caught
fire
FOAM CHARACTERISTICS
Knockdown Speed and Flow- ability to spread across a
fuel surface or around obstacles
Heat Resistance-able to resist the destructive effects of
heat radiated from any remaining fire
Vapour Suppression. capable of suppressing the
flammable vapours to break the fire triangle.
Alcohol Resistance-foam blankets that are not
alcohol-resistant will be destroyed if used on
alcohol-based cargoes.
cohesive properties- to stick together
sufficiently to establish and maintain a vapour
tight blanket
light enough-to float on flammable liquids, yet
heavy enough to resist winds
TYPES OF FOAMS
Chemical foam
• formed by mixing together a solution of an alkali, an acid,
water and a stabilizer.
• forms a foam or froth of bubbles filled with carbon dioxide
gas.
• 7 to 16 volumes of foam are produced for each volume of
water.
• Needs a device called a foam hopper or separate tanks
Mechanical (Air) Foam
• produced by mixing a foam concentrate
with water to produce a foam solution.
• The bubbles are formed by the turbulent
mixing of air and the foam solution.
TYPES OF MECHANICAL FOAMS
Protein Foam
produced by the hydrolysis of waste protein material, such asprotein-rich animal waste and vegetable waste that ishydrolyzed
Fluoroprotein Foam (FP).
formed by the addition of special fluorochemical surfactantswith protein foam
Film Forming Fluoroprotein Foam (FFFP)
combination of fluorochemical surfactants with protein foam
release a film on the surface of the hydrocarbon.
Aqueous Film Forming Foam (AFFF)• combination of fluorochemical surfactants and synthetic foaming
agents
• film spreads rapidly causing dramatic fire knockdown.
Alcohol Resistant-Aqueous Film Forming Foam (AR-
AFFF)• combination of synthetic stabilizers, foaming agents, fluorochemicals
and alcohol resistant additives
• offers good burnback resistance, knockdown and high fuel tolerance
on both hydrocarbon and alcohol fuel fires.
Synthetic Foam• made up of alkyl sulfonates.
• It foams more readily than the proteins and requires less water
important where the water supply is limited
CATEGORIES OF FOAM SYTEMS
Low Expansion Foams
• expansion ratio of 12:1 when mixed with air
• effective in controlling and extinguishing most flammable liquid(Class “B”) fires
• typically used on tanker deck foam systems
Mid Expansion Foams
• expansion ratio of between about 20:1 to 100:1
• truly three dimensional; it is measured in length, width, height, andcubic feet
High-expansion foam
• designed for fires in confined spaces
• Heavier than air but lighter than oil or water
LIMITATIONS ON THE USE OF FOAM
Because they are aqueous (water) solutions, foams are
electrically conductive
Like water, foams should not be used on combustible-
metal fires.
not suitable for fires involving gases and extremely low
temperature liquids.
If placed on burning liquids whose temperatures exceed
100°C (212°F), the water content of the foam may cause
frothing, spattering or slopover.
Sufficient foam must be available.
ADVANTAGES OF FOAM
effective smothering agent and provides cooling effect.
sets up a vapor barrier that prevents flammable vapors
from rising
Can be used on Class “A” fires because of its water
content.
effective in blanketing oil spills
uses water economically
most effective extinguishing agent for fires involving large
tanks of flammable liquids.
can be made with fresh water or seawater, and hard or
soft water
does not break down readily and extinguishes fire
progressively
Foam stays in place, covers and absorbs heat from
materials that could cause re-ignition
Foam concentrates are not heavy, and foam systems do
not take up much space.
PRACTICAL ISSUES
Water Temperature and Contaminants
more stable when generated with lower temperature water.
temperature range 1.7°C to 26.7°C
Combustible Products in Air
It is desirable to take clean air into the foam nozzle at all times
Water Pressures
Nozzle pressures should be held between 3.4 bar and 13.8 bar (50 and 200 psi)
Non-ignited Spills
Where flammable liquids have spilled, fires can be prevented by prompt coverage of the spill with a foam blanket
Electrical Fires
not generally recommended for use on electrical fires
Vaporized Liquids
not recommended for use on materials that react with water, such as magnesium, titanium, potassium etc.
HIGH EXPANSION FOAM SYSTEM AND EQUIPMENT
FOAM GENERATOR
Delivers large quantity of expanded foam by blowing air
through a screen
Because of high expansion ratio requires little water
FOAM GENERATOR
FOAM GENERATOR SCREEN
FOAM GENERATOR SCREEN
FOAM GENERATOR SCREEN
1) Proportioning Devices
Eductor
most common form of proportioning equipment works on
the Venturi principle.
extremely reliable and simple pieces of equipment
Around-the-Pump Systems
an eductor is installed on the discharge side of the water
pump
water flow causes a vacuum that picks up and introduces
the foam concentrate into the water
Balanced Pressure Foam Proportioners
extremely versatile and accurate
The principle of operation based on the use of a
modified venturi proportioner commonly called a
ratio controller.
2) FOAM NOZZLES
designed to air aspirate (expand) the foam solution and form finished foam.
High expansion foam nozzles expands foam in excess of 100:1, when high expansion foam concentrates are used.
3) FOAM MONITORS
are permanently-installed foam discharge units
capable of being aimed and projecting large quantities of foam substantial distances.
normally mounted on a rotating base (360-degree circle)
4) VALVES AND PIPING
must be adequately designed to match the flow rates of the equipment, and a thorough understanding of the system
control valves is critical for quick and effective operation of the system
Color coding of the valves
4) VALVES AND PIPING
5) FOAM CONCENTRATE STORAGE
stored in tanks ready to supply the proportioning system
The concentrate tank should be kept filled with liquid halfway
The tank should be kept closed to the atmosphere
SOLAS REQUIREMENTS
FOAM CONCENTRATE
Foam concentrates to be of the type approved by administration
Capable of rapidly discharging foam @ at least 1 m in depth per minute
Volume of foam = 5 x volume of largest space
Expansion ratio not to exceed 1000:1
INSTALLATION REQUIREMENTS
• System should provide effective foam production and
distribution
• Foam generator delivery ducting to be protected
against fire risk, withstand 925 deg C.
• Foam delivery ducts to be constructed of steel
having thickness > 5 mm
• Dampers to be automatically operated by remote
control
• All system equipment to be readily accessible and
simple to operate
ABS REQUIREMENTS FOR FOAM EXTINGUISHING SYSTEMS
Design and Certification of Piping Components
• All valves, fittings and piping to comply with the
applicable requirements
• be suitable for the intended pressures
Pipe and Pipe Joints
the wall thickness, type and design of the pipe joints to
comply with the requirements
Materials
• materials used in the system should not to be rendered ineffective by heat.
• material to have a melting temperature higher than the test temperature specified in an acceptable fire test.
Pumps
• should be tested in the presence of a Surveyor
Pressure Vessels the tank is to be considered a pressure vessel and is to
comply with the requirements as applicable.
System Component Certification fixed fire-extinguishing system components are to be
certified.
Accordingly, components such as foam system eductors, proportioners, monitors, nozzles, etc., are to comply with the certification requirements
STARTING PROCEDURE AUTOMATIC START
Stop the supply fan and exhaust fan in the E/R.
Break the Destruct plate and push the system standby switch.
Alarm sound for evacuation in the E/R.
Start the Emergency fire pump manually.
After evacuation is confirmed push the foam discharge switch.
TO STOP;
Push the system stop switch.
Stop the Emergency fire pump.
MANUALLY START AT LOCAL SIDE.
Check all Valves.
Start the Emergency fire pump.
Check pressure gauge, indicate 4 bar.
Open valve and start foam liquid pump.
TO STOP:
Stop the Emergency fire pump.
Close the valves.
EXAMPLE CALCULATION OF THE CAPACITY OF
FOAM SYSTEM FOR OIL CARRIER SHIP
PARTICULARS
• BEAM = 14.5 M
• LENGTH OF CARGO AREA = 56 M
• LENGTH OF LARGEST CARGO TANK = 9 M
• CARGO DECK AREA = 14.5 M ×56 M = 812 M2
• HORIZONTAL SECTIONAL AREA OF SINGLE LARGEST
TANK = 14.5 M ×9 M = 130.5 M2
• PROPOSED MONITOR SPACING = 9 M
AREA PROTECTED BY LARGEST MONITOR = 9 M × 14.5 M = 130.5 M2
14.5 m 9m
56m
LESSONS LEARNT
Proper maintenance should be done including putting back the cover
Blowing/purging the line after hydraulic pressure testing
Inspection of the foam nozzle after test
Foam line on board to be pressure tested regularly
Draining the line to prevent accumulation of water
WHERE IS HIGH EXPANSION FOAM SYSTEM
USED ?
ENGINE ROOM
PURIFIER ROOM
INCINERATOR ROOM
PUMP ROOM
PACKING OF FOAM
CONCENTRATES
20 litres Plastic Can
Size (ca. cm) 38 x 38 x 18
Tara ca. kg 1,4
Suitability Synthetic, Protein
Net weight approx Synthetic 20 Kg, Protein 23 Kg
Stackable 2 high, to 40°C, shrink-wrapped onto a
pallet
20 litres Plastic Can
Blue
Size (ca. cm) 29 x 26 x 39
Tara ca. kg 1,2
Suitability Synthetic, Protein
Net weight approx 25 – 30 Kg
Stackable 2 high, to 40°C, shrink-wrapped onto a
pallet
200 litresValenthene
Barrel
Size (ca. cm) 60 x 90
Tara ca. kg 21
Suitability Synthetic, Protein
Net weight approx 200 – 225 Kg
Stackable 2 high
1000 litres Palett
Container
Size (ca. cm) 100 x 120 x 116
Tara ca. kg 80
Suitability Synthetic, Protein
Net weight approx Synthetic 1040 Kg, Protein 1150 Kg
Stackable 2 high
MAINTENANCE AND INSPECTION OF SYSTEM AND
APPLIANCES.
Operational readiness
• To be in good order and readily available for immediate use while the ship is in service.
Maintenance and Testing
• should be carried out in accordance with the ship's maintenance plan.
• Inspections should be carried out by the crew in accordance with manufacturer's maintenance and inspection guidelines
MONTHLY TESTING AND INSPECTIONS
• Verify all control and section valves are in the
proper open or closed position, and all pressure
gauges are in the proper range.
QUARTERLY TESTING AND INSPECTIONS
• Verify the proper quantity of foam
concentrate is provided in the foam
system
ANNUAL TESTING AND INSPECTIONS.
o visually inspect all accessible components
o functionally test all fixed system audible alarms
o flow test all water supply and foam pumps for proper pressure and capacity
o Ensure all piping is thoroughly flushed with fresh water after service
o test all system cross connections to other sources of
water supply for proper operation;
o verify all pump relief valves, if provided, are properly set
o examine all filters/strainers to verify they are free of
debris and contamination
o verify all control/section valves are in the correct
position
blow dry compressed air or nitrogen through the
discharge piping
confirm the pipework and nozzles of high expansion foam
systems are clear of any obstructions, debris and
contamination
take samples from all foam concentrates carried on
board and subject them to the periodical control tests
test all fuel shut-off controls connected to fire-protection
systems for proper operation.
FIVE-YEAR SERVICE
perform internal inspection of all control valves
flush piping with fresh water, drain and purge with air
check all nozzles to prove they are clear of debris
test all foam proportioners to confirm that the mixing
ratio tolerance is within +30 to -10% of the nominal
mixing ratio
TESTING OF FOAM SAMPLES
No Type of foam concentrate Minimum frequency
1 All Fixed systems except protein based non-
alcoholic
Within 3 years from the date
of manufacture and every
year thereafter.
2 All Fixed systems of protein based non-
alcoholic
Annually.
3 All factory-sealed portable containers excluding
protein based
Ten yearly.
4 All factory-sealed portable containers of protein
based concentrates
Five yearly.
5 All non-sealed portable containers Within 3 years from the date
of manufacture and every
year thereafter
