04b fsi design guides

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Construction II for 2006/07 Design Guides forFire Services Installations

8 February 2007

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Design Guide for Fire Services Installations

1. Fire Services Provision.

2. Fire Services System Design.

3. Recommended Design Practice.

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1. Fire Services Provision

1.1 Audio/Visual Advisory System• Required for any floor area exceeding 2,000 m2

with transient occupants. Indication signs of the system are not required to show on the general building plans. Submit detailed design to FSD separately as early as possible.

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1.2 Automatic Actuating Devices• Automatically actuated fire door/shutter/curtain

to be provided at locations for the purpose of fire compartmentation or gas flooding systems. Fire shutter to be operated by smoke detectors c/w manual controls on both sides except fire shutter located in carpark areas which to be operated by heat detector c/w manual control. Automatic actuating devices not to beconnected to building fire alarm and direct telephone link.

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1.3 Automatic Fixed Installations Other Than Water

• Provision of automatic gas flooding system to be avoided except for essential usage with no other alternative. Consider to use CO2 system for un-occupied area before using FM200 (heptafluoropropane).

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1.4 Automatic Fixed Installations Using Water• Automatic sprinkler system designed to LH/

OH(I/II/III/IIIS)/ HH to be provided for all areas including staircases, common corridor and toilets but exclude boiler/battery/cold storage (Group I minor)/consumer electrical equipment/mechanical plant/lift motor/fuel oil tank/fuel pump rooms/D.G. store. Alarm signal to be transmitted to F.S. Communication Centre via direct telephone link.

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1.4 Automatic Fixed Installations Using Water• Water supply to sprinkler tank to be

single/double end feed as confirmed by WSD. Sprinkler system for curtain wall building of six storeys and above shall be one grade in excess of that normally required for the accepted risk category. This can be dispensed with if project architect confirms the building is constructed in accordance with FRC code 1996.

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1.4 Automatic Fixed Installations Using Water• Provide sprinkler for above ground oil/gas

boiler room and underground gas boiler room. • Provide automatic water drencher system in

accordance with "FOC Rules for the Installation of External Drenchers (4th Edition)" and/or "Codes of National Fire Protection Association for Water Spray Fixed System for Fire Protection (Standard 15)".

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1.4 Automatic Fixed Installations Using Water• Water to be supplied at 10 l/min per m2 of

surface area of opening to be protected. Independent water tank is required for each building block with 30 minutes of water storage.

• External drencher system operated by heat detector or sprinkler c/w manual control for protection of external wall opening to be provided for refuge floor. Calculation to be based on refuge floor with larger external wall opening.

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1.4 Automatic Fixed Installations Using Water• Water tank volume to be agreed with FSD for

building block with 3 or more refuge floors.• Automatic water spray system to be provided in

accordance with "Codes of National Fire Protection Association for Water Spray Fixed System for Fire Protection (Standard 15)".

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1.4 Automatic Fixed Installations Using Water• Water to be supplied at the rate of application as

per NFPA Standard 15 para. 4.4 for the surface area to be protected. 30 minutes of water storage is required. Locate water tank and pump room on ground or basement level where space is available.

1.5 Emergency Generator• To be provided to supply standby electricity to

all fire service installations and fireman's lift as required in the Code of Practice. Locate the engine exhaust flue satisfying EPD'srequirements.

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1.6 Emergency Lighting• To be provided throughout the entire building

and for all exit signs and routes leading to ground level and backed up by emergency generator and/or secondary battery.

• Central battery emergency lighting system to be provided for cinema/theatre and other specified premises used for entertainment.

• Emergency lighting in building not equipped with emergency generator to be provided with secondary battery.

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1.6 Emergency Lighting• Emergency lighting to be activated within 5

seconds for all bowling alleys, commercial buildings, hotel buildings and institutional buildings. Battery type emergency lighting is required to fulfil this requirement. Where emergency generator is provided, emergency lighting shall also be backed up by the emergency generator. Allow provisions for ease of monthly discharge test for 1 minute and weekly voltage/ hydrometer tests for central battery system.

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1.7 Exit Sign and Directional Sign• Sufficient exit and directional sign of self

contained battery type to be provided at locations to ensure that all exit routes from the floors are clearly indicated as required by the configuration of staircases serving the building.

• Battery backup is required for exit sign and directional sign in bowling alleys, commercial buildings, hotel buildings and institutional buildings to meet with the 5-second activation requirement.

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1.8 Fire Alarm System• Manually operated fire alarm system

comprising manual breakglass and alarm bell to be provided at each hosereel location. The system to be linked to the automatic fire alarm system and FS Communication Centre via direct telephone link.

• Visual fire alarm system to be provided for area intended to be accessible to public and the alarm signal shall form part of the fire alarm system in accordance with FSD Circular Letters 4/2001 (Part 1) and Clause 9.7 of BS 5839: Part 1: 1988.

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1.8 Fire Alarm System• According to the Design Manual - Barrier Free

Access 1997, visual fire alarm is required in all areas accessible by the public for buildings intended to be used by the public. Refer to FSD Circular Letter No. 4/2001 (Part 1) on extent of application. FSD allows the use of emergency generator or electricity before the main switch as the secondary supply source for visual fire alarm system.

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1.8 Fire Alarm System• Additional alarm bells may be required at

locations other than those adjacent to hosereelsin order to comply with the requirements on sound level stipulated in BS 5839: Part 1.

• In large buildings and in special premises supervised by trained staff, alarm zoning provided for phased evacuation to be indicated on the drawings for FSD approval.

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1.9 Fire Control Centre• To be provided for high rise buildings (over 30

m) and special premises (e.g. hotel, industrial building, aircraft maintenance, etc.). However, it is strongly recommended to be provided for complex building even it is of low rise. To be located on street level readily accessible to FSD personnel.

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1.10 Fire Detection System• Automatic fire alarm and detection system in

accordance with “Rules of the Loss Prevention Council for automatic fire detection and alarm systems for the protection of property” (LPC Rules) and BS5839: Part 1: 2002 to be provided for areas not protected by automatic sprinkler system.

• Heat detection system to be provided for boiler/ battery/consumer electrical equipment/mechanical plant/lift motor/fuel oil tank/fuel pump rooms/D.G. store.

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1.10 Fire Detection System• Smoke detection system to be provided for the

entire floor of the building excluding toilets, bathrooms and staircases which are covered by sprinkler system, if any part of that floor is used for sleeping accommodation. Alarm signal to be transmitted to F.S. Communication Centre via direct telephone link.

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1.11 Gas Detection System• Required for flammable or toxic gas storage

and/or emission including SF6 type transformer room, cold storage (Group II), mechanical plant room, road tunnel and petro-chemical complex .

1.12 Portable Hand Operated Approved Appliances

• Required for all non-sprinkler protected areas like boiler/battery/cold storage/consumer electrical equipment/mechanical plant/lift motor/fuel tank rooms/D.G. store, etc.

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1.13 Pressurization of Staircase• Not to be provided for staircase where there is

natural venting of staircases or aggregate area of openable windows of all floors exceed 6.25% of the floor area calculated on a floor by floor basis.Provision to be avoided wherever practical by satisfying the conditions specified in the Code of Practice. To be confirmed by the Project Architect with calculation shown on building plans. Design to be submitted by RPE(BS or Mech) or equivalent.

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1.14 Smoke Extraction System• Not to be provided for building with no fire

compartment to exceed 7,000 m3; or the aggregate area of openable window of the compartment exceeding 7,000 m3 to exceed 6.25% of the floor area of that compartment.; or the design fire load not exceed 1,135 MJ/m2.

• Provision to be avoided wherever practicable by satisfying the conditions specified in the Code of Practice. To be confirmed by the Project Architect with calculation shown on building plans.

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1. 14 Smoke Extraction System• To be provided for atrium if the compartment

of atrium exceeds 28000m3 or if any other level forming that compartment exceeds 7000m3..

• Hot smoke test may be required for smoke extraction system in atrium and complex building. FSD should be consulted at an early stage to confirm whether the test is required or not.

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1. 14 Smoke Extraction System• If smoke extraction system is designed by using

fire engineering approach, the methodology should be approved by FSD. Design to be submitted by RPE(BS or Mech) or equivalent.

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1.15 Ventilation/Air-conditioning Control System• To be provided to stop mechanically induced

air movement within a designated fire compartment. FSD's requirements to be complied with. Refer to Codes of Practice for the type of mechanical ventilation systems which are exempted from VAC provision.

• Refer B.S.B. Circular No. 3 of 2003 for examples of VAC tripping method.

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1.16 Dangerous Goods Stores/Fuel Oil Tank Room

• Details for the storage/use of dangerous goods as defined in Chapter 295 of the Laws of Hong Kong to be submitted to the Fire Services Department.

• FSD has different requirements for different types of dangerous goods. Fire damper for door louvre is required to be actuated by detector. Electrical apparatus to be suitable for the classified hazardous zone.

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1.17 Others• For buildings with life safety risk, all linings

for acoustic, and thermal insulation purposes in ductings, and concealed locations shall be of Class 1 or 2 Rate of Surface Spread of Flame as per British Standard 476 : Part 7 or its international equivalent, or be brought up to that standard by use of an approved fire retardant product.

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1.17 Others• For buildings with life safety risk, all linings

for acoustic, thermal insulation and decorative purposes within protected means of escape shall be of Class 1 or 2 Rate of Surface Spread of Flame as per British Standard 476 : Part 7 or its international equivalent, or be brought up to that standard by use of an approved fire retardant product.

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1.17 Others• Protection for hospital lifts which are designed

for evacuation purpose shall satisfy every condition for a Fireman’s lift with the exception of the internal floor area of car, and the minimum rated load factors.

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2.1 Hydrant and Hose Reel SystemHydrant outlet not less than 800mm nor more than 1200mm above finished floor level (f.f.l.) with design water pressure between 400kPa -700 kPa.Hose reel will normally cover area with 30 meters radius and capable of projecting a jet not less than 6 meters in length.

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2.1 Hydrant and Hose Reel SystemThe minimum effective quantity of water required to be available, having regard to the floor area factor of the largest floor is as follows,Floor Area (gross) Water Storage RequiredNot exceeding 230m2 9 m3

Over 230m2 but not exceeding 460m2 18 m3

Over 460m2 but not exceeding 920m2 27 m3

Over 920m2 36 m3

Locate the water storage tank at the top of the building so that the system is fed by gravity as far as possible.

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2.1 Hydrant and Hose Reel SystemFixed fire pumps capable to provide adequate flow for three hydrant outlets (each with a flow of 450L/min at a running pressure of not less than 350kPa) operating simultaneously with an aggregate flow of not less than 1350 L/min for industrial buildings or two hydrant outlets (each with a flow of 450L/min at a running pressure of not less than 350kPa) operating simultaneously with an aggregate flow of not less than 900 L/min for other buildings

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2.1 Hydrant and Hose Reel SystemFixed fire pump shall be duplicated for duty and standby use. Should the duty pump electrically or mechanically fail to operate within 15s the standby pump shall be energized to become the duty pump. Jockey pump shall be set to operate at 95% of the required system pressure and stop when the system pressure is restored to 100% level. The jockey pump shall stop when the fire pump is put into operation.

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2.1 Hydrant and Hose Reel SystemIntermediate booster pumps shall be provided in all buildings where the height between the topmost hydrant and the lowest Fire Services Inlet is in excess of 60m to maintain the flow and pressure in the rising main system. Twin hydrant outlet shall be fitted with independent handwheel.

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2.1 Hydrant and Hose Reel SystemHose reel pipe riser shall be not less than 50mmin diameter as specified in BS 5306: Part 1 (only 40mm riser is required in para. 5.14 of the FSCOP)Attenuation for alarm bell concealed in hose reel cabinet shall be checked to ensure sound can be clearly heard when the cabinet door is in close position.

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2.1 Hydrant and Hose Reel SystemWhen no flow condition of duty pump is simulated by closing the stop valve at the duty pump discharge, the fixed fire pump shall change over to standby pump.Gate valve of hose reel shall be installed not deeper than 500mm from front of cabinet.

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2.1 Hydrant and Hose Reel SystemFixed fire pump room shall not houses potable/ flushing pump installation.Auto air relief valve shall be provided at the top of FH riser.HR cabinet door shall not obstruct MOE when in open position.Height of HR nozzle shall not be installed higher than 1,350mm.

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2.1 Hydrant and Hose Reel SystemPump ‘start/stop’ control button or indicators and alarm buzzer for intermediate booster pump shall be provided at FS inlet.Pump running, faulty and power on indicators shall be provided in central FS panel.

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2.1 Hydrant and Hose Reel SystemFixed fire pump shall not be stopped other than manually reset at local control panel.FS inlet shall be provided with independent non-return valve and each FH riser be provided with independent FS inletPriming tank shall be provided for fixed fire pump with negative suction head

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2.2 Automatic Sprinkler SystemTo control the fire for subsequent extinguishment by the fire brigade but often the sprinklers will have accomplished extinguishment prior to their arrival.In accordance with the Loss Prevention Council Rules (LPC Rules) for Automatic Sprinkler Installations (with suitable modification pertinent to Hong Kong which incorporate BS5306: Part 2 : 1990 ) or other standards acceptable to the Director of Fire Services.

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2.2 Automatic Sprinkler SystemTo deal mainly with solid-fuel fires, but can serve also to hold a flammable-liquid fire in check and to extinguish some oil fires (e.g. transformer oil fires) by deluge sprinklers purely using water; to effectively extinguish it, suitable foam concentrate to be added to the water.

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2.2 Automatic Sprinkler SystemThe effective water capacity is the amount of water that can be used effectively inside a tank without having the least sign of occurrence of a vortex that could draw air into the water being conveyed to the pump. Thus, a certain portion of internal volume of the tank cannot be included in the effective capacity calculation.

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2.2 Automatic Sprinkler SystemHazard Group Height between H/L Sprinkler Capacity of the water tank (m3)LH 15 9LH 30 10LH 45 11OH Group I 15 55OH Group I 30 70OH Group I 45 80OH Group II 15 105OH Group II 30 125OH Group II 45 140OH Group III 15 135OH Group III 30 160OH Group III 45 185OH Group IIIS 15 160

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2.2 Automatic Sprinkler SystemIf city water supply to the sprinkler tank is of double-end-feed, (from 2 mid-level reservoirs), capacity can be reduced as follow,

Hazard Group Min. cap. of the water tank with in-fill (m3) Cap.of the water tank (m3)LH 2.5 30OH Group I 25 60OH Group II 50 60OH Group III 75 60OH Group IIIS 100 90

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2.2 Automatic Sprinkler SystemThe hazard classification dictate the minimum amount of water which must be provided at the fire in the form of spray and this is normally expressed as the `design density’. The expected max. area of the sprinkler system which will be activated by the fire is also dictated and this `assumed maximum area of operation’ is expressed in square meters. Design densities and assumed max. area of operation are,

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2.2 Automatic Sprinkler SystemHazard Classification Min. design density(mm m/min) Assumed max.

area of operation (m2)Light 2.25 84Ordinary (Group I) 5 72Ordinary (Group II) 5 144Ordinary (Group III) 5 216Ordinary (Group III Special) 5 360High 7.5-30 260-375

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2. Fire Services System Design.2.2 Automatic Sprinkler System

Colour code to distinguish sprinklers of different nominal temperature ratings:-Fusible Link type (℃) Colour

68 to 74 Un-coloured93 to 100 White141 Blue182 Yellow227 Red

Quartzoid Bulb type (℃) Colour of Bulb57 Orange68 Red79 Yellow93 Green141 Blue182 Mauve204 to 260 Black

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2.2 Automatic Sprinkler SystemThe response time index (RTI) is a measure of sprinkler thermal sensitivity and sprinklers are graded according to the sensitivity range into which they fall. The three response classes are : standard response (RTI between 80 and 200); special response (RTI between 50 and 80) and quick response (RTI below 50). Recessed, concealed and horizontal sidewall sprinklers are not classified and are referred to as `unrated’.

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2. Fire Services System Design.2.2 Automatic Sprinkler System

The deflector plate of the sprinkler head must be mounted parallel to the surface to which it is fixed. All shafts must have one head installed at the top of the shafts. If the shaft is built from combustible material, additional heads should be installed at alternate floors. If the shaft is built of non-combustible material, heads should be located as required. In the case of combustible stairs, sprinklers should be installed to protect both the underside and the top of the staircase.

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2.2 Automatic Sprinkler SystemSuspended ceilings exceed 800 mm deep to be protected by sprinklers as well as the room space below.The number of sprinklers controlled by one set of valve shall not exceed 500 in case of light hazard and 1000 in case of other hazard.

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2.2 Automatic Sprinkler SystemDry pipe system is used where the system pipework may be subjected to freezingtemperatures such as in cold stores, fur vaults etc. or where the temperature is maintained above 70oC as in drying ovens etc.. The installation is pressurized with air within the pressure range recommended by the alarm valve manufacturer and not exceed 400 kPa.

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2.2 Automatic Sprinkler SystemA drop of the pressure to a predetermined value opens the installation dry alarm valve and primes the installation. Each installation is served by an independent air supply system. In cold room, the installation is fitted with upright sprinklers and automatic means are fitted to automatically shut down the air circulation fans of cooling system when the sprinkler system operates.

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2.2 Automatic Sprinkler SystemPre-action system is also a type of dry pipe installation. There are two types of pre-action installation. Type 1 is used to prevent a premature discharge of water from pipework or sprinklers that have suffered mechanical damage; and Type 2 is used to facilitate an early discharge of water from a dry pipe installation by opening the installation main control valve, thus filling the installation control pipework with water, upon operation of a fire detection system.

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2.2 Automatic Sprinkler SystemFor Type 1 system, the water is normally flow into the pre-action pipework when the sprinkler is opened and the fire detection system is operated. For Type 2 system, the water fill the pre-action system pipework upon operation of a fire detection system before the sprinkler is operated. Type 2 system will normally be used for pre-action system.

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2.2 Automatic Sprinkler SystemThe number of dry sprinklers will not exceed 500 and 1000 per installation for light hazard and ordinary/high hazard installation respectively. Audio and visual warning of pump power failureshall be provided at control panel.Thermal overload cut-off is not necessary for sprinkler pump and sprinkler pump protection shall be protected by HRC fuse.

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2.2 Automatic Sprinkler SystemSprinkler shall be provided underneath the platform of the chute inside refuse collection room. Sprinkler head provided at top of refuse chute shall be of 57°C. Duplicate ‘pump power supply’ indicators for each phase of building shall be provided.

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2.2 Automatic Sprinkler SystemLength of sprinkler suction pipe from tank shall be less than 30m. Sprinkler provision for open cell ceiling shall be supported with calculations of ceiling free area.Sprinkler shall be provided underneath ventilation duct with width greater than 800mm, or 1000mm if over 150mm from wall.

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2.3 Gaseous Extinguishing SystemGaseous extinguishants are effective medium for the extinction of flammable liquid fires and fires in the presence of electrical hazards. Gaseous systems are usually used for hazards which are located inside buildings, or around which protective screens can be erected. They are suitable for most combustible material except those which contain their own oxygen supply, or chemicals that react with the gas.

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2.3 Gaseous Extinguishing SystemCarbon dioxide, halon 1301 (BTM) and halon1211 (BCF) were the common gases used for non water-based automatic fire suppression system in the past. However, halons have been prohibited form importing into Hong Kong for local consumption since Jan 94. There are two basic alternatives to replace halons.

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2.3 Gaseous Extinguishing SystemThe halocarbon agents extinguish fire by reaction with the combustion process and by cooling the atmosphere in the enclosure. They are clean , environmentally acceptable and may be regarded as `chemical gas’. The inert gas agents are permanent gas blends based on nitrogen which extinguish fire by reducing the oxygen content of the atmosphere from 21% to below 15%.

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2.3 Gaseous Extinguishing SystemThe unit cost of the gas for the chemical agent is much higher than for the inert gas agent but the quantity required is far less. This means that halocarbon option may be more suitable where storage is restricted. Surveyor report for gas cylinder shall be submitted to FSD for approval.Mechanical emergency manual release shall be provided.

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2.3 Gaseous Extinguishing SystemInert gas agents are stored in gaseous rather than liquid form, the frictional losses in the pipework will be very small thus the storage bottles for inert gas agents can be positioned some distance away from the risk.Clean agents including FM200, NAFS-III, Inergen and CEA-410 systems are considered as acceptable halon alternative.

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2.3 Gaseous Extinguishing SystemDesigned and installed in accordance with either BS 5306 Part 4 or NFPA 12 Only be used in normally unoccupied areas where egress of personnel can be accomplished in thirty (30) seconds.Carbon dioxide obtained by converting dry ice to liquid will not be acceptable.

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2.3 Gaseous Extinguishing SystemCarbon dioxide is stored in rechargeable cylinders to hold it in liquid form at ambient temperature. There are two types of storage system, the high pressure system and the low pressure system. For high pressure system, carbon dioxide is pressurized to a corresponding nominal pressure of 5860 kPa at 21°C. The normal filling density would not be in excess of 68%.

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2.3 Gaseous Extinguishing SystemCarbon dioxide total flooding systems is designed to discharge CO2 into the entire enclosed space in order to produce a concentration sufficient to extinguish a fire anywhere within the space. The design concentration (34% for surface fire and 50% for deep seated fire) to be achieved within 1 minute and 7 minutes for surface fire and deep-seated fire respectively.

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2.3 Gaseous Extinguishing SystemCarbon dioxide system is actuated when fire is detected by smoke or heat detectors. Sufficient detectors is installed to give duplicate coverage of the whole of the protected area and connected in cross-zones.

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2.4 Manual and Automatic Fire Alarm SystemManual alarm system consist of breakglass units and alarm sounders connected to a control panel, only operated and the alarm raised when activated by an individual having detected a fire incident. Automatic systems consist of smoke and heat detectors, in addition to those in manual alarm system to raise the alarm whether or not personnel are present at the time, thus giving early warning of a fire incident.

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2.4 Manual and Automatic Fire Alarm SystemAutomatic fire detection and alarm (AFA) system provides warning of fire danger and permits counter-action to be taken usually before the danger has reached serious proportion. AFA system shall be designed and installed in accordance with the specifications given in the BS5839: Part 1: 2002 and FSD Circular 1/2002

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2.4 Manual and Automatic Fire Alarm SystemFire alarm systems may be installed in buildings to satisfy one, or both, of two principal objectives, i.e. protection of life and protection of property. The objectives may differ in time or place. Because of the great variety of applications for system, BS5839 fire alarm systems are divided into a number of different Categories.

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2. Fire Services System Design.2.4 Manual and Automatic Fire Alarm System

Category M System - manual alarm systemCategory L System - automatic alarm system intended for protection of life. It is subdivided into L1 - systems installed throughout all areas of the building, thus offer the earliest possible warning of fire to achieve the longest available time for escapeL3 - systems installed only in defined parts of the building thus giving a warning of fire at an early 72


2.4 Manual and Automatic Fire Alarm Systemstage to enable all occupants, other than possibly those in the room of fire origin, to escape safely, before the escape routes are impassible.L2 - with L3 coverage plus the objective of affording early warning of fire in specified areas of high fire hazard levelL4 -systems installed within those parts of the escape routes comprising circulation areas

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2.4 Manual and Automatic Fire Alarm SystemL5 - systems in which the protected area and the location of detector is designed to satisfy a specify fire safety objective. Often the design is based on a fire risk assessment or form parts of a fire engineering solution.Category P Systems - automatic alarm system intended for protection of property. It is subdivided into

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2.4 Manual and Automatic Fire Alarm SystemP1 - systems installed throughout all areas of the building, thus offer the earliest possible warning of fire so as to minimize the time between ignition and the arrival of fire fightersP2 - systems installed only in defined parts of the building to provide early warning of fire in areas of high fire hazard level.

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2.4 Manual and Automatic Fire Alarm SystemBS5839 does not recommend which Category of systems need to be installed in any given premises. However, an informative annex (Annex A) is attached with the standard to provide information on the Categories of systems that are typically installed in various types of premises.

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2.4 Manual and Automatic Fire Alarm SystemManual fire alarm systems are often sufficient to satisfy legislation in workplaces in which no one sleeps. Automatic fire detection system is usually required by legislation to supplement the manual system in premises in which people sleep. AFA might also be necessary to satisfy legislation under the following circumstances,

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2.4 Manual and Automatic Fire Alarm System- AFA forms part of a fire engineering solution- AFA detection is needed to operate fire protection system such as door closing facilities or smoke control system- the low level of occupancy of a building may create potential risk to occupants before they are aware of the fire

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2.4 Manual and Automatic Fire Alarm SystemFire detectors are designed to detect one or more of the four characteristics of fire, namely, heat, smoke, combustion gas (such as carbon monoxide) and infra-red or ultraviolet radiation.Heat detectors may take the form of either point type detectors or line type detectors. The detection system may be designed to respond when a fixed temperature is reached.

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2.4 Manual and Automatic Fire Alarm SystemSmoke detectors detect smoke either by means of reduction in current flows between electrodes (ionization chamber type) or the scattering of light results from the presence of smoke (optical smoke type) or the obscuration of the light between the light source and the receiver (optical beam type).Combustion gas detectors respond to the gases produced by a fire such as carbon monoxide.

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2.4 Manual and Automatic Fire Alarm SystemFlame detectors detect the infra-red and/or ultraviolet radiation that is emitted by flame.In selection of the type of fire detectors, we should consider the speed of response required, the need to minimize false alarms and the nature of the fire hazard.Heat detectors are less sensitive and not suitable for the protection of areas where warning of the presence of smoke is required.

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2.4 Manual and Automatic Fire Alarm SystemHowever, they have the greatest immunity to false alarms.Optical smoke detectors are sensitive optically dense smoke but less sensitive to small particles. They are well suited for use in escape routes because they detect visible smoke and might operate before the escape route becomes impassible.

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2.4 Manual and Automatic Fire Alarm SystemOptical beam smoke detectors is economical and effective for the protection of large, open plan spaces with relatively high ceilings, particularly if access to point smoke detectors for maintenance.In general, smoke detectors give faster responseto most fire than heat detectors, but are more likely to give false alarms.

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2.4 Manual and Automatic Fire Alarm SystemAs recommended in BS5839, heat detectors may be used in any area other than the following,- Cat. P system in which a small fire has the potential to cause unacceptable damage (products of combustion may be corrosive and cause considerable damage without burning the contents of the affected area.

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2.4 Manual and Automatic Fire Alarm System- escape routes in Cat. L system - areas in which the production of smoke could present a threat to occupants’ escape before it is likely to be detected by people or heat detectionSmoke detectors may be used in any area other than the following,- the principal fire hazard is the presence of flammable liquids or gases that produce little smoke

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2.4 Manual and Automatic Fire Alarm System- areas in which high potential for false alarms (e.g. generator room)- Cat. L systems, smoke detectors installed within corridors and stairways that form part of the means of escape should be of optical type, unless the use of optical detectors would significantly increase the rate of false alarmUse optical smoke detectors for smouldering fire

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2.4 Manual and Automatic Fire Alarm SystemThe limits of ceiling height for installation of detectors (general) are as follows,Heat detectors (Class A1) - 9.0mHeat detectors (Other Classes) - 7.5mPoint Smoke Detectors - 10.5mOptical Beam Smoke Detectors - 25.0m

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2.4 Manual and Automatic Fire Alarm SystemThe limits of ceiling height for installation of detectors (Cat P System and 5 min. fire services attendance) are as follows,Heat detectors (Class A1) - 13.5mHeat detectors (Other Classes) - 12.0mPoint Smoke Detectors - 15.0mOptical Beam Smoke Detectors - 40.0m

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2.4 Manual and Automatic Fire Alarm SystemThe greatest concentration of smoke and heat will generally occur at the highest parts of enclosed areas and therefore detectors should normally be sited at these locations. Heat detectors should be sited so that the heat sensitive element is not less than 25mm nor more than 150mm below the ceiling or roof. If a protected space has a pitched roof, smoke detector should be installed in each apex.

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2.4 Manual and Automatic Fire Alarm SystemThe spacing for detectors under flat ceilings is 7.5m if the nearest detector is a smoke detector(i.e. area coverage of 100 sq.m) and 5.3m if the nearest detector is a heat detector (i.e. area coverage of 50 sq.m). In BS5839, a comprehensive guidelines for different Category of system and various application had been stated.

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2.4 Manual and Automatic Fire Alarm SystemIn system that incorporate more than 40 automatic fire detectors, it is not `acceptable’(i.e. the user should instigate an in-depth investigation by specialist) if in any rolling period of 12 months, either- the average rate of false alarm exceeds one false alarm per 20 detectors per annum or- more than two false alarms are initiated by any single manual call point or detector location

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2.4 Manual and Automatic Fire Alarm SystemThe standby battery capacity for Fire Services Panel should be determined by consultation with the battery manufacturer and should take into account the standby load, the alarm load, any required de-rating to take account of the higher current drawn in the alarm condition and a de-rating factor to take account of battery ageing during the anticipating life of the battery.

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2.4 Manual and Automatic Fire Alarm SystemThe capacity of battery shall maintain the fire alarm and control system in alarm condition for 30 minutes and maintain the system at normal condition for not less than 24 hours (or 18 hoursif emergency generator is installed).The battery shall maintain the automatic power failure alarm for 72 hour duration for sprinkler control system(consider to use two battery system).

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2.4 Manual and Automatic Fire Alarm SystemThe minimum capacity of valve regulated lead acid batteries should be calculated in accordance with the following formula:

C min = 1.25 (T1 I1 + D I 2/2)where

C min = minimum capacity of the battery when new at the 20 h discharge rate and at

20°C in ampere-hours;

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2.4 Manual and Automatic Fire Alarm System

T1 = total battery standby period in hours;I1 = total battery standby load in amperes;I2 = total battery alarm load in amperes;D = a de-rating factor.

When C min/20 is equal to or greater than I2, it can be assumed than D = 1.

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2.4 Manual and Automatic Fire Alarm SystemWhen C min/20 is less than I2, the value of D should either be based on battery manufacture’s data or should be 1.75. In practice, C min is unlikely to correspond exactly to an available battery capacity and therefore the next highest available capacity size should be used.Battery capacity calculation shall be documented.

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2.4 Manual and Automatic Fire Alarm SystemFor total floor areas >300m2, zoning of detectors shall not cover area more than one floor levelexcept for stairway.The floor area of single zone should not exceed 2000m2, other than in the case of a zone comprising mainly a single, open plan area not exceed 10000m2.

For non addressable system, the floor area of single zone should not exceed 2000m2.

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2. Fire Services System Design.2.4 Manual and Automatic Fire Alarm System

The search distance (the distance that has to be traveled by anyone responding to a fire alarm signal after entry to the zone in order for the location of fire to be determined visually) shall not exceed 60mSensing element of smoke detector shall be installed between 25mm to 60mm from soffit of ceiling.Sensing element of heat detector shall be installed between 25mm to 150mm from soffitof ceiling. 98


2.4 Manual and Automatic Fire Alarm SystemThe detector and annunciator panel shall be of FSD approved type.Breakglass unit shall not cover more than one floor levelSmoke detector shall be provided to entire floor with sleeping risk (heat detector may be used in kitchen).

99


2.4 Manual and Automatic Fire Alarm SystemDetector shall be provided to area not covered by sprinkler, e.g. MDF room, pump room, etc.Electrical earthing shall be provided to safety barrier in intrinsically-safe detector installation.Detector shall be provided to void with beam depth greater than 10% of ceiling height.Detector shall not be positioned more than 1.5m from open area or void.

100


2.4 Manual and Automatic Fire Alarm SystemDetector shall be provided to ceiling void with depth greater than 80mm and void containing combustible irrespective of its depth. (except for LV power cable in metal conduit/trunking)AFA shall be provided to basement area (except car parking area and safe deposit vault) and intermediate pump enclosure.

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2.4 Manual and Automatic Fire Alarm SystemDetectors not to be mounted within 500mm of any walls, partitions or obstructions to flow of smoke and hot gases with depth over 250mm.Ceiling obstructions such as beams deeper than 10% of the overall ceiling height should be treated as wallWhere an area contains partitions or racks that reach within 300mm of the ceiling, the partitions should be treated as wall

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2.4 Manual and Automatic Fire Alarm SystemWhere structural beams or ductwork or lighting fittings less 250mm depth that create obstacles to the flow of smoke, detectors should not be mounted closer to the obstruction than twice the depth of the obstruction

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2.5 Audio and Visual Alarm SystemA system of records/ signals either verbal, graphic or musical or direct transmission over a Public Address System to advise staff and other occupants of emergency condition and the action to be followed. It supplement exit signs and fire alarm warning devices and when operated in the event of a fire, provides audio / visual indication of safe direction of egress from the area.

104


2.5 Audio and Visual Alarm SystemSupplied and installed to all areas and places controlled and classified under Places of Public Entertainment Ordinance, Cap 172 and to other areas as required in FSD Requirements and Circular Letters. In special occupancy premises e.g. hospitals, cinemas, an agreed sound signal may be broadcast to give early warning to staff of emergency condition which may or may not necessitate action by them at that time.

105


2.5 Audio and Visual Alarm SystemThe floor is evacuated by operating the lights on that floor in flashing mode and the evacuation routes are indicated by low-level Directional Signs. Under BS5839, the fire alarm bell is required produce a minimum sound level of either 65dBA or 5dBA above any background noise likely to persist for a period longer than 30 seconds, whichever is greater, at any accessible point in the building.

106


2.5 Audio and Visual Alarm SystemFor sounders to be used in premises such as hotels, boarding houses, etc. where it is required to wake sleeping persons, the sound level should be 75 dBA minimum at the bedhead.The frequency produced by fire alarm sounders should lie in the range of 500Hz to 1000Hz. The sounders should be provided near the control and indicating equipment to draw attention to the indications of fire.

107


2.5 Audio and Visual Alarm SystemThe level of sound provided should not be so high (say for example 120 dBA) as to cause permanent damage to hearing. To estimate the fire alarm level within the same room/area e.g. in the public area, we need only to consider the attenuation of sound due to distance effect.

108


2.5 Audio and Visual Alarm SystemFor the attenuation of sound in air, we may use the inverse square law as the rule of thumb in estimation, i.e. Lp – Lp

’ = ∆ Lp = 20 log (d / do) where Lp is the sound level of the bell at the distance of do =1m, and Lp

’ is the sound level after the attenuation of distance d. We can take 65 dBA as the minimum criterion, or use 5-15 dBA above the ambient sound level as the criterion when the background noise level is high.

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2.5 Audio and Visual Alarm SystemIf the fire alarm bell is located in a separate room/area, the sound level generated by the fire alarm bell will be attenuated by the furnishings in the room where it is situated and by the wall/door through which the sound passes.After the average sound level is calculated for the room where the fire alarm bell is situated, the sound level in the next room can be estimated by calculating the attenuation due to door/obstacle.

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2.5 Audio and Visual Alarm SystemWhen the door of the room is opened, the sound passing through the door will be dominant. Attenuation through the wall is therefore not be considered. Only the attenuation due to entry and due to furnishings in the next room will be considered. Additional paths such as air ducts, etc. for the noise to travel to the next room will reduce the attenuation and should also be considered.

111


2.5 Audio and Visual Alarm SystemStrobe light on its own which is required to be installed in conjunction with fire alarm systems inside buildings does not required specific approval from FSD. Only beacon lamp integrated with sounder or intrinsically safe beacon lamp is required to be of approved type.Also, traditional red colour for flashing light is for achieving a better fire alarm alert effect.

112


2.5 Audio and Visual Alarm SystemThe visual alarm system shall be of flashing light operating at 24V DC providing a minimum of 75 candela (cd) light output. The system shall comply with Section 6-4 of NFPA 72 : National Fire Alarm Code or BS 5839. In NFPA 72, Clause 6-4.2.2, the light source shall not exceed 1000 candela (cd) (effective intensity). The intensity of light varies from 15 cd to 185 cddepending on the size of the room and the number of visual alarm unit.

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2.5 Audio and Visual Alarm SystemFor area with sleeping risk, in order to offset the obscuration effect of smoke near the ceiling, a value of 177cd would be required when the notification appliance is located within 24 inches of the ceiling, and a value of 110cd would be used when the distance is greater than 24 inches. For flashing unit, the light pulse shall not exceed two flashes per second not be less than one flash every second. The pulse duration shall be less than 0.2 second.

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2.5 Audio and Visual Alarm SystemIf more than two flashing units are installed in a room, they shall flash in synchronization or be spaced at more than 16.76m apart i.e. requiring a higher light intensity level. For sleeping area having no linear dimension greater than 4.87m, the intensity of the unit shall be 110cd if the distance from ceiling to top of the lens is greater than or equal to 0.61m and 177cd if the distance if less than 0.61m.

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2.6 Emergency Lighting SystemEmergency lighting shall be of battery operated type for building not provided with generator to fulfill the 15 second requirement after power changeover.Exit sign shall be provided to the common area in high rise domestic building.Emergency lighting shall be provided throughout the entire building and for all exit signs and routes in accordance with FSD Requirements Circular Letters and FSDCOP.

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2.6 Emergency Lighting SystemProvided within 2m from each exit door; near intersections of corridors, near each staircase so that each flight of stairs receives direct light; near each change in direction; near any change in floor level; near fire fighting equipment and fire alarm call point.

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2.6 Emergency Lighting SystemThe minimum illumination provided at floor level shall be 0.2 lux anywhere along the centre line of the defined escape route and 0.1 lux over a central band 1 meter wide. The average luminance for undefined escape routes should be not less than 1 lux. For staircase, the illumination should not less than 2 lux. The lux values should be measured at the mid-point between any two emergency lighting fittings.

118


2.6 Emergency Lighting SystemAt least two emergency lighting in any one installation to cater for the case of the failure of any one lamp.All emergency lighting fitting shall be of non-flammable type (resistance to flame and ignition) complying with BS EN 60598-2-22. If the central battery emergency lighting system is used, there is a greater flexibility in the choice of lighting fitting.

119


2.6 Emergency Lighting SystemRecommended to provide a separate lighting system for the battery/emergency lightingbecause:- the power of the lighting is smaller. It can be solely designed to meet with the fire service requirements during power interruption without taking into account of the requirements during other period of normal use.

120


2.6 Emergency Lighting System- the whole battery/emergency lighting system including lighting fitting can be separated from the electrical contract and therefore it can be installed/maintained by a registered fire service contractor as required by Fire Services Department.- with smaller power requirement of battery lighting, the capacity of central battery system can be made even smaller and thus the cost is reduced.

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2.6 Emergency Lighting SystemMay select a separate system of energy efficient down lights of small size using 5W-25W lamps to meet with the illumination requirements in BS5266. The battery-connected lighting can be of non-maintained type and be activated only during power interruption. For areas without ceiling, fluorescent light fitting or other lamps of suitable types can be used.

122


2.6 Emergency Lighting SystemIf higher illumination level is required during power interruption for other client’s requirements, it can be met by providing emergency power supply to the lighting designed for normal use. They should be separated from the battery connected emergency lighting system where possible.Exit signs should be positioned between 2m and 2.5m above FFL according to BS5266

123


2.6 Emergency Lighting SystemThe capacity of the battery for emergency lighting required is 2 hours while international standard normally required the battery to be tested for 1 hour or 3 hours. FSD has clarified that Clause 2.9 (ii) of COP apply to Central Battery System only and for self-contained emergency luminaires, the maintenance should follow Clause 12 of BS5266-1:1999

124


2.6 Emergency Lighting SystemEN60598-2.22 required the life span of dry battery for battery lighting to be 4 years; i.e. the battery shall be replaced in 4 years Battery charger shall provide the rated charge performance specified by the battery manufacturer to charge the batteries within 24 hours over the rated ambient temperature

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2.6 Emergency Lighting SystemIf electronic ballast is used for emergency lighting, care shall be taken to ensure that the electronic ballast can withstand the transient high voltage build up during the changeover from battery to normal power supplyFSD allows the use of radioactive self-luminous exit/directional sign. Remind the building owner to obtain licence from the Hong Kong Radiation Board.

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3. Recommended Design Practice

Though FSD submission is not mandatory for works carried out by ArchSD, we are committed to have the same design standard. Sprinkler pipework shall be installed to falls so that air can be vented. The water can also flow to the low points and be drained off for maintenance or when other considerations demand.Use Ni-MH battery or products having equivalent functions in FS system

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Recycling system shall be provided to restrict water damage after a fire is extinguished; to avoid closure of the main installation stop valve if modifications are made to the installation pipework or if sprinkler heads are to be replaced; to prevent water damage caused by accidental mechanical damage of the installation pipework or sprinklers.

128


As halocarbon gases are heavier than air, for halocarbon gases systems, provide openings in the room at low level to allow heavy gases to leak out of the protected area. High Pressure Carbon dioxide system is normally used.Clean agent used is normally FM200 except in areas with high ceiling height or with low temperature or with limitation in storage spaces for the clean agent that makes the use of FM200 unsuitable.

129


Even in building with comprehensive fire detection, the provision of manual call points will still normally be of great value, people in the vicinity of a fire will normally be aware of the fire, and able to raise the alarm by use of a manual call point, before it is detected automatically.Heat detectors that operate only when the rate of rise of temperature is abnormal, but not when a fixed temperature is reached do not comply with BSEN54-4 and ought not to be use.

130


At the design stage of every system, there should be formal consideration of the potential for false alarms, with a view to confirming that design is such that the frequency of false alarms is likely to be acceptableAny relevant design information regarding false alarms should be recorded and documented in accordance with the recommendations of Clause 40 of BS5839

131


Audio/visual warning indicator for emergency generator ‘on/failure’ shall be provided at local panel and FS control panel.Cooling and exhaust duct for generator passing through compartment shall be provided with fire damper.Annunciation panel to be located on street level readily accessible to FSD personnel, or in Fire Control Centre where provided.

132


Tripping of ventilating fan shall be by smoke detection device with manual override switch provided at FS control panel.FSD’s approval of Automatic Actuating Device design is required for closing time of horizontal fire shutter not exceeding 60 seconds. FSD will inspect the actuating device and the operation of the fire door/shutter/curtain.

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Use pre-action or pre-action recycling sprinkler system for computer room where possible. Limit the volume of D.G. Store within 44 m3.Ceiling mounted gas fire extinguisher to be used to protect D.G. store and other areas requiring gas flooding system with volume smaller than 44 m3.Check and ensure the transformer provided by Supply Company is non-flammable type.

134


Locate water tank and pump room on ground or basement level where space is available. Only one sprinkler inlet is required for each zone. Provide duplicate alarm valve for all buildings except no life safety risk. Supply water tank to be refilled to its full capacity within 6 hours by automatic means or by a transfer pump powered by essential power supply.

135


Sprinklers installed in heated rooms including kitchen/cooking area/autoclave room to have a temperature rating of 93oC. Fast response sprinkler system to be provided in basement with sprinkler flow switch connected to the general fire alarm.Provide one FS inlet for each hydrant riser and a common header not higher than 30m above ground level to link up all risers.

136


Two stages fuel capacity alarm/control to be provided to alert management/to shut down other essential load when the fuel storage for generator is reduced to that required to maintain a minimum 6-hour continuous operation for fire service installation. FSD’s approval required for one generator set serving more than one block.

137


Include the provision of Exit sign and directional sign under the fire service installation contract for single responsibility and better co-ordination. They shall be connected to both main and emergency power supply. If the building is not equipped with an emergency generator, exit sign and directional sign shall be backed up by secondary battery.For new projects, centrally supplied emergency lighting system should be considered with priority.

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