Systems
1. Calculation of the necessary quantity of CO2
Calculation of the necessary quantity of CO2 is sub-
ject to the provisions set out in G.1.
2. CO2 Containers
2.1 Design and Construction
2.1.1 The rated CO2 supply is to be stored in
pressure vessels at a pressure of 18 to 22 bar.
2.1.2 With regard to their material, manufacture, construction, equipment and testing, the containers must comply with the requirements contained in Section 8 (Pressure Vessels).
2.1.3 The containers may be filled with liquid CO2
up to a maximum of 95 % of their volumetric capacity calculated at 18 bar
The vapour space must be sufficient to allow for the increase in volume of the liquid phase due to a tem- perature rise corresponding to the setting pressure of the relief valves.
2.2 Equipment
2.2.1 Pressure monitoring
The container pressure is to be monitored and an in- dependent visual/audible alarm signalling both high pressure prior to the attainment of the setting pressure of the relief valves and low pressure at not less than 18 bar is to be provided.
2.2.2 Monitoring of liquid level
Each container is to be equipped with two level gauges, one of which must provide permanent monitoring of the liquid level.
A liquid level of 10 % or more below the set level shall trip a visual/audible alarm.
Where more than one space is protected by the CO2
system, a remote indicator is to be provided at all release stations outside the room in which the con- tainer is located. A remote indicator may be dispensed with if, after release, the discharge of the rated quantity of CO2 is regulated automatically, e.g. by an
automatic timer.
2.2.3 Safety relief valves
Each container is to be fitted with two safety relief valves with shutoff valves on the inlet side. The shut- off valves shall be interlocked in such a way that the cross-sectional area of one relief valve is available at all times.
The setting pressure of the relief valves must be at least 10 % above the cut-in pressure of the refriger- ating units.
The capacity of each relief valve must be so that the quantity of gas produced by the action of fire on the container can be discharged without the pressure in the container exceeding the setting pressure of the relief valves by more than 20 %. For the calculation see Rules for Ships Carrying Liquefied Gases in Bulk, Volume IX, Section 8.
The blow-off line is to discharge into the open.
2.2.4 Insulation
Containers and piping which are normally filled with CO2 are to be insulated in such that after failure of the
refrigeration, assuming a container pressure equal to the cut-in pressure of the refrigerating units and an ambient temperature of 45 oC, the setting pressure of
the relief valves is not reached before a period of 24 h.
The insulating material must be at least not readily ignitable and be sufficiently robust. Protection against steam penetration and damage from outside is to be provided. See also Rules fo Refrigerating Installations, Volume VIII, L.
3. Refrigerating plant
3.1 At least two complete, mutually independent, automatical refrigerating sets are to be provided. The capacity of the refrigerating sets shall be such that the required CO2 temperature can be maintained with an
ambient temperature of 45 C and a seawater temperature of 32 C.
3.2 The failure of a refrigerating set must cause the standby set to start up automatically. Manual switchover must be possible.
3.3 Separate electrical supply must be provided from the main busbar.
3.4 At least two circulating pumps must be available for the cooling water supply. One of these pumps can be used as standby pump for other purposes provided that it can be put into operation im- mediately without endangering other essential sys- tems.
3.5 The supply of cooling water must be avail- able from two sea chests, wherever possible from either side of the ship.
4. Location and disposition
CO2 containers and the corresponding refrigerating
equipment are to be located in special rooms. The disposition and equipping of the rooms are to comply with the applicable provisions of G.3.
5. Piping, valves and fittings
Unless otherwise specified below, G.4., 5. and 6. apply analogously together with Section 11, B. wherever relevant.
5.1 Relief valves are to be fitted to isolable pipe sections in which the heating of enclosed CO2 can
produce pressures exceeding the design pressure of the pipe.
5.2 The flooding lines are to be so designed that, when flooding occurs, the vaporization of CO2 does
not occur until it leaves the nozzles. The pressure at the nozzles must be at least 10 bar.
5.3 A filling connection with the necessary means of pressure equalization is to be provided on either side of the ship.
6. Monitoring
An alarm is to be fitted in the engine control room for
the following variations from the reference condition: - Pressure above maximum or below
minimum in accordance with 2.2.1, - Liquid level too low in accordance with
2.2.2,
- Failure of a refrigerating set.
This alarm may function as group alarm "Fault in the CO2 fire extinguishing system".
7. Release
7.1 The automatic release of CO2 flooding is not
permitted.
7.2 If devices are fitted for automatically gauging the rated quantity of CO2, provision must also
be made for manual control. G.5.2 also applies.
8. Warning systems, general arrangement
plans and warning signs
Signs giving the following information are to be permanently fixed in the CO2 cylinder room and to the
valve groups for the flooding of individual spaces with CO2 :
- Name of space and gross volume in m3
- Necessary volume of CO2
- Number of nozzles for the space
- Flooding time in minutes (i.e. the time the flooding valves must remain open)
G.7., 8. and 9. also apply as appropriate.
9. Tests
9.1 After installation, lines between tanks and distribution valves are to be pressure-tested at least 1,5 times the pressure setting of the relief valves. Lines which pass through accommodation spaces are to be tested after installation at a pressure of 50 bar gauge. A test pressure of 10 bar is required for all other lines.
The performance of the test is to conform to G.10.1.
9.2 G.10.2 and G.10.3 apply wherever relevant.
I. Other gas fire extinguishing systems and steam fire extinguishing systems.
Extinguishing gases other than CO2 may be applied
only if approved in accordance with international regulations (IMO) and accepted by the flag state Authority.
Steam may be used as extinguishant in limited local applications (e.g. scavente trunks) if agreed upon with BKI1).
K. Foam Fire Extinguishing Systems
1. Foam concentrates
1.1 Only approved foam concentrates may be used; see also D.1.3.
Foam concentrates must be able to produce an ef- fective foam even when sea water or brackish water is used. They must be frostproof to at least - 5 C.
1.2 Distinction is made between low- and high-expansion foam.
In the case of low-expansion foam, produced by adding 3 - 6 % foam concentrated the foam expansion ratio (i.e. the ratio of the volume of foam produced to the mixture of water and foam concentrate supplied) shall not exceed 12 : 1
For high-expansion foam, produced by adding 1 - 3 % foam concentrate, the expansion ratio may be 100: 1 up to 1000 :1. Foam concentrate for the pro- duction of multi-purpose foam may be used. Deviations from these expansion ratios require the approval of the Society.
Foam concentrates intended for use in the cargo area of chemical tankers must be alcohol-resistant if this is necessitated by the List of Product, Rules for Ships Carrying Dangerous Chemical in Bulk, Volume X, Section 17; see Foam Fire Extinguishing Systems for Chemical Tankers, Rules for Ships Carrying Dangerous Chemical in Bulk, Volume X, Section 11.
Tankers for the carriage of alcohols and other flammable polar liquids shall be provided with alcohol resistant foam concentrate.
2. Low-expansion foam systems for tankers
(deck foam systems)
2.1 The foam fire extinguishing system is to be so designed that foam is available for the entire cargo deck area as well as for any cargo tank, the deck of which has ruptured.
2.2 The deck foam system shall be capable of simple and rapid operation. The main control station for the system must be suitably located outside the cargo area and adjoining the accommodation areas. In the event of a fire in the spaces to be protected it must be easy to reach and to operate.
2.3 Capacity of the foam fire extinguishing system pump and supply of foam solution:
The rate of supply of foam solution is to be calculated in accordance with the following formulae. The rate is to be based on the largest calculated value. a) 0,6 liters per minute per square meter of the
cargo deck area, where cargo deck area means the maximum breadth of the ship multiplied by the total longitudinal extent of the cargo tank spaces.
Q = 0,6 · L · B [l/min] or
b) 6 liters per minute per square metre of the horizontal sectional area of the single tank having the largest such area.
Q = 6 · l · b [l/min] or
c) 3 liters per minute per square metre of the area to be protected by the largest monitor and lying entirely forward of the monitor, subject to a minimum of 1250 liters/minute. Q = 3 · B · 0,75 l1 [l/min]
The minimum supply of foam concentrate shall be such that, based on the largest value calculated by applying a), b) and c), the production of foam is guaranteed for at least 30 minutes on tankers without an inert gas system and for at least 20 minutes on tankers with an inert gas system.
Smin = Q · s · t [l]
Q [l/min] = foam solution L [m] = length of cargo area B [m] = breadth of ship
l [m] = length of largest cargo tank b [m] = breadth of largest cargo tank Smin [l] = minimum supply of foam con-
centrate
s = dosing rate (for synthetic foam concentrate normally 0,03)
l1 [m] = throw of monitor
t [min] = duration of foam application.
2.4 Foam distribution and capacity of
monitors
2.4.1 The foam from the fixed foam system is to be discharged through monitors and foam applicators. Each monitor must be capable of supplying at least 50 % of the required foam solution. The delivery rate of a monitor may not be less than 1250 liters/minute. On tankers of less than 4000 dwt, foam applicators may be provided instead of monitors.
2.4.2 The number and position of the monitors is to comply with the requirements specified in 2.1. The capacity of any monitor in liters per minute of foam
solution must be at least three times the deck area in square meters protected by that monitor, such area being entirely forward of the monitor.
2.4.3 The distance from the monitor to the farthest extremity of the protected area forward of that monitor shall not be more than 75 % of the monitor throw in still air conditions.
M = 3 · B · 0,75 l1 [l/min]
M [l/min] = delivery rate of one monitor 0,5 · Q,
but not less than 1250 l/min B [m] = breadth of ship
l1 [m] = throw of monitor
2.4.4 A monitor and a hose connection for a foam applicator shall be situated to both port and starboard at the poop front or the accommodation spaces facing the cargo deck. In addition, connections for foam applicators are to be sited between the monitors to give greater flexibility in the fighting of fires. The capacity of each foam applicator may not be less than 400 liters per minute and the applicator throw may not be less than 15 m in still air conditions.
2.4.5 On tankers of less than 4000 dwt, one hose connection each for a foam applicator is to be provided to port and starboard at the poop front or the accommodation spaces facing the cargo deck. At least four foam applicators must be available. The number and disposition of foam hydrants are to be such that foam from at least two applicators can be directed on to any area of the cargo deck. The capacity of each foam applicator must be equivalent to at least 25 % of the quantity of foam solution calculated in accordance with 2.3 a) or 2.3 b). The capacity and throw of the foam applicators may not be less than those specified in 2.4.4.
2.4.6 Immediately forward of each monitor, both the foam main and the fire main are to be fitted with shutoff valves to enable damaged sections of these lines to be isolated.
2.5 Operation of the foam system at its required capacity shall permit the simultaneous use of the water fire extinguishing system as per E. over the full length of the ship on deck, in accommodation spaces, control stations, service spaces and machinery spaces.
2.6 The supply of foam concentrate and the necessary pumps are to be located outside the area to be protected.
3. High-expansion foam systems
3.1 Capacity of the system
3.1.1 The equipment producing the foam must be of sufficient capacity to enable the largest space being
protected to be filled with foam at the rate of at least 1 m depth per minute without allowance for installed machinery and equipment.
3.1.2 The supply of foam concentrate must be sufficient for the largest space being protected to be filled with foam at least five times. The equipment must be ready for immediate use at all times.
3.2 Foam distribution
Foam is to be conveyed to the spaces being protected through fixed ducts. The outlets in these ducts are to be arranged in such a way as to ensure uniform dis- tribution of the foam. Inside the space where the foam is produced, a shutoff device must be fitted between the foam generator and the distribution system.
3.3 Foam generators, pumps, supply of foam
concentrate
3.3.1 Foam generators, pumps and their power supply and stored quantities of foam concentrate are to be located in enclosed spaces outside the spaces to be protected.
3.3.2 Where the emergency fire pump is used to supply water to the foam generator, the capacity of the pump must be sufficient.
3.4 Test equipment
Foam generators are to be installed in such a way that they can be tested without foam entering the protected spaces.
4. Low-expansion foam systems for boiler rooms and machinery spaces
Low-expansion foam systems do not substitute for the fire extinguishing systems prescribed in Table 12.1
4.1 Capacity of the system
The system must be so designed that the largest area over which fuel can spread can be covered within five minutes with a 150 mm thick blanket of foam.
4.2 Foam distribution
4.2.1 The foam solution must be conveyed through fixed pipelines and foam distributors to the points at which oil fires are liable to occur.
4.2.2 Foam distributors and controls are to be arranged in suitable groups and positioned in such a way that they cannot be cut off by a fire in the protected space.