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Chapter 1: Fire geometry and smoke movement in buildings
With any of the methods used for smoke zones,
pedestrian door opening forces must be considered. The
pressure differences between barriers are important not
only in the force to open the door, but also the force
necessary to overcome the door closer. NFPA 101, the
Life Safety Code establishes a maximum force of 30 lbf
(133.35 N) to set a door in motion that is an accepted
benchmark for designers. Occupants must be able to
open doors leading to escape routes while the smoke
control system is in operation.
Types of systems
Smoke management utilizing active and passive
methods in combination to modify smoke movement
must be engineered into a system that is focused upon
property or people protection. While passive methods of
smoke management do exist (see NFPA 204), dynamic
smoke control systems using mechanical equipment to
meet design goals dominate. NFPA 92B, Guide for
Smoke Management Systems in Malls, Atria, and Large
Areas, provides methodologies for determining smoke
development in large spaces. NFPA 92A,
Recommended Practice for Smoke control Systems, is
used for the design, installation, testing, operation, and
maintenance of systems for smoke control.
A VM-1 smoke control system (SCS) when installed and
programmed in accordance with this design manual and
the criteria set forth by the smoke control system
designer will help to:
•
Provide a tenable environment in evacuation routes
during the time necessary to evacuate people from
the area
•
Restrict the movement of smoke from the fire area
•
Assist in protecting life and property
•
Maintain tenable conditions in nonfire areas that will
enable fire personnel to conduct search and rescue
operations in addition to attacking the seat of the fire
A VM-1 SCS should be designed, installed, and
maintained such that the system will remain effective
during evacuation of the protected areas. Other
considerations determined by the smoke control system
designer may dictate that a system should remain
effective for longer periods. Areas to evaluate in
determining VM-1 SCS integrity are:
10
•
Reliability of power sources
•
Arrangement of power distribution
•
Location, and methods of protection for VM-1
system panels
•
Building occupancy type
The design, installation, testing, operation, and
maintenance of new and retrofitted mechanical air
conditioning and ventilation systems for the control of
smoke will require the involvement of several
interdependent disciplines or parties:
System designer. Building equipment and controls are
the responsibility of the system designer. The system
designer:
•
Determines the type of smoke control system to be
used
•
Defines the size of the expected or design fire
•
Performs tenability calculations
•
Establishes and defines smoke zones based on
building barriers and determines the sizing of fans
and location of dampers
The system designer may be an architect, engineer, or
fire protection professional knowledgeable in the theory
and application of smoke management and control. The
system designer creates a specification used by the
VM-1 SCS designer to create the smoke control system.
The specification defines how the total system must
operate under fire or smoke conditions.
VM-1 SCS designer. Smoke control system operation is
the responsibility of the VM-1 fire alarm and smoke
control system designer. The specifications for operation
of a smoke control system define the methods of
fire/smoke detection for a particular area and the
resulting outputs for smoke removal or control functions
that must take place. Control functions performed by a
VM-1 panel include the startup and shutdown of HVAC
or exhaust fans, smoke damper closure, and door
closure.
Authority having jurisdiction (AHJ). The AHJ, typically a
fire official, is important in the determination of firefighter
control station locations and final acceptance and testing
of the smoke control system. Involvement of the AHJ
early in a project helps to ensure that the system
requirements (typically NFPA 92A) will be met by the
total system design. The AHJ can establish clear
VM-1 Smoke Management Application Guide
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