(c) Upon activation of any duct-mounted smoke detector in addition to the
actions outlined above paragraph 2.13.2.2, the smoke dampers installed at the
air-handling unit shall close.
RETURN AIR):
2.13.2.4.1 In addition to what is stated in paragraph 2.13.2.3 above, for the
supply air systems larger than 420 Cu M/Min (15,000 CFM) capacity and using
100 percent outdoor air, the air handling units shall be isolated by
providing smoke dampers in the supply air ducts as shown in Smoke and Fire
Protection Control Diagram 2.13.4. This damper shall be closed when the
duct-mounted smoke detector, installed in the main supply air duct, is
energized. The smoke damper is required only if the unit serves more than one
story.
2.13.2.4.2 Both he NFPA Codes and the VA Design Criteria do not require
either a duct- mounted smoke detector or a smoke damper in the main exhaust
air duct to be connected to the exhaust air fan.
2.13.2.5 SMOKE BARRIER
2.13.2.5.1 For a fully sprinklered building with quick response sprinklers,
duct mounted smoke detectors or smoke dampers are not required in supply,
return, and exhaust air ducts crossing the smoke barriers. This is a trade
off permitted by the Life Safety Code NFPA 101.
2.13.2.5.2 If the building is not fully sprinklered or sprinklered with
normal response sprinklers, for each duct penetration of the smoke barrier, a
dedicated duct mounted smoke detector and an accompanying smoke damper are
required. The sequence of operation shall be such that, when activated, the
duct-mounted smoke detectors, through its auxiliary contacts, shall:
(a) Close the associated smoke dampers.
(b) Send an alarm signal to the building fire alarm system.
(c) Send an alarm signal and a printed message to Engineering Control Center
(ECC).
(d) The corresponding supply, return, and exhaust air fans shall continue to
run. The fans may be sequenced to shutdown if any excessive build-up of the
air static pressure could result due to volumetric imbalance. The system
designer/reviewer shall, therefore, evaluate the air balance for each system
involving damper closure and make a determination on a case-by-case basis
about the need to stop the fans.
(e) Space-mounted smoke detector installed at the corridor above smoke door
shall close all smoke dampers installed in ducts passing above the corridor
smoke door.
2.13.2.6 ATRIUMS: The smoke control system for atriums shall be designed in
accordance with the following:
2.13.2.6.1 Provide an engineered smoke control system primarily designed to
remove the smoke from the atrium so that it does not contaminate the
HVAC DESIGN MANUAL
2-50
HVAC SYSTEMS AND EQUIPMENT
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