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Chapter 05

Chapter 05






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    Chapter 05 Chapter 05 Presentation Transcript

    • 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 start
    • 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 types
      • 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