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FIRE SERVICES INSTALLATIONS
Web presentation started in May 1998.
Principal author / editor: K P Cheung, Department of Architecture, Hong Kong University
Other contributors: as acknowledged in various chapters / sections
CONTENT (The following order of the content is in line with page 3 of HKFSD-COP-FSI)
O. General
1. Audio / visual advisory systems2. Automatic actuating devices3. Automatic fixed installations other than water4. Automatic fixed installations using water5. Deluge systems6. Drencher systems7. Dust detection systems8. Dynamic smoke extraction systems9. Emergency generators10. Emergency lighting11. Exit signs12. Fire alarm systems13. Fire control centre14. Fire detection systems15. Fire hydrant / hose reel systems16. Firemen’s lifts17. Fixed automatically operated approved appliances18. Fixed foam systems19. Gas detection systems20. Gas extraction systems21. Hose reels22. Portable hand-operated approved appliances23. Pressurization of staircases24. Ring main systems with fixed pumps25. Sprinkler systems26. Static smoke extraction systems27. Supply tank28. Ventilation / air conditioning control systems29. Water spray systems30. Water supplies
O. General
The fire service installations (FSI) described in this document are primarily for educatingarchitectural students of HKU, and are arranged in the order presented in the Code ofPractice for Minimum Fire Service Installations and Equipment (COP-FSI), published byHong Kong Fire Services Department (HKFSD).
This COP-FSI, is published together with the Code of Practice (Inspection and Testing ofInstallations and Equipment) – (COP-I&T), by HKFSD in one volume named:
CODES OF PRACTICEFOR
MINIMUM FIRE SERVICE INSTALLATIONSAND EQUIPMENT
ANDINSPECTION AND TESTING OF
INSTALLATIONS AND EQUIPMENT
O.1 COP-FSI
The COP-FSI is issued and administered on the following grounds stated in Section 1.4and 1.3 of COP-FSI:-
Approval of plans for building works
The Building Authority may, under Section 16(1)(b) of the Buildings Ordinance, refuse togive his approval of any plans of building works where:
“The plans are not endorsed with or accompanied by a certificate from the Director ofFire Services certifying either:
(i) that, having regard to the purpose to which the building is intended to be put(which purpose shall be stated in the certificate), no fire service installation orequipment is necessary in connection with the building that will result from thecarrying out of the building works shown on the plans; or
(ii) that the plans have been examined and are approved by him as showing all suchfire service installations and equipment as in his opinion, having regard to thepurpose to which the building is intended to be put (which purpose shall be statedin the certificate), comprise the minimum fire service installations and equipmentnecessary for the building in accordance with the Code of Practice publishedfrom time to time by the Director of Fire Service.”
Discretionary powers of the Director of Fire Services
“For the avoidance of doubt, the Director of Fire Services may, in the case of anyparticular building, vary any of the requirements of the Code (whether by requiring theprovision of any fire service installations or equipment not indicated in the Code either inaddition to or in substitution for any fire service installations or equipment so indicated orby relaxing any of the requirements in the Code or otherwise) where, in his opinion, sucha variation is required in order to ensure the provision of all such fire service installationsand equipment, as having regard to the purpose for which the building is intended to beput, comprise the minimum fire service installations and equipment necessary for thatbuilding / premises, or as the case may be, where such a variation is not inconsistent withthe provision for the building of all such fire service installations and equipment asaforesaid.”
O.2 COP-I&T
The following preliminary note stated in FSD-COP-I&T highlights the legal grounds forissuing and implementing this COP:-
“Where the plans of a building have been certified by the Director of Fire Service underS.16B(1)(b)(ii) of the Buildings Ordinance as showing all such fire service installationsand equipment as in his opinion, having regard to the purpose to which the building isintended to be put, comprise the minimum fire service installations and equipmentnecessary for such building, the Building Authority may, under S.21(6)(d) of thatOrdinance, refuse to issue a temporary occupation permit or an occupation permit (whichis necessary before the building can be occupied in any way except by not more than twocaretakers) unless the applicant for the permit produces a certificate from the Director ofFire Services certifying that he is satisfied that the fire service installations and equipmentshown on the plans have been provided and are in efficient working order and satisfactorycondition.
This Code of Practice (Inspection and Testing of Installation and Equipment) is publishedfor information only, to indicate the type and nature of inspections and tests whichinstallations and equipment must normally pass in order so to satisfy the Director of FireServices and to give guidance as to the conduct of inspections and tests. It does not laydown any hard and fast rules. Special factors and circumstances may require variations inrespect of any particular building, and in particular case the Director may requireadditional inspections or tests before he is so satisfied.”
O.3 Contents of COPs
The contents of the COPs are:-
COP - MINIMUM FIRE SERVICE INSTALLATIONS AND EQUIPMENTPart I - GeneralPart II - Table and definitions of systems / installations / equipmentPart III - Classification of premises and definitionsPart IV - Requirements for premises (i.e. FSI requirements)Part V - Specification and testing (i.e. for FSI)
COP – INSPECTION AND TESTING OF INSTALLATIONS AND EQUIPMENT
PRELIMINARY NOTEPart I - GeneralPart II - Inspections and testsPart III - MiscellaneousAppendices - Checklists for inspection and testing of FSIs
The content of COPs have to be read in detail, cross referenced with the related ordinance/ Regulations and FSD circular letters, before applying them for the project underconsideration. The following is an abstract of Part IV of COP-Min. FSI – Clause 4.15 on“Commercial buildings – high rise”.
Commercial buildings – high rise
REQUIREMENTS – SYSTEMS / INSTALLATIONS / EQUIPMENT FOR:-
i) Audio / visual advisory systemsii) Automatic actuating devicesiii) Automatic fixed installations other than water
iv) Emergency generatorsv) Emergency lightingvi) Exit signsvii) Fire alarm systemsviii) Fire control centreix) Fire detection systemsx) Fire hydrant / hose reel systemsxi) Fireman’s liftsxii) Portable hand-operated approved appliancesxiii) Pressurization of staircasesxiv) Sprinkler systemsxv) Static or dynamic smoke extraction systemsxvi) Ventilation / air conditioning control systems
EXTENT
i) Required for any pat or parts of building where the area occupied by any onesingle occupancy on any one floor exceeds 2,000 square metres AND where theoccupants, due to their transient presence either as shoppers, audience or guests,are exposed to risks to require additional advice through such systems.
ii) As required by that equipment which needs to be automatically actuated.
iii) To be provided to areas where the use of water is undesirable for the occupancyor trade.
iv) An independently powered generator of sufficient electrical capacity to meet theessential services it is required to provide.
v) Emergency lighting shall be provided throughout the entire building and all exitroutes leading to ground level.
vi) Sufficient directional and exit signs to ensure that all exit routes from any floorwithin the building are clearly indicated as required by the configuration ofstaircases serving the building.
vii) One actuating point and one audio warning device to be located at each hose reelpoint. This actuating point should include facilities for fire pump start and audiowarning device initiation.
viii) Minimum of one, additional to be provided according to the complexity of thebuilding.
ix) To be provided in areas not covered by the automatic fixed installations.
x) There shall be sufficient hydrants and hose reels to ensure that every part of thebuilding can be reached by a length of not more than 30 m of Fire Services hoseor hose reel tubing.
xi) Lift or lifts as designated.
xii) As required by occupancy.
xiii) Required where:a. natural venting of staircase is not provided; andb. the aggregate area of openable windows of the rooms / units of the building
does not exceed 6.25% of the floor area of those rooms / units, calculated ona floor by floor basis; and
c. the cubical extent of the building exceeds 28,000 cubic metres; andd. the designed fire load of the building is likely to exceed 1,135 MJ/square
metre
The number of pressurized staircase to be provided shall be determined by thetable stipulated under the definition of Pressurization of Staircases in Pt. IIprovided that the number of pressurized staircases required shall not exceed thetotal number of staircases required by the Code of Practice for Means of Escape.
xiv) Required covering all parts of the buildings including staircases and commoncorridors.
xv) Required fora. atrium of the building, if the compartment of the atrium exceeds 28,000
cubic metres, or any basement level or floor of building forming part ofthat compartment which exceeds 7,000 cubic metres, and
b. any fire compartment exceeding 7,000 cubic metres in that buildingwhere:i. the aggregate area of openable windows of the compartment does
not exceed 6.25% of the floor area of that compartment, andii. the designed fire load is likely to exceed 1,135 MJ/square metre
xvi) When a ventilation / air conditioning control system to a building is provided, itshall stop mechanically induced air movement within a designated firecompartment.
ADDITIONAL REQUIREMENTS
i) All linings for acoustics and thermal insulation purposes in ductings andconcealed locations shall be of Class 1 or 2 Rate of Surface Spread of Flame asper British Standard 476: Part 7 or its international equivalent, or be brought upto that standard by use of an approved fire retardant product.
ii) All linings for acoustic, thermal insulation and decorative purposes withinprotected means of escape shall be of Class 1 or 2 Rate of Surface Spread ofFlame as per British Standard 476: Part 7 or its international equivalent, or bebrought up to that standard by use of an approved fire retardant product.
iii) Any intended storage or use of dangerous goods as defined in Chapter 295 of theLaws of Hong Kong should be notified to the Director of Fire Services.
O.4 Reference
Text Books
Burberry P. Environment and Services. The Mitchell Publishing Company Limited.London. 1988. (HKU Main Lib. 696 B94)
Hall F. Building Services and Equipment. Vol. 2. Longman. London. 1985. pp. 69-102. (HKU Main Lib. 696 H17)
Reid E. Understanding Buildings. A multi-disciplinary approach. Longman Scientific &Technical. England. 1984. pp. 178-193. (HKU Main Lib. 690 R35)
Further Reference
Other reference as listed in the various sections to follow:
See other reading reference in “Fire safety in buildings” of Technology Teaching(http://arch.hku.hk/teaching)
8. Dynamic Smoke Extraction Systems
8.1 COP-FSI Requirements
The COP-FSI defines “Dynamic smoke extraction system” as “A mechanical ventilatingsystem capable of removing smoke and products of combustion from a designated firecompartment, and also supplying fresh air in such a manner as to maintain a specifiedsmoke free zone below the smoke layer.”
The COP-FSI specification of the system is summarised as follows:-
Basic Consideration
- system be simple and reliable- control smoke away from egress / escape route- extract air point at high level; at least one extract point to be
within each 500 sq.m; and coverage distance < 30m- make-up air rate be 80% of extract rate by mass- make-up point at low level- free grille area be based on air velocity:-
< 6 m/s for mechanically propelled< 3 m/s for not mechanically propelled
- fire separation in compartment be maintained- smoke discharge 5m away from any building openings
above 3m for horizontal dischargeabove 6 m for downward discharge
Smoke Extraction Ductwork
- within same fire compartment: as DW142 standard;- passing other compartments: to be of maximum Fire Resistance
(B.S. 476: pt 24) of the passing compartments; and pass impact test of BS 5669 underdropping height of 1m
- pass pressure test of DW 143- smoke extraction shaft contain no other services
Temperature Rating for Equipment
- temperature rating be 250 deg. C for 1 hour- essential electrical supply and high temperature cabling- switch, control device or houses in 2-hour F.R.P. enclosure- smoke extract fans and other equipment exposed to hot smoke temperature to
withstand: 250°C for 1 hour
Control and Actuation
- ‘fail-safe’ design- zone actuation as by “Fire” signal in AFA systems, or from the independent smoke
detectors for S.E.- no interruption from other services- multiplex control unit be approved type
- at F.S. panel, to provide with:-manual on / off control switch, and indication light on fan status
- fan status sensor be centrifugal switch or pressure switch
Standby or Duplicate Equipment
- apply for sleeping risk premises, or S.E. system used > 12 hr. per day- duplicate on fan, motor, drive, starters, etc.- automatic changeover on duty equipment in failure
Basement
- separate system for each compartment- at least 2 independent plants and ductwork for each system- E.A. be 8 air changes per hour of compartment volume- emergency power for 2 adjacent compartments with highest electrical load
Hotel
- E.A. be 10 air changes per hour of the internal means of escape or as calculated byfire load
- distance between any supply and extract point < 10 m- 1 system to serve up to 10 fire compartments- system shall operate 2 compartments simultaneously
8.2 Some case studies of dynamic smoke extraction systems
8.3 The basics of smoke control systems (containing design reference) K P Cheung,Department of Architecture, HKU, July 1998
A. What is Smoke?
(e.g. Volatiles from Burning Wood Soot)5 x 10-4 um
Smoke Visible Dust GRIT
0.3 um Smoke Powder76 um 103um
Pre-ignition Particles
(e.g. CH4, CO)
10-4 um 10-3 um 10-2 um 0.1 um 1 um 10 um
Less than 0.01 um , detection by 1 to 4below:
Ionization DetectorOperating Range
1. Particle counting 0.01 um to 0.3 um
2. Modified light scatterdetector
Ionization Detector Sensitive(Turbulent Atmosphere)
Obscuration Detector Sensitive,Light Scatter Detector Sensitive(Quiescent Atmosphere),for 0.3um and above
3. CO detector
4. Semi-conductor detector(Flammable gas detector)
B. How does smoke affect life?
Example: Polyurethane foam --- CH3 CN AcetonitrileCH3 = CH . CN AcrylonitrileHCN Increasing temperature
Also: PVC HCl
Smoke contains toxic and irritant gases. Fatality is often caused by inhalation of smoke.e.g. in UK, 1971, over 50% fire fatality caused directly by inhalation of smoke.Inhalation can also paralyse victims who would then be exposed to high temperatures(burn) and O2 deficient atmosphere. (asphyxiation) – indirectly death caused by smoke.
C. Measurement of smokiness
1. By filtration or by precipitation to determine the concentration (e.g. ppm) ofparticulate matter in the smoke; usually for small size particles ≤ 10-2 um.
2. By attenuation of a light beam: Common method and practical, as it relatesdirectly to visibility which affects people searching for escape route.
Beer’s Law (Lambert Law):
I = Ioe –EML
obscura
ob ,unit initiated in Edinburgh University
)(decibel/m2.303
EM
L
Ilog
L
l
L
D Smokiness
EML/2.303 I
I log D
o
o
===
==
D = Optical densityIo = Light transmitted without smokeI = Light transmitted with smokeE = Constant Depending on the Nature of the smoke particlesM = Conc. of material in smoke obstructing lightL = Length of light path
Visibility
1 ob = 10 m visibility with diffused light
D. The purpose of smoke control
1. To prevent fire spread. ]2. To facilitate fire fighting. ] *3. To reduce damage due to smoke and heat. ]
** 4. To keep MOE smoke free or to an acceptablesmokiness. ( MOE = means of escape, or egress )
* As a part of fire venting – Suitably conducted would lessen a fire due to convective heatloss.
** Interest of building controller.
E. The basic requirements of smoke control systems
Principles: Containment, Removal, Dilution.
ILLUSTRATION I(A Shopping Mall or an Atrium of Two-storeys )
Smoke Reservoir Extract (Mechanical/Natural)
Smoke Layer
Replenishing Air 2.5 m minimum
Detached Traces of Smoke Fire (To be Controlled at 5 MW, design fire size)Being Diluted
HMSO published a design manuals in 1990, 1994 – See reference.
In a building, air/smoke pressures are generated by :
1. Wind pressure – measurement by wind tunnel modelling. (Now also CFD )2. Mechanical pressure – estimated by calculation & experience.3. Fire pressure – Max. = 15 Pa – 20 Pa4. Stack effect : Tall building5. Local Stack effect: across the door separating a fire room
ILLUSTRTION II
Tall building with Staircase Pressurization, and smoke extraction
Pressurization Air Staircase Extract (Mech./Natural)(Fresh Air) Door Lobby (Protected)
Door Smoke Shaft
Main Equation: ( See BS 5588 : Part 4 )
Q = 0.827 X A x p1/N
P = P1 – P2 = 50 Pa (Pressurization level) , for exampleQ = Air flow rate, m3/sA = Area of restriction , m2
N = 2 for door; 1.6 for cracks round windows
Main Criteria:
Egress Velocity = 3 m/s to 4 m/s for permanent openingEgress Velocity = 0.8 m/s for intermittent opening.Staircase / Lobby at 50 Pa above the accommodation.
BS5588: Part 4 : 1978 illustrates two cases, but the principles can be applied for othersituations. e.g. Many doors open for long time for people escape, such as in largedepartment stores. (Note : The update one is BS 5588 : Part 4 : 1988 )
For tall buildings, computer calculation on smoke movement has been used. The smallerand the more in number the rooms area, the more reliable the solution would be.
• See new BS5588: Part 4: 1998, for updated concepts and design guidelines.
Sprinkled Building
SmokeOffice
P2P1
ILLUSTRATION III(Factory – Single Storey)
Fire Ventilators
Roof
Factory
Fire Air
Well developed control technique based on FRN No. 7 (See reference). Commercialsmoke ventilation products are available.
People Movement is closely related to smoke control: (See A Separate Paper onpeople movement by K P Cheung)
Within the period of the escape time ( in many codes ,this is 2 ½ minutes), peoplehave to be inside a protected escape route which has to be free of smoke.
An ideal is to establish a people/place/time history (people movement quantified) vs.smokiness/place/time history (smokiness quantified).
Present UK (and HK) codes of escape route are formulated on few observations andexperiments, and have no scientific principles in analysing people movement. WhileRussians were ahead in this field (See reference), especially in congested people flow,queuing people flow, converging and diverging people flow, and in flow bottle neck,and other high people density conditions. The Russian technique needs the initialformation of people streams, and then proceed with calculations in a deterministicmanner.
In people stream formation ,there are recent studies using fuzzy logic analysis on thechoice of escape route by people.
People Safety: More of Government concern.Property Safety: More of Insurers’ concern.
8.4 Design reference for smoke control systems and staircase pressuirzation
1. Hobson P J. Stewart L J. Pressurization of Escape Routes in Buildings. FireResearch Note No. 958, DOE and JFRO. UK. 1972.
2. Smoke Prevention and Extraction Installations for Buildings. Loss PreventionAssociation of Japan, 1977. Translated into Chinese by Building Industry PublishingHouse of China. 1983.
3. BS 5588: Part 4: 1978. Code of Practice for Fire Precautions in the design ofbuildings. Smoke control in protected escape routes using pressurization. HMSO.UK. (Basic study guide)
3a. BS 5588: Part 4: 1998. “Fire precautions in the design, construction and use ofbuildings. Part 4. Code of Practice for smoke control using pressure differentials.”
4. Klote J H. Fothergill J W. Design of Smoke Control Systems for Buildings.ASHRAE. USA. 1983.
5. Codes of Practice for Minimum Fire Service Installations and Equipment andInspection and Testing of Installations and Equipment. Fire Services Department.Hong Kong.
6. Mui D H F. Pressurization of staircase – a look at practicability. Hong KongEngineer. The Hong Kong Institution of Engineers. Nov 1991.
7. Cheung K P. Staircase pressurization – The Rationale and the Alternatives,ASHRAE Transactions Vol 93, Part 2. USA. 1987.
8. Chow W K. Lam L W. Cheung K P . Lam K C. Field Tests on StaircasePressurization System in Hong Kong. Far East Conveyance on EnvironmentalQuality in Hong Kong, Nov 5-8, 1991. ASHRAE. USA.
9. Cheung K P. Lam L W. Chow W K. Design separately for the pressure requirementand velocity requirement in a “Staircase Pressurization System” – A case study. InProceedings of CLIMA 2000 Conference, CIBSE/ASHRAE/CIB/REHVA, London.Nov 1993.
10. Klote J H. Milke J A. Design of Smoke Management Systems. ASHRAE. 1992.11. ASHRAE HANDBOOK 1995 – HVAC Applications, Chapter 48 – Smoke
Management.12. BS 5588: Part 7: 1998. Code of Practice on Smoke Control in Atria.13. Morgan H. Gardner J P. Design principles for smoke ventilation in enclosed
shopping centres. HMSO UK. 1990.14. Hansell G O. Morgan H P. Design approaches for smoke control in atrium buildings.
HMSO UK. 1994.15. Predtechenskii V M. Millinskii A I. Planning for foot traffic flow in buildings
(1969). Translated from Russian, Amerind Publishing Co. Put. Ltd., New Delhi,India, 1978.
16. FPETOOL Software – NIST – USA.17. National Fire Codes of NFPA – USA – NFPA 92B-91 (Mall, Atria), 204M-91
(Smoke and heat venting), 90A-93 (Air-conditioning , Ventilating systems), 92A-93(Smoke control systems), 101-94 (life safety).
12. Fire Alarm Systems
COP-FSI defines “Fire alarm systems” as “Any manually operated system designed togive warning of fire”.
Normally, this system consists of break glass units (manual call points), alarm bells, andelectrical /electronic fire control panels wired together, such that when a break glass unitis actuated, the alarm bells of the entire building will sound, unless the system is silencedmanually at the fire control panel.
In very tall buildings in Hong Kong, the sounding of the bells may be limited to the firefloor, 2 floors above it, and one floor below it, to prevent evacuation of people to occur atthe same time. Other automatic fire detectors such as smoke / heat detectors and / orsprinkler flow detector, may be connected and to the same fire control panel with themanual fire defection system using the break glass units, and to sound the same set ofbells.
The control panel is normally housed in a Fire Control Centre, or in a prominent positionnearby the firemen’s lift access, and / or the location of the building guard.
For more information, see Section 14. Fire Detection System.
13. Fire Control Centre
COP-FSI defines “Fire control centre” as “A compartment (situated at street level havingdirect access to open air and vehicular approach) containing annunciator boards, controls,terminals, etc. of the Fire Protection and Life Safety Systems within that building /complex.
14. Fire Detection Systems
14.0 General
COP-FSI defines: “Fire detection systems” as “Any system designed to detectautomatically the presence of smoke, heat, combustion products or flames and givewarning of same.”
Loss Prevention Council, UK (LPC, UK) approves the follow items for fire detection andalarm systems:-
- Certificated fire detection and alarm system firms (in UK)- Fire detection and alarm systems- Control and indicating equipment- Detectors- Manual call points- Line units- Sounders- Fire resistant cables- UL910 cables (UL is Underwriters’ Laboratories of USA)- Central stations for fire alarm systems- Signalling systems for central stations- Control and indicating equipment to BS 3116: Part 4: 1974
Currently, HKFSD basically uses FOC (Fire Offices’ Committee) Rules for AutomaticFire Alarm Installations for the protection of property, 12th edition, 1985 (Note that theRole of FOC has been taken over by LPC since 1986). The content of these FOC Rulesfor AFA is:-
Foreword1. General information2. Classification of installations3. Protection4. Equipment5. Zones6. Wiring7. Certification, testing and maintenanceAppendix A Listed companies certificateAppendix B Log book format
FSD is discussing actively with the industries and professionals to adapt LPC Rules forAFA for use in Hong Kong. These rules comprise clauses written by LPC, adding to thebasic BS5839: Part 1: 1988.
14.1 AFDA system description
The various components of fire detection and alarm systems are shown in a schematicdiagram. (See figures at http://arch.hku.hk/teaching/project/301control.htm andhttp://arch.hku.hk/teaching/intgtech/111.htm)
There exits a variety of fire detectors:-
Heat Detectors
• Point type (fixed temperature) – The detector responds when the air temperaturesurrounding the detector rises to a certain level.
• Pont type (Rate-of-Rise, ROR) – The detector responds to a certain rate of rise oftemperature of the surrounding air.
• Point type (fixed temperature and ROR) – The detector responds when either of theabove conditions occurs.
• Beam type – A receiver mounted on one side of a large volume emits a light beam(normally laser) that reaches the receiver on the other end. The signal received willchange if the air temperature or the rate of temperature rise of the air changes. Thecontrol panel will compare the signal received with preset fire signal referencememory, to check if a fire really occurs. To surveille a larger volume, some beamdetectors employ reflecting mirrors interposed between the laser sender and receiver.
• Linear heat detector – 2 cables insulated from each other run around the surveilledspace / object. Heat generated will melt the insulation, causing cables coming intocontact or giving different signals at the receiving panel. The location of fire can alsobe reported, knowing the distance of the affected portion of the linear heat detectorfrom the panel.
Smoke Detectors
• Point type (optical) – Light is emitted inside the detection chamber into which smokecomes. A receiver inside the detection chamber receives the light scattered by thesmoke particles. Traditional detectors decide from the received signal if a fire occurs.Analogue addressable detectors let the fire control panel and its memorised firereference library decide if a fire should be announced, or a warning signal, or a faultsignal.
• Point type (Ionization) – The smoke particles / air particles inside the detectionchamber of the detector are ionized by an ionization source which is normallyAmericium 241. The amount of ionized particles reach the receiver will reflect theamount of smoke present. Refer to point type – optical, for signal analysis.
• Beam type – This is similar to beam type heat detector except that the signal receivedby the analysing panel is calibrated to respond to smoke growth and presencecharacteristic of fire situations.
• Aspirating smoke detectors – Air is drawn by a tubing system to a sensor which isnormally now a laser source and a receiver of the scattered laser (i.e. smoke scatterslaser) for raising a warning / fault / false / fire alarm.
Flame Detector
Flame emits strong infrared radiation. Flame detectors respond to this to give alarms.
Gas Detectors
Combustible gas detectors are normally point types. One type makes use of catalyticeffect of a chemical compound inside the detector to cause the combustible gas to changeits chemical nature, at the same time inducing changes in electronic flow which aredetected and analysed to give a signal of the presence of a dangerous concentration of thecombustible gas.
The detectors are linked to control panels to form a detection and analysis systemclassified as:-
• Zoned system - several detectors forming one fire detection zone, several zones in abuilding.
• Addressable system – each detector is giving an address showing at the fire detectioncontrol panel if the detector detects fire, a fault signal.
• Analogue addressable fire detection system – the magnitude of the detected signalcan be continuously monitored and the threshold for giving out warning, and alarmcan be set at the panel.
An AFA fire signal is connected automatically to HKFSD Fire Control Centre so thatFSD will send firemen to the affected building upon receipt of the fire signal.
The following LPC listed companies produce various types of smoke / heat detectors andsystems, and their web sites contain a lot of updated product and related technologyinformation:-
Caradon Gent http://www.apgate.com/elec/company/co_13633.htm
Apollo http://www.crowcon.com/apollo.htm
Cerberus http://www.cerberus.ch/
Edwards http://www.edwardsinternational.com/product.htm
Hochiki http://www2.hochiki.com/
Honeywell http://207.88.216.196/Cfire.htm (of http://www.honeywell.com/) contains,among other information, an article called: Excel Fire Alarm System- The Essentials of Fire Detection Alarm
Kidde http://www.kidde.co.uk/
Nittan http://www.nittan.com
Notifier http://www.notifier.com/
Thorn http://www/bsdirectory.com/docs/24_4.htm
The following web sites contain information on aspirating smoke detectors:-
Cerbeurs http://www.cerberus.ch/
Stratos http://www.dialspace.dial.pipex.com/town/square/hu07/stratos.htm
Hygood http://www.hygood.co.uk/
VERDA http://www.vsl.com.au/vesda/
Kidde http://www.kidde.co.uk/
14.2 Reference
RULES OF THE FIRE OFFICES’ COMMITTEE AND FIRE OFFICES’ COMMITTEEOF IRELAND FOR AUTOMATIC FIRE ALARM INSTALLATIONS FOR THEPROTECTION OF PROPERTY, 12th EDITION, February 1985
The Loss Prevention Certificate Board. List of Approved Fire and Security Products andServices, Annual Publication. Loss Prevention Council, UK.
BS5839: Fire detection and alarm systems for buildings. BS5839: Part 1: 1988 Code ofPractice for system design installation and servicing.
15. Fire Hydrant / hose reel system
15.0 General
COP-FSI defines “Fire hydrant / hose reel systems” as “An installation of pipes, watertanks, pumps, hydrant outlets and / or hose reels in a building to provide a ready meansby which a jet of water can be delivered in any part of the building for the purpose of firefighting”.
See the specification of this system laid down in the COP-FSI.
15.1 Important Notes
It is important to note that for fire hydrant systems that:-
• It is preferable to locate the water storage tank at the top of the building, so that thesystem is fed by gravity as far as possible. Of course a transfer pump and a transfertank (could be less than 1 cu.m) have to be installed at ground / podium basementlevel to transfer water to the Roof tank.
• It is the intent of the COP-FSI that no unnecessary pressure loss should occur in thewater path starting from the fire engine at road level pumping water to firemen’snozzles, via any pipework, the fire hydrant in the building, and the flexible hoseconnected to the hydrant. Particular caution should be given to the use of integratedpressure reducing hydrants which could prohibit the optimum use of fire fightingwater under certain conditions (Cheung, 1998b). It is always wise to useconventional simple hydrants.
• The pipework should be designed to fulfil the requirements of COP-FSI, COP-I&T;and also the unstated requirements with which firemen operate the fire hydrantsystem.
The testing requirements of COP-FSI, COP-I&T cover a few limited cases howfiremen use fire hydrant systems. There are a lot other conditions not stated in theCOPs under which firemen operate the fire hydrant system (Cheung, 1998a, 1998b).If the fire hydrant system is not designed to cope with these conditions as far aspossible initially, the occupants of the building will suffer when a fire occurs. Thekey point is to design the hydrant system to enable the minimum use of flexible hoseand portable fire pumps by firemen, when all fixed/intermediate pumps in thebuilding fail to operate.
• Hong Kong is the most-densely built city in the world and is having the highest priceper unit residential area. Also residential fatal fires do occur. It is advisable to allowtee off from the Roof hydrant water tank to feed sprinklers (or just cut-off sprinklers)
inside residential units, with flow detector alarm connected to the manual breakglassalarm system. No sprinkler control valve is needed, but an independent sprinklerinlet should be provided. The smallest hydrant tank which is 9 cu.m can supply onesprinkler and one hosereel nominally for 112 minutes (Note that: one sprinklerdischarges 60 l/min to cover 12 sq.m and one hosereel discharges norminally about20 l/min. Even one cut-off sprinkler installation at every flat will greatly enhance firesafety in residential buildings. This proposal is very cost-effective (Cheung, 1998c).
• Locate hosereels such that when the user fails to fight the fire, and even if visibility isgreated impaired, he can hold on the hose and follow the path to go back to thelocation of the hose reel and escape into corridors / protected lobbies / staircases,without being trapped by the heat / smoke of the fire. If the temperature is too high,he can crawl on the floor and spray the water of the hosereel on to himself, gaining ahigh chance of not being injured.
• For very tall buildings, fire hydrant systems have to be designed with the refuge-floorbased fire evacuation and fire fighting approach (Cheung, 1997).
For normal buildings, see http://arch.hku.hk/teaching/ on Building Services Projects forexamples of Fire Hydrant and Hosereel Schematics.
15.2 Reference
Cheung, K.P., (1998a). An analysis of a fire hydrant / standpipe / wet riser system of a40-storey residential building in Hong Kong. J. Applied Fire Science, Vol. 7 (1) 55-71,1997-98.
Cheung, K.P., (1998b). A discussion on the use of landing valves having integratedpressure reducing devices in tall buildings: Part I, for valves with fixed ratio pressurereduction. Building Services Engineering Research & Technology. CIBSE, UK, 1998.
Cheung, K.P., (1998c).
Cheung, K.P., (1997) Chan H.W., A discussion on the design principles of fire hydrantsystems and sprinkler systems in refuge-floor based fire safety design in tall buildings.Fire Safety Conference. The Federation of Engineering Societies – China Association forScience and Technology. Zhuhai, China, October 1997.
17. Fixed automatically operated approved appliances
COP-FSI defines “Fixed automatically operated approved appliances” as “Any fireservice equipment which is manufactured, used or designed to be used as an independentunit for the purpose of extinguishing, attacking, preventing or limiting a fire, butautomatic in operation and fixed in position, e.g. a BCF sprayer unit in a DangerousGoods store.”
Note that BCF (Halon 1211, which is
longer produced for commercial use, due to its ozone depletion effect. Also BTM,Bromo-
trifluoro-methane,
production.
Traditionally BCF sprayers were used. The sprayer bottle contains the agent underpressure. When the glass bulb sensor is actuated by high temperature, it bursts like aglass-bulb sprinkler, releasing and spraying the pressurised agent into the protected space.
The following web sites contain the related product information:-
22. Portable hand-operated approved appliances
22.0 General
COP-FSI defines “Portable hand-operated approved appliances” as “Any fire serviceequipment which is manufactured, used or designed to be used as an independent unit forthe purpose of extinguishing, attacking, preventing or limiting a fire, e.g. water type,foam, inert gas, any chemical extinguishers, fire blankets and sand buckets.”
22.1 Various fire extinguishers and their fire extinction principles
There are two classifications adopted in Hong Kong for fire extinguishers:-
By National Fire Protection Association, USAClass A: Fires involving ordinary combustible materialClass B: Fire involving flammable liquids, gasesClass C: Fires involving live electrical equipment where the electrical non-
conductivity of the extinguishing media is of importanceClass D: Fires involving combustible metalsClass K: For commercial cooking areas (used after the fire protection system is
activated, since 1998)
By British Standards Institution, UKClass A: Fires involving ordinary combustible materialClass B: Fires involving flammable liquids
Bromo-chloro-difluoro-methane, is no
Cl
F - C – F, Br
F Br - C – F, F
is depleting ozone, and is also banned from commercial
Class C: Fires involving gases or liquefied gasesClass D: Fires involving combustible metalsClass E: Electrical fires
Each fire extinguisher (F.E. imported from UK, USA, Mainland etc.) is marked with theClass(es) of fires the F.E. can tackle.
Different fire extinguishers contain different fire fighting agents operating on differentprinciples of fire suppression, namely, starvation (the limitation of fuel), smothering(covering the fuel with a fire blanket, resulting in the limitation of oxygen, and limitingproduction of vapour combustibles from the fuel), cooling (the lowering of temperature),chemical flame inhibition.
Portable fire extinguishers can be divided into the following five main groups, dependingupon the extinguishing agent they contain:
Group 1: Water extinguishers:(a) gas pressure(b) stored pressure(c) soda / acid
Group 2: Dry powder extinguishers
Group 3: Foam extinguishers:-(a) mechanical or gas pressure(b) chemical
Group 4: Carbon dioxide extinguishers
Group 5: Vaporising liquid extinguishers
Can you explain the principles with which each type of F.E. extinguishes the relatedclasses of fires? (See answer)
In chemical flame inhibition, the hydrogen radicals, which promote chain reaction for fireto sustain, will be combined with Fluorine, Chlorine, Bromine, Iodine atoms of thegaseous extinguishing agents such as BCF, BTM – Bromo-Trifluoro-Methane
radicals, chain reaction and heat generation. Fire then stops. It should be cautioned thatthere might be little cooling by the gaseous agent. If the hot object which just stoppedburning is not further cooled down, dilution of the gaseous agent due to leakage orotherwise may subsequently cause burn-back of the object (i.e. The object burns again).
Dry powder extinguishes a fire also by the flame inhibition principal.
Fire extinction is best understood with the mechanisms of combustion:-• combustion is a reaction which is a continuous combination of a fuel with certain
elements, prominent among which is oxygen, in either a free or combined form• for combustion to occur, fuel, oxygen, heat have to co-exist (The fire triangle)• the reaction is exothermic, self-catalysed, self-sustained• heat and light and smoke (normally particles from incomplete combustion)
to form stable HF, HCl, HBr, HI. This results in reduction of hydrogen
Br F - C – F, F
Combustion proceeds in the following sequence:• Heat is applied to the fuel• certain volatiles / vapour evolve from the decomposition of the fuel• flame starts when
- ignition temperature is reached- adequate gas / vapour / volatile / combustible dust concentration is reached
22.2 Reference
¡§±Ð§A¥Î®ø̈¾³]³Æ¡ ̈“Teach You How To Use Fire Service Installations” (in Chinese)contained in pages 18 to 23 of CHOICE, Monthly Bulletin, The Consumer Council, HongKong, February 1998. See an article (See Reference) related to use of F.E., by H.K.Consumer Council.
Hall, J.P.,
23. Pressurization of staircases
23.1 COP-FSI states:-
“Pressurization of staircases” means – “A system designed to protect staircases against theingress of smoke by maintaining the air within staircases at pressures higher than those inadjacent parts of the building”.
The number of staircase(s) requiring pressurization shall be determined by the cubicalextent of the basement, or building as the case may be, according to the table provided inthe COP-FSI.
For hotels, COP-FSI requirements on staircase pressurization is summarised as:-
- Required when openable window area of rooms does not exceed 6.25% of floor areaon a floor by floor basis, and natural venting is not provided.
- No. of staircase to be pressurized
Cubicle Content (m3) No.
< 56,000 156000 to 112000 2112000 to 168000 3over 168000 4
- pressure at stairwell: 50 Pa min.- maximum door opening force: 133 N- single injection for building height below 30 m and multiple injection above- system to cater for opening of doors in 3 floors and main exit door
23.2 The basic requirements for a staircase pressurization system, the problems andthe uncertainties
(i) Pressure Requirement
A minimum pressure level (Note: in Hong Kong - 50 Pa) to be maintained betweenthe staircase / lobby and the fire floor, when the door separating the staircase / lobbyand the fire area is closed; and
(ii) Velocity Requirement
(Note: in Hong Kong – 0.75 m/s) to be achieved for air flowing from the staircase/lobby into the fire area when the doors interposed between the staircase and the firearea are opened partly or wholly; and
(iii) Door Opening Force Requirement
The force applied at any door opening handle or push plate of the doors separatingthe staircase / lobby and the accommodation area shall not to exceed a certain valueunder all circumstances (Note: in Hong Kong this value is 133 N).
There however still exists a number of problems and uncertainties pertaining to the currentdesign technique of staircase pressurization systems of delivering the pressurized air to thestaircase / lobby, making the aerodynamic reliability very low. That is, the pressurerequirement primarily and the velocity requirement are almost impossible to be achievedtogether practically. For example, a system for a staircase serving a 3-storey basementunder the test conditions could not meet all the criteria, even though the system is equippedwith a variable pitch axial fan injecting air to the bottom of the staircase, and an air-reliefdamper installed at the top of the staircase at ground level.
This calls for a re-appraisal of these problems and uncertainties, and re-thinking of therationale and design techniques of staircase pressurization.
THE PROBLEMS AND THE UNCERTAINTIES
The uncertainties pertaining to staircase pressurization systems have long been stated, yetstill untackled. These uncertainties are: -
(i) The number of doors, and the periods of time that they are opened (including thedoors at the roof and ground level).
(ii) The stack effect due to the difference between the temperatures inside the staircase,the accommodation area, the fire floor, and the outside
(iii) The external wind effect
For example, a 15.6 m/s wind blowing onto a building of 60 M tall, with a neutral plan atthe mid-height, an outside temperature of -18°C and an inside temperature of 21°C, themaximum pressure due to stack effect and wind effect could be 55 Pa and 117 Parespectively, summing up to 172 Pa. Should these conditions occur, the system wouldcertainly fail if designed on 50 Pa.
Even though these uncertainties are neglected, and the actual number of doors to beopened/closed are confirmed in testing conditions, the following problems inherent with thecurrent practice of delivering pressurized air to the staircase/lobby (i.e. one air source forproviding the pressure requirement and the velocity requirement) greatly hamper satisfactionoperation of the systems:-
(i) The basic performance characteristics of axial fans and centrifugal fans, and in mostcases coupled with ducts, grilles and dampers, do not cope equally well both withthe design pressure and velocity requirements together.
(ii) There is a lack of a high degree of sophistication, and the speed of response topressure change , and control for the system which should include motoriseddamper control for proper air delivery at every level of the staircase, and accuratepressure sensors to be installed at every level.
Assuming control sophistication can ensure the system perform satisfactorily under testingconditions, the uncertainties above would easily defeat the system performance. In one case,the pressure inside the staircase could be designed to 92 Pa at most, in order to meet theopening force limit of 133 N. The wind effect alone illustrated above could not beovercome yet, not to mention other uncertainties.
The above is abstracted from a paper called “Design separately for the pressure requirementand velocity requirement in a staircase pressurization system – a case study” written by K PCheung, L W Lam, W K Chow, presented to CLIMA 2000 Conference, London, Nov,1993).
23.3 Design Reference for Staircase Pressurization and Smoke Control
(Same as Section 8.4)
25. Sprinkler System
25.0 General
COP-FSI defines “sprinkler systems” as “A system designed to discharge water underpressure from sprinkler heads (detecting devices) at / or near the point of origin of the fireand to sound an alarm.”
25.1 General Concepts on Sprinkler Systems
25.1.1 Brief History of Sprinkler Development
Major A Stewart Harrison of the First Engineer Volunteers of London invented the firstsprinkler in 1864. However it was until 1874 when Henry S Parmelee of Connecticut ofUSA produced the first widely used automatic sprinkler with heat sensitive device, thatsprinklers became widely used for fire protection. Throughout this 125 years, many rules,codes, regulations and standards have been produced for automatic sprinkler installations,firstly started by the fire insurance associations and later by national authorities. Newsprinklers such as Early Suppression Fast Response Sprinklers have also emerged.
The fire insurance company offers an annual premium reduction to the building owner fora properly installed with an automatic sprinkler system. This premium reduction could beas high as 45%, provided that other fire safety features such as compartmentation,portable fire extinguishing equipment etc. as required by the insurance company, are alsoinstalled. This annual premium reduction, together with the much less anticipated loss in
case of fire, help encourage the building owner to spend an initial amount of money toinstall sprinkler systems. A sprinkler system is usually about 1% to 1.5% of the totalbuilding cost, or 3% to 5% of the total electrical and mechanical services installation cost.
The UK and US have always been the leading countries in sprinkler research anddevelopment. In recent years West Germany and Japan also contribute substantially inthe sprinkler industry.
The sprinkler rules used in Hong Kong are primarily Loss Prevention Council (LPC, UK)Rules for Automatic Sprinkler Installations, which comprise BS5306 Part 2 and LPCTechnical Bulletins.
Occasionally the following sprinkler rules are also used:
- National Fire Code 13-Standard for the Installation of Sprinkler Systems published bythe National Fire Protection Association, U S A
- Loss Prevention Data 2-8N-Installation of Sprinkler Systems, published by FactoryMutual Engineering Corporation of USA
Since 1974, Hong Kong Fire Services Department has specified sprinkler installations fornearly all commercial and industrial buildings and primarily enforced the FOC (FireOffices’ Committee, UK) Sprinkler Rules which are now superseded by the LPC (UK)Sprinkler Rules, with minor local adaptations. These rules are also applied by the fireinsurance companies in general in Hong Kong. The criteria and design described in thislecture, therefore refer to these rules (i.e. LPC Rules).
25.1.2 The components of a Sprinkler System
The sprinkler systems are designed to deal mainly with solid-fuel fires, but can serve alsoto hold a flammable-liquid fire in check and to extinguish some oil fires (e.g. transformeroil fires) by deluge sprinklers, by purely using water. With suitable foam concentrateadded to the water, its fire fighting capability on oil fires can be greatly enhanced.
Each system is designed for its particular function, and its features may vary widelyaccording to the purpose. In general, a system will consist of the following items: (Fig25.1.2a)
- A water storage capacity or adequate running supply, to feed the system.
- An adequate method of pumping water from the supply to the system.
- Distribution pipework capable of conveying all the water required to feed thesprinkler heads, without unnecessary pressure losses.
- A sprinkler installation valve connected to a hydraulic motor alarm gong to give anaudible mechanical water motor alarm when the valve opens to allow water to flow tothe sprinklers discharging water.
- A series of distributor heads (i.e. sprinklers – close / open type; open jet nozzles)capable of passing the design flow rates of water and distributing the water as a spray,over the area to be protected.
- A detector, or detector system, capable of actuating the fire fighting / protectionsystem. The detector can be the sprinkler itself or other detection device / system.
- Other features include flow detectors, pressure switches for starting pumps, andcontrol / signal monitoring alarm panels etc. The sprinkler schematic diagram for ahigh rise building (Fig 25.1.2b) also helps explain these features. Note the differencein location of sprinkler installation valves and the pressure switches for controlling
pumps for high rise sprinkler installation (The highest sprinkler is more than 45mfrom the lowest sprinkler in the building) and low rise (within 45m ….) sprinklerinstallations.
25.1.3 The Fire Hazards
Sprinkler systems are designed for three main classes of hazards, which are described inthe LPC Rules as:-
Light Hazard (LH)Ordinary Hazard (OH)High Hazard (HH)
These hazards are further subdivided as follows:
LH – No subdivisionOH Group I, II, III, III Special (IIIS)HH-Process HH, high-piled storage hazards, potable spirit storage hazards, oil andflammable liquid hazards
The types of occupancy covered by each class are listed in Sections 5.2, 5.3 and 5.4 of theLPC Rules, highlighted as follows:
Light Hazard (LH)
In non-industrial occupancies where the quantity and combustibility of the contents arelow, rooms and corridors not more than 126 sq.m in area and bounded by elements ofconstruction with a fire resistance of not less than 30 min shall be classified as lighthazard.
No room may have more than six sprinklers.
Rooms larger than 126 sq.m or with walls of lower fire resistance are classified asordinary hazard, group I.
LH occupancies include hospitals, hotels, museums, libraries, other institutional buildings,offices.
Ordinary Hazard (OH)
In non-industrial occupancies, rooms which exceed the limits specified for light-hazardclassification shall be classified as ordinary hazard, group I.
Commercial and industrial occupancies involving the handling, processing and storage ofmainly ordinary combustible materials, which are unlikely to develop intensely burningfires in the initial stages, shall be classified as OHI, II, III, IIIS.
OHI occupancies include: restaurants, cafes, manufacturing processes with largely non-combustible products, e.g. abrasive wheel manufacturers, breweries, dairies, etc.
OHII occupancies include: retail shops (with up to fifty employees), biscuitmanufacturers, some chemical works, engineering works, potteries, tobacco factories.
OHIII occupancies include: manufacturing processes of a greater hazard than Group II,but still not especially hazardous, e.g. aircraft, boots and shoes, carpets, clothing, corn andprovender, paper goods, plastics (but not foamed plastics), warehouses (where storage isnot above specified heights).
OHIIIS occupancies include: cotton mills (processes preparatory to spinning), distilleries,match factories.HH – Process Hazards: 4 Types (see LPC Rules)
Aircraft hangars, firework manufacturers, manufacturers of foamed plastics and foamedrubber goods, paint and varnish, etc.
HH – High Piled Storage Hazards
Category I Certain ordinary combustibles stored in bulk, in pallets or on racking, toheights exceeding 4m.
Category II Various combustible goods stored to heights, exceeding 3m, e.g. baledcork, chipboard, alcohols and lacquers in cans, non foamed plastics, etc.,on racks or in pallets.
Category III Foamed plastics and foamed rubber products generally, celluloid, asphaltpaper (vertical) rubber goods, etc., stored to heights exceeding 2.1m.
Category IV Offcuts and random pieces of foamed plastics and foamed rubber, etc.,stored to heights exceeding 1.2m.
25.1.4 Design Water Densities
Sprinkler systems are designed to give a design density of water discharge according tothe category of hazard, and to maintain this density over certain specified minimum area,for a certain minimum period.
The water supplies available, the pumping capacity and the distribution pipework musttherefore be designed to achieve the above minimum performance requirements for theappropriate hazard classes, summarised as follows:-
Minimum duration of water
Hazard Design Water Density * Minimum Area (sq.m) availability
LH 2.25 mm/min. 84 sq.m 30 min.
OHI, II, III, IIIS 5.0 mm/min. 72, 144, 216 sq.m 60 min.
HH (Process) 7.5 to 12.5 mm / min. 260 sq.m 90 min.
HH (Storage) 7.5 to 30.0 mm/min. 260 to 300 sq.m 90 min.
Note: * This minimum area is defined in LPC Rules (BS5306: Part 2 – Section 14) asAMAO – Assumed Maximum Area of Operation, and minimum duration ofwater availability is expressed in Table 24 of BS5306: Part 2.
25.1.5 The various sprinkler systems (See http://www.reliablesprinkler.com/sprinkler.htm)
The following systems are described in detailed in the LPC Rules.
System Use
a. Wet Pipe System – all pipeworkfilled with water (most widelyinstalled type)
Office, department store etc. for non-frozen normaltemperature conditions.(See system schematic diagram athttp://arch.hku.hk/teaching/intgtech/113.htm)
System Use
b. Dry Pipe System (with waterunder pressure below the valves)
Used where the system pipework may be subjected tofreezing temperatures at any time of the year, orwhere the temperature conditions are artificiallymaintained close to or below freezing point such as incold stores, fur vaults etc. or where the temperature ismaintained above 70°C as in drying ovens etc.
c. Alternative wet and dry pipesystem (a standard sprinklersystem embodying a CompositeAlarm Valve or a combinationset comprising a Wet AlarmValve and Dry Pipe Valve).
During the “Winter” period the system piepwork isnormally charged with air under pressure, and thesystem below the valve with water under pressure.
During the “Summer” period the Dry Pipe Valve is“decommissioned” and the system pipework ischarged with water under pressure, operating as astandard Wet Pipe System.
d. Pre-action system. This systemincorporates a system of heat orsmoke detectors installed in thevicinity of the sprinklers in a DryPipe or Alternate Wet and DryPipe System. The detectionsystem is linked to the sprinklersystem Pre-Action Valve,causing it to ‘trip’ and flood thesprinkler system pipework withwater even before a sprinklerhead has opened. The systemnow operates as a standard WetPipe system and water is readilyavailable at the sprinkler head.Discharge of water can onlyoccur, however, when thesprinkler head operates.
For special applications e.g. some industrial processes(hot and cold environments), some computer rooms.
e. Wet pipe or alternate wet and drypipe system incorporating tailend dry pipe system.
Tail end for cold (frost) conditions and hot areas suchas ovens. Rarely applicable in Hong Kong.
f. Wet pipe system incorporatingtail end alternate systems.
Tail end protected areas do not frost in certain time ofthe year.
g. Deluge sprinkler system (asystem of open sprayers ornozzles, controlled by a quickopening Deluge Valve which isactivated by a system of heatdetectors or sealed sprinklersinstalled in the same area as theopen sprayers or nozzles).
For industrial processes where simultaneous dischargeof water is necessary e.g. oil filled transformer, oiltank cooling.
25.1.6 Sprinklers
A sprinkler (close nozzle type) is a nozzle set off after the heat sensing element (fusiblealloy or glass bulb) is released from its normally tensioned location by the heat of theenvironment. It serves dual purposes as a heat sensing device and a fire fighting deviceby discharging water. Nearly all fires in sprinklered buildings are either extinguished orcontrolled by sprinklers. Human intervention on the fire scene is essential after sprinkler
discharge for ensuring that the fire is completely extinguished and will not burn back, thefire / water damage is minimised – (salvage work).
LPC (Loss Prevention Council) approves sprinklers, and issues. A List of ApprovedAutomatic Sprinkler Equipment which contains the approved sprinklers.
The discharge patterns and philosophy of conventional spray and sidewall sprinklers aredifferent (Fig 25.1.6a).
Sprinkler type, discharge pattern, temperature rating, and speed of response to fire, arekey elements in classifying sprinklers(See http://www.reliablesprinkler.com/sprinkler.htm).
LPC performs about 20 tests for sprinklers before approving them. These tests includebore check, checking crush load of glass bulb, thermal testing, pressure testing etc.
25.1.7 Other Components
Other components include:- Pipework – See Section 5 of LPC Rules (i.e. Section 5 of BS5306: Part 2) .- Water flow detector and pressure switch installed at sprinkler installation valve and at
electrically monitored subsidiary stop valve (LPC Rule 20.1.4 and Fig. TB.13.F1) togive remote indication at the Fire Control Room / Point with sprinkler flow detectorsignal to be connected to HKFSD Control Centre for automatic reporting of fire.
- The sprinkler installation valve set and alarm gong (Fig 25.1.7a).- Pumps and tanks to be provided in accordance with Section 4 of LPC Rules to suit
the occupancies defined in Section 1 of LPC Rules.- Pumps starting devices (Fig 25.1.7b).
25.1.8 Reference
LPC Rules for Automatic Sprinkler Installations – published by the Loss Prevention, UK.LPC Rules comprise BS5306: Part 2 (Fire extinguishing installations and equipment onpremises. Part 2. Specification for sprinkler systems), and LPC Technical Bulletins (TB).Both BS5306: Part 2 and TBs are updated / added from time to time. (The address ofLPC is: Melrose Avenue, Borehamwood, Hertfordshire WD6 2BJ, UK.)
LPC List of Approved Fire and Security Products and Services. Annual publication.
Nash P. The essentials of sprinkler and other water spray fire protection systems.Building Research Establishment Current Paper CP79/75. Department of EnvironmentUK, August 1975.
Nash P. Young R A. Automatic sprinkler systems for fire protection. 2nd Edition.Paramount Publishing Limited. 1991. (HKU Main Lib. 628.9252 N2)
Web Site of Reliable Sprinklers (http://www.reliablesprinkler.com/home.htm)
26. Static Smoke Extraction Systems
26.1 COP-FSI defines “Static smoke extraction system” as “A smoke extraction systemutilizating smoke reservoirs; localised ducting; and permanent openings and / orautomatic opening of windows, panels or external louvers actuated by smoke detectors; toremove, on the principles of natural ventilation, smoke and products of combustion froma designated fire compartment.”
The COP-FSI further states that:-
Static smoke extraction system may be provided, as the alternative to the Dynamic smokeextract system if ALL of these three conditions are satisfied:
(a) smoke reservoirs each not exceeding 500 square metres in area can be provided underthe ceiling by fixed or automatically operated smoke screens to the specifications ascontained in Part V of the COP-FSI, and
(b) the horizontal distance between the perimeter of any smoke reservoir and the externalwall of the building where windows, panels or external louvers functioning as smokeoutlets are installed, does not exceed 30 metres and that one side of the reservoir shallabut the external wall, and
(c) the aggregate area of windows, panels or external louvers functioning as smokeoutlets is not less than 2% of the floor area this system serves, and that at least half ofthese outlets are operable by automatic actuating devices.
The COP-FSI specification for the system is summarised below:-
Smoke Reservoir
- 500 sq.m- perimeter to discharge < 30 m
Smoke Barrier
-non-combustible, 1 hr. F.R.depth below lowest beam:-800mm for “below ground” floor500 mm for “above ground” floor- above finished floor >= 2 m- -“fail safe” design for movable barrier- -openings for other services < 100 mm x 100 mm
Smoke Discharge
- free area > 2% of the serving floor area- ½ of discharge be permanently open, or automatically actuated on smoke signal- actuation be “fail-safe”, and back-up by essential supply- smoke detector in each 250 sq.m- manual quick release be provided at height < 1.8 m- sign to remind not obstructing the vent
26.2 Some Case of Static Smoke Control Systems
26.3 Basics of Smoke Control Systems
(Same as Section 8.3)
26.4 Design Reference
(Same as Section 8.4)
KPC/cn//Paper_FireService/Feb. 1, 99
