chapter 05

Automatic Fire Sprinkler Systems

Chapter 5

Learning Objectives

• Describe an automatic fire sprinkler system• Discuss the myths and realities associated with

automatic fire sprinkler system operation• State the factors that determine requirements to

install automatic fire sprinkler systems• Discuss the design concepts behind automatic

fire sprinkler systems

Learning Objectives (continued)

• List and describe different occupancy and commodity classification

• Describe different types of automatic fire sprinkler systems and the best applications for those systems

• Discuss the inspection and test requirements for acceptance of water-based fire protection systems

Introduction• Automatic fire sprinkler system: network of

piping with sprinkler heads at specific intervals– Upon activation, applies water over the fire area

• Common myths:– All sprinkler heads operate simultaneously– Sprinkler heads activate for no reason– Water discharged will cause a flood or drown a

person– Costs more to repair water damage than fire damage– Smoke detector activation will cause sprinkler to

operate

Introduction (continued)

• Facts about sprinkler heads:– Operate independently, only in fire area– Undergo numerous tests by third-party organizations

• Rarely accidentally activate

– Exposure to fire and smoke damage limited• Fire hose could cause substantially more damage

– Majority of smoke detectors operate independently of sprinkler systems

Effectiveness in Property Protection

• Basis for sprinkler system design is to keep a fire at a relatively small size, under control

• Prevents extensive damage that would have closed the facility, injured occupants

• Frequently, businesses never recover from a fire when there are injuries or loss of life

Effectiveness in Life Safety• Primary purpose is to provide property

protection– Not necessarily life safety

• Sprinklers provide some level of life safety– Systems may interact with other building safety

systems

• Residential systems provide higher level of life safety

• Not more than two people have died in a fire where complete sprinkler system installed

Required Installations• Most early requirements came from property

insurance companies• Requirements changed with development of

model codes– Changes were gradual– Code changes only affected new building construction

• Incentives provided for installation of automatic fire sprinkler systems

• Model codes today establish requirements based on use and occupancy conditions

Design and Installation Standards

• Published standards available from model code and insurance organizations

• Three primary standards:– NFPA 13: Installation of Sprinkler Systems– NFPA 13D: Installation of Sprinkler Systems in One-

and Two-Family Dwellings and Manufactured Homes– NFPA 13R: Installation of Sprinkler Systems in

Residential Occupancies Up To and Including Four Stories in Height

NFPA 13, Standard for the Installation of Sprinkler Systems

• First published in 1896• Performance objective: maintain control of a fire• Contain the fire to general area of origin by

applying water• Sprinkler heads cover all spaces in the building

– Includes concealed combustible spaces, attics, above and below ceilings

• In many cases, sprinkler can suppress the fire

NFPA 13D, Standard for the Installation of Sprinkler Systems in

One- and Two-Family Dwellings and Manufactured Homes

• Published in 1975• Addresses residential fire problem

– Places sprinklers in home where fire likely to start– Excludes small bathrooms, closets, unheated areas

• Standard relies on research and testing data

NFPA 13R, Standard for the Installation of Sprinkler Systems in Residential Occupancies Up to and

Including Four Stories in Height• Concerns hotels, motels, apartments, condos• Loosely follows NFPA 13 requirements• At least one FDC in the building• Places sprinkler heads where fire most likely to

Other Fire Sprinkler Standards• Other standards deal with level of hazard

exceeding NFPA 13• Standards state the applicability

– Establish design criteria based on conditions– Specify sprinkler head characteristics and appropriate

• Do not specify installation methods or dictate how to lay out a system

• Ultimately the design professional determines the type of system best suited to the hazard

Design Concepts for Automatic Fire Sprinkler Systems

• Design starts with classifying the occupancy, commodities, storage arrangement– Evaluate the combustibility

• System must deliver enough water to absorb energy from the fire

• Design professional decides whether to use a pipe schedule or hydraulic design

Design Concepts for Automatic Fire Sprinkler Systems (continued)

• Density/area curves: graphic representation of a minimum amount of water over a specific area

• Amount of water is minimum design density– Area of coverage is the remote area

• Contractor records system information on hydraulic design information sign

Fire Sprinkler System Components

• Components require listing or approval from third-party testing and certification laboratory– Underwriters Laboratories, FM Global

• Many supporting components are common to all the different types of fire sprinkler systems

• Each type of automatic sprinkler system uses specific type of valve

• Some design and installation objectives require special types of sprinkler heads

Pipe and Fittings• Join together to provide a conduit for water• Must handle maximum permitted system working

pressure of 175 psi• ASTM standard establishes internal and external

pipe dimensions and wall thicknesses• Thinner pipe has larger internal diameter

– Offers hydraulic design advantages because there is less friction loss

• CPVC pipe dominant type of piping used for residential installations

Gauges

• Pressure gauges important• Some systems have water gauges

– Other systems have water and air gauges

• Help to determine whether there is a problem with the system

• Should not be subject to freezing temperatures• Each should have a control valve capable of

draining

Valves• Water control valves permit water to flow into

and through the system when open– Prevent water flow, isolate parts of the system when

closed

• Valves placed in locations that are clearly accessible

• Water control valves must be indicating-type– Must handle 175 psi

• Check valves permit water or air to flow in one direction

Support and Stabilization of Pipe• Majority of piping runs horizontally across ceiling

– Fasteners stabilize the pipe– Riser clamps hold vertical pipes in position

• All supporting materials must be made of ferrous materials for heat resistance

• Spacing and location of hanger components depend on the size and type of piping

• Hanger assembly consists of fastener, threaded rod, ring that holds the pipe– Bracing, guides, restraints provide stability

Automatic Sprinkler Heads

• Spray device that distributes water over a limited area at a designated flow rate

• Reduces heat from a fire– Limits and controls fire’s growth

• Heat-activated– Heat-sensitive element head releases so that the

parts holding back the water fall away

• Each head operates independently

Automatic Sprinkler Heads (continued)

• Frame holds other pieces in place• Heat-sensitive element attach to the frame,

hold orifice cap in place• Orifice is the smooth opening in the head

through which water flows from the pipe• Orifice cap covers the orifice• Deflector creates the spray pattern of the water

Automatic Sprinkler Heads (continued)

• Types of sprinkler heads– Old Style, Standard Spray, Specialty Heads– Pendent, Upright, and Sidewall Heads– Special Application Sprinkler Head Identification– Heads for Particular Conditions and Applications– Heads for Aesthetic Purposes

• K-factor classifies the head by factor number• Modern heads resemble heads of 100 years ago

Types of Systems

• Four basic types of automatic fire sprinkler systems

• Each has characteristics appropriate for particular situations and applications

• Most commonly installed types of systems• Basis for other types of water-based fire

protection systems

Wet Pipe Systems

• Least expensive, most frequently installed– Easiest to maintain, modify, and most reliable

• Limited area sprinkler systems provide protection without installing full building system

• Require dedicated water supply and usually have an alarm check valve

• Clapper inside the valve acts as a check valve• Common in almost every type of building

Figure 5-29 Wet pipe sprinkler system schematic

Dry Pipe Systems• Best system to protect building where temperature

falls below 40 degrees– Unheated warehouses, attics, loading docks, etc.

• Pressurized air maintained in the system piping until system activates

• Dry pipe valves prevents water from entering the system until needed– Operates on water-to-air differential

• Size and layout of system affects time to deliver water

Figure 5-31 Dry pipe sprinkler system schematic

Pre-action Systems

• Similar to dry pipe systems, using closed sprinkler heads

• Normally no water in system piping• Fire detectors release the pre-action valve• Require two separate events before water

discharges– Fire detector activates and releases pre-action valve– Sprinkler head activates to flow water

Figure 5-35 Pre-action sprinkler system schematic

Deluge Systems

• Operate similar to pre-action systems• Open to the atmosphere because sprinkler

heads open to the atmosphere• Open sprinkler heads do not have a heat-

sensing element• Discharge immediate and simultaneous from all

sprinkler heads• Deluge valve receives signal from detection

system

Figure 5-37 Deluge sprinkler system schematic

Residential Sprinkler Systems• Benefits derive from change in emphasis from

property protection to life protection• Design concepts:

– Prevent flashover– Improve occupants chance for rescue or escape

• Vast majority are wet pipe systems• Many share water supplied by domestic water line• Residential sprinkler head satisfies different

testing criteria

Inspection, Testing, and Maintenance Requirements

• Approval process for automatic sprinklers similar to fire lines and standpipes

• Approving authority determines if system installed according to plans

• Requirements are in various standards used to design the systems

• Most periodic inspections, tests and maintenance follow inspection and test protocols

Acceptance Inspections and Tests

• Acceptance inspections during construction similar from system to system

• Flushing: incoming fire line requires flushing before connecting water supply to sprinkler

• Hydrostatic air tests: subjects system to predetermined pressure for minimum duration

• Hydrostatic tests for residential systems: verify no system leaks with source water pressure

Acceptance Inspections and Tests (continued)

• Visual inspection: confirm the design and installation meet standards

• Operation of Components: verify that the system will operate when needed

• Main Drain Test: establishes that the incoming water supply is adequate, with no impairments

Periodic Inspection, Testing, and Maintenance

• Provide a level of certainty that the system will operate when called upon

• Same tests used to accept a system can be used to verify proper operation– Conducted at regular intervals

• Impairments result from a lack of maintenance, component failure, etc.

• Typical impairments: closed control valves, damaged sprinkler heads, broken piping, etc.

Summary

• Sprinkler systems designed to keep a fire small and under control

• Not all automatic sprinkler systems are alike• For well over 100 years, sprinkler systems have

protected property and life• Automatic fire sprinkler systems offer building

owners and homeowners a reliable, effective, economical, and proven protection system

chapter 05

sprinkler systems design

sprinkler standards

sprinkler system design

sprinkler systemschapter

water sprinkler heads

complete sprinkler system

sprinkler systems model

protection systems

Business

chapter 05

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