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HomeMy WebLinkAboutLetter; Automatic Fan Shut Down RequirementsUNr FIRE MARSHAL'S \� Z/1' . OFFICE cn: a, St. Lucie County Fire District (561) 462-2312 • FAX (561) 462-2323 AUTOMATIC FAN SHUTDOWN REQUIREMENTS FOR AIR HANDLING SYSTEMS. 2400 Rhode Island Ave. Fort Pierce, FL 34950 The requirements for•anteniatic fan shut down -in air handling systems are the requirements of the Standard Mechanical Code, 1997 Edition, Chapter 4, Section 406, and the National Fire Protection Association, Life Safety Code NFPA 101. In determining which code to comply with, the following information is necessary. 1. A/C units make up a system and is referred to in the codes as an air handling system. 2. The NFPA Life Safety Code, Occupancy Chapters 8 through 31 references Heating, Ventilation, and air Conditioning and shall comply with Section 101-7-2 of the Life Safety Code. 3. Section 101-7-2 requires air conditioning, heating, ventilating ductwork, and related equipment to be installed in accordance with NFPA 90A, Standard For The Installation Of Air Conditioning and. Ventilation Systems, or NFPA 90B, Standard For The Installation of Warm Air Heating and Air Conditioning Systems. 4. NFPA 90A. Scope: This standard applies to all systems for the movement of environmental air in structures that: a. Serves spaces over 25,000 cubic feet in total volume, or b. Serve buildings of Type III, IV, and V construction over three stories in height, regardless of volume: .The construction types indicated are in accordance with NFPA 220. 5. NFPA 90A. For the purpose of this standard, a space is considered as the entire building or a portion thereof separated from other portions of the building_by fire resistance rated construction and whose environmental air does not mix with that of any other space. For spaces not exceeding 25,000 cubic feet in volume, reference the Standard Mechanical Code, Chapter 4, Section 406. 6. Spaces not exceeding 25,000 cubic feet in total volume shall be in accordance with the Standard Mechanical Code, 1997 Edition. 7. Automatic fan shut down requirements. NFPA 90A. a. Location: Smoke detectors listed for use in air distribution systems shall be located: 1.) Downstream of the air filters and ahead of any branch connections in air. supply systems of greater than 2,000 cfin capacity. 2.) At each story prior to the connection to a common return and prior to any recirculation or fresh air inlet connection in air return systems over 15,000 cfin capacity and serving more than one story. Exception #1; Return systems smoke detectors are not required when the entire space served by the air distribution system is protected by a system of area smoke detectors. Exception #2: Fan units whose sole function is to remove air from inside the building to outside the building. b. Function. Required smoke detectors shall automatically stop their respective fan(s) upon detecting the presence of smoke. Exception: Where the return air fan is functioning as part of an engineered smoke control system and a different mode is required. C. Installation. Listed duct type smoke detectors shall be installed in accordance with NFPA 72, National Fire Alarm Code. 1.) When an approved protective signaling system (fire alarm) is installed in the building the smoke detectors shall be connected to the protective signaling system in accordance with NFPA 72. Activation of any air distribution system smoke detector will cause a supervisory signal to be indicated at a constantly attended location or will cause an alarm signal. 2.) All detection devices used for the operation of smoke dampers, fire dampers, fan control, smoke doors, and fire doors shall be monitored for integrity in accordance with NFPA 72, 1-5.8 where connected to the fire alarm system serving the protected premises. 3.) When smoke detectors are installed in a building not equipped with an approved protective signaling system, the system shall a.) cause a visual and audible signal in a normally occupied area, and b.) smoke detector trouble conditions shall be indicated visually or audibly in a normally occupied area and shall be identified as air detector trouble. c.) The above signal requirements can be annunciated with a simple remote test station with a sounder.. 8. Smoke detectors having power supplied separately from the signaling system (fire alarm) for the sole function of stopping fans do not require standby power. STANDARD MECHANICAL CODE Automatic Fan Shutdown Requirements: a. Systems serving buildings or spaces less than 25,000 cubic feet in volume shall comply with the requirements of the Standard Mechanical Code, Chapter 4, Section 406, 1997 Edition. b. Capacity greater than 2,000 cfin. Recirculating air systems with a fan capacity greater than 2,000 cfin shall automatically shut down by means- of an approved smoke detector placed in the return air stream prior to any exhausting from the building or mixing with fresh air makeup. C. Capacity 2,000 cfrn or less. Reciculating air systems with a fan capacity of 2,000 cfm or less, but serving an area used for egress, shall have automatic fan shutdown. This would be foyers, lobbies, stairways, corridors, and passageways.