Presentation on theme: "KURSUS PENGENALAN KEPADA PERKHIDMATAN MEKANIKAL DALAM BANGUNAN"— Presentation transcript:
1KURSUS PENGENALAN KEPADA PERKHIDMATAN MEKANIKAL DALAM BANGUNAN
2AN INTRODUCTION TO FIRE FIGHTING DESIGN CARBON DIOXIDESYSTEM
3CONTENTS INTRODUCTION DESIGN STANDARDS SYSTEM OPERATION CARBON DIOXIDE CYLINDERSCARBON DIOXIDE CONTROL PANELDISCHARGE NOZZLEAUTOMATIC DETECTORS AND ALARM BELLSPIPEWORK AND FITTINGSWARNING SIGNS
4AUTOMATIC CARBON DIOXIDE SYSTEM Consists of CO2 cylinders, steel piping, discharge nozzles, heat/smoke detectors, gravity shutter, alarm system etc.Discharged after a time delay upon detection of fire.Usually for Transformer room, Switchroom, Standby Generator room and High Switch Gear room.
5DESIGN STANDARDSIn the UBBL (1984), the By-laws relating to Carbon Dioxide is By-laws 235 and the applicable standard is:NFPA 12
6SYSTEM OPERATIONQuantity of agent should be sufficient to ensure rapid extinction.The protected area should be flooded with CO2, concentration of 50% at 21C, with period of 30 seconds, adjustable up to 60 seconds.Total discharge shall not exceed 1 minute.For deep seated total discharge shall not exceed 7 minutes or 30% discharge within 2 minutes.Supply Voltage 240V A.C, 50 Hz.A 24V D.C standby battery in case of mains voltage failure.
7SYSTEM OPERATIONThe space protected by two or more heat or smoke detectors.8. The indicator light on the control panel should illuminate and audible warning sounded via alarm bell.
8CARBON DIOXIDE CYLINDERS Gas stored in a liquefied form at ambient temperatures.Working pressure of 59 bars at 21C and pressure tested at 228 Bars.Name plate specifying the number, filling weight and the pressurisation level.All cylinder supplying the same manifold outlet for distribution.Where more than three cylinders are required, a pilot cylinder should be provided to activate the discharge from each cylinder.
9CARBON DIOXIDE CONTROL PANEL Should indicate the operation of the system hazards to personnel, or failure of any supervised device.Complying with MS 1404 and BS 7273.Alarm should be provided to give warning of a discharge.A device should be incorporated into the system to shut down any exhaust fans and activate solenoid operated curtains across louvres before discharge.
10DISCHARGE NOZZLEThe discharge nozzle should consists of the orifice and any associated horn, shield or baffle.Discharge orifices should be of corrosion resistant metal.Permanenrly marked to identify the nozzle and to show the equivalent shield orifice diameter regardless of shape.Discharge nozzle should be provided with frangible disc
11Automatic Detector and Alarm Bells The Automatic detection is usually by means of either heat or smoke detectors.Should be resistant to corrosion.The alarm bells should produce an alarm at least 65dBA or 5dBA.The bell should be of the trembling (not single stroke).
12WARNING SIGNSWarning and instruction signs should be installed at entrances to and inside protected areas at prominent positions.
13PIPE WORK AND FITTINGThe material of piping and fittings must be of non-combustible heat resisting.Maintain its own shape in room temperature during the outbreak of fire.All piping should be of API Schedule 40/80 steel pipe.
14SAMPLE CALCULATION FOR CO2 SYSTEM PROJECT : NEW MORTUARY FOR PENANG HOSPITALROOM NAME : STANDBY-GENERATOR ROOM
15STAND BY–GENERATOR ROOM Area = 5.5 X 6.0m = 33m²Volume = 5.5 x 6.0 x 4.15m = 137 m³Nozzle coverage area = m²Nos of nozzle required = 33/ = ~ 2 nos.Flooding Factor = 1.35kg/m³Design Concentration = 50%Actual weight of CO¸ = 137m³x1.35kg/m³= 185kgNos of cylinder = 185kg/45kg= 5 nosConsider 30% volume of C0¸ to be used= 0.3x137m³= 41m³
16Design manual based ondesired flow rate = 30°CTherefore flow rate for 2 minsQ = 41m³ (exp.30°C) = 73.2kg0.56m³/kg@ 2mins = 73.2kg = 37kg/mins2minTime of discharge of CO² at volume= 185kg = 5mins37kg/minPipe sizing for flow rate, Q = 37kg/minsPipe size = 20mm