Flashcards in 4 Building Systems Deck (107)
Provides for the removal of trash and garbage from upper floors extending through the building with openings on each floor the depositing of trash or linen
Part of exhaust system for commercial cooking appliances that produce grease laden vapors.
Standard for the installation of air conditioning and ventilation systems
Hvac ducts often travel vertically through multistory buildings. with few minor exceptions the code requires hvac duct to be
Enclosed in fire rated shaft
Nfpa 90a requires hvac ducts be in an enclosure rated at
1 hr for les than four story building, 2 hr for higher buildings.
True, false. Hvac systems cannot distribute products of combustion throughout the structure.
False. Hvac can spread combustion products
Channel or enclosure , sheet metal, used to move heat and cooling through a building. Hollow pathways used to move air from one area to another in ventilation system
In building construction, refers to generally inaccessible spaces between layers of building materials. May be large enough to spread fire.
Duct detectors are provided for fans with capacities exceeding
2000 cubic feet per min
Natural gas collects in what parts of buildings
Upper parts, it's lighter so it rises.
Log, propane, collects in what part of buildings
Lower parts, it's heavier so it sinks.
Sometimes interstitial spaces are used as what for hvac
Return air plenum. Instead of duct work, though limited by code
Smoke control system
Engineered system designed to control smoke by using the mechanical fans to produce air flows and pressure differences across smoke barriers to limit and direct smoke movement
Automatic smoke control
Smoke control systems in hvac disengaged to be automatically initiated by fire protection detection sensors, actuating dampers or venting smoke outside.
Automatic smoke control requires careful coordination of fire protection sensors because
Improper coordination of sensors and false activations can cause automatic smoke control to mitigate the wrong area.
Advantage of manual smoke control system
Elimination of system disruption from false alarms. Specific control of system through firefighter smoke control station, manual takes priority over automatic.
Disadvantage to manual smoke control
Delay in mitigating smoke in building, potentially allowing fire headway
Smoke control system should not be activated using
The manual pull stations to avoid pull stations being activated in area other than fire and improperly activating system in wrong area
Two methods to protect stairwells from smoke
Smoke proof tower. Stairwell pressurization
Smoke proof tower
Smoke proof enclosure that makes use of vestibule between corridor and the stairwell that is open to outside air, isolating stairs from interior of building.
Blower or fan pressurizes stairs to keep smoke out
Standard for smoke control systems utilizing barriers and pressure differences.
Stairwell pressurization method where fan supplies air at a single point
Single injection method, can cause loss of pressure if door opened close to fan
Stairwell Multiple injection system
Air forced into stairwells at multiple levels through ducts to overcome limitations of single method.
Compensated pressurized stairwell
Air pressure is adjusted based on pressure detected in stairwell, adjusting as doors open an close
Stairwell pressurization, over pressure relief
Weighted dampers to outside forced open if stairwell is over pressurized. Automatic dampers opened by pressure switches. P
Smoke and heat vent minimum size for small hatchways
Vertical boards, fire resistive half walls, that extend down from the underside of a roof underneath and ceasing the opening for roof vent, intended to limit spread of fire and smoke
Curtain boards are designed to reduce fire spread and increase efficiency of fire and heat vents, minimum depth of boards is
No less than 20% of the ceiling height.