910.1 General.

Smoke and heat vents or, where approved by the Commissioner of Buildings, mechanical smoke exhaust systems, and draft curtains shall be installed when required by the construction codes, including the Building Code, this code or the rules, and shall be designed and installed in accordance with the construction codes, including the Building Code.

910.2 Maintenance.

Automatically and manually operated heat vents and engineered mechanical smoke exhaust systems shall be inspected periodically and an operational test of each shall be conducted at least once every 12 months. A record of each inspection and test shall be maintained as required by FC 107.7 and 901.6.2.

   Exception: Gravity operated drop out vents need only be inspected.

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.