(IV-7-3) General Safety

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Rules IV Industrial Services Part 7 Offshore Technology Chapter 3 General Safety Section 9 Fire and Gas Detection Alarm Systems Rooms located underneath the GIS rooms which are not properly segregated from or sealed to the GIS room shall be sufficiently ventilated during attendance of personnel, as SF6 is heavier than air and will replace breathable air in case of a major leakage after a release to lower locations/decks. For the above reasons, any leakage or loss of SF6 shall be avoided and SF6 containments are to be appropriately monitored during operation or maintenance with suitable technical measures, e.g. Gas sensors, SF6 leakage/pressure monitoring, etc. National regulations concerning safe SF6 handling shall be observed (e.g. BGI 753 for Germany). A.2.3 Concerning the arrangement of Gas Sensors, the specific properties of the Gases to be detected shall be observed, e.g. Hydrogen is very fugitive and will accumulate right underneath the ceilings, as being much lighter than air. A.3 Fire & gas alarm system The Fire and Gas Detection and Alarm systems shall be capable of indicating at the main control station by audible and visual means the presence and location of a fire and an accumulation of hazardous gas. Fire and Gas Alarms shall be also transmitted to the Onshore Control Room to facilitate consecutive action, especially in the case of normally unmanned Offshore Substations. A.4 Equipment For technical details of fire or gas sensors and controllers as well as public address and general alarm system components, please refer to GL Rules for Instrumentation (IV-7-6), Section 1. B Manual Alarm B.1 Manual fire alarm B.1.1 Sufficient manual fire alarm stations (Manual Call Points, MAC’s) shall be fitted at suitable locations throughout the installation/unit. The locations of MAC’s shall include the exits from day rooms, stairways, control stations, passageways and escapes. B.1.2 The distance between MAC’s shall not exceed 20 m wherever possible. B.1.3 If MAC’s are not sufficiently well lit by emergency lighting close-by, they are to be provided with an indicator lamp. B.1.4 Manual Call Points may be part of a fire detection loop (see C.6, below). B.2 Man-overboard alarm Additionally to the Manual Call Points, Man-overboard alarm pushbuttons shall be installed at suitable locations on open deck areas on the Offshore Substation. C Arrangement of Fire Detectors and Alarm Loops C.1 Every alarm loop shall not cover more than one fire zone and, as far as practicable, not more than one deck or a stairway connecting more than two decks. C.2 Where there are arrangements for the separate flooding with fire extinguishing media of two or more adjoining spaces, separate fire alarm loops have also to be provided. C.3 A fire alarm section monitoring a service area or an accommodation area shall not include a machinery space of category A. Edition 2013 Germanischer Lloyd Page 9–2
Rules IV Industrial Services Part 7 Offshore Technology Chapter 3 General Safety Section 9 Fire and Gas Detection Alarm Systems C.4 For areas provided with automatic pressure water spray systems, separate alarm loops per section are to be allocated. C.5 Generally the number of the detectors shall not exceed 20 per alarm loop. The number of detectors grouped in each loop within a machinery space should not exceed 10. C.6 Manually actuated alarms, i.e. Manual Alarm Call points (MAC), may be incorporated in a loop together with automatic alarms. C.7 The arrangement and number of fire detectors have to be such that all areas with an increased fire risk are covered. This applies in particular to Transformer and Reactor rooms/areas, Medium and High Voltage Switchgear Rooms, Machinery spaces (e.g. Generator enclosures/rooms and control and working spaces). C.8 Detectors should not be mounted close to ventilation outlets or in positions where the flow of air may affect their operation, or where they are liable to suffer mechanical damage. C.9 Ceiling-mounted detectors shall normally be located at least 0.5 m from walls. C.10 The maximum distance between detectors (and the maximum area monitored) shall not exceed the following figures: • for heat detectors: 9 m (37 m 2 ) • for smoke detectors: 11 m (74 m 2 ) The distance from walls shall not exceed • for heat detectors: 4.5 m • for smoke detectors: 5.5 m C.11 The installation of a type tested aspirating smoke detection (ASD) system can be approved by GL. The arrangement and setup of an ASD system shall be such that a detected fire can be clearly assigned to a fire zone. Concerning the arrangement and dimensioning of the sampling pipes of the ASD system the manufacturer requirements shall be strictly followed. D Public Address and General Alarm System D.1 Public address system D.1.1 In addition to the general emergency alarm a public address (PA) system is generally required on all normally or temporarily manned Offshore Substations. The PA system shall be operable from strategically important locations and from the central control station. It shall be audible throughout the accommodation area, at the crew’s normal working places and at the strategically important locations. D.1.2 If the public address system is used to transmit the general emergency alarm (PA/GA system), the following requirements shall be fulfilled: • The requirements for the general emergency alarm shall be satisfied. • At least two amplifiers are to be provided, each of them separately supplied and fused. • At least two loudspeaker circuits, supplied from separate amplifiers, are to be installed in each fire zone, respectively in its subdivisions. • The loudspeaker circuits are to be so arranged that transmission at a reduced loudness is maintained in the event of a failure of an amplifier or loudspeaker circuit. • Where loudspeakers with built-in volume controls are used, the volume controls must be disabled by the release of the alarm signal. Edition 2013 Germanischer Lloyd Page 9–3
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(IV-7-3) General Safety

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