FIRE PROTECTION SYSTEMS Bourhan Tachtouch Professor Mechanical Engineering Department KFUPM, Dhahran 31261

FIRE PROTECTION IN BUILDINGS Buildings are designed to minimize heating, cooling and lightening to reduce energy consumption They can be designed to reduce the size of fire-fighting systems and retard the spread of smoke and fire.

Fire has three elements: Fuel High temperature Oxygen * Building fire will be extinguished if deprived of any of these elements * Architects and engineers all participate in the control of these elements that cause fire in buildings

Products of combustion High temperature CO2

Many of the elements of building fire safety, but not all of them, are covered by building codes These codes prescribe the minimum requirement or acceptable protection Designers can go further than the codes requires to enhance fire safety

Codes and standards Code: a mandatory set of formalized design requirement which have been adopted by a government body and that are enforced by law A code may be a standard which has been adopted by a certain government body. Such as Uniform Building Code (UBC)

Standard A voluntary set of formalized design requirements which have been prepared by professional group associated with building design and that are not mandatory These standards like ASHRAE standards The codes and standards are either perspective-based or performance based.

Perspective-based Typically prescribe design strategies that are passive means of limiting the spread of fire and protecting life (e.g. construction material, interior finishes, maximum distance to exist, etc.) Codes allow some relaxing of such prescription when active fire-suppression systems ( such as sprinklers) are designed into building

Performance-based Describes how the building will perform under fire ( using computer simulation)

Common building fire safety codes and standards Uniform building code (UBC) National Fire Protection Agency (NFPA) Local Safety Enforced Requirements

Who Is Responsible? Architects and engineers are all responsible and should participate in the control of the fire elements in buildings Considerations of fire protection take part both in the architectural and engineering design phases of buildings

Fire –proofing structure Architectural Egress , fire barriers Structural Fire –proofing structure Mechanical Sprinklers, standpipes & hose systems, smoke control

Fire resisting materials Electrical Fire alarm systems Interior design Fire resisting materials

Fire Hazards Three categories: Light hazard: normal buildings Ordinary hazard: factories, industrial areas Extra hazard: refineries, gas stations

Fire thermal products (flame and heat ) are responsible for about 25% of deaths in building fires Fire non-thermal products ( smoke and gases) are responsible for about 75% of deaths in building fires. Gases ( CO2, CO, H2S, SO2, NH3, …) are either toxic or displaces oxygen resulting in insufficient oxygen which leads to health problems

Normal concentration of oxygen in air is about 21% If it is reduced to: 15% - diminished muscular skill 14-10%- faulty judgment and rapid fatigue 10-6% - collapse but revival is possible with increased oxygen supply

Objectives of fire safety Protection of life Protection of property 1. The building contents 2. The building itself Continuity of operation Protection of adjacent buildings

Maximum travel distance limits are determined by codes Allowable travel distances to exit are increased when automatic fire suppression systems ( sprinklers for example) are used As a designer you should be aware that at 30% of building fire deaths result from fire cutting off the path to exit

Example A multi story office building is 30 m wide by 80 m long What capacity ( exit door and stairs ) is required per floor?

Solution Gross floor area = 30x80=2400 m2 Occupant load = 9.3 m2/person Building population per floor=2400/9.3 =258 persons Width of exit doors (to stairs)=258x0.2 =51.6 in = 131 cm Two stairs @90 cm clear door into each 180 cm > the minimum of 131 cm. then it is OK

Width of stairs Width of stairs= 258x0.3=77.4 in=197 cm Two stairs @ 120 cm each 240 cm > the minimum of 197 cm then it is ok

PROTECTION FOR PROPERTY EASY ACCESS TO BUILDING FOR FIRE FIGHTING INTERNAL FIRE SUPRESSION SYSTEMS (EXTINGUISHERS, SPRINKLERS, HOSES AND STAND PIPES) ADEQUATE WATER TO FIGHT THE FIRE ( elevated tanks on building)

Exposure Protection It is common in areas where highly flammable surroundings pose a serious threat of fires originating outside a building

NON –FLAMMABLE BUILDING MATRIAL

COMPARTMENTATION Has become more important as buildings have become lightweight structures incorporating decreased fire resistance and open floor areas that encourage the spread of fire

Codes established the maximum floor areas permissible for variance constructions and occupancies Many codes require fire stopping around 93 m2 of suspended ceiling area and 186 m2 for attic floor area

Structural protection Allows the building to continue to stand during a fire and enables it to be salvaged rather than demolished after fire

Continuity of Operation For building functions, it is desirable to minimize the disruption of operation that fire will cause To achieve this the following can be considered:

Fire /alarm suppression systems HVAC systems to evacuate a building of smoke after the fire put out Provision for water proofing floors in sprinkler-served buildings (sloping water proof floors with drains)

Protection of adjacent buildings Setbacks Zoning Access for firefighting personnel and equipment

Smoke management It kills more people in building fires than heat or structural collapse Design for smoke management , fire resistance and fire suppression

Objectives Reduce deaths Reduce property damage Provide continuity of operation with minimal smoke interference

Factors in smoke management Heat Buoyancy Air velocity Building location High and low buildings

Confinement The most passive design response to smoke is to try to confine it to the fire area itself Refuges ( exclude smoke from specially protected areas)

Dilution At early stages of fire, the dilution of smoke with outside air may help in evacuation process

Exhaust Using air velocity and pressure to control smoke

Advantages of Exhaust They can move toxic gases from refuge areas They help fire fighters by improving th air quality in the vicinity of the fire itself They can help control the direction that a fire takes by creating air currents that a fire will follow

They remove unburned but combustible gases from a fire before gases can cause a back draft or flashover (smoke explosion) They keep smoke out of refuge areas even when doors are temporarily open With them, the tall-building stack effect, complicated by buoyancy and wind is likely to overcome smoke management system They can help to remove smoke after fire

HVAC systems, sprinklers and smoke Two systems within the building must be closely coordinated with smoke exhaust systems: 1. HVAC 2.Fire detection/suppression (sprinklers) system

HVAC system As the fire detection system activates the smoke exhaust fans it must also override the conventional HVAC system operation If the HVAC system is VAV, then all supply control valves (dampers) must be moved to their full open position

Sprinklers system It can hamper the functioning of smoke exhaust systems, both by creating a curtain of water that inhibits the movement of smoke and by cooling the smoke, thus reducing its buoyancy as less buoyant smoke descends, visibility decreases and the danger of smoke inhalation increases

Automatic ventilating hatches Heat and smoke venting devices (no fans) For smaller buildings

Fire suppression mediums Water : Is the most popular medium for building fire suppression Is readily available Is relatively low in cost!!!! When changed into vapor , it absorbs 2500 kJ/kg at atmospheric pressure and its volume increases to 1700 times which helps in pushing away the oxygen needed by the fire

Disadvantages Water damages building contents It conducts electricity Many flammable oils will float on water surface since the specific gravity of these fluid is less than one Steam can harm fire fighters

Carbon dioxide CO2 Used in applications where rapid fire suppression is required and where water might cause damage such as computer equipment rooms , electronic installations, libraries, museums, and record storage rooms Smother fire by displacing oxygen

Used in tightly confined spaces that are free of people and animals ( e.g. display cases, mechanical or electrical chases, ….) Stored as a liquid under great pressure, when released as gas , it provides cooling as well as smothering action CO2 does not leave residue after its use, non-toxic and usually causes no damage to electrical equipment

Disadvantages It requires concentration of 21% to 62% of that of air ( 9% concentration results in loss of consciousness), not good environment for fire fighters or trapped persons It should be of low concentration with early alarm evacuation before use After CO2 dissipation re-ignition is possible

Foams They are masses of gas filled bubbles Light, therefore, float on surfaces of burning liquids, that means smothering and cooling effect Highly expandable and fast spreading. Foam expansion into steam reduces oxygen content to less than that required for combustion (7%), therefore suppressing fire.

A cooling effect is also achieved by the action of breaking bubbles Effective in flammable liquid fires (popular in airplane hangers)

Halogenated Agents Halogenated hydrocarbons, known as ‘halons’ are stored as liquid with one or more hydrogen atoms replaced by halogen atoms Halon 1301 is the most widely used agent effective against classes A,B,C fires common on portable fire extinguishers The number indicates: 1- carbon atom, 3 –fluorine atoms, o- chlorine atom, 1 –bromine atom

Class A: Interior wall and ceiling finish, flame spread 0-26, smoke developed Class B: Interior wall and ceiling finish, flame spread 26-75, smoke developed Class C: Interior wall and ceiling finish, flame spread 76-200, smoke developed

Halons primarily inhibit flames chemically rather physically (exact process unknown) Light weight and space saving relative to other mediums It extinguishes fire little harm to contents, popular choice where a clean fire suppression agent is required and people are present and content with high value such as in commercial aircraft, computer rooms, museums , libraries, telephone exchanges and kitchens

Halons does not wet or leave residue after use Under normal conditions, Halon is 5 times heavier than air Not good for burning metals or self-oxidizing materials such as gunpowder More expensive than CO2 or water

Halon Operation and Maintenance Used in application where rapid fire suppression is required and where water might cause damage such as in computer equipment rooms , electronic installations libraries, museums and record storage rooms Typically , the hazard area is protected with central Halon storage tank connected to a fixed pipe distribution network to the protected area

Should be of low concentration less than 10% , doors should be auto close HVAC and air distribution systems should be shutdown when the system is discharging to prevent the leakage for Halon 1301 from the protected area and therefore insure effective fire suppression Greater than 10% Halon concentration means potential serious toxic effects (Halon is CFC gas)

A Halon 1301 fire suppression system should be installed , inspected and maintained by trained or certified contractor Should be checked for nozzles placement and blockage Should be checked for proper operation and functioning of the automatic detection and control systems

Fire suppression systems Portable fire extinguishers: Classified according to the type of fire or hazard for which they are designed Designed to suppress small fires (typical maximum discharge time span is 8 to 90 seconds) Many contain water, water mixture, dry chemicals , and/or gases Travel distance and time is a main factor in fire extinguishers placement

Classes of fire extinguishers Class A For use on ordinary combustibles such as wood , trash, paper and textile Content: water, water-based agents, or multipurpose chemical agents

Class B For use on flammable liquids or liquid petroleum products fires such as flammable gases , greases, paints, solvents, plastics and rubbers Contents: requires smothering or flame –interrupting chemicals (blanketing) such CO2, sodium, and potassium bicarbonate base dry chemicals (Purple K, with purple color powder), foam , or halogenated agents

Class C Used for electrical fires or near energized electrical equipment (over-heated fuse boxes and other electrical sources and wiring Classification refers to sources of ignition rather than to fuel as in classes A and B Contents: non-electrically conducting extinguishing agents such as CO2 , sodium, and potsium bicarbonate base dry chemicals or halogenated agents

Class D Used in combustible metals fires such as magnesium, titanium, sodium-potassium alloys, etc. Contents: dry powders such as graphite or sodium chloride vase

Classes A, B and C are: Multi-purpose dry chemicals extinguishers Content: ammonium phosphate (with yellow color powder) Not ideal for electrical fires because it leaves hard residue

Fire Extinguishers Operation and Maintenance Should be placed uniformly in visible and easily reached locations along normal paths of protected egress away from potential fire hazards Extinguishers suitable for more than one class of fire should be used in the same facility Should not be carried more than 22.5 m for classes A, C and D hazard and no more than 15 m for class B hazard and at least 15 cm from the floor for cleaning and to avoid obstruction

Should be clearly marked for the intended use Inspect all extinguishers when installed and thereafter on regular bases 9monthly or more frequent) Should be checked frequently for pressure, charge , weight, operation and cleanness Recharge all rechargeable type extinguishers using the agents specified on their nameplates

Check frequently for their proper location, access and visibility Check for corrosion and dents Check for leakage or clogged nozzles Locate indoors or provide shading avoiding areas with high temperature (> 49oC, 120 F) Record date of inspection/recharging using maintenance tags

Should be trained on by occupants Hydrostatic testing , a pressurization of the extinguisher to test cylinder structure, is required every 5-12 years depending on the type of extinguisher, cylinder or shell Hydrostatic testing must be performed by component personnel who have suitable testing equipment and facilities (normally performed by outside contractors)

Standpipes and hoses Essential in tall and industrial buildings Water is supplied at a minimum pressure of 448 k Pa (65 psi) at the topmost outlet from: Public water system with adequate water pressure Overhead gravity or pressure tank Automatic or manually controlled up feed fire water pumps

Code requirements for number of standpipes is based on: Usually located at or near fire stairs so that hoses will be able to reach every part of the building Code requirements for number of standpipes is based on: 30.5 m (100 ft) length of extended unlined fire hoses 22.9 m (75 ft) length of lined hoses

In theoretical situations, the direct route to fire source can be used, therefore , the required standpipe hose length will be sufficient However, in real situations , the fire fighters carry equipment and hoses filled with water and approaching fire along smoke –filled corridors at extreme heat, indirect route will require more hose length than the theoretical one

Types of Standpipes Standpipes and hoses with a separate water reserve, up feeding pumping or fire department connection are listed in three classes and five types. The major differences are whether the system is for first aid or full scale fire fighting or whether the systems has an automatic water supply or manual one

Classes Class I systems: For full scale fire fighting and required for sprinklered and un-sprinklered buildings three stories high as well as in Malls

Class II For first air fighting before the fire trucks arrive. They use 38 mm hose connection The difficulty for untrained personnel to handle 100 ft hose with 378 liter/min flow

Class III Combine the characteristics of Class I and Class II They serve for both first aid and full scale fighting

Combine systems are either class I or III standpipe systems that also supply water to sprinkler system

Combination standpipe system Joint use standpipe system for both fire and sprinkler heads can be used. Adequate water supply and pressure must be available (min 6 in standpipe riser). Separate fire hose and sprinklers valves allow independent control at each floor level

Standpipe system types Dry standpipes Water pipes 9normal;ly empty) used to connect hoses by fire fighters to ground level fire hydrants. Located at or near fire stairways or outside of buildings Wet standpipes Wet standpipes are filled with water under pressure at all times . Can be used by trained building occupants in each floor of the building

Standpipe system types Automatic wet systems- the pipes are filled with water and connected to water supply capable of automatically meeting the fire fighting demand Automatic dry systems- the pipes are filled with pressurized air and are connected to water supply capable of automatically meeting the fire fighting demands

Semiautomatic dry system-the pipes are filled with air and connected to the water supply Manual dry systems-the pipes are filled with air and there is no connection to a water supply other than that provided by the fire department Manual wet system- the pipes are filled with water with a connection to domestic source

Standpipes Operation and Maintenance Inspect al fire hoses on regular basis (monthly) and schedule them for replacement at ten –year interval Perform annual pressure test of hydrants and hoses Install isolation valves on standpipe systems to allow work on a branch line without putting the entire system out of service

May install check valves on the standpipe systems at coming water source to prevent water from escaping the system when pressure drops or when fire department connections are not in use Provide drainages system. Locate drain valves at the lowest possible point downstraem of the isolation valves

Sprinkler System Design Impacts Unlike the fire hose, a sprinkler is likely to be already positioned above the point of a fire and is capable of being deployed in seconds , not minutes They are relied on as a proven automatic fire suppressers

Automatic sprinkler systems consists of horizontal pattern of pipes placed just below or within the ceiling of the industrial buildings, warehouses, stores, theaters ,, etc in which a fire hazard require their use

Alarm Gong An alarm gong mounted on the outside of the building warns of water flow through the alarm valve on the actuating of sprinkler head This warning gives the building personnel an opportunity to make additional fire arrangement that can minimize loss and speed the termination of the fire In this way the sprinklers can be turned off to prevent excess water damage to building content after the fire is out

Siamese Connections Siamese connections (fire department connections) are connections used by local fire department to pump water into the standpipe system

Siamese Operation and Maintenance Must be readily visible and accessible to the fire department without obstruction by equipment, structure or vegetation Should have its fire department connections located on street side of the building

Should be identified with proper signs indicating their parts of the building served by them and their type ( i.e. standpipe , sprinkler, or combination) Should be hydrostatically tested at time of installation Should be inspected regularly for proper operation Should be checked for threads freedom of movement , cleanness and readiness for use Hoses and hydrants should be checked regularly for pressure and proper working conditions

Provision for Drainage Sprinklers can release a huge amount of water It has to be removed

Water supply Elevated water tank in the building They supply a constant pressure on the distribution lines, store sufficient water to balance supply and demand, prevent excessive starting and stopping of the pump and provide a dependable fire reservoir

When gravity tanks are used with sprinkler systems they should provide enough water to operate 25% of the sprinkler heads for 20 minutes Disadvantages: Unsightliness Freezing Heavy weight

Valves They are required to allow the sprinkler to be shut off for maintenance , system modification or replacement of all sprinkler heads that have operated after a fire Indicating valves of various types (open or closed) usually open

Sprinkler Construction orientation and Rating The common sprinkler head contains water by a plug or cap that is held tightly against an orifice by levers or other restraining devices Common types of sprinkler heads are upright (SSU), pendant (SSP), or sidewall types Upright heads sit on top of the exposed supply piping Pendant heads hang below piping, which can be concealed above suspended ceilings

Flow control sprinklers close automatically once temperatures at the ceiling are sufficiently reduced

Sprinkler Spacing and Hazard The spacing of sprinkler heads and the sizing of their spaces are complex and designed by professionals The guidelines for preliminary sprinkler location are: Degree of hazard faced by the occupant (tables 24-8 and 24-9) Maximum floor area to be protected by any sprinkler system Piping can be hydraulically designed

A complication factor that is the expectation that only a small percentage of the sprinklers will actually open A detailed sizing procedure would consider both the available pressure at the highest sprinkler and the expected flow rate (500-5000 gpm) The sprinkler actual performance is :

Q- flow rate, gpm K- K factor , table 2-47 P- pressure , psi In SI units: Q- L/min K-K factor(14.3 x I-P K factor) P- pressure in bars

Sprinklers are designed for maximum working pressure 175 psi and 500-750 gpm. Light hazard systems need a minimum residual pressure of 15 psi and 500-750 gpm Ordinary hazard systems need a minimum residual pressure of 20 psi and 850-1500 gpm

Residential sprinklers It a fast response device with a tested ability to enhance survivability in the room of fire origin and it is listed for protection of dwellings units They have the ability of delivering water to the walls and high enough on the walls to prevent the fire from getting above the sprinkler

Quick response sprinklers Fast response are required in all light hazard occupancies. Like hotels, motels and offices.

Sprinklers Overview Usually required in large basement areas, windowless buildings, hospitals and health care facilities, hazardous materials storage areas and large public occupancy area Consist of horizontal pattern of ceiling pipes with outlets and sprinkler heads Sprinkler heads can be upright, pendant or sidewall type

Automatic sprinklers activated by abnormally high temperature which should be 13.9 o C greater than expected maximum ceiling temperature, 577-77 (135-170 o F) for ordinary sprinkler heads Sprinkler system discharged water prevents fire spread from the area of origin. It cools burning materials by direct contact of water particles , absorbs heat, wets unburned combustibles and displaces oxygen

Sprinkler heat sensitive controls may be made of : Metal alloys that fuse Organic materials that soften Organic liquids that expand and rupture their glass enclosure Water supply may not close unless a main valve is manually closed

Water supply may close automatically (flow control sprinkler) once the ceiling temperature is reduced to ≤35o C All types of sprinkler must replaced after use Floor opening (stairwells, escalators, …) can be protected by sprinklers of high velocity water spray nozzles Adequate water drainage system must be provided

Types of sprinkles Wet – pipe (most common): Water is always standing under pressure in all pipes and mains Used in heated areas or areas not subject to water piping freezing Dry-pipe (used where freezing might be a problem) Pipes are filled with compressed air or nitrogen gas under pressure ( to avoid rust) until the opening of a sprinkler head permits water flow The system must be drained and re-pressurized after fire

Pre-action Similar to dry-pipe except that water is admitted by a pre-action valve to the pipes before any sprinkler head has opened with a very early alarm as a result of signals received from supplemental fire detection system )smoke or heat sensors) Used in building with contents subject to water damage such as computer rooms an retail stores

deluge All sprinklers heads go off at once where a deluge valve will permit water flow only after a fire detection system is activated Used in buildings with expected rapid spread of fire such as air-craft hangers, areas where flammable liquid fires may breakout and in buildings with especially high ceiling

Combined sprinklers and standpipes system Combined systems use the water piping that serve both outlets for fire department use and outlets for automatic sprinklers

Sprinkler systems operation and maintenance Should be located to detect a fire readily and to discharge water over the greatest area considering all obstructions (structural elements, lighting fixtures, HVAC ducts, and partitions) in reality only a percentage of sprinklers will actually open to extinguish fire Riser is a vertical water supply pipe that should be of sufficient size to supply sprinklers an any one floor

Risers should be located as to eliminate long dead end pipe runs Cross-mains supply water to the branch lines that supply water to sprinklers Adequate water drainage and slope mist be provided in sprinkler-served areas Keep supply valve open

Do not shut supply valve prematurely during a fire Flush out system regularly and clear from debris at intake using filter screens Take necessary precautions to avoid wet sprinkler system piping freezing in cold areas Keep sprinkler heads clear from obstructions or stored materials

Check sprinklers for corrosion Insure adequate sprinklers water supply at all times Insure sprinkler system working conditions at all times

Sprinklers layout Individual sprinkler heads are connected together along branch lines Layout of sprinkler system id a function of Building occupancy and hazard conditions: Light hazard- normal buildings Ordinary hazard- factories, industrial areas Extra hazard refineries, gas stations

Coverage area (m2) Depends on the physical characteristics of the sprinkler head and available water flow and pressure

Spacing between sprinkler heads (m) Maximum spacing is normally 4.5 m Must not be too close to wet each others delaying activation when needed If do ( i.e. less than 1.8 m around escalator opening) they should be separated at midway by cross or recessed baffle pockets

Sprinkler systems pipe sizing Find required sprinkler operating water pressure using equations or manufacture’s data Find static pressure loss due to elevation Find pressure losses in pipes, valves and fittings Find equivalent pipe length

Find available pressure . It must be greater than the system pressure Find the pressure drop per unit length (pa/m) at required flow (charts) Larger pipe sizes are often used to achieve lower friction losses, especially when available water pressure is low

Housekeeping and fire prevention Separate fuels from ignition sources Allow smoking only in designated areas Avoid the accumulation of excess rubbish that might represent fire fuel source Store all flammable and combustible liquids in proper storage

Do not store flammable materials near fire ignition sources ( e. g Do not store flammable materials near fire ignition sources ( e.g. boiler rooms, electric rooms, home water heater, etc.) Use only the minimum amount of flammable or combustible liquids at the workplace at one time Report hazards which could cause fire to ignite Inspect electrical equipment for proper operation and safety Identify trouble spots properly

General fire prevention strategies Implement regular fire safety awareness and educational programs Insure proper maintenance and operation of critical safety components/systems such as electrical equipment and electrical wiring and connections Prevent overloading electrical outlets beyond their permitted capacities

Follow manufacturers recommendations in operating and maintaining electrical equipment and appliances Implement continuous maintenance employee safety training Train operators on fire fighting operations in case of fire Publicize fire prevention rules and enforce them

Industrial fire suppression sustems This subject is broad due to The many types of industrial hazards The many fire suppression options and methods available The many fire suppression mediums available

Typical industrial hazards Flammable liquids storage rooms Printing machines areas Electric motors rooms Pump rooms Paint lockers Wood furnishing areas Transformer rooms

Typical industrial fire protection means Total flooding Local applications using tank side type of discharge Local applications using overhang type of discharge

Typical industrial fire extinguishing mediums Multi-purpose dry chemicals Potassium bi-carbonate (purple-K) dry chemicals Sodium bi-carbonate dry chemicals Carbon dioxide Halon 1211 Foam

References Stein, B. and J. S. Reynolds, Walter Grondzik and Alison Kowk, 2006. Mechanical and electrical equipment for buildings, 10th edition , John Wiley &Sons, New York Fuchs , Sheldon J. 1992. 2nd edition. Complete building equipment maintenance desk book. Prentice Hall, New Jersey , USA Egan, M. David. 1978. Concepts in building safety . John Wiley & Sons, New York , USA