Building Construction Related to the Fire

Service

Chapter 4 — Building Systems

Learning Objective 1

Discuss the various types of stairs and the structural requirements related to each.

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Purpose of Stairs

• Access various levels of structure• Basic component of building

egress during emergency• Exit stairs• Convenience stairs• Buildings four + stories required to

have one stairway that extends to roof

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Basic Components of Stairs

• Requirements specified in applicable building code

• Step– Run – Horizontal measurement of

tread– Riser – Vertical distance between

treads

• Hand rails and guards

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(Continued)

Basic Components of Stairs

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Types of Stairs

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Stairs as Part of the Means of Egress

• Protected stairs• Exterior stairs• Fire escapes

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Smokeproof Stair Enclosures

• Codes require minimum of one for stairs serving five stories or higher and floor levels more than 30 feet (10 m) below level of exit discharge

• Typically located on exterior perimeter of building and entered through ventilated vestibules or open exterior balconies

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Active Smokeproof Enclosures

• Pressurize stairwells when building is in fire mode

• Dedicated mechanical air-handling system is activated by automatic fire/smoke detection equipment

• Pressurization system keeps stair enclosure free of smoke even when a door is open to the fire floor

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(Continued)

Active Smokeproof Enclosures

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Passive Smokeproof Enclosures

• Accessed through a vestibule or exterior balcony

• Designed to provide means for smoke to be vented to outside before entering the stair enclosure

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(Continued)

Passive Smokeproof Enclosures

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Open Stairs

• Serve as path for fire and smoke spread

• Codes typically allow use only when they connect no more than two adjacent floors above the basement level

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Learning Objective 2

Discuss the various types of elevators and their safety features.

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Safety Oversight

• Stringently controlled and monitored by all levels of government

• Most regulations based on ASME/ANSI A 17.1, Safety Code for Elevators

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Types of Elevators

• Hydraulic• Electric

– Drum– Traction

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Safety Features of Elevators

• Terminal device• Buffers• Speed reducing switch• Overspeed switch• Car safeties

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Elevator Hoistways

• Constructed of fire-resistive material and equipped with fire-rated door assemblies

• Located in atrium not required to be enclosed

• Enclosures usually required to have one- or two-hour fire rating

• May be enclosed with concreteBuilding Construction

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(Continued)

Elevator Hoistways

• Required to be vented at top• Fire-rated vestibules at each floor• Number required based on number

of elevators• Express elevators• Single hoistways• Elevator zones

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(Continued)

Elevator Hoistways

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Elevator Doors

• Car and hoistway doors open together

• Car door can be pushed open any time

• Some types need to be reset before car will move again

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Access Panels

• Emergency exits from car if stopped in a blind hoistway

• Hinged access hatch through top of car or panels on sides of car

• Top exits• Side exits

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Learning Objective 3

Discuss moving stairways, walkways, and conveyors as they relate to firefighting concerns.

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Moving Stairs (Escalators)

• Electrically powered steps moving continuously in one direction

• Standard – 100 ft. per min. (30 m/min)

• Vertical opening needs to be protected if serving more than two floors

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(Continued)

Moving Stairs (Escalators)

• Partial enclosure uses separate fire rated enclosure for up and down escalators

• Should be stopped and used as fixed stairs in emergency

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Moving Walkways

• Move people horizontally• Operation

– Attached metal plates in continuous pathway with moving handrails

– Moving rubber-like belts over metal rollers

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Conveyor Systems

• Manufacturing or storage occupancies

• Transport items and material• Types• Often pass through fire barriers

– Penetrations usually protected by fire door or shutter or water-spray method

– Methods to prevent incomplete door closure

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Learning Objective 4

Describe the uses of vertical shafts and utility chases and their impact on firefighting.

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Vertical Shafts

• Utility chase – Vertical pathway that contains utility services

• Provide vertical path for smoke and fire and serve as area of origin for fires

• Built using fire-rated construction but may contain combustible materials

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Pipe Chases

• Contain piping for various services• May use stacked mechanical

equipment rooms instead of pipe chases

• Plumbing pipes form pathways in walls and drain into vertical pipe which connects to sewer pipe and extends above roof to ventilate

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Refuse and Laundry Chutes

• Have openings on each floor; often terminate at grade level or basement

• Create frequent fire response• Material mostly combustible• Constructed of noncombustible

material with rated doors, typically surrounded by fire-rated shaft enclosure

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(Continued)

Refuse and Laundry Chutes

• Sprinklers required at top of chute and termination room

• Access must be in separate room from corridor

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Grease Ducts

• Part of exhaust system for commercial cooking appliances

• Travel vertically to carry grease vapors outside; often use in-line fans or roof fans

• Must be enclosed in fire resistive construction

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Learning Objective 5

Describe the functions and components of HVAC systems and how they impact firefighting.

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HVAC Systems

• Include heating, cooling, filtering, humidifying, and dehumidifying

• Regulate the intake of outdoor air and recirculation of indoor air

• Cooling systems past and present• Hydronic system• Forced air systems

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HVAC System Components

• Outside air intakes• Fans• Air filtration• Air heating and cooling

equipment• Air ducts

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Courtesy of Gregory Havel, Burlington, WI.

Learning Objective 6

Distinguish between various smoke control methods.

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Smoke Control Systems

• Mechanical equipment used to produce pressure differences across smoke barriers to inhibit smoke movement

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Automatic Smoke Control

• Switch to fire operations can be accomplished by smoke detectors, sprinkler waterflow switches, or heat detectors

• Fire operation opens or closes dampers to redirect air flow and exhaust smoke

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(Continued)

Automatic Smoke Control

• Pressure sandwich• Automatic operation is relatively

fast• System detectors must be

designed to eliminate possibility of detector outside fire area being activated first resulting in wrong dampers being operated

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Manual Smoke Control

• Eliminates system disruption due to false alarms; gives specific system control

• Can be controlled from various places• If equipped with both, manual takes

priority over automatic• Slower than automatic• Firefighter’s smoke control station

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Smoke Control in Stairwells

• Smokeproof tower– Vestibule between corridor

and stairwell that is open to atmosphere

• Pressurized stairwell– Uses blower or fan to provide slightly

greater pressure in stairwell than corridor

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(Continued)

Smoke Control in Stairwells

• Methods to prevent loss of pressure when doors are opened to stairwell– Single injection– Multiple injection system– Compensated system– Modulating air supply– Overpressure relief

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Smoke and Heat Vents

• Release smoke and heat from roof

• Enable faster and safer interior attack; dissipate some thermal energy of fire

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(Continued)

Courtesy of Ed Prendergast

Smoke and Heat Vents

• Individual small area hatchways with single- or double-leaf metal lids or plastic domes

• Curtain boards increase effectiveness

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Learning Objective 7

Discuss the various types of electrical equipment found in building structures and the hazards posed by each.

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Voltage

• High voltage – Operates at 600 volts or higher

• Low voltage – Operates at less than 600 volts

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Transformers

• Convert high voltage to appropriate voltage for use in buildings

• Method of cooling transformer unit directly affects hazard presented

• Air-cooled transformers• Oil-cooled transformers• 480/277 volt services

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(Continued)

Transformers

• Transformers located inside or outside building

• Fires involving electrical equipment usually de-energize equipment early

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Emergency and Standby Power Supplies

• Generators• Lead-acid batteries

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Courtesy of McKinney (TX) Fire Department

Summary

• Building systems provide the ability for occupants to use the space efficiently, safely, and comfortably.

• Many building systems must penetrate both vertical and horizontal fire-rated components providing the opportunity for fire and smoke to spread throughout the building.

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(Continued)

Summary

• Firefighters need to be aware of the potential for fire and smoke spread due to building systems and note any possible loss of integrity of vertical building elements during company inspections.

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Building Construction

Review Questions

1.What are the basic components common to all stair types?2.Why are fire escapes no longer permitted in new construction?3.Where are conveyor systems typically found?

(Continued)

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Review Questions

4.In what ways do HVAC systems potentially affect fire events?5.What are the potential hazards encountered with lead-acid batteries?

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