Fans conforming to AMCA 801 [forced-draft] [and] [induced-draft] shall be
furnished as an integral part of boiler design. Fans shall be centrifugal
with [backward-curved blades] [radial-tip blades] or axial flow type. Each
fan shall be sized for output volume and static pressure rating sufficient
for pressure losses, excess air requirements at the burner, leakages,
temperature, and elevation corrections for worst ambient conditions, all at
full combustion to meet net-rated output at normal firing conditions, plus
an overall excess air volume of 10 percent against a 20 percent static
overpressure. Noise levels for fans shall not exceed 85 decibels in any
octave band at a 0.914 m 3 foot station. [Forced draft fan bearings shall
be air cooled.] [Induced-draft fans shall be designed for handling hot flue
gas at the maximum outlet temperature in the boiler. Induced draft fan
housings shall be provided with drain holes to accommodate the drainage of
condensation. Induced draft fan bearings shall be [air-cooled]
[water-cooled]. Induced draft fan scroll sheets and rotor blades shall
have protective liners.]
2.2.2.1
Draft Fan Control
[Forced-draft centrifugal fans shall have inlet vane controls or shall have
variable speed control where indicated. Inlet vanes shall be suitable for
use with combustion control equipment.] [Induced-draft centrifugal fans
shall have outlet dampers and shall have variable speed control.]
[Induced-draft fans shall have inlet vane controls.] Axial propeller fans
shall have variable propeller pitch control.
2.2.2.2
Draft Fan Drives
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NOTE: Where motor starters for mechanical equipment
are provided in motor control centers, delete the
description of motor starters.
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Fans shall be driven by electric motors. Electric motor shall be [drip
proof] [totally enclosed nonventilated] [totally enclosed fan cooled]
[totally enclosed fan-cooled, suitable for installation in a Class II,
Division 1, Group F, hazardous location conforming to NFPA 70]. [Motor
starter shall be [magnetic across-the-line] [reduced voltage start] type
with [general purpose] [weather-resistant] [watertight] [dust-tight]
[explosion-proof] enclosure and shall be furnished with four auxiliary
interlock contacts.]
2.2.3
Draft Damper
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NOTE: Select between manual and automatic dampers.
Normally, manual dampers are adequate for single
boilers less than 600 kW (2,000,000 Btuh) capacity.
Select automatic dampers for modular boilers.
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Boilers shall be provided with [manual] [automatic] dampers, draft hoods,
or barometric dampers as recommended by the boiler manufacturer to maintain
proper draft in the boiler. Draft damper shall be provided in a convenient
and accessible location in the flue gas outlet from the boiler. Automatic
damper shall be arranged for automatic operation by means of a [damper
regulator] [furnace draft regulator] [damper motor].
SECTION 15569A
Page 25
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