(IV-7-3) General Safety

Rules IV Industrial Services
Part 7 Offshore Technology
Chapter 3 General Safety
Section 8
Active Fire Protection
G.2.6.3 The mechanical ventilation of the protected space is to be stopped automatically before the
discharge of the extinguishing gas.
G.2.6.4 Audible and visual alarms shall be provided in the protected space and additional visual
alarms at each access to the space.
G.2.6.5 The alarm shall be actuated automatically by opening of the release station door. For installations
with a design concentration in excess of the NOAEL, see G.2.1.3, means shall be provided to safeguard
that the discharge of extinguishing gas is not possible before the alarm has been actuated for a
period of time necessary to evacuate the space but not less than 20 s.
G.2.6.6 Audible alarms shall be of horn or siren sound and be clearly distinguishable from other audible
signals.
G.2.6.7
power.
Electrical alarm systems shall have power supply from the main and emergency source of
G.2.6.8 For the use of electrical alarm systems in gas dangerous zones refer to GL Rules for
Instrumentation (IV-7-6).
G.2.6.9 Where pneumatically operated alarms are used the permanent supply of compressed air is to
be safeguarded by suitable arrangements.
G.3 Tightness of the protected space
G.3.1 Apart from being provided with means of closing all ventilation openings and other openings in
the boundaries of the protected space, special consideration shall be given to G.3.2 through G.3.4.
G.3.2
G.3.3
A minimum agent holding time of 15 min shall be provided.
The release of the system may produce significant over pressurization in the protected space.
G.3.4 Escape routes which may be exposed to leakage from the protected space shall not be rendered
hazardous during or after the discharge of the extinguishing gas. Control stations and other locations
that require manning during a fire situation shall have provisions to keep the concentrations of products
below values considered hazardous for the required duration of exposure.
G.4 Warning signs and operating instructions
G.4.1 Warning signs are to be provided at each access to and within a protected space as appropriate:
• "WARNING! This space is protected by a fixed gas fire extinguishing system using .......... Do not enter
when the alarm is actuated!"
• "WARNING! Evacuate immediately upon sounding of the alarm of the gas fire extinguishing system."
G.4.2
Brief operating instructions are to be posted at the release stations.
G.4.2.1 A comprehensive manual with the description of the system and maintenance instructions is to
be provided. The manual shall contain an advice that any modifications to the protected space that alter
the net volume of the space will render the approval for the individual installation invalid. In this case
amended drawings and calculations have to be submitted to GL for approval.
G.5 Documents
Prior to commencing of the installation the following documents are to be submitted to GL for approval:
• arrangement drawing of the protected space showing machinery, etc. in the space, and the location
of nozzles, containers (modular system only) and release lines as applicable
• list of volumes deducted from the gross volume
• calculation of the net volume of the space and required supply of extinguishing gas
Edition 2013 Germanischer Lloyd Page 8–12