§ 50.52. Automatic system.
(a) An automatic fire alarm system is a system designed to detect products of combustion and provide automatic notification to all building occupants. It shall be composed of detection devices, alarms, power source, wiring, and other related components as necessary. All detection devices shall be listed as meeting U.L. 268, 1981 Edition.
(b) Automatic detectors shall be installed to comply with the requirements of the applicable occupancy division.
(c) Automatic detectors shall be securely mounted on outlet boxes. Detectors shall not be recessed into the mounting surface unless they have been tested and listed for recessed mounting. Detectors may be ceiling or side wall mounted with a minimum of 4 inches clearance from a ceiling to wall jointure measured from the jointure to the top of the detector. Side wall mountings shall not exceed 12 inches measured from the ceiling and side wall jointure to the top of the detector.
(d) Automatic detectors shall be installed within the spacings or coverage used in the testing and listing of the detectors by any of the accepted independent testing agencies. The following considerations shall be made when determining spacing:
(1) Smooth ceilings. Normal spacings up to heights of 12 feet or less shall be used. Reduced spacing for areas over 12 feet in height shall be used.
(2) Sloped ceilings. Detectors within 3 feet of the peak, measured horizontally, with additional required detectors at normal spacings based on horizontal measurements shall be used.
(3) Beamed ceilings. Beams over 8 inches in depth shall reduce normal detector spacings. Beams over 18 inches in depth and on 8 feet or more centers shall have each bay treated as a separate area requiring a minimum of one automatic detector.
(4) Partitions. Partitions that extend to within 18 inches of the ceiling will not influence detector spacing. Partitions less than 18 inches from the ceiling may affect detection capabilities requiring reduced detector spacing.
(5) Corridors. When spacing detectors in corridors, the distance from the end wall of the corridor to the first detector shall not exceed 1/2 of the maximum distance allowed between first and second detectors in the corridor. The maximum distance allowed between the first and second detectors in a corridor shall be based on the spacing used when the detector was tested for listing by the accepted independent testing agency.
(6) Detector spacing for electromagnetic hold open devices. When doors are held open by electromagnetic devices, automatic detectors shall be installed at each location. A minimum of one automatic detector is required when the distance from the top of the door to the ceiling is 24 inches or less. Automatic detectors are required on both sides of the door when the distance from the top of the door to the ceiling is over 24 inches. The mounting distance of the automatic detector from the door shall not be less than the distance measured from the top of the door to the ceiling with a minimum distance of 12 inches and a maximum distance of 5 feet. The detectors may be side wall or ceiling mounted with a preference for ceiling mounting. Approved automatic closing devices with built-in hold open mechanism and detector may be used in lieu of wall or ceiling mounted devices.
(7) Special areas. The Department may approve alternative spacing of automatic detectors in special areas for specific hazards.
(e) Automatic fire detectors shall be classified into one of the four groups as follows:
(1) Heat fire detectors are devices that are designed to be sensitive to the rise in temperature produced by a burning substance. Heat detectors are generally classified as fixed temperature detection units, rate compensation detection units and temperature rate-of-rise detection units.
(i) Fixed temperature detection units may be the bimetallic, electrical conductivity, fusible alloy, heat sensitive cable, liquid expansion or other approved types that will respond when its operating element becomes heated to a predetermined level. When automatic fire detection is required, fixed temperature detection units shall be installed in boiler rooms, kitchens and other high heat or varying temperature areas where the normal or occasional environment prohibits the use of more sensitive fire detectors. The fixed temperature sensing setting shall be commensurate with the area installed.
(ii) Rate compensation detection units are to be considered for use in the same areas as required for fixed temperature detection units.
(iii) Rate-of-rise heat detection units may be the pneumatic spot-type or thermoelectric effective type heat detection units that respond when the temperature around the unit rises at a rate exceeding a predetermined amount. When automatic fire detection is required, rate-of-rise heat detection units shall be installed in lavatories, closets 25 square feet or less and other areas where the normal or occasional environment would prohibit the installation of more sensitive fire detectors. Rate-of-rise heat detection units may be installed with combination fixed temperature elements.
(2) Smoke detectors are devices which detect visible or invisible particles of combustion. Operating principles of smoke detectors may be the photoelectric light scattering type, photoelectric light obscuration type, projected beam type, ionization type utilizing radioactive material, resistance bridge type or cloud chamber type. When automatic fire detection is required, smoke detection units shall be installed in all occupied and unoccupied spaces not protected with other type fire detectors or fire suppression systems. Under certain hazards, the department may require smoke detectors in addition to a fire suppression system. Smoke detectors may be utilized as combination units with heat detectors or other fire detection units.
(3) Duct mounted fire detectors are devices designed to be sensitive to fire conditions in ducts utilized for heating, ventilating, air conditioning or other purposes. Duct mounted fire detectors may be classified as heat duct detectors or smoke duct detectors.
(i) When an automatic fire detection system is required in a building, air duct systems between 2,000 and 15,000 CFM shall have a heat detector installed at such a duct location that the flowing fire temperatures will be sensed during all modes of operation of the air duct system. Air duct systems over 15,000 CFM shall be equipped with duct heat detectors and smoke duct detectors, installed at such duct locations that the flowing fire temperatures will be sensed during all modes of operation of the air duct system. Not less than one heat detector and one smoke detector shall be installed in each system, additional detectors shall be added if needed to sense all modes of operation.
(ii) A smoke duct detector shall be installed in all ducts that penetrate a smoke barrier partition and connect to a smoke damper for automatically restricting the spread of smoke in that particular duct.
(iii) All duct mounted fire detectors shall be connected to the building manual or automatic fire alarm system. When a duct detector alarms, it shall automatically shut down its associated supply fan and any associated smoke dampers to restrict the spread of heat and smoke through the air duct system.
(iv) Ducts having an automatic extinguishing system shall not be required to have heat or smoke duct detectors but shall operate the fire alarm system, supply fans and dampers as described in this paragraph.
(4) The Department may require other detectors which would include fire detectors not mentioned in the above classifications such as flame detectors, fire-gas detectors or other fire detectors which are sensitive to a specific fire related phenomenon.
(f) Automatic fire alarm systems shall comply with § § 50.53, 50.55 and 50.56 (relating to general fire alarm requirements; maintenance; and testing new equipment).
Cross References This section cited in 34 Pa. Code § 55.52 (relating to automatic systems); 34 Pa. Code § 55.82 (relating to large personal care homes); and 34 Pa. Code § 57.52 (relating to automatic alarms).
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