(IV-7-3) General Safety

Rules IV Industrial Services
Part 7 Offshore Technology
Chapter 3 General Safety
Section 8
Active Fire Protection
G.2.2
Calculation of the supply of extinguishing gas
G.2.2.1 The supply of extinguishing gas shall be calculated based on the net volume of the protected
space, at the minimum expected ambient temperature using the design concentration specified in the
system's type approval Certificate.
G.2.2.2 The net volume is that part of the gross volume of the space which is accessible to the free
extinguishing gas including the volumes of the bilge and of the casing. Objects that occupy volume in the
protected space shall be subtracted from the gross volume.
G.2.2.3 The volume of free air contained in air receivers located in a protected space shall be added to
the net volume unless the discharge from the safety valves is led to the open air.
G.2.2.4 For systems with centralized gas storage for the protection of more than one space the quantity
of extinguishing gas available need not be more than the largest quantity required for any one space
so protected.
G.2.3
Gas containers
G.2.3.1 Containers for the extinguishing gas or a propellant needed for the discharge shall comply in
respect of their material, construction, manufacture and testing with the relevant Rules on pressure vessels.
G.2.3.2
The filling ratio shall not exceed that specified in the system's type approval documentation.
G.2.3.3 Means are to be provided for the installation’s/ unit's personnel to safely check the quantity of
medium in the containers.
G.2.4
Storage
G.2.4.1 Centralized systems
Gas containers in centralized systems are to be stored in a storage space complying with the requirements
for CO 2 storage spaces, see G.1.7, with the exception that storage temperatures up to 55 °C are
permitted, unless otherwise specified in the type approval Certificate.
G.2.4.2
Modular systems
G.2.4.2.1 All systems covered by these requirements may be executed as modular systems (with the
gas containers, and containers with the propellant if any, permitted to be stored within the protected
space) provided the conditions of G.2.4.2.2 through G.2.4.2.9 are complied with.
G.2.4.2.2 Inside a protected space, the gas containers shall be distributed throughout the space with
bottles or groups of bottles located in at least six separate containers. Duplicate power release lines have
to be arranged to release all bottles simultaneously. The release lines shall be so arranged that in the
event of damage to any power release line, five sixth of the fire extinguishing gas can still be discharged.
The bottle valves are considered to be part of the release lines and a single failure shall include also failure
of the bottle valve.
For systems that need less than six containers (using the smallest bottles available), the total amount of
extinguishing gas in the bottles shall be such that in the event of a single failure to one of the release lines
(including bottle valve), five sixth of the fire extinguishing gas can still be discharged. This may be
achieved by for instance using more extinguishing gas than required so that if one bottle is not discharging
due to a single fault, the remaining bottles will discharge the minimum five sixth of the required
amount of extinguishing gas. This can be achieved with minimum two bottles. However, the NOAEL value
calculated at the highest expected engine room temperature may not be exceeded when discharging the
total amount of extinguishing gas simultaneously.
Systems that cannot comply with the above (for instance where it is intended to locate only one bottle
inside the protected space) are not permitted. Such systems shall be designed with bottle(s) located outside
the protected space, in a dedicated room complying with the requirements for CO 2 storage spaces
(see G.1.7).
Edition 2013 Germanischer Lloyd Page 8–10