FC 911 — Explosion Control

Section FC 911: Explosion Control

911.1 General. Explosion control shall be provided in the following locations: 1. Where a structure, room or space is occupied for purposes involving explosion hazards as set forth in FC Table 911.1. 2. Where quantities of hazardous materials specified in FC Table 911.1 exceed the maximum allowable quantities set forth in FC Table 5003.1.1(1). Such areas shall be provided with explosion (deflagration) venting, explosion (deflagration) prevention systems, or barricades in accordance with this section and NFPA 69 or NFPA 495, as applicable. Deflagration venting shall not be utilized as a means to protect buildings from detonation hazards. FC Table 911.1 Explosion Control Requirements Material Class Explosion Control Methods Barricade Construction Explosion (deflagration) venting or explosion (deflagration) prevention systems Hazard Category Combustible dusts a — Not required Required Cryogenic fluids Flammable Not required Required Explosives Division 1.1 Division 1.2 Division 1.3 Division 1.4 Division 1.5 Division 1.6 Required Required Not required Not required Required Required Not required Not required Required Required Not required Not required Flammable gas Gaseous Liquefied Not required Not required Required Required Flammable liquids IA b IB c Not required Not required Required Required Organic peroxides e Unclassified Detonable I Required Required Not permitted Not permitted Oxidizer liquids and solids 4 Required Not permitted Pyrophoric material e Detonable Required Not permitted Pyrophoric gases e Nondetonable Not required Required Unstable (reactive) e 4 3 detonable 3 nondetonable Required Required Not required Not permitted Not permitted Required Water-reactive liquids and solids e 3 detonable 3 nondetonable 2 detonable 2 nondetonable Required Not required Required Not required Not permitted Required Not permitted Required Special Uses Energy Storage System — Required Required Grain processing — Not required Required Where explosion hazards exist d Detonation Deflagration Required Not required Not permitted Required a. Combustible dusts that are generated during manufacturing or processing. See definition of Combustible Dust in FC Chapter 2. b. Storage or use. c. In open use or dispensing. d. Rooms containing dispensing and use of hazardous materials when an explosive environment can occur because of the characteristics or nature of the hazardous materials or as a result of the dispensing or use process. e. Unclassified detonable organic peroxides (see FC Chapter 62), detonable pyrophoric materials (see FC Chapter 64), detonable unstable (reactive) materials (see FC Chapter 66) and detonable water-reactive materials (see FC Chapter 67) are considered as explosives for purposes of storage. 911.2 Required deflagration venting. Areas that are required to be provided with deflagration venting shall comply with the following requirements: 1. Walls, ceilings and roofs exposing surrounding areas shall be designed to resist a minimum internal pressure of 100 pounds per square foot (psf) (4788 Pa). The minimum internal design pressure shall not be less than five times the maximum internal relief pressure specified in FC 911.2(5). 2. Deflagration venting shall be provided only in exterior walls and roofs. Exception: Where sufficient exterior wall and roof venting cannot be provided because of inadequate exterior wall or roof area, deflagration venting shall be allowed by specially designed shafts vented to the exterior of the building. 3. Deflagration venting shall be designed to prevent unacceptable structural damage. Where relieving a deflagration, vent closures shall not produce projectiles of sufficient velocity and mass to cause life threatening injuries to the occupants or other persons on the property or adjacent public streets. 4. The aggregate clear area of vents and venting devices shall be governed by the pressure resistance of the construction assemblies specified in FC 911.2(1) and the maximum internal pressure allowed by FC 911.2(5). 5. Vents shall be designed to withstand loads in accordance with the construction codes, including the Building Code. Vents shall consist of any one or any combination of the following to relieve at a maximum internal pressure of 20 pounds per square foot (958 Pa), but not less than the loads required by the construction codes, including the Building Code: 5.1. Exterior walls designed to release outward. 5.2. Hatch covers. 5.3. Outward swinging doors. 5.4. Roofs designed to uplift. 5.5. Venting devices listed for the purpose. 6. Vents designed to release from the exterior walls or roofs of the building when venting a deflagration shall discharge directly outdoors where an unoccupied space not less than 50 feet (15 240 mm) in width is provided between the exterior walls of the building and the property line. Exception: Vents complying with the requirements of FC 911.2(7). 7. Vents designed to remain attached to the building when venting a deflagration shall be so located that the discharge opening shall not be less than 10 feet (3048 mm) vertically from window openings and exits in the building and 20 feet (6096 mm) horizontally from exits in the building, from window openings and exits in adjacent buildings on the same property, and from the property line. 8. Vent lines shall discharge outdoors. 911.3 Explosion prevention systems. Explosion prevention systems shall be of an approved type and installed in accordance with this code and NFPA 69. Where the building or structure or part thereof is provided with a fire alarm system, explosion prevention system alarms shall be transmitted to the fire alarm system control panel and to an approved central station. 911.4 Barricades. Barricades shall be designed and installed in accordance with NFPA 495.