Presentation on theme: "Fire Detection, Alarm, and Suppression Systems"— Presentation transcript:
1 Fire Detection, Alarm, and Suppression Systems 1
2 Introduction Recognized functions of detection and alarm systems. To notify occupants of a facility to take necessary evasive action to escape the dangers of a hostile fireTo summon organized assistance to initiate or assist in fire controlTo initiate automatic fire control and suppression systems and to sound an alarmTo supervise fire control and suppression systems to assure that operational status is maintainedTo initiate a wide variety of auxiliary functions involving environmental, utility, and process
3 Introduction These systems may include components that operate: MechanicallyHydraulicallyPneumaticallyElectricallyMost are state-of-the art and operate electronically
4 IntroductionAutomatic Sprinkler Systems remain the most reliable form of protection.They result in less business interruption and less water damage than traditional firefighting interventionApproximately 70% of all fires are controlled by the activation of 5 or fewer sprinklers.
5 Types of Alarm SystemsLocal system or protected premises fire alarm systemIs a localized system meant to be activated by manual means, (EXAMPLE:) Pull Stations in local schools.
6 Optional Features For Local Systems Automatic fire detection devices may be added allowing the system to sense presence of fire and initiate the signal.
7 Four Basic Types of Automatic Alarm-Initiating devices
8 Heat Detector Fixed Temperature Heat Detectors Systems using fixed temperature detectors are among the oldest in serviceThey are inexpensive and are the least prone to false activationsThey are the slowest to react or activate of all the various types of alarm initiating systems.
9 3 Primary Principles in which fixed temperature devices detect heat Expansion of heated materialMelting of heated materialChanges in resistance of heated material
10 Fusible Devices (Fixed temperature) Associated mainly with automatic sprinklers, but they are also used in fire detection and signaling systems
11 Frangible Bulb (Fixed Temperature) Holds electrical contacts apart in alarm system. The vial of liquid has a bubble in it that heats and ruptures the bulb at a predetermined temperature
12 Continuous Line Detector (Fixed Temperature) Detect heat over a linear area parallel to the detector rather than in one spot in which located such as the fusible link.
13 Bi-Metallic Detector (Fixed Temperature) Uses two metals with different thermal expansion rates.When heated on expands faster than the other causing the strip to bend or arch making or breaking a circuit and initiating the alarm
14 Rate-of Rise Heat Detectors Operate on the principle that the temp in a room will increase faster from fire than from atmospheric temp.Typically designed to alarm when the temp rise exceeds 12–15 degrees F/min.All rate-of-rise detectors reset after activation if undamaged.
15 Rate-of Rise Heat Detectors Pneumatic Rate-of-Rise DetectorThe most common typeA dome shaped chamber with a flexible metal diaphragm in the base.A small hole allows air exchange during normal conditions.During a fire, the hole is too small to allow the heated air to escape, thus forcing the metal diaphragm to contact the alarm circuit.
16 Rate-of Rise Heat Detectors Pneumatic Rate-of-Rise Line DetectorConsists of a system of tubing for wide area coverage.The space in the tubing acts as the air chamber, operating the same as the pneumatic detector.
17 Rate-of Rise Heat Detectors Rate Compensated DetectorDesigned for use in areas subject to temp changes that are slower than those under fire conditionsConsists of an outer metallic sleeve that encases two bowed struts that have a slower expansion rate than the sleeve. When heated rapidly, the outer sleeve expands, reducing tension on the inner strips, allowing contact.
18 Rate-of Rise Heat Detectors Thermoelectric DetectorOperates on the principle that when two wires of dissimilar metals are twisted together at one end, an electrical current is generated at the other.Rapid heat changes generate more current and cause activation.
20 Smoke DetectorsBecause it detects smoke & not heat, it can activate more quickly.Comes in two basic types:PhotoelectricIonization
21 Smoke Detectors Photoelectric Sometimes called a visible products-of-combustion detectorUses a photoelectric cell coupled with a specific light sourceThe photoelectric cell functions in two ways to detect smoke:Beam ApplicationRefractory Application
22 Smoke Detectors Photoelectric Beam Application Uses a beam of light across the area being monitored & onto the photoelectric eye.The cell constantly converts the light to current, which keeps the switch open.When smoke obscures the beam, the circuit closes & the alarm activates.
24 Smoke Detectors Photoelectric Refractory Uses a light beam that does not strike the photocell and produces no currentWhen smoke enters the chamber, it causes the light beam to be refracted (scattered)Light strikes the photocell causing current to flow, which closes the switch & activates the alarm
26 Smoke Detectors Ionization During combustion, minute particles & aerosols too small to be seen by the naked eye are produced.These particles can be detected by devices that use a tiny amount of radioactive material, usually americium, to ionize air molecules.These ionized particles allow current to flow between negative & positive plates in the chamber.
27 Smoke Detectors Ionization When the particulate particles of combustion (smoke) enter the chamber, they attach themselves to electrically charged molecules of air (ions), making the air less conductive.The decrease in current flowing between the plates initiates the alarm.
31 Fire Gas DetectorsWhen fire burns in a confined space it changes the makeup of the atmosphere within the space. Depending on the fuel some of the gasses released are:Water Vapor (H2O)Carbon Dioxide (CO2)Carbon Monoxide (CO)Hydrogen Chloride (HCl)Hydrogen Cyanide (HCN)Hydrogen flouride (HF)Hydrogen Sulfide (H2S)
32 Fire Gas DetectorsOnly water vapor, carbon dioxide & carbon monoxide are produced by all firesThis makes it practical to monitor only carbon dioxide & carbon monoxide for general fire detection purposesUses either semiconductors or catalytic elements to sense the gas & trigger the alarm
33 Combination Detectors Include fixed temp/rate-of-rise, combo heat/smoke & combo smoke/fire gas.Combination detectors are more versatile and responsive to fire conditions.
34 Indicating DevicesA large assortment of visual & audible devices are available.Indicators may be used singularly or in combination with other devices.
35 Automatic Alarm Systems A local alarm sends a signal to an off-site location which notifies the local authoritiesSignals come through dedicated wire-pairs, leased phone lines, fiber-optic cable, or wireless communication links.
36 Auxiliary System There are three basic types: Local Energy System Shunt SystemParallel Telephone System
37 Auxiliary System Local Energy System Municipal fire-alarm box system Occupancy is attached directly to a hard-wired or radio-type municipal fire alarm boxWhen an alarm trips in the protected occupancy, it trips the alarm & sends the signalCan be manually activated at the alarm box
38 Auxiliary System Shunt System The municipal alarm circuit extends (is “shunted”) into the protected propertyWhen an alarm is initiated on the premises, either auto or manually, the alarm is transmitted to the alarm center over the municipal system
39 Auxiliary System Parallel System Does not interconnect with a municipal circuitIt transmits an alarm directly to the alarm center over a municipally controlled telephone circuit that serves no other purpose.
41 Remote Station SystemSimilar to auxiliary, but is connected to the FD communications center or through an answering service by means other than the municipal system.Can be connected via:Leased phone linesDedicated radio frequency
43 Proprietary SystemUsed to protect large commercial & industrial buildings, high rises, & groups of commonly owned buildings in a single location, such as a college campus or industrial complex.Each building has its own system wired into a common receiving point.The receiving station is staffed by trained personnel.
44 Proprietary SystemModern proprietary systems can be complex with a wide range of capabilities:Transmitting coded alarm & trouble signalsMonitoring building utility controlsMonitoring elevator statusMonitoring fire & smoke dampersPerforming security functions
46 Central Station System Similar to proprietary, but there is no on-site receiving point. The signal is transmitted to a contracted service off-site called the central station.Typically an alarm company that contracts with individual customers.Central station employees receive the alarm & contact the proper authorities.Commonly connected via supervised phone linesCentral Station Systems should comply with NFPA 72, National Fire Alarm Code
48 Auxiliary ServicesMany newer systems offer auxiliary services in addition to monitoring:Shutting down or altering HVACClosing smoke or fire door or dampersIncreasing air pressure in stairwells to exclude smokeOverriding elevator controlsMonitoring operation of burner managementMonitoring refrigeration systemsControlling personnel access to hazardous areasDetecting combustible or toxic gases
49 Automatic Sprinkler Systems Automatic sprinkler protection consists of a series of sprinklers (sprinkler heads) arranged so that the system will automatically distribute sufficient quantities of water directly to a fire to either extinguish or contain it until FF’s arrive.Water is supplied through a series of pipes
50 Automatic Sprinkler Systems There are two general types of coverage:CompleteProtects the entire buildingPartial / Limited AreaProtects certain high hazard areas, exit routes or places designated by code or by authority having jurisdiction
51 Automatic Sprinkler Systems There are two guidelines used to establish sprinkler systems in occupancies:NFPA 13, Standard for the Installation of Sprinkler SystemsNFPA 13D, Standard for the Installation of Sprinkler Systems in One & Two Family DwellingsThese standards specify head spacing, size of pipe, pipe hanging & all other details.Standards also specify design area to calculate the system.All components should be listed by a nationally recognized testing lab such as Underwriters Laboratory (UL)
52 Automatic Sprinkler Systems Sprinkler system failures are very rare. Some causes of failure include:Partially or completely closed main water control valve.Interruption of municipal water supplyDamaged or painted over headsFrozen or broken pipesExcess debris or sediment in pipesFailure of a secondary water supplyTampering or vandalism
53 Automatic Sprinkler Systems Sprinkler System Effects on Life SafetySprinklers enhance safety because they discharge water directly on a fire while it is relatively small.Limits the products of combustion.Prevents fire spread upward in multi-story buildings.
54 Automatic Sprinkler Systems Sprinkler System Effects on Life SafetySituations where sprinklers are not as effective:Fires are too small to activate a headSmoke reaches occupants before sprinkler activationSleeping, intoxicated or handicapped persons occupy the fire building
55 Automatic Sprinkler Systems Sprinkler System FundamentalsThe system starts with a water main & continues to the control valve.RiserVertical piping to which the sprinkler valve, one-way check valve, FDC, alarm valve, main drain & other components are attached.Feed MainPipe connecting the riser to the cross mains.
56 Automatic Sprinkler Systems Sprinkler System FundamentalsCross mainsDirectly service a number of branch lines to which the sprinklers are installed.Extend past the last branch lines & are capped to facilitate flushing.System piping decreases in size from the riser outward.
57 Automatic Sprinkler Systems Sprinklers (Heads)Discharge water after the release of a cap or plug that is activated by some heat responsive element.Commonly identified by the temp at which they are designed to operate.The temp is identified by color coding the sprinkler frame arms, colored liquid in bulb-type sprinklers, or by stamping into the head.
59 Automatic Sprinkler Systems Fusible LinkTwo levers press against the frame securing a cap that holds back the water.When the fusible link melts, water pushes the levers & cap out of the way.Water then strikes the deflector to disperse the water.
61 Automatic Sprinkler Systems Frangible BulbA small bulb filled with liquid & an air bubble is used to hold the orifice closed.Heat expands the liquid which absorbs the bubble causing the pressure inside the bulb to shatter at the proper temp.The liquid is color coded to designate the breaking temp.
62 Automatic Sprinkler Systems Chemical PelletA pellet of solder, under compression, within a small cylinder melts at a predetermined temp.This allows the plunger to move down and release the valve cap parts.
64 Automatic Sprinkler Systems Head Position TypesThere are 3 basic positions of heads:PendantExtends down from the underside of piping.UprightSits on top of the piping.SidewallExtends from the side of the pipe.Special PurposeSpecific atmospheres or applications.
66 Automatic Sprinkler Systems UprightPendantSidewallRecall Recessed
67 Automatic Sprinkler Systems Sprinkler StorageA storage cabinet for housing extra sprinklers & a sprinkler wrench should be installed in the area protected by the sprinklers in accordance with NFPA 13 & 13D.Changing of heads is typically performed by the buildings occupants who are qualified to perform sprinkler work.
68 Automatic Sprinkler Systems Sprinkler Storage Cabinets
69 Automatic Sprinkler Systems Control ValvesEvery system is equipped with a main control valve.Control valves are used to turn off the water supply to the system so heads can be replaced, maintenance, or operations interrupted.Valves are located between the water supply & the system.
70 Automatic Sprinkler Systems Control ValvesUsually located directly under the sprinkler alarm valve or outside the building near the sprinkler system it controls.Control valves should be secured in the open position or supervised to maintain control.Control valves are indicating and manually operated.An indicating valve shows if the valve is open at a glance.
72 Automatic Sprinkler Systems Control valvesOutside Screw & Yoke (OS&Y)Has a yoke with a threaded stem that controls opening & closing.When the stem is out, the valve is open.Post Indicator Valve (PIV)The valve is inside a hollow metal post.A window on the post displays OPEN or SHUT.
74 Automatic Sprinkler Systems Control ValvesWall Post Indicator Valve (WPIV)Similar to a PIV, but it extends through a wall with the target & valve operating nut outside.Post Indicator Valve Assembly (PIVA)Does not use a target with the words OPEN or SHUT, but it has a sight area that is open when the valve is open & closed when the valve is closed
76 Automatic Sprinkler Systems Operating ValvesSystems employ various valves such as:Alarm test valveLocated on a pipe that connects the supply side of the alarm check valve to the retard chamber.Inspectors test valveLocated in a remote part of the system.Has the same size orifice as 1 head to simulate the activation of 1 head.Main drain valveUsed to drain the system for maintenance, etc.
77 Automatic Sprinkler Systems Water Flow AlarmsEither operated hydraulically or electrically.Hydraulically operated alerts people in the building & passersby by the water flowing through a water wheel & sounding a water gong.Electrically alerts people in the building & passersby as well as the alarm co.
80 Automatic Sprinkler Systems Water SupplyEvery system should have a supply of adequate volume, pressure & reliability.Must deliver the required volume to the highest head in a building at a residual pressure of 15psi.The minimum flow depends on the hazards, occupants & contents to be protected.
81 Automatic Sprinkler Systems Water SupplyThe system is designed to supply a fraction of the heads. In the event of a large fire or pipe rupture, the system will need outside supply & pressure to operate effectively.This additional supply is usually provided by a pumper through the FDC.The FDC is usually a siamese with two 1 ½” female connections with a clapper valve or one large connection connected to a clapper inlet.
82 Automatic Sprinkler Systems Water SupplySprinkler FDC’s should be supplied by a pumper with a minimum capacity of 1000gpmA minimum of two 2 ½” hoses should be connected to the FDC.The pumper should be connected to a main other than the building supply main.Your SOG should specify at what pressure a system is supported.
84 Automatic Sprinkler Systems Applications of Sprinkler SystemsWet-PipeUsed in locations that will not be subject to temps below 40 degrees F.Contains water under pressure at all times.May be equipped with a retard chamber to catch excess water during pressure surges. This reduces the chance of false alarm activations.
86 Automatic Sprinkler Systems Dry PipeUsed in locations where piping is exposed to temps below 40 degrees F.All pipes are dry & pitched to help drain them toward the main drain.Air under pressure replaces water in the pipes above the dry-pipe valve.The dry pipe valve keeps water out of the piping until a head is activated.
88 Automatic Sprinkler Systems Dry PipeDesigned so that a small amount of air pressure holds back a greater pressure of water.Accomplished by having a larger surface area on the air side of the clapper valve.The required air pressure for a system should be 20psi above the trip pressure.
90 Automatic Sprinkler Systems Dry PipeBecause of the size of some systems, several minutes can be lost before water arrives at the activated head.Systems that have a capacity over 500 gallons must have an accelerator.The accelerator speeds up release of water into the system.
92 Automatic Sprinkler Systems Preaction SystemA dry system that employs a deluge-type valve, fire detection devices & closed sprinklers.Used where it is especially important to prevent water damage if pipes are broken.The system will not discharge water into piping except in response to either smoke or heat detection systems.
93 Automatic Sprinkler Systems Preaction SystemFire detection devices operate & release water into the system actuation unit which allows water into the piping.The water remains in the piping, ready for release until a head is activated.When water enters the system, an alarm is activated.
94 Automatic Sprinkler Systems Deluge SystemThe purpose is to wet down the area where a fire originates by discharging water from all open heads in the system.Normally used to protect extra hazardous occupancies.Activation is usually controlled by flame, heat and/or smoke detecting devices plus a manual device.
95 Automatic Sprinkler Systems Deluge SystemBecause it is designed to operate automatically & sprinklers do not have heat- responsive elements, it is necessary to provide a separate detection system.The detection system is connected to a tripping device to activate the system.Deluge valves may be operated manually, hydraulically or pneumatically.
97 Automatic Sprinkler Systems Residential SystemsDesigned to prevent total fire involvement in the room of origin to allow occupants of the dwelling to escape.May be wet or dry-pipe systems.Employ quick-response heads.Piping can be steel, copper or plastic.Must have a pressure gauge, flow detector & main drain.
98 Automatic Sprinkler Systems Residential SystemsCan be connected to public water system or the dwelling domestic water supply.Operate just like wet or dry-pipe systems.Some even have 1 ½” FDC.
99 Fires at Protected Occupancies Considerations when fighting fires in occupancies the have activated sprinklers:In addition to normal FF ops, the 1st due engine must make every effort to adequately supply the sprinkler system.Check to see that sprinkler control valves are open & sufficient flow is provided.
100 Fires at Protected Occupancies Factors to consider:Control valves should be closed when the IC determines that ops will waste water, produce heavy water damage or hinder final extinguishment by personnel.Sprinkler systems should be restored to service by qualified occupancy personnel, before the FD leaves the premises.
101 Fires at Protected Occupancies Firefighters may be required to stop the flow of water to a particular head to prevent further damage until the system drains below that point.Firefighters should carry wedges, etc to accomplish this & become familiar with the procedures to do so.