Chapter 12

transcript

Smoke Control and Management Systems

Chapter 12

Learning Objectives

• Define smoke control and smoke management• State the design goals for smoke control and

smoke management systems• Name the three general methods used to control

smoke movement• Describe the four pressure differential methods

used to control smoke• Describe five design requirements or operational

characteristics of smoke control systems

Learning Objectives (continued)

• List the different life safety and fire protection systems that interface with smoke control systems and describe how they interact

• Discuss the importance of the acceptance testing and annual retesting processes for smoke control systems

Introduction• Smoke and toxic gases can migrate outside of the

fire area– Smoke travels along stairways, ducts, corridors,

elevator hoistways, etc.

• Spread of smoke and toxic gases can cause much damage, injuries, and death

• Passive design approach uses walls, etc., to create barriers

• Active design approach uses mechanical systems to exhaust the air

Figure 12-1 Manually operated smoke and heat vent in stairway

Code Required Smoke Control and Smoke Management

• Code-mandated installation of smoke control limited to certain structures

• Many structures facilitate quick evacuation– Significantly compartmentalized to inhibit smoke

travel

• Installation of these systems in every structure is unnecessary

• Requirements exist for occupancies with significant evacuation challenge

Smoke Containment, Removal, and Opposed Airflow

• Basic goal of smoke control is to mitigate the spread of smoke

• Smoke control techniques can be standalone or integrated into a building-wide approach

• Systems use 100% outdoor air for positive pressurization– 100% exhaust to the outdoors for smoke relief

• General approaches: containment, removal, opposed airflow

Containment by Pressure Differentials

• Stairway pressurization: prevents or reduces smoke intrusion into egress stairways

• Floating zone/floor-by-floor pressurization: uses the HVAC system

• Elevator hoistway pressurization: similar to stairway pressurization

• Refuge area pressurization: prevents smoke intrusion into refuge areas

Figure 12-2 This mechanical fan and duct line supply air to pressurize a stairway

Figure 12-3 Air supply grill for stairway pressurization

Figure 12-4 Mechanical fan unit for “sandwich effect” pressurization

Figure 12-5 Exhaust vent in corridor for “sandwich effect” pressurization

Smoke Removal• Best suited for large volume spaces, such as

atriums, indoor stadiums, and airport terminals• Provides vertical cross-flow ventilation from floor

to roof• Large volume spaces have no barriers

– Smoke and toxic gases will rise and spread throughout the area

• Unpolluted air fed at a slower rate than the exhaust system rate– Fed from a level lower than the fire

Figure 12-6 Atrium

Figure 12-7 Atrium exhaust vent

Containment by Airflow Direction

• Airflow velocity across openings controls smoke when pressure differential strategy is not practical

• Uses large volumes of air that flow in a particular direction; smoke cannot migrate

• Used to manage fires in railway tunnels• Rarely used by engineers: complex control and

large air volumes required• Supplying large amounts of air may fuel the fire

Design Requirements and Operational Characteristics

• Operational characteristics found in model codes:– Immediate and automatic operations on activation of

waterflow devices and smoke detectors– Manual operation and override– Primary/backup power source– Minimum operation for 20 minutes– Ability to maintain the smoke level six feet above

highest level of walking in the means of egress

Fire Protection Systems and Smoke Control

• Containing smoke and gases in the area of fire origin contingent upon many factors

• Best opportunity to control smoke:– Properly operating fire detection system– Automatic fire sprinkler systems– Rapid firefighter response

Interface with Fire Protection Systems and Other Life Safety Systems

• Smoke control systems interconnect with fire protection, HVAC, elevator and backup power

• Activation of an automatic initiating device starts smoke control system operation– Activation by manual pull station not recommended

• Failure to shut down HVAC systems could be worst contributor to smoke movement

• Functional components of the system should be monitored

Figure 12-8 Beam detector

Figure 12-9 Smoke Control Panel

Figure 12-10 Smoke control panel in fire control room

Testing and Performance Verification

• Generally the engineer who designed the smoke control system develops a detailed test plan

• Testing usually follows the testing of all other life safety and fire protection systems

• Process usually starts with operational testing at the component level– Continues with functional testing of individual systems

• All tests should be witnessed and documented

Annual Testing• Systems should undergo functional and

performance testing on an annual basis• Annual tests should address:

– Functional performance of individual components and systems

– Integrated performance verification

• Individual system and integrated performance testing should be done by trained personnel– Same qualifications as person who did the initial

acceptance testing

Summary• Smoke control and management systems can

contain smoke to the area of origin• Three general methods:

– Containment– Exhaust– Opposed airflow

• Important to connect smoke control with fire protection, HVAC, and other building systems

• All smoke control systems should undergo functional and performance testing annually

Chapter 12

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