SECTION 5.18  INDUSTRIAL OVENS FOR BAKING AND DRYING PROCESSES

Subsection 5.18.1.  Application

Application

5.18.1.1.  This Section applies to industrial baking and drying ovens which during operation contain flammable vapours given off by the products being baked or dried.

Subsection 5.18.2.  Location

Prohibited location

5.18.2.1.  Ovens shall not be located in any storey below grade.

Subsection 5.18.3.  Construction

Oven materials

5.18.3.1.  Industrial ovens shall be constructed of noncombustible materials with smooth interior surfaces to permit cleaning.

Limiting temperature on combustible construction

5.18.3.2.  The roof and floor of ovens and heaters and associated ductwork shall have sufficient clearance or be insulated where necessary to prevent the temperature from exceeding 90°C at any combustible part of the building assembly.

Explosion vents

5.18.3.3.  (1)  Explosion vents shall be provided for ovens where fuel or vapour hazards are present.

(2)  Explosion vents shall be designed in accordance with NFPA 68, “Standard on Explosion Protection by Deflagration Venting”.

(3)  Existing explosion vents that provide a vent ratio of 0.2 m² of vent area for each cubic metre of oven volume are deemed to satisfy the vent ratio for the purposes of NFPA 68 in Sentence (1).

(4)  Openings or access doors equipped with explosion release hardware shall be acceptable as explosion vents.

Duct and stack restrictions

5.18.3.4.  (1)  Ducts, stacks and associated insulation in systems for the removal of flammable vapours shall

(a)   be constructed of noncombustible materials,
(b)   not pass through firewalls, and
(c)   discharge outdoors not less than

(i)   1.5 m from unprotected building openings, and
(ii)   6 m from air intake openings.

Subsection 5.18.4.  Ventilation

Oven ventilation

5.18.4.1.  Ovens in which flammable vapours may be present or through which products of combustion are circulated shall be ventilated in accordance with NFPA 86, “Standard for Ovens and Furnaces”.

Fan interlocks

5.18.4.2.  (1)  In ovens where flammable vapours may be present, interlocks shall be provided to ensure that energy sources and ignition devices are de-activated when

(a)   the ventilating fans stop, or
(b)   the excess temperature controls are activated.

Continuous-process oven interlocks

5.18.4.3.  (1)  In continuous-process ovens where flammable vapours may be present, interlocks shall be provided to ensure

(a)   that ventilating fans are operating before conveyors can be started, and
(b)   that the conveyors are stopped when

(i)   the ventilating fans stop, or
(ii)   the excess temperature controls are activated.

Subsection 5.18.5.  Maintenance

Cleaning of ovens and ductwork

5.18.5.1.  (1)  Ovens and associated ductwork shall be inspected, cleaned and maintained internally and externally at intervals sufficient to prevent the accumulation of combustible deposits.

(2)  Access doors or panels shall be provided to permit inspection, cleaning and maintenance of ovens and associated ductwork.

(3)  Fixed noncombustible ladders, steps or grab rails shall be provided to permit access to the doors or panels required in Sentence (2).

Subsection 5.18.6.  Fire Protection

Portable extinguishers

5.18.6.1.  Portable extinguishers shall be provided in conformance with Section 6.2.

Standpipe and hose systems

5.18.6.2.  A standpipe and hose system shall be installed in conformance with the Building Code and equipped with spray nozzles so that all parts of an oven structure can be reached by a hose stream.

Fire access doors

5.18.6.3.  Doors or other means of access shall be provided in ovens and associated ductwork so that portable extinguishers or hose streams may be used in all parts of the equipment.

Automatic fire protection

5.18.6.4.  Ovens containing or processing sufficient combustible materials to sustain a fire shall be protected by an automatic sprinkler system or other fixed extinguishing systems.