Fire Protection Systems

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FIRE PROTECTION SYSTEMS

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Fire Protection System Design Strategy Comprehensive Strategy

Prevent fires from starting in the first place Education Administrative procedures Signage Inspections Fire safety program

Fire alarm and detection systems Detect fires early to initiate quick evacuation

Design safe egress from building Exits, Stairwells, Corridors Emergency lighting and ventilation

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Design Strategies (cont’d) Fire suppression systems

Sprinkler Standpipe and Hose Chemical

Smoke Control systems Remove smoke from exits Provide fleeing occupants with breathable air

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Design Strategies (cont’d) Compartmentalization

Break a building into small compartments to contain fire and smoke

Fire Separation Fire rated wall, floor, ceiling assemblies that impede

the spread of fire

Use of non-combustible materials Use of low flame spread and smoke developed

finish material

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Flame Spread ASTM E84 – Test Method for Surface-Burning

Characteristics of Building Materials (Steiner tunnel test). Rates surface-burning characteristics of building materials and interior finishes, and provides data on smoke density.

Flame spread classifications: Class A: 0-25 Class B: 26-75 Class C: 76-200

Local building codes generally restrict use of materials in different occupancies based upon flame spread and smoke developed ratings. For example, NYSED Manual of Planning Standards requires

finishes in corridors, passageways, stairways to be Class A.

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Sources of Ignition Spontaneous Combustion Electrical Sources

Arcing Lightning

Mechanical Friction

Other Intentional (arson) Cigarettes

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Fire Issues Products of combustion – CO, CO2, other

gases Fire quickly consumes oxygen Lack of oxygen

Rapid deterioration of human capabilities Muscle control Thinking, consciousness, etc.

Poor visibility

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Fire Issues (cont’d) Vertical shafts promote spread of smoke, heat

Elevators Escalators Atriums

HVAC systems can spread smoke Windowless buildings – prevent entry by firefighters Interior finishes – can spread fire, give off smoke High rise buildings (g.t. six stories) – complicate

firefighting, rescue

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Fire Alarm and Detection Systems

Design Standards Fire Code of NYS – defines minimum standards where fire alarm and

detection system is required, general design requirements NFPA 72 – National Fire Alarm Code – defines specific design

standards

Functions of a fire alarm and detection system: Initiate alarm

Manually Automatically

Notify occupants Audible alarms Visual alarms

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Functions (cont’d) Automatically signal fire department or central station Recall elevators Supervise special systems:

Fire pump operation, power availability Sprinkler system status

Unlock doors Automatically close doors that are part of fire separations Automatically release smoke relief hatches Control operation of HVAC supply and exhaust fans

Total shut down Special smoke management systems

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Typical Fire Alarm System

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Fire Alarm Control Panel

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Fire Alarm Systems (cont’d) Types

Conventional (off/on “dumb” devices) Addressable

Analog Digital

Equipment Manual Fire Alarm Boxes (Pull Stations) Mounting – not less than 3.5 and not more than 4.5 ft above floor level

(ADA requires maximum 48” high forward reach) Spacing:

At exit doorways within 5’ of each exit doorway on each floor; on both sides of opening 40 feet and wider, and within 5 feet each side

Additional boxes such that distance of travel to any box less than 200 feet on same floor

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Manual Alarm Station at Exit

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Fire Alarm Systems (cont’d) Heat Detectors

Applications Where smoke is ordinarily present Top of elevator shafts where sprinklers are present

Types Fixed Combination fixed/rate of rise

Location On ceiling not less than 4” from sidewall, or on sidewall

between 4” and 12” of ceiling

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Fixed Type Heat Detector

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Fire Alarm Systems (Cont’d) Heat Detectors (cont’d) Typical Spacing

Fixed: 15’x15’ Combination fixed/rate of rise: 50’x50’ All points on ceiling within 0.7 x listed spacing

Special considerations – beam construction, sloped ceilings – refer to NFPA 72 for spacing requirements.

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Smoke From Cooking Appliances Can Set Off Smoke Detector

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Stages of a Fire Incipient – invisible combustion gases, without

smoke or flame, no appreciable heat release Smoldering – heat still absent, combustion

gases now visible as smoke Flame – actual fire is produced, a column of

gases made luminous by intense heat Heat – follows concurrently or just after flame

stage – tremendous amounts of heat released

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Smoke Detectors Types

Spot Beam

Design: Ionization Photoelectric

Spot Detector Accessories Integral alarm

Typical use – motels and similar sleeping spaces

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Photoelectric Spot Smoke Detector with Integral Alarm Photoelectric detectors

operate using principle of “smoke obscuration”

Smoke interposed in light beam between small emitter and detector

Decreased light intensity at detector causes alarm to sound

Device in photo also includes integral alarm – used in motels and similar sleeping spaces.

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Principle of Operation – Ionization Detector

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Smoke Detectors (cont’d) Applications

Spot detectors For general fire detection Close doors, operate smoke dampers

Beam detectors High ceilings where spot detectors impractical

Location On ceiling not less than 4” from sidewall, or on sidewall

between 4” and 12” of ceiling

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Smoke Detector Mounted on Wall

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Smoke Detectors (cont’d) Typical Spacing (spot)

30’x30’ All points on ceiling within 0.7 x listed spacing g.t. 3’-0” from HVAC diffusers, supply grilles

Special considerations – beam construction, sloped ceilings – refer to NFPA 72 for spacing requirements.

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Typical “Listed” Smoke Detector Spacing

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Incorrect Application of Smoke Detector Area covered = 60’ x

15’ = 900 s.f. Distance to corner

exceeds 0.7 x listed spacing (0.7 x 30 = 21’)

Two smoke detectors would be required for this room.

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Beam Smoke Detector Smoke rising to ceiling

will obscure light beam. Receiver will detect change

in beam intensity and cause alarm to sound.

Often used in atrium spaces, high “cathedral ceilings”, similar spaces.

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Notification Appliances Audible

Refer to NFPA 72 for sound pressure levels Mounting

Wall – top not less than 90” a.f.f., not less than 6” below ceiling (where ceiling heights allow)

If combined with visual appliances, entire lens of visual appliance not less than 80” nor greater than 96” a.f.f.

Spacing Such that they can be heard throughout building Refer to NFPA 72 for specific requirements

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Audible Visual Device in School Cafeteria

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Audible Visual Fire Alarm Appliance

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Notification Appliances (cont’d) Visual Appliances

Location Wall mounted – entire lens 80” -96” a.f.f. Ceiling mounted permitted when device is specifically listed for

this application. Spacing

Refer to NFPA 72 When two or more in same field of view, must be synchronized

(can be harmful to persons with epilepsy)

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Remote Annunciator Panel at School 80

An annunciator panel displays at remote entries and other locations the zone or device that is in alarm – generally located at main entries.

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FIRE SUPPRESSION SYSTEMS

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Types of Fire Suppression Systems Standpipe and Hose Systems

A reliable water supply, piping, hose connections to permit manual extinguishing of a fire.

Sprinkler SystemsA reliable water supply, piping, sprinklers, to permit automatic extinguishing of a fire.

Chemical Extinguishing SystemsBoth manual and automatic systemsUse a chemical extinguishing agent where water is not effective, or cannot be used.

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Standpipe and Hose SystemsClassification:

Class I – 2-1/2” hose connections for firefighter’s use, 100 psi at uppermost hose connection.

Class II – 1-1/2” hose connections for occupant use, 100 psi at uppermost hose connection.

Class III – 2-1/2” and 1-1/2” hose connections for both firefighter’s and occupant use.

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Diagram of a Typical Standpipe System

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Standpipe Hose Valve at Intermediate Stairwell Landing

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Typical Backflow Preventer for Fire Protection Service A backflow preventer

prevents water contained in building piping systems from flowing back into the community water main.

Water piping in buildings may contain foul and/or hazardous materials.

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Classification (cont’d) Type I and III standpipes are the most

common. Design Standard

• NFPA 14 Standard for the Installation of Standpipe, Private Hydrant, and Hose Systems.

• Current edition is 2003• As of 2004, NYS Building Code adopts the 2000

edition.

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Combined Systems

A combined system is a standpipe that also supplies automatic sprinklers on each floor.

Combined systems were first permitted by NFPA in 1976 to encourage owners of high rise buildings that already had standpipes to install sprinkler systems.

A sprinkler crossmain is connected to the standpipe at each floor. A typical connection detail is contained in NFPA 14 Figure A-5-9.1.3.1 (a) and (b).

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Diagram of a Typical Combined Sprinkler and Standpipe System

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A Typical Flow Control Assembly Located in a Stairwell

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Buildings that Require Standpipeand Hose Systems Buildings where standpipes and hose systems are

required: Any building where the highest floor level is 30 ft. or more

above the lowest level of fire department vehicle access. Places of Assembly Covered Mall Buildings (e.g. Shopping Malls) Stages Underground Buildings Check the applicable building ordinance for specifics

(NYS 905.3)

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Water Supplies Water supply must be among the following:

• Public waterworks with adequate pressure• Automatic fire pump connected to public

waterworks• Manually controlled fire pump in combination

with pressure tanks.• Pressure tanks installed in accordance with NFPA

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Water Supplies (cont’d.)• Manually controlled fire pumps operated by

remote control devices at each hose station.

• Gravity tanks in accordance with NFPA 22

• Automatic fire pumps connected to the public waterworks are the most common.

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Water Supply Capacity Water supply capacity

• The capacity of the supply is calculated as follows: 500 gpm for the first standpipe 250 gpm for each additional standpipe Not to exceed 1250 gpm

Water supply must have minimum 30 minutes duration for calculated flow

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Additional Classification of Standpipes Wet

• The standpipe system is always filled with water. Dry

• The standpipe system contains no water.• Generally used only in unheated buildings (e.g., parking

garages.) Automatic

• Water supply capable of supplying system demand automatically.

• Most common type

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Additional Classification of Standpipes (Cont’d) Manual

• Connected to small water supply to maintain water in the system, but inadequate to meet demand.

• Relies on fire department pumper to supply necessary system demand.

Other types: semi-automatic dry, manual-dry (see NFPA 14 for explanations.)

The Building Ordinance (NYS Building Code) prescribes which type is required.

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Fire Pumps Fire Pumps

• Since most water main pressures are generally less than 100 psi at the street, a fire pump is usually required to provide adequate pressure.

• Fire pumps must be provided with an emergency power source.

• Fire pumps generally require a separate, fire rated (2 hr.) room or enclosure.

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Typical Electric Fire Pump Installation

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Location of Hose Connections Location of Hose Connections

• Height: not less than 3 ft and not more than 5 ft above floor (usually 4 ft).

Class I Systems• In exit stairways at each intermediate landing between

floor levels.• Each side of wall adjacent to exit openings of horizontal

exits.• Each exit passageway at entrance from building areas into

passageway.

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Location of Hose Connections (Cont’d)

In covered mall buildings at entrance to each exit passageway or exit corridor, and exterior public entrances to mall.

At highest landing of stairways with access to roof, and on roof where stairways do not access the roof.

Additional 2-1/2” hose connection at hydraulically most remote riser to facilitate testing.

See NFPA 14 for more requirements.

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Location of Hose Connections (Cont’d) Class II Systems

• 1-1/2” hose stations so that all portions of each floor level are within 130 ft of a hose connection.

Class III Systems• As required for both Class I and Class I Systems

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Drainage of Standpipes Each standpipe to be equipped with a means

for draining Usually a drain valve is located at lowest

point of standpipe, downstream of isolation valve

Drain to an approved location• Often drained to spill at grade

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Fire Department Connections At least one fire department connection for

each zone of each Class I and Class III system High rise buildings require two remotely

located fire department connections for each zone

Height: +18” to +48” above adjoining grade

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Fire Department Connections (Cont’d) A check valve is required downstream. No shutoff valve is permitted between the fire

department connection and the system. Dry piping between connection and check

valve should be galvanized steel. Signage is required at each connection. See

NFPA 14, Ch. 4-3.5.2 for details.

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Sprinkler Systems Definition and purpose – a reliable water supply, piping,

sprinklers, valves and accessories for the purpose of automatically extinguishing a fire.

Governing Design Standards Local building code or ordinance – prescribes where sprinkler

systems are required NFPA 13 Standard for the Installation of Sprinkler Systems –

prescribes how sprinkler systems are to be designed and constructed Factory Mutual (FM) – An insurance company standards

organization; it may, through the building owner’s insurance company, impose additional restrictions/requirements for overall building fire protection systems.

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Sprinkler Systems (cont’d) Types of sprinkler systems:

Wet Dry Pre-action Deluge

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Sprinkler Systems (cont’d) Wet system

Piping is filled with water under pressure at all times.

When one or more sprinkler heads open, water is automatically discharged.

Used in heated buildings or portions of buildings that are heated.

Most common type of system.

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Diagram of a Wet Pipe Sprinkler System with Water Motor Alarm Both pendant and

upright sprinklers may be used.

During operation, the alarm check valve diverts a small portion of water to the water motor alarm – does not rely on electricity to sound alarm.

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A Typical Wet Pipe Sprinkler Alarm Valve Installation

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Wet Pipe Alarm Valve

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Wet Pipe Sprinkler with Electric Alarm An electric alarm bell is

operated through a water flow switch inserted into the main riser.

When a sprinkler opens, water flow activates flow switch, and alarm sounds.

Requires a reliable source of power from an emergency source.

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Sprinkler systems (cont’d) Dry system

Piping is filled with compressed air. A dry system valve blocks the entry of water into the

piping. Air pressure in the piping holds the valve closed. When one or more sprinkler heads open

Air is first released through the head(s) Air pressure in the piping system drops. Dry system valve swings open. Water floods the piping system.

Used in unheated buildings, or portions of buildings that are not heated, e.g., attics.

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Diagram of a Dry Pipe Sprinkler System Upright heads must be

used, in order to allow the piping to drain completely.

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Sprinkler systems (cont’d) Pre-action system Requires operation of both a fire detector and

a sprinkler head opening before water is released. Piping is filled with pressurized air. A fire detection system (smoke, heat detectors, manual

pull station) is wired to the pre-action valve; valve is opened only when fire detection system is activated.

Water floods piping.

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Pre-action system (cont’d) Water is released from each sprinkler head that

opens. Used for rooms that contain valuable equipment

or materials that could be damaged be release of water, where fire detection must be verified independently. Main frame computer rooms Laboratories

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Diagram of a Pre-Action System

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Sprinkler Systems (cont’d) Deluge System

All sprinklers are open When water fills the piping system, all sprinklers

discharge water simultaneously Diagram is similar to pre-action system Applications:

Where severe fire hazard exists that can be extinguished safely with water E.g. – a Fireworks Factory

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Sprinkler systems (cont’d) Where required:

Governed by the local building code or ordinance If not required by code, insurance companies

often offer reduced rates, or won’t insure buildings without sprinkler systems.

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Some Sprinkler Types Recessed Pendant

Sprinkler Glass tube holds metal disc

seated in valve seat Glycerin in glass tube

expands when heated and will shatter glass

Water is released Spray pattern is established

by deflector

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Recessed Pendant Sprinkler with Brass Finish

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Old Style Sprinkler with Fusible Link, (Upright Style Shown)

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Sprinkler with Wire Guard and Deflector Disk (Pendant Style Shown) This sprinkler would be

used to protect combustible materials in storage racks

Wire guard protects sprinkler from damage as racks are loaded/unloaded

Deflector plate prevents water may be discharged from above from cooling this sprinkler and preventing its operation

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Concealed Sprinkler Decorative white disk is

soldered to the sprinkler body – solder melts first, plate falls to floor, exposing sprinkler

Exposed sprinkler will now operate like a standard sprinkler - releases water as temperature increases

Can be used in Light Hazard Occupancies

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Partial Data Sheet for a Typical Concealed Sprinkler

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Sidewall Sprinkler

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Sprinkler systems (cont’d) Requirements for water supply capacity and

spacing of sprinklers depend upon the building’s occupancy classification

Occupancy Classes: Light Ordinary Group 1 Ordinary Group 2 Extra Group 1 Extra Group 2

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Light Hazard

Quantity and/or combustibility of contents is low; fires with relatively low rates of heat release are expected.

Examples: Churches Libraries Restaurant seating areas

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Ordinary Hazard Group 1 – combustibility is low, quantity of

combustibles is moderate, stockpiles of combustibles do not exceed 8 ft, fires with moderate rates of heat release expected.

Examples: Automobile parking and showrooms Bakeries Restaurant service areas

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Ordinary Hazard (cont’d) Group 2 – quantity and combustibility of

contents moderate to high, stockpiles do not exceed 12 ft, fires with moderate to high rates of heat release expected.

Examples: Chemical plants - ordinary Dry Cleaners Library large stack room areas

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Extra Hazard Group 1 – combustibility is low, quantity of

combustibles is very high, dust, lint or other materials are present, possibility of rapidly developing fires with high rates of heat release, but little or now combustible or flammable liquids.

Examples: Aircraft hangers Plywood and particle board manufacturing Printing

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Extra Hazard (cont’d) Group 2 – moderate to substantial amounts of

flammable or combustible liquids Examples:

Flammable liquids spraying Plastics processing Varnish and paint dipping

In all cases, refer to NFPA 13 and AHJ (Authority Having Jurisdiction) for quidance in assessing occupancy classification

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Sprinkler systems (cont’d) Maximum Area of Coverage (Standard Spray

Upright and Pendant Sprinklers) Light hazard: 225 s.f., maximum 15’ between sprinklers Ordinary hazard: 130 s.f., maximum 15’ between

sprinklers Extra hazard: 90 s.f., maximum 12’ between sprinklers

(see NFPA 13 for exceptions) Protection Area per sprinklers:

S x L, where S = spacing between sprinklers or twice distance to end wall, whichever is greater.

L = spacing between branch lines or twice the distance to end wall, whichever is greater.

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Sprinkler systems (cont’d) Maximum distance from walls: less than ½ spacing. Minimum distance to walls: 4” Where walls are angled or irregular, the maximum

distance to any point on floor – 0.75 spacing, with maximum perpendicular distance to wall not exceeded.

Minimum distance between sprinklers: 6’ (see exceptions NFPA 13)

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Sprinkler Location Deflector position

Standard spray pendant or upright heads: minimum 1” to maximum 12” from ceiling.

Standard spray sidewall sprinklers: minimum 4” to maximum 6” from ceiling. (In special situations, 6 to 12” – see NFPA 13)

Critical point – the farther the sprinkler is from the ceiling, the longer it will take for the heat to collect at the ceiling plane and set off the sprinkler.

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Typical Symbols

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Sprinkler Spacing Examples Light Hazard Occupancy

225 s.f. per sprinkler Maximum 15’ between

branch lines and between sprinklers on branch lines

Maximum 15/2 = 7.5 from wall to outermost sprinkler and branch lines

Here, S=L=15’

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Sprinkler Spacing Example No. 2

Occupancy Hazard:

Ordinary Group 1 Maximum coverage

per sprinkler: 130 s.f. Maximum spacing: 15’

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Example No. 2 – Proposed Solution Area of coverage is 10’x

13’ = 130 s.f. Maximum spacing is 13’,

which is less than the maximum 15’ allowed

Maximum distance to wall is 6.5’, which is ½ the largest spacing (13’)

Yet this solution does not comply with NFPA 13!

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Example No. 2 (cont’d) Area of coverage of

sprinkler in NW corner is: (6+5) x 13 = 141 s.f.

The number of sprinklers required is actually (41’ x 39’)/130 s.f. per sprinkler = 12.3; the proposed solution has just 12

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Example No. 2 (cont’d) Here is one correct

solution. More sprinklers are

required in order to comply with both spacing and area of coverage requirements.

S=12’ (2 x 6); L=9’-8” A=12’ x 9’-8” =

116.04 s.f

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Example No. 2 (cont’d) If a 2’x2’ suspended

tile ceiling is used, the sprinklers will not be centered within the tiles.

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Example No. 2 (conclusion) Since we have more

sprinklers than are needed, we can shift the centerlines slightly to achieve center of tile placement of sprinklers.

In this example, the dashed area represents greatest coverage, = (5’-6” +5’-0”) x (5’-0” + 6’-0”) = 126.5 s.f.

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Sprinkler Systems (cont’d) Sprinkler Classifications

Design and performance Area of coverage Speed of response

Standard response Fast response

Orientation Concealed Flush Pendent Recessed Sidewall Upright

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Sprinkler Classifications (cont’d) Special service conditions

Dry Corrosion resistant Intermediate level sprinkler/rack storage sprinkler