J IruSTRTICT-O-GRAMffisFsI THE HANDS-ON TRAINING GUIDE

FOR THE FIRE INSTRUCTOR

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FIXED EXTINGUISHING SYSTEMS

TIME REQUIRED 2 hours

INTRODUCTION

Fire fighters are encountering fixed extinguishingsystems with increasing frequency. Property ownersinstall fixed systems to protect sensitive or valuablematerial that may be damaged by traditional firefighting methods. Some businesses are required, bycode or ordinance, to install a fixed extinguishingsystem to protect all or part of their occupancy. Stillother systems are installed at the request of theinsurance company.

Regardless of the reason for the system beinginstalled, a fire fighter should understand how itworks. Some systems can leave hazardous or toxicvapors even after extinguishing the fire. Fire fightersunaware of this could enter an area with improperpersonal protective equipment.

Fixed systems, unlike sprinkler systems, are designedto extinguish the fire. Fire fighters should be ex-tremely cautious when responding to a protectedstructure with smoke showing, as the system hasprobably not work as designed. Sprinklers have aneffectively limitless supply of extinguishing agent(water). Fixed systems have a finite amount of agent,usually contained in a small tank or cylinder. Oncethat agent is expelled there is no further action takento control the fire until the arrival of fire fighters.Given the types of occupancies usually protected by

Copyright @ 2001 lntemational Society of Fire Sewice Instructors

All rights reserved. No part of this document may be reproduced, in any form or by any means, without permission in writing from the publisher.

fixed systems a fire that was not extinguished has thepotential to become devastating.

OBJECTIVES

1. Given a lecture and reading assignments, thestudent will list five types of fixed fireextinguishing systems, with I00Vo accuracyand state their intended applications.

2. Given a lecture and reading assignments, thestudent will list three occupancies thatwould require fixed fire extinguishingsystems, with I007o accuracy.

3. Given a lecture and reading assignments, thestudent will list four types of foam systems,with 1007o accuracv.

MOTIVATIONFixed extinguishing systems help lower the possibil-ity that the fire department will be called to certainhigh risk areas. Have the class discuss good and badaspects of that. Examples may include: Pros - firesare extinguished in the incipient stage, fire fighterand public safety are increased by reduced responses,property damage is reduced by early application ofextinguishing agents; occupants or employ-ees may get a feeling of overconfidence, firescontrolled but not extinguished may not be reportedin a timely fashion, property damage may be in-creased by accidental discharge of the agent.J

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actuated by a product of combustiondetector.

Semi-fixed system type A

A semi-fixed system type A has dis-charge piping permanently in place, butnot connected to a permanent foamsupply. Typically a mobile foamsolution apparatus (usually a fire truck)supplies the foam concentrate. Thissystem is often used for subsurfaceinjection of foam into a tank farm fire. Itis similar to a dry standpipe system.

Semi-fixed system type B

A semi-fixed system type B provides afoam solution pre-piped throughout afacility, usually via foam hydrants.Foam must be applied manually to a firefrom these supplies.

High expansion foam system

In a high expansion foam system anautomatic detection device or manualpull station releases foam to cover entirebuildings to a depth of several feet.They utilize a powered foam generatorand deliver the foam through fixedpiping. Ventilation is usually neededahead of the progression of the foam toensure proper movement through theprotected area.

Foam/water system

A foam/water system is essentially adeluge sprinkler system with foamadded to the water.

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ACTIVITYDivide the class into small groups. Give each gtoupan occupancy type and ask them to determinewhether and what type of fixed system would beappropriate. The instructor should serve merely as afacilitator unless incorrect information is being givenunchallenged by anyone else in the class. Each groupshould report to the class.

Possible Occupancy types:

1. A warehouse with rolled paper storage(Foam - sprinklers with AFFF)

2. A restaurant with several deep-fat fryers(Dry chemical system or wet chemicalsystem)

3. A manufacturer using a fuming acid as aningredient in processes (High expansionfoam)

4. A high tech computerized X-ray room at ahospital (Halon, Carbon Dioxide or watersprinklers)

REFERENCESIFSTA Manuals: Private Fire Protection, FireInspection and Code Enforcement; Course Guide forNFA/OLFSP class, Fire Protection Structures andSystems Design, NFPA 1001, 1031, 12,I2A,l2B,16 .164. r7 .

ACKNOWLEDGMENTThe materials in this Instruct-O-Gram are providedcourtesy of Ken Brown of the Iowa City Fire Depart-ment.

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The Instruct-O-Gram is the monthly training outline of the International

Society of Fire Service Instructors (ISFSI). The monthly Instruct-O-

Gram is provided as one of the benefits of membership in ISFSI.

Call 1 -800-435-0005 for informationon other benefits of membership.

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V. Foam

Foam is used in applications where water alonemay not be an effective agent. This includesareas such as flammable liquid processing orstorage areas, aircraft hangars and rolled paperor textile storage areas. Foam systems arecovered in NFPA 1l and 1lA.

A. How foam works

Foam works by:a Smothering prevents air and flammable

vapors from combininga Separating intervenes between the fuel

and the fire

a Cooling lowers the temperature of thefuel and adjacent surfaces

a Suppressing prevents the release offlammable vapors

B. How foam is generated

u Foam Concentrate is the raw liquidfoam prior to the introduction of waterand air

a Foam Proportioner is a device thatintroduces the proper amount of foamconcentrate into water

a Foam Solution is a foam, water mixbefore introduction of air

a Foam (finished foam) is the finalproduct after the introduction of air

Four elements are necessary to produceeffective fire fighting foam: Foam concen-trate, water, air and mechanical agitation.They must be blended in the proper ratios toproduce high quality foam. Usually,proportioners and foam nozzles are designedto work together to create foam. Usingunmatched elements can lead to low qualityfoam.

C. Proportioning rates

Fire Fighting foam is 947o to 99.5Vo water.Foams are designed to be used in /2, l, 3 or6 percent solutions. High expansion foamsare used at /2, 2 or 3 percent. Foams forpolar solvent fuels require 3 or 6 percentsolutions. Foams should only be used at thepercentage they were designed to be used at.

Expansion rates

1. LowExpansion

Low expansion foam (such as AFFF orFFFP) has a small airlsolution ratio(about I:7 to l:20).It is most effectivewhere the temperature of the fuel doesnot exceed 2I2"F

2. High and Medium Expansion

Medium Expansion Foam has anairlsolution ratio between I:20 and 1:200.High Expansion Foam has an airlsolution ratio between 1:200 and1:1000. High and medium expansionfoams are effective as space fillers inconfined or hard to reach areas. Highexpansion foams used as an additive insprinkler systems assist in penetration oftight bulk storage.

Foam nozzles and sprinklers

Foam nozzles and sprinklers (foam makers)are the delivery system for the foam solu-tion. It is best to use nozzles and sprinklersthat are specifically designed for foam.

Foam/water sprinklers are the most commonmethod of delivering foam to an automaticfoam system. These systems are designedfor AFFF foam. They are usually designedto inject air by using the venturi effect.However, sometime a normal sprinkler headis used for a lower quality foam that aeratessimply through the water falling through theair.

System descriptions

1. Self-containedsystem

A self contained system containseverything necessary to produce foamwithin the system. Water and foamconcentrate (or a premixed solution) arein a tank under pressure.

2. Fixed system

A fixed foam extinguishing system ispiped from a central foam station. Thefoam is delivered through fixed outletssuch as sprinklers, usually deluge type.These systems may be either localapplication or total flooding. Most are

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design to Halon systems. Both are availablein local application or total flooding variet-ies. A local application system reduces theoxygen content in the air to less thanl5%o.Total flooding systems require that an areabe sealed off completely through closeddoors and windows and air ducts. But whileHalon systems interrupt the chain reaction offire, Carbon Dioxide systems extinguish thefire by the removal of oxygen. Since CarbonDioxide has a vapor density of about 2.5 it isheavier than air. The gas is stored at about -

110"F. This extreme cold is what causes thecloud that is visible when a CO, extin-guisher is discharged. After activation of aCarbon Dioxide system, the atmosphere willbe as much as 34Vo COr. Concentrations thishigh essentially remove oxygen from thefire. Of course, the removal of oxygen froma fire also removes it from living things.Nine percent Carbon Dioxide in air isconsidered the maximum concentration forpeople to tolerate without quickly losingconsciousness. People have been killed fromCarbon Dioxide systems discharging beforethey were able to exit the area. Due to itselectrical conductive ability and its tendencyto produce static electricity, Carbon Dioxideis not a viable substitute for Halon agents insensitive computer areas. The static electric-ity can erase data stored on computer disks.Therefore, property owners must decidewhether their hardware or their data is morevaluable and make fire protection decisionsaccordingly. If hardware is the primary assetthen a Carbon Dioxide system may bepreferable. If data is the primary asset, thena simple water sprinkler system may be thebest choice. Carbon Dioxide systems arecovered in NFPA 12.

Components

In the past heat detectors, either fixed or rateofrise, were used as actuation devices forCarbon Dioxide systems. Recently, however,smoke and even flame detectors are beingused. The three means of actuation are:Automatic, triggered by a product ofcombustion detector and preceded by analarm; Normal Manual, triggered by a pullstation and activating an alarm; EmergencyManual, used only when the other two

V.

methods fail, causing a discharge of agentwith no pre-alarm. Carbon Dioxide can bestored in either high pressure (850 psi) orlow pressure (large tanks at 300 psi at 0'F)tanks. The tanks are connected to thenozzles through fixed piping.

C. Inspecting and testing

Carbon Dioxide systems need to be checkedannually by properly trained individuals,preferably licensed by the manufacturer.Agent cylinders should be checked semian-nually and replaced if 5Vo of weight or lU%oof pressure is lost. Cylinders must behydrostatically tested every 12 years.

Other Gasequs Agents

Newer gaseous agents that do not containhalocarbons are also covered under NFPA 2001.

A. Inergen (IG-541)

Inergen was the first and is the most popularHalon alternative. Inergen is 40Vo Argon,52Vo Ni1.rogen and 8Vo Carbon Dioxide. Thecarbon dioxide in Inergen increases respira-tions and allows people to work in theenvironment after a release for up to 30minutes even where the oxygen level is wellbelow that necessary to support combustion.Inergen has no adverse effect on the environ-ment because the gasses are all naturallyoccurring and not manufactured. It has adesign concentration of 35Vo in air. It istoxic at 43Vo to 52Vo in alrr.

B. Argonite (IG-55)

Argonite is a mixture of 50Vo Argon and507o Nitrogen. It works by reducing oxygenbelow the level required to support combus-tion. Argonite has no adverse effect on theenvironment because the gasses are naturallyoccurring and not manufactured. It has adesign concentration of 36Vo in air. It istoxic at 43Vo to 52Vo inair.

C. Argon (IG-01)

Argon, an inert gas, is used to reduce thelevel of oxygen. Argon has no adverse effecton the environment because is naturallyoccurring and not manufactured. It has adesign concentrationof36Vo in air. It istoxic at 33Vo to 43Vo in air.

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extremely valuable where a"clearr" agent isrequired. Their use has declined in recentyears due to their impact on the ozone layer.Their manufacture and installation has beenseverely curtailed for several years, butexisting systems may stay in place. Allmanufacture of CFC's will be banned in2000 by the Montreal Protocol treaty signedin 1990. Halons are specifically exempt dueto their irreplaceability. However, their usewill most certainly by phased out over thenext few years. Many companies, includingthe US Navy, are searching for an effectivereplacement for Halon systems.

I. Halon 1301

Halon 1301 does not pose much of ahealth hazard at concentrations below10Vo. Betw een l}Vo and I 5Vo applica-tions all occupants must be evacuatedwithin 30 seconds. Above l5%o concen-trations, SCBA must be supplied. 1301is stored and discharged as a liquid butvaporizes immediately. Halon 1301decomposes at about 950o into Hydro-gen Fluoride, Hydrogen Bromide,Bromine and other compounds. Theseproducts are toxic. SCBA must be wornin an area where Halon 1301 hasextinguished a fire. Halon 1301 systemsare covered in NFPA 12A.

2. Halon 1211

Halon 1211 has a higher boiling pointthan 1301, allowing it to be projected ina liquid stream over greater distances.Halon is used in portable extinguishersand local application fixed systems, butis only approved for total floodingsystems in areas that are not intendedfor human occupancy. 1211 decomposesat about the same temperature as 1301,leaving similar toxic products. Halon1211 systems are covered in NFPA 12B.

3. CarbonTetrachloride

Carbon Tetrachloride (Halon 104) waswidely used as an extinguishing agentuntil its toxic properties were discov-ered. Many simple fixed systems werein use. Typically, the system consistedof a glass bulb filled with Carbon

Tetrachloride. The bulb was suspended' in air, held in place by a wire with a

fusible link or sometimes even wax.When the fusible material melted thebulb would drop onto a sharp, usuallymetal, spike, which broke the bulb andreleased the agent. "Carbon Tet" is stillsometimes encountered, but thesesystems should be removed.

4. Other Halogenated Agents

Many other halogenated agents are orhave been used for fire control includ-ing:

a Halon 1011 (Chlorobromomethane)

a Halon I2\2(Dibromodifluoromethane)

a Halon 2402 (Dibromotetrafluoroethane)

a Halon 1001 (Methyl Bromide)

5. New Halon Replacements

New Clean Agent systems are coveredunder NFPA 2001. They are coming intomore common use as Halon systemsdischarge or are replaced or upgraded.

a. CEA 614 - CuH1a, Used for localapplication

b. CEA 410 - C4H1o, Used for totalflooding application

c. HFC 23 (FE-13) CHF, isTrifluoromethane

d. HCFC-124 _ CHCIFCF3Chlorotetrafl uoraethane

e. FM200

f. Triodide FIC-13I1 - CF3I

g. Halotron 1

B. Inspecting and testing

Halon and other halogenated systems shouldonly be tested by qualified individuals. Theyshould be inspected semi-annually. All tankswhich have lost 57o of weight or I}Vo ofpressure should be replaced. All spacesequipped with Halon systems are required tohave waming signs.

IV. Carbon Dioxide

A. Description

Carbon Dioxide systems are similar in

PRESENTATIONInteractive Lecture

Fixed extinguishing systems are usually used wheresprinklers would be impractical or ineffective. Onedisadvantage of fixed systems is that they onlycontain a finite amount of extinguishing agent, unlikesprinklers which can have a virtually limitless watersupply. Additionally, sprinklers are consideredeffective when they control a fire, while specialextinguishing systems need to actually extinguish thefire to be effective.

I. Dry Chemical

Dry chemical systems are used where rapidknockdown is required. Agents include SodiumBicarbonate (NaHCO3) and Potassium Bicar-bonate (KHCO3) [BC fires] andMonoammonium Phosphate (NH5PO4) IABCfiresl. They are used for:

a Quenching operationsa Dip tanksa Paint Spray Booths* Kitchen Cooking areasa Exhaust duct systems

Systems may be set up as either local applicationor total flooding. In either case, clean up isdifficult due to water resistance and smallparticle size. Dry Chem systems are not consid-ered "clean" agents and not recommended forareas with sensitive electrical equipment.

A. Description

Dry Chemical systems contain: A storagetank for expellant and agent, Piping to carrythe gas and agent, Nozzles to disperse theagent and an Actuating mechanism.Expellant can be either nitrogen or carbondioxide. Containers can be of any size orshape, though most are in the 30 to 100pound range. Nozzles can be either One-position or two position. One positionnozzles project a straight stream of agentonto a specific surface while two positionnozzles project a fan shaped stream of agentto protect a larger area. Actuation is gener-ally a fusible link or a manual pull station.Occasionally actuation is done manuallyonly. On systems with automatic actuation awaming device is needed to ensure evacua-tion of the affected area. Dry Chemicalsystems work by intemrpting the chain

reaction of fire. Thev are covered in NFPAr7.

B. Inspecting and testing

Dry Chem systems should be inspectedmonthly to ensure readiness. The inspectionshouldinclude: Checking pressure gauges toensure proper operating pressure, Checkingfor obvious damage, checking for obstruc-tions to manual actuators, checking tamperseals to ensure that they are intact. Inaddition to this monthly inspection, systemsshould be inspected every six months toensure that system requirements have notchanged and that the system is entirelyintact. Fusible links should be changed everyyear'

II. Wet Chemical

Wet chemical systems are typically a solution ofwater and either potassium carbonate or potas-sium acetate. These systems are particularlyeffective on fires involving wood, paper, cookingoils, grease and flammable liquids. They are notrecommended for electrical fires because of theconductive properties of the solutions. A wetchemical system has the same components of adry system. Fires are controlled by: removal offuel, smothering, cooling and inhibition of thechain reaction. They are covered in NFPA 17A.

III. Halogenated Agents

A. Description

Halogenated agents are Alkyl Halides,combinations of Carbon and members of theHalogen family of elements. They arenamed by the number of Carbon, Fluorine,Chlorine, Bromine and Iodine atoms in themolecule. Halon I2I7 and 1301 weredeveloped to replace Carbon Tetrachloride(Halon 104) when it was discovered that itwas highly toxic. Halon 1211(Bromochlorodifluoromethane) and 1 301(bromotrifluoromethane) are widely used infixed extinguishing systems. Halon 1211 istypically used as a local application systemwhile Halon 1301 is used in a total floodingsystem. Halons are very effective in class Band C fires and also have limited applicationin A fires. They work by intemrpting theuninhibited chain reaction. Bromine is theactive agent in Halon systems. They are

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