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W:\Electrical\MANUAL\OVEN OPERATING INSTRUCTIONS\GENERAL INSTRUCTIONS\Oven General Instructions
Rev. B.doc
3-4.2 Ovens designed for use with fuel gas having a specific gravity greater than air
(such as propane) shall be located at or above grade and shall be located to
prevent the escape of the fuel gas from accumulating in basements, pits, or
other areas below the oven.
3-4.3 Fresh air inlets and exhaust outlets must never be restricted. If filtered air is
provided, there must be adequate filter capacity to prevent any reduction in
airflow even under adverse loading of the filter. The filters must be periodically
inspected and replaced as required.
3-4.4 A sufficient quantity of building make-up air should be admitted to oven rooms
and buildings to provide the air volume required for oven safety ventilation and
adequate combustion air for fuel fired equipment. Buildings should not operate
under a negative pressure.
3-4.5 The oven is equipped with an exhaust outlet. This outlet must be connected to
an exhaust stack for discharge to an outside location, and in a manner in
accordance with local codes and requirements; or connected to outside indirectly
through a fume incinerator or other approved pollution device. The exhaust
outlet is sized to fit standard stove pipe components. Exhaust gas temperature
is the same as internal oven temperature. Caution must be taken to protect
combustible building materials from coming in contact with the hot exhaust stack.
3-4.6 The minimum safe exhaust rate must be confirmed for ovens equipped with a
powered forced exhauster to handle flammable solvent vapors or products of
combustion from fuel fired equipment. The exhaust rate has been set at the
factory and dampers cut off and screwed in place or in some other manner
limited to prevent exhaust rate from being reduced below safe minimum exhaust
rate.
After installation, this exhaust rate must be confirmed. This must be done at the
outlet of the stack from the building. The exhaust rate must meet or exceed the
minimum rate indicated on the Safety Design Form located on the side of the
oven. If it is necessary to open the exhaust damper to increase the exhaust rate,
it must be cutoff or locked in position to prevent accidental closing.
Exhaust rate must be checked again if any changes are made to ventilation
system, duct work, or building ventilation. Adding additional equipment, which
requires ventilation, to the building will require additional make up air to the
building to prevent the building from operating under negative pressure.
Operating building under negative pressure will reduce exhaust rate from oven to
below safe minimum exhaust rate.
3-4.7 For additional ventilation information, refer to NFPA 31 “Standard for the
Installation of Oil-Burning Equipment”, NFPA 54 “National Fuel Gas Code” and
NFPA 91 “Standard for Exhaust Systems for Air Conveying of Vapors, Gases,
Mists and Noncombustible Particulate Solids” (see Appendix B).
3-5 EXHAUST DUCTWORK
3-5.1 Wherever oven ducts or stacks pass through combustible walls, floors, or roof,
either non-combustible insulation or clearance (or both) shall be provided to
prevent combustible surface temperatures from exceeding 160F (72C).
3-5.2 Where ducts pass through non-combustible walls, floors or partitions, the space
around the duct shall be sealed with non-combustible material to maintain the
fire resistance rating of the barrier. Ducts that pass through fire walls should be
avoided. Local, city and state codes may apply to duct installation.
