COMBUSTIBLE AND EXPLOSIVE DUSTS

§ 385.30 Scope and Application of Provisions; Technical Standards

   (a)   The intent and purpose of Sections 385.30 to 385.34 are to prescribe requirements for safety to life and property in connection with manufacturing processes or storage in which combustible or explosive dust may be present or may result from manufacturing or storage.

   (b)   Wherever combustible or explosive dusts may accumulate, measures for the prevention of dust fires or explosions and safety measures for minimizing the effects of explosions shall be taken in conformity with the provisions of Sections 385.30 to 385.34 and with generally recognized standards for safety to persons and property. When deemed necessary, the Board of Building Standards and Building Appeals may promulgate supplementary rules and regulations. In the absence of such rules and regulations, conformity with the standards listed in Section 3101.07 of the Building Code shall be accepted as conformity with generally recognized standards for safety to persons and property.

(Ord. No. 991-49. Passed 6-27-49, eff. 6-27-49)

§ 385.31 General Requirements for Buildings

   (a)   After June 27, 1949, all buildings or parts of buildings in which materials producing flammable dust or explosive dust are stored or handled which were not used for such purpose on June 27, 1949, shall be of Type I, fireproof construction or Type II, incombustible construction and shall be either independent buildings or separated from other occupancies by occupancy separations designed to withstand probable explosion pressures and having a fire resistance rating of not less than four (4) hours.

   (b)   All buildings where magnesium, aluminum or other specially hazardous powder is manufactured, processed or handled in unsealed containers, shall be isolated buildings located not less than three hundred (300) feet from other buildings not part of the same plant, and not less than three hundred (300) feet from lines on adjacent premises where buildings may be built.

   (c)   Buildings liable to explosion pressure from explosive dust and constructed of light incombustible construction shall, except as provided in subsection (b) hereof, be located not less than seventy-five (75) feet from all adjoining buildings and from all lines on other premises on which buildings may be built.

   (d)   The construction and interior finish of rooms or places where dust may accumulate shall be such as to eliminate, so far as possible, surfaces, ledges or other places where dust may settle or accumulate.

   (e)   So far as possible all equipment shall be and shall be maintained dust-tight. Equipment in which explosive dust may accumulate shall be provided with approved explosion vents. Equipment which may accumulate charges of static electricity shall be suitably grounded.

   (f)   Equipment, bins and vaults in which dusty material is produced, processed or handled shall, so far as practicable, be equipped with devices or systems for removing the dust in a safe manner to a safe location or with systems of inert gas for fire and explosion prevention installed in conformity with the applicable code listed in Section 385.30.

   (g)   No open flames and no motors or other electrical devices which may emit sparks shall be permitted within rooms or spaces where combustible or explosive dust may accumulate. All motors and switches which are not of approved dust-proof types shall be located outside of the room, space or equipment in which dust may accumulate. No construction or repair work involving the use of welding equipment or of open flames or of sparking devices, shall be performed within any room or space which is not dust-free or in which dust-producing equipment is in operation.

   (h)   Whenever there is the possibility of ferrous metal being present in material processed, approved separators for the removal of such metal shall be provided and operated.

(Ord. No. 991-49. Passed 6-27-49, eff. 6-27-49)

§ 385.32 Dust Collectors and Dust Removal Systems

   (a)   Dust collectors, other than water-spray type collectors, shall be located in separate fire-resistive and explosion-resistive vented rooms or shall be placed outside of buildings.

   (b)   Sections 3155.75 to 3155.77 shall govern blower and exhaust systems installed for the purpose of removing or conveying dust, stock and refuse by means of air either under positive pressure or exhaust suction.

(Ord. No. 991-49. Passed 6-27-49, eff. 6-27-49)

§ 385.33 Explosion Venting

   (a)   All rooms or spaces in which combustible or explosive dust may accumulate shall have provisions for explosion venting in conformity with the following minimum requirements:

   Minimum Requirements for Explosion Venting

 

Type of Building or Structure	Cu. ft. of Building Content for each sq. ft. of Vent Area Provided
Heavy reinforced concrete construction	80
Light reinforced concrete or steel construction, with masonry exterior walls	65
Light steel frame or incombustible construction having little explosion resistance	50

 

   (b)   The requirements prescribed in subsection (a) hereof shall apply to dust having explosion characteristics similar to grain dust. For dust which produces greater explosion pressures, larger vent areas shall be provided as specified in the applicable standard listed in Section 385.30 and as approved by the Fire Chief.

   (c)   In enclosed processing equipment, spray drying chambers and dust collectors, vent areas shall be not less than one (1) square foot for each thirty (30) cubic feet of volume unless such equipment, chambers or collectors are designed and constructed to resist explosion pressures. When such equipment, chambers or collectors are designed to resist explosion pressures, the specified vent areas may be reduced but shall be in no case less than one (1) square foot for each fifty (50) cubic feet of volume vented.

   (d)   Rooms or spaces in which dust may accumulate shall have provisions for venting consisting of hinged sash, thin glazing or light incombustible construction, installed so as to relieve explosion pressures.

   (e)   Where explosive dust may accumulate, all enclosures of belt conveyors, galleries and roofs over storage bins shall be of light incombustible construction installed so that they will serve to relieve explosion pressures.

(Ord. No. 991-49. Passed 6-27-49, eff. 6-27-49)

§ 385.34 Existing Buildings and Structures

   No building or other structure or part thereof shall be maintained in use for any manufacturing process which produces combustible or explosive dust, or for the storage of any material involving explosive or combustible dust, for more than one (1) year after June 27, 1949, unless:

   (a)   All elevator legs, spouts, hoppers, and other conveyors are reasonably dust-tight and are so maintained;

   (b)   A suitable and approved dust removal system is provided, maintained and operated wherever dust may accumulate within the interior of a building, or a system of inert gas for fire and explosion prevention is installed in conformity with the applicable code listed in Section 385.30;

   (c)   No open flame or spark-producing equipment is provided or maintained within rooms where dust may accumulate;

   (d)   Separators for the removal of ferrous particles are provided and operated ahead of all grinding or pulverizing machines whenever ferrous particles may be present;

   (e)   All crushing, drying, pulverizing and conveying equipment and systems, and all other equipment which may accumulate static charges, are effectively grounded.

(Ord. No. 991-49. Passed 6-27-49, eff. 6-27-49)