Engineering Manual o.. - HVAC.Amickracing

SMOKE MANAGEMENT FUNDAMENTALSINTRODUCTIONSMOKE MANAGEMENT FUNDAMENTALSThis section describes objectives, design considerations,design principles, control applications, and acceptance testingfor smoke management systems. A smoke management systemmodifies the movement of smoke in ways to provide safety forthe occupants of a building, aid firefighters, and reduce propertydamage. References are at the end of this section which includesmoke control codes.Smoke is a highly toxic agent. Information from U.S. FireAdministration estimates that in 1989 approximately 6,000 firefatalities occurred in the United States, and 80 percent of thesedeaths were from inhalation of smoke. Furthermore, anadditional 100,000 individuals were injured, and fire damageexceeded $10 billion.Long term effects on humans from repeated exposure tosmoke and heat is a major concern. According to the NationalInstitute of Building Sciences, “The significance of time ofhuman exposure is the fact that brief exposure to a highly toxicenvironment may be survived, while a lengthy exposure to amoderately toxic environment can lead to incapacitation,narcosis, or death.” 1 The primary toxic agent produced inbuilding fires is carbon monoxide. Other toxic agents includehydrogen cyanide, hydrogen chloride, sulphur dioxide, acrolein,aldehydes, carbon dioxide, and a variety of airborne particulatescarrying heavy metals (antimony, zinc, chromium, and lead).Early smoke management systems used the concept of passivecontrol to limit the spread of fire and smoke. This methodevolved from early fire containment methods used in high risebuildings. With passive control, HVAC fans were shut downand dampers were used to prevent smoke from spreadingthrough ductwork. This application required very-low-leakagedampers. Fire walls or barriers, used to prevent the spread offire, were enhanced to prevent the spread of smoke.In the late 1960s, the concept of active smoke control wascreated. With active control, the HVAC fans activate to preventsmoke migration to areas outside of fire zones. This methodincludes pressurized stairwells and a technique sometimescalled the pressure sandwich or zoning in which the floorsadjacent to the fire floor are pressurized and the fire floor isexhausted.DEFINITIONSAHJ: Authority Having Jurisdiction. (There may be more thanone authority.)ASHRAE: American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.Atrium: A large volume space within a floor opening or seriesof floor openings connecting two or more stories,covered at the top of the series of openings, and usedfor purposes other than an enclosed stairway, elevatorhoistway, escalator opening, or utility shaft.Buoyancy: The tendency of warmer air or smoke to rise whenlocated in cooler surrounding air. Caused by thewarmer air being less dense than the cooler air,resulting in pressure differences.Combination fire and smoke damper: A device that resiststhe passage of air, fire, and smoke and meets therequirements of UL 555, Standard for Fire Dampers,and UL 555S, Standard for Leakage Rated Dampersfor Use In Smoke Control Systems.Covered mall: A large volume space created by a roofed-overcommon pedestrian area, in a building, enclosing anumber of tenants and occupancies such as retail stores,drinking establishments, entertainment and amusementfacilities, and offices. Tenant spaces open onto, or directlycommunicate with, the pedestrian area.Expansion: The increase in the volume of smoke and gas causedby the energy released from a fire.Fire damper: A damper that meets the requirements of UL555, Standard for Fire Dampers, and resists the passageof air or fire.FSCS: Firefighters’ Smoke Control Station.Large volume space: An uncompartmented space, generallytwo or more stories in height, within which smokefrom a fire, either in the space or in a communicatingspace, can move and accumulate without restriction.Atria and covered malls are examples of large volumespaces.NFPA: National Fire Protection Association.Pressure sandwich: An application where only the zonesadjacent to a smoke zone are pressurized and the firezone is exhausted to limit the spread of smoke.Smoke: The airborne solid and liquid particulates and gasesdeveloped when a material undergoes pyrolysis orcombustion, together with the quantity of air that isentrained or otherwise mixed into the mass.Smoke Control System: A system that modifies the movementof smoke in ways to provide safety for the occupants ofa building, aid firefighters, and reduce property damage.ENGINEERING MANUAL OF AUTOMATIC CONTROL 160