Layout Of System; Codes And Standards - Honeywell AUTOMATIC CONTROL Engineering Manual

SMOKE MANAGEMENT FUNDAMENTALS
Any alarm activation of a smoke management system that is
common to all strategies in the building, such as stairwell
pressurization, atria, and exhaust, is acceptable.
For a smoke management system to function reliably, building
leakage must be controlled during and after construction. Any
penetrations of smoke barriers and walls used for pressurization
must be carefully considered in order to maintain the intended
smoke control.
Smoke management typically includes control of fires by
automatic sprinklers. Designing smoke management systems
for sprinklered buildings is quite practical. However, designing
smoke management systems for buildings that do not have
sprinkler systems is extremely difficult. Complicating the design
task are problems with estimating the fire size and dealing with
higher static pressures (or airflows).
Smoke vents and smoke shafts are also commonly used as a
part of the smoke management system to vent pressures and
smoke from fire areas; however, their effectiveness depends on
the nearness of the fire, the buoyancy of the smoke, and other
forces driving the smoke.

LAYOUT OF SYSTEM

Smoke management equipment should be located in a
building where it can best facilitate smoke control for various
building layouts. The following guidelines apply:
— Follow the drawings and specifications for the job.
— Locate the smoke controls near the mechanical
equipment used to control the smoke.
— Try to minimize the length of runs for sensors,
actuators, power, and communications wiring in order
to reduce the possibility of wiring being exposed to
areas where there might be a fire.
Appendix A of NFPA 92A describes an example of a
Firefighters' Smoke Control Station (FSCS). The FSCS allows
firefighters to have control capability over the smoke control
equipment within the building. The FSCS must be able to show
clearly if the smoke control equipment is in the normal mode
or the smoke control mode. The example in NFPA 92A includes
location, access, physical arrangement, control capability,
response time, and graphic depiction. This example is for
information only and is not a requirement.

CODES AND STANDARDS

The integration of fire alarm and smoke control is covered in
UL 864, Standard for Control Units for Fire-Protective
Signaling Systems. Compliance with this UL standard for
engineered smoke control systems requires the following:
— Compliance with NFPA 92A, Recommended Practice
for Smoke Control Systems
ENGINEERING MANUAL OF AUTOMATIC CONTROL
— End-of-process verification of each control sequence
— Annunciation of any failure to confirm equipment
operation
— Automatic testing of dedicated smoke control systems
Controls that meet UL Standard 864 are listed under UL
Category UUKL. Standby power and electrical supervision
items listed in UL864 are optional for smoke control systems.
According to NFPA 92A, control sequences should allow
smoke control modes to have the highest priority; however,
some control functions should not be overridden. Examples of
these functions are duct-static high pressure limit control (use
a modulating limit control, if a concern) and shutdown of the
supply fan on detection of smoke in a supply air duct.
Manual override of automatic smoke control systems should
be permitted. In the event of multiple alarm signals, the system
should respond to the first set of alarm conditions unless
manually overridden.
All related energy management functions should be
overridden when any smoke control mode is activated by an
actual alarm or during the testing process.
During the planning stage of a project, design criteria should
include a procedure for acceptance testing. NFPA 92A states
that, "Contract documents should include operational and
acceptance testing procedures so that all parties—designer,
installers, owner, and authority having jurisdiction—have a clear
understanding of the system objectives and the testing
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procedure." ASHRAE 5-1994 Commissioning Smoke
Management Systems is intended to ensure proper operation.
Legal authority for approval of smoke control systems is from
the Authority Having Jurisdiction (AHJ). The AHJ uses local
building codes as its primary standard. Local building codes
are established using several reference standards or codes
including the following:
— Model Building Codes:
– Building Officials and Code Administrators
International (BOCA), Inc.
– International Conference of Building Officials
(ICBO)
– Southern Building Code Congress, Inc. (SBCCI)
– Western Fire Chiefs Association (WFCA)
- National Mechanical Code (NMC)
- American with Disabilities Act (ADA)
— National Fire Protection Association (NFPA)
Standards:
– NFPA 92A, Recommended Practice for Smoke
Control Systems
– NFPA 92B, Guide for Smoke Management
Systems in Malls, Atria, and Large Areas
– NFPA 90A, Installation of Air
Conditioning Systems
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