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Document Number
PEC-EN-GDE-J-09023
Revision
1
Applicability
All
Document Type
Guidelines
Building Fire Alarm System
REVISION / APPROVAL HISTORY
1
30-Dec-2013
Revised to incorporate LL points
Nitin De
0
18-Dec-2011
Original issue
Yashwant Sonar
Rev
Date
Description of Change
Developer
Records of approval are retained in the QMS Page 1 of 16
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Debkumar Lahiri / Nitin Dighe / S.Gurumurthy Debkumar Lahiri / Nitin Dighe / S.Gurumurthy Reviewer
Haresh Sharma
Haresh Sharma Approver
Document Number
Document Title
Revision
PEC-EN-GDE-J-09023
Building Fire Alarm System
1
CONTENTS 1.0
PURPOSE ........................................................................................ 3
2.0
SCOPE............................................................................................ 3 2.1
3.0
Effective applicable date of this document ................................................. 3
DEFINITIONS .................................................................................... 3 3.1
Definition .......................................................................................... 3
3.2
Acronyms........................................................................................... 3
4.0
REFERENCES .................................................................................... 4
5.0
RESPONSIBILITY & AUTHORITY.............................................................. 4
6.0
DESCRIPTION ................................................................................... 4 6.1
Components of BFAS ............................................................................. 5
6.2
Detector Location ................................................................................ 7
6.3
Selection of Gas Detector....................................................................... 8
6.4
Selection of Fire Detector ...................................................................... 9
6.5
Control Panel.....................................................................................12
6.6
Control Philosophy ..............................................................................14
7.0
RECORDS .......................................................................................15
8.0
FLOWCHART ...................................................................................16
9.0
APPENDICES....................................................................................16
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1.0
PURPOSE
The purpose of this design guide is to outline minimum requirements that need to be considered for developing the specification and evaluating the offers for Fire and Gas Detection System for Buildings considered in EPC onshore oil & gas projects. A typical content list is presented in this document. Detailed description of each section is not provided in this document. Document in reference list should be referred as a detailed guide on relevant sections of the Philosophy. 2.0
SCOPE
This design guide applies to all Petrofac onshore oil & gas projects for preparing specifications and for the technical evaluation of Fire and Gas Detection System for Buildings. This design guide is to be adopted for EPC projects in absence of any project specific philosophy. The recommended contents of this document may be suitably modified as per project requirement. This specification defines the minimum requirements for the design, engineering, installation and commissioning of UL/ FM/ VDs approved Fire & Gas Detection System for buildings used in onshore hydrocarbon plants. This specification describes the field detection and actuating equipment for the Fire & Gas Detection system, and the functionality of the system as a whole. The fire detection and alarm system covered here shall facilitate early warning alarm to alert the Fire stations/ Local Control Room of the plant/ workshop complex about the out-break of fire so that a timely action is initiated to prevent/mitigate loss of life and property. 2.1
Effective applicable date of this document
Approval date 3.0
DEFINITIONS
3.1
Definition
Not applicable 3.2
Acronyms BFAS BGU BS DCS ESD
: : : : :
Building Fire Alarm System Break Glass Unit British Standards Distributed Control System Emergency Shutdown Page 3 of 16
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F&G FM HSSD HVAC HC H2S H2 ISA IR IS LED LEL MCP NFPA PLC PAGA SCADA SPDT UV UL UPS VESDA 4.0
: : : : : : : : : : : : : : : : : : : : : :
Fire and Gas System Factory Mutual High Sensitivity Smoke Detector Heating Ventilation & Cooling System Hydro Carbon Hydrogen Sulphide Hydrogen International Society of Automation Infra Red Indian Standards Light Emitting Diode Lower explosive limit. Manual Call Point National Fire Protection Association Programmable Logic Controller Public Address and General Alarm Supervisory Control and Data Acquisition Single Pole Double Throw Ultra Violet Undertaker Laboratory Uninterrupted Power Supply Very Early Smoke Detection Apparatus
REFERENCES
This design guide has been constructed by referencing experience on various projects in which such Systems have been implemented. The system and its components shall conform to the latest editions of the UL/FM/VdS standards and relevant stipulations of NFPA & IS Codes as applicable. Installation shall be done as per relevant NFPA standards. 5.0
RESPONSIBILITY & AUTHORITY
Not applicable 6.0
DESCRIPTION
A brief and structured guide line is presented below which addresses features of F&G Detection system along with the inert gas flooding and with suitable interface to DCS /PLC and PAGA system and Fire Station. In hydrocarbon industries, the buildings are exposed to internal and external hazards risks. The building fire alarm system is required to address the risk associated Page 4 of 16
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with imminent or established fire and leakage of combustible/ toxic gas. The F&G system is meant for early detection of fire or gas leakage. In event of early detection, some time is made available for automatically initiating actions to prevent outbreak of fire.
6.1
Components of BFAS
Typically a BFAS will contain the following components – 6.1.1 Smoke detectors In most of the buildings, the Fire protections are provided against electrical fire likely to occur due to short circuit in electrical systems or cable fault/fire. Most of the cable fires are usually associated with the large generation of smoke. Hence sensing smoke at early stage can prevent fire from occurring. To sense smoke, the smoke detectors are provided in cable ducts, false flooring and false ceiling of the control buildings. For reliable detection, the two types of detectors such as ionization type (suitable for incipient stage of fire) and optical type (suitable for smoldering stage of fire) are employed in cross zone. 6.1.2 Flame detectors To check presence of actual flame (suitable for third stage of fire when ignition temperature has reached), the flame detectors such as UV/IR or IR type or Multi-spectrum IR type are employed. 6.1.3 Heat detectors To check the rise in temperature (suitable for last & fourth stage of fire when heat is released) in surrounding area, rate of rise type (bimetallic or thermo-electric sensors) or absolute fixed type (bimetallic or fusible link devices) thermal detectors are employed. 6.1.4 Gas detectors The hydrocarbon or toxic gas detectors are employed in buildings for protection of assets and human beings. The detectors are installed in inlet of Air handling unit. In event of high level of hydrocarbon or toxic gases, the inlet dampers are closed automatically with suitable pre-warning. In event of presence of toxic gases, separate purifying unit, if installed at the inlet, may be started for reducing the toxic content. Hydrogen detectors are usually used in the electrical battery room to detect any leakage of hydrogen gas from the batteries. If inert gas flooding is used for fire suppression, then oxygen monitors are employed inside the building to detect the presence of sufficient oxygen for operators to enter the building again after release of inert gas. Page 5 of 16
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6.1.5 Break Glass Unit / Manual Call Points These items are used at pre-fixed locations and at predefined intervals as per the applicable codes and standards. An observer can initiate fire/gas alarm and executive actions by initiating a command through BGU/MCP contact input. 6.1.6 Sounders/Horns/Bells and Beacons Audible Sounders/Horns/Bells of predefined decibel level are used at strategic locations to alert human beings of the fire and gas events. Beacons of predefined intensity and other features like color of light, flickering frequency etc. are used to raise the visual alarm. 6.1.7 Addressable Detector and System Addressable detectors allow automatic identification of the detector that has initiated the action, and in-turn allows automatic diagnostic alarms and online replacement of detectors. Such detectors are connected to controller unit through redundant bus or through ring network. Only after confirmation of through voting logic, the alarm or any executive action is initiated. This kind of system is expandable and it is possible to add additional F&G zones, if required. The fault in a loop or a zone shall not affect the function of the other loops or detection by other groups. Also, removal of detectors shall not break a loop. The building shall be divided into separate zones and executive actions on HVAC and any other device shall be accordingly segregated and designed. 6.1.8 Power Supply The F&G systems are generally powered from redundant UPS supply. As per NFPA guidelines, the F&G system is also powered from dedicated dual back-up batteries, which will provide stable supply, allowing orderly shutdown and monitoring if power is lost. For sizing of the batteries, consider requirement of installed spares & spare space in F&G system 'Control Devices'. The back-up battery capacity allows continued monitoring by the F&G system for a nominal period of not less than 24 hours. This period is to be confirmed by the project requirements/applicable codes and standards followed for project risk assessments. A common power supply fault alarm is provided for connection to DCS. Contacts are generally volt free contacts. 6.1.9 Calibrators Kits of Calibration gases in bottles, aerosols or cans, smoke detector test gas, Heat detector tester etc. are required for commissioning of the system and for future Page 6 of 16
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maintenance. The number of bottles or cans is decided based on the actual number of detectors and the calibration frequency as per the project requirements and the applicable codes. 6.1.10 Interface and Executive Actions a) Interfaces to the actuating devices such as deluge valves, pneumatic solenoid and pilot valves, extinguisher release. b) Interfaces to other Systems of the plant such as HVAC System, Plant F&G System, Plant ESD System, DCS, Package Equipment (such as Gas Turbines, Process gas Compressors etc. which may be housed with noise-hood / enclosures) F&G Detection System, PAGA System, Emergency Power Generator. 6.1.11 Release of Inert gas Automatic release of inert gas is initiated after confirmed fire detection. The choice of inert gas depends upon type of assets to be protected and also on the project requirement/site environmental policy on inert gas mixture. Most of the inert gas mixtures work on principle of reducing oxygen in affected area and there by extinguishing fire. Hence before release of the inert gas, the persons in the affected rooms are evacuated by pre-warning through use of timer, signboards, and audio-visual alarms. Interlocks are implemented with Security Access system to ensure that nobody is trapped inside the building and gets suffocated during the release of the inert gas. 6.2
Detector Location
All detectors are located and spaced in accordance with NFPA Code 72 E/BS 5839/other applicable Codes/Local regulations. The selection and combination of detectors is done on the basis of overall safety and reliability of the system, keeping in view 100% coverage area by each detector. Further, the selection of type of detectors and their locations and mountings are based on their ability to ensure the earliest response to imminent or established fire or leakage of hydrocarbon / toxic (H2S) gases, with consideration to the following as a minimum:
Requirements of referenced standards, particularly NFPA-72E, NFPA-70, ISA-92 and ISA-12
Equipment layouts: Placement of detectors shall not interfere with equipment maintenance. The optical type detectors shall have unobstructed view of the hazard.
In control building, the fire detectors and smoke detectors shall be mounted below false flooring and above false ceiling with remote indicator to indicate false/ actuated state.
Ease of Maintenance: The fire and gas detectors shall be installed in a location accessible for calibration and maintenance. Page 7 of 16
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Avoidance of spurious alarms and trips
The Gas Detectors shall be installed in Air Inlet of HVAC system with adequate provision for checking/calibration.
6.3
Selection of Gas Detector
For the purpose of selecting gas detectors, following general factors are considered
Combustible Gas (HC) & Flammable gas (H2) Detectors shall be able to perform to the temperature, humidity, air velocity and vibration specification prescribed in ISA 12.13.01. Toxic Gas (H2S) Detectors shall be able to perform to the specifications prescribed in ISA 92.0.01 Part I.
Temperature Effects: The detectors shall be calibrated at their mean operating temperature. All components, including the sensor, shall be designed for operation within the ambient temperature range for the location of the installation. Where high temperatures are unavoidable, high-temperature rated detectors with remote sensing heads shall be employed.
Effects of Humidity: The detector housing shall be suitable for corrosive environment.
Air Velocity: Sensors shall be located away from prevailing winds, heating and cooling system. Air circulation patterns and effects of other equipment that affect circulation shall be taken into consideration while finalizing the location of the detectors. Where widely varying wind direction changes are expected, multiple detectors shall be installed to provide the required cover.
Vibration: Sensors shall be located away from vibration prone areas. If this is not possible, the sensors shall be mounted on flexible mounts or flexible conduit.
Sensors shall be typically located approximately 1 m from the expected emission point, and preferably in the direction of ignition sources and / or populated areas.
Special consideration shall be given to the properties of the process gas (refer Process Design Criteria for properties of process fluids), specifically its vapor density and predominant component. For lighter-than-air gases, the detectors shall be placed above the probable leakage point. For heavier-than-air gases, the detectors shall be placed 300-450 mm above the grade.
Detector locations shall take into account the possible flow pattern of the leaking gas or vapor and ventilation system airflow.
The number of detectors shall be based on the number of potential leakage sources.
Perimeter detection of leakages shall be considered in areas containing large amounts of light hydrocarbons (e. g. process areas or pressure storage areas) to alert operations to initiate a manual response or to actuate an automatic response (e. g. unit shutdown or firewater spray system). These detectors shall be installed along a unit boundary adjacent to an ignition source.
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Indoor or partially enclosed installations that may require gas detection (such as turbine enclosures, compressor stations, etc.) shall be protected with open path or point detection system.
Where buildings are equipped with HVAC, pressurizing or a ventilation system, a combustible-gas and / or toxic-gas detector shall be located in the inlet to the system and also in air locks. 6.4
Selection of Fire Detector
The fire detection system comprises a variety of addressable fire detection devices and sensors, including addressable Optical Flame Detectors, Smoke Detectors, Thermal Detectors and Manual Call Points. These detectors are installed in combinations to increase the reliability. 6.4.1 Optical Flame Detector Optical flame detectors are the UV/IR or IR or Multi-spectrum/Triple IR type and make use of such sensor, filters, and / or design to reject phenomena such as electric arcs, heaters, artificial light sources, lightning and are completely "solar blind". The detectors are able to detect all types of flaming fires. The flame detector shall be selected taking in to consideration the fuel source and the cone of vision of the selected detector to ensure adequate coverage of the potential hazard. UV detectors may be used where they are not exposed to external UV rays, such as in compressors and power generating enclosures. Detectors are powered from 24 VDC, with a 4-20 mA signal loop to cover the calibrated range. Detector faults are signaled by a 4 mA signal. Sufficient margin are allowed between fault, normal and alarm levels to minimize spurious alarms. Optical flame detectors have automatic, self-diagnostic circuitry that continuously monitors the optical surfaces, sensor sensitivity and electronic circuitry, and gives fault status. Any detector malfunction shall be alarmed on the F&G Alarm panel and DCS. 6.4.2 Smoke Detectors The system uses addressable type of UL/FM/VDS listed automatic wired Photoelectric & Ionization Smoke detectors, which are installed in all the manned rooms and corridors, including concealed floor and ceiling voids. Addressable Ionization smoke detectors are used in general-purpose areas to provide early response to smoldering or flaming fires in their incipient stages. A detector base is provided for connecting the individual detectors to the F&G system so that detector can be removed without removing any wiring. Page 9 of 16
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Addressable Photoelectric smoke detectors are used in electric equipment and control room areas. It shall be possible to reset all detectors from panel after fault signal has been indicated. Two independent smoke detector loops are installed in each area where executive action is required on detection of fire for reliability. Detectors, which are not visible, such as in ceiling void or under floor, are provided with remote LED's located in the room being monitored. The smoke detectors incorporate an integral LED indicator for confirmation that the unit is active. A detector base is provided for connecting the individual detectors to the F&G system. Smoke detectors remain in alarm state until reset by the F&G system. It is possible to reset all detectors from panel after fault signal has been indicated. Disconnection of one or more Smoke detectors in a transmission path shall not impair the operation of the remaining Smoke detectors and the transmission path. Either wiring break or short circuit is automatically indicated by audio-visual warning in the form of fault alarm. Isolators are provided for protection against short circuits. The sensitivity of the detector is not to vary with any change in ambient temperature, humidity or voltage variations. The detectors will have in-built arrangement such that puff of smoke or hot air pockets shall not trigger the alarm. The detector shall be able to sense incipient fire by detecting the presence of visible and invisible products of combustion like wood, paper, cloth, PVC, Bakelite nylon foam, acrylic thermocol, photo film, nylon, polyester, painted sheets, Teflon leather etc. The detector performance shall not be affected by an air current of 5 m/sec. Where air velocity is expected to be higher, smoke guard/ baffle shall be used. The detector shall be protected against dust accumulation/ ingress. Smoke detectors may require separate power supply (e.g. separate 24 V DC). In such a case, the power distribution and power source for these detectors to be considered. Such power supply shall be arranged from the power supply which feeds the building Fire and Gas system so that it meets the uninterrupted power supply requirement. Intrinsically Safe smoke detectors may be used for the battery room applications. Sometimes project specification require smoke detector with in-built relay contacts. For such cases IS certification for the ‘detector + base (relay)’ to be mandatorily verified before procurement. Following shall be checked: i.
Hazardous area certification requirement as per the contract to be verified. Page 10 of 16
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ii. iii.
The certification is valid for the area where these detectors are intended to be installed. System interface: If IS certified smoke detectors including base (relay)’ is not available, addressable Intrinsically Safe certified smoke detectors can be used in battery rooms, which can be interfaced with the Fire Alarm panel. This eliminates the requirement of relay contacts in-built in the Smoke Detector base.
6.4.3 Thermal Detectors Thermal detectors are used in all indoor spaces including all rooms and equipment enclosures, including concealed floor and ceiling voids. Rate of rise thermal detectors are used where an early warning of smoldering fires is required, such as storerooms and equipment rooms where air flow or high humidity may inhibit the response of smoke detectors. Fixed temperature or rate compensated type heat detectors shall be used within areas unsuitable for smoke detection where a rapidly achieved high temperature can be expected, such as machinery rooms or equipment enclosures. These are set at approximately 12o C above maximum ambient temperature within the area. Thermal detectors remain in alarm state until reset by the F&G system. All visible detectors incorporate an LED indicator as an integral part of the detector head or its mounting base. Concealed thermal detectors are provided with an LED "repeater" that is located in a visible location. Normally, unmanned equipment rooms or offices have indicators in the corridor. The detector circuitry cause the LED to remain illuminated while the detector is in the alarm condition. 6.4.4 Manual Call Points & ESD Stations Manual Call Points are provided to alarm and initiate the F&G deluge. These are laid out and segregated according to the fire zones. MCPs are installed at strategic locations all over the building to initiate F&G actions and ESD. MCP is provided with current limiting resistances permanently fitted inside the unit and not wired on the terminals provided for field wiring. All MCPs may require a double action to activate the alarm. They may be the break-glass, pushbutton type with protection (lid/cover) for accidental actuation. Each unit is surface mounted at a height of 1.4 meters and is provided with a striker connected to the station by a chain. Page 11 of 16
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Each unit is wired to the F&G system in the Control Room. The MCP is provided with test key to test functionality without breaking the glass. The operation of MCP causes the change in the loop current to be detected by the F&G system. All MCP are Epoxy Red in color. All MCP confirm to specifications and tests as specified in BS 5839:Part-II 6.5
Control Panel
The Fire & Gas detection system panel is independent of DCS/Process PLC and constitutes the following:
Gas detector Controller/Monitor Cards, Logic & auxiliary relays, power distribution scheme, hooter mounted on a separate panel in safe area.
Hooter is provided for alarms only.
The front panel mounted Gas/Fire detection controllers/ monitors are installed in mating cases or mounting bins recommended and supplied by the manufacturer for panel mounting. All wiring to these controllers are terminated on terminal blocks and/or multi-pin connectors provided as an integral part of the case. Routine calibration adjustments are accessible from the front of the panel without having to remove any wiring or causing loss of the instrument function. In addition, total removal of the instrument and replacement with a spare is possible from the front of the panel.
The modules are plug-in type permitting the removal of the modules without disturbing the system wiring. Each module has a maximum of 4 channels (one detector per channel) per modules. Gas/Fire circuit are so designed that any channel can be put out of service for repair, without affecting the other.
Each module has the following:
Reset Button to acknowledge/reset alarm
Test button for Operation Check
Calibration switch, when put in calibration mode, inhibits operation of alarm output, enables checks for alarm LED's and reference level and also permits access to meter fine zero, meter span and alarm level contacts.
Automatic malfunction detection in case of open circuit (sensor element and line breaking), over range, short circuit and earth fault
Indicator LEDs for the following: Malfunction warning for each channel, Power on, Calibration mode, Test mode, Low alarm for each channel, High alarm/ trip for each channel.
Alarm Contact: For each detector, module is able to generate minimum 2 independently adjustable (adjustable over entire range of detection) SPDT relays for each alarm level for the purpose of alarming & logic solving. Page 12 of 16
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Besides PLC/Logic Processor related cabinets, other main components of Fire & Gas Detection system panel shall be: a) Critical Annunciator Panel. b) Matrix panel. c) Common Facilities as data logger, event printer, communication to DCS and SCADA if required.
Critical Annunciator Panel: Annunciator Panel is provided for critical alarms. The annunciation sequences are as per ISA-S18.1, 'Annunciator sequences and specifications'. The annunciation lamps are capable of removal and replacement from the panel front via individual snap out windows or a swing out hinged door on which all windows are mounted. Minimum critical alarms to be provided are given below: a) Line monitoring fault b) Gas detection malfunction c) Fire detection malfunction d) Fire Water Pump common alarm e) Fire Water Pump - Start f) Fire Water Pump - Failed to Start g) Fire Water Pump - Shutdown h) Fire Water Pump - on Manual i) Fire water header Pressure- Low j) Diesel Generator- Running k) Diesel Generator- Fault l) Gas Fault- Compressor m) Instrument Air Pressure- Low Low n) F&G System o) ESD p) Confirmed H2S detection q) Confirmed HC-H2 detection r) Confirmed Fire detection
Matrix Panel: Matrix panel provide graphic status of Fire & Gas Detection system & Fire suppression system area-wise for the entire plant/building. Area-wise status indication shall include the following: a) Low HC b) High HC c) Low H2S d) High H2S e) Low H2 f) High H2 g) Flame Page 13 of 16
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h) i) j) k) l) m) n) o)
Heat Smoke Manual Alarm Call point- Fire Alarm Extinguisher- Released Deluge- Valve open Deluge- Valve closed Deluge- Pressure Low System Fault Area-wise control devices shall include the following: a) Extinguisher Auto-Manual-Inhibit 3-way selector switch b) Extinguisher Manual release Pushbutton c) Reset Pushbutton d) Deluge- Open valve e) Deluge- Close valve It may be noted that sometimes Building F&G system is considered as a part of the Main Plant F&G system.
6.5.1 Control Panel Interface Fire & Gas detection system panel are interfaced with the following systems of the plant to confirm to SAFE chart requirements:
6.6
DCS & ESD system.
Pneumatic Panel
Central Control Panels for package items (such as Gas Turbines, Process gas compressors, etc)
PAGA system for alarm tones
Field Sounders/Horns
Extinguisher systems
HVAC System
Deluge panel
Diesel and electric fire pumps
VESDA system
Diesel/Gas Generator Plant Control Philosophy
The Cause and Effect diagrams are prepared as per standards mentioned together with the project requirements of specification. All shutdown interlock and alarm circuits are designed to operate in a fail-safe mode. F&G logics are designed to de-energize to actuate gas/fire shutdown interlocks. Page 14 of 16
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6.6.1 Alarms
In addition to signaling on the F&G matrix and alarm annunciator, fire and gas detection shall result in separate and distinct audible and visual alarms at Control room/equipment enclosure/field area.
Visual alarms shall be color coded to the project requirements to distinguish between fire, combustible gas and toxic gas leakage.
For gas detection, distinct visual and audible alarms in the Control room shall be provided for the two levels of detection.
Silencing of audible alarms shall not de-activate visual alarms until detection falls below the alarm level.
Visual and audible alarms are different for each level of detection.
F&G Detection system are suitably interfaced with plant DCS. DCS have an over view graphic for each F&G zone. The graphic displays individual detector analogue value, alarm and fault status, and deluge valve and extinguisher release status. A separate graphic displays the fire water pumps run and fault status and fire water pressure.
6.6.2 Paging Distinct plant audio-alarm is provided for confirmed HC-H2 gas leakage, confirmed H2S gas leakage, confirmed fire through paging system. Dry volt free contacts shall be provided for the input signals. 6.6.3 Actuation Fire alarm is actuated by any of the following:
Activation of Fire Detectors as defined in 'Detector voting'.
Manual activation of extinguisher from Extinguisher Control cubicles/stations.
Deluge valve activation push-button.
On activation of fire alarm, the following actions are activated.
7.0
Alarm on DCS, Annunciations and Paging system, Indication on F&G matrix.
Shutdown Power, trip ventilation system and automatic actuation of Extinguisher system.
Start fire water pump and start the emergency generator as per safe chart. RECORDS
Not applicable
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8.0
FLOWCHART
Not applicable 9.0
APPENDICES
Not applicable
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