minimize vibration. [A threaded drain connection to accommodate a 25 mm 1
inch standard pipe shall be located at the lowest point in the scroll. A
flush-type access door shall be included in the scroll and held by
quick-release clamps and located as specified. Inlet and outlet duct
connections shall be flanged]. [The inlet of the fan shall be equipped
with an inlet box of the same steel thickness as the housing.] Seals shall
be provided to minimize leakage where the shaft passes through the housing
or inlet box. [Scroll sheets and rotor blades shall have liners.] Induced
draft fans shall be insulated as specified in Section 15080A THERMAL
INSULATION FOR MECHANICAL SYSTEMS. Fans shall be factory painted with the
manufacturer's standard finish. If drawings so indicate, the induced-draft
fan housing shall be designed to support the portion of the boiler stack
that is resting on the housing. Fans shall have [inlet vane control]
[inlet damper control] [variable speed control]. Inlet vanes or dampers
shall be suitable for use with combustion control equipment. The fan shall
be equipped with [precision anti-friction bearings that meet the
requirements for a minimum rating life of 100,00 hours] [the self-aligning
sleeve type] [or] [roller bearings mounted in suitable pillow blocks].
Fans with backward curved blades may have self-aligning anti-friction
bearings. Fan bearings shall be air cooled. Air balanced pillow blocks or
auxiliary seals shall be provided to prevent the aspiration of oil from oil
slinger type bearings. The oil reservoir shall be provided with heat
slingers for control of air movement over the bearing housing in order to
prevent a buildup of ambient temperature. Means for lubrication shall be
provided in accordance with the manufacturer's standard practice. Parts
requiring lubrications shall be so located as to make the lubricating
points easily visible and accessible. Hydraulic lubrication fittings shall
be in accordance with SAE J534. Where use of high-pressure lubricating
equipment, 1000 pound-force per square inch or higher, will damage grease
seals or other parts, a suitable warning shall be affixed to the equipment
in a conspicuous location. All parts requiring lubrication shall be
properly lubricated before delivery. 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 1, Division 1, Group F,
hazardous location conforming to NFPA 70]. Motor starter shall be magnetic
[across-the-line] [reduced voltage start] with [general-purpose] [weather
resistant] [watertight] [dust-tight] [explosion-proof] enclosure and shall
be furnished with four auxiliary interlock contacts. Fans shall be
directly or indirectly connected to the driving motor. If the fan is
indirectly connected, a V-belt designed for 50 percent overload capacity
shall be provided, and the motor shall be mounted on the base in a manner
that will permit tightening of the belt.
2.3.5
Flue Ducting
Each boiler shall be connected to the stack or flue by means of a smoke
connection constructed of black iron or steel sheet not less than 1.214 mm
0.0478 inch, nominal thickness. Clear distance between any portion of the
smoke connection surface and any combustible material shall be not less
than that specified in NFPA 211. Joints and seams shall be securely
fastened and made airtight. Suitable clean-outs shall be provided to
permit cleaning the entire smoke connections without dismantling. Duct
construction shall conform to SMACNA HVAC Duct Const Stds. Plastic
materials polyetherimide (PEI) and polyethersulfone (PES) are foirbidden to
be used for vent piping of combustion gases.
SECTION 15846A
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