length at least two times shaft diameter. Fan wheel assembly shall be
dynamically balanced. Lubrication of bearings shall be safely accomplished
while unit is operating. Oil lubricated sleeve bearings shall be fitted
with reservoir.
2.5.11.3
Gear Drive Speed Reducer
Shall have a service factor of not less than 1.5 and shall be reversible.
Oil level, vent and drain lines shall be nonferrous metal, vibration
isolated, and extended to maintenance access points. Nonlubricated,
dynamically balanced, floating shaft and couplings shall be provided.
Construction shall be stainless steel or corrosion protected metals.
2.5.11.4
Fan Shafts
Wet service belt drive fan shaft shall be supported by drip and splash
protected, grease lubricated, split-bolted, pillow block antifriction
bearings. Lubrication provisions shall include automatic grease relief to
visible point and grease supply fittings extended to permit lubrication
under operating conditions. Belt drive shall be [reversible,] one-piece,
integral-back, multiple-groove type, constructed of synthetic fabric or
fiber reinforced neoprene.
2.5.11.5
Motors
Enclosure shall be totally enclosed, [single] [two] speed, [nonreversing]
[reversing] type, fitted with 120 volt a.c. resistance heaters. [Reversing
starters shall be fitted with adjustable time delay deceleration relays.]
Manufacturer's standard, adjustable set point, manual reset type vibration
cut-out switch shall provide to deenergize fans upon excessive vibration.
2.5.12
Vibration Isolation
Unit shall be vibration isolated from supporting structure by mountings
which limit imbalanced force transmissibility to [5] [_____] percent at
lowest equipment revolutions per minute.
2.5.13
Corrosion Protection
Galvanize cast and wrought ferrous metal in accordance with [ASTM A 123/A
123M] [ASTM A 653/A 653M]. Sheared edges shall receive additional
corrosion protection of a zinc rich coating. Other steel items specified
to be galvanized shall be coated in accordance with ASTM A 153/A 153M.
2.5.14
Unit shall be fitted with [modulating manual] [vortex] [inlet] [internal
bypass] [and discharge] damper controls [in addition to [on-off] [fan]
[and] [pump] [cycling] [and] [fan motor speed control]]. Dampers shall be
constructed of aluminum or galvanized, steel and fitted in such a manner as
to preclude freeze-up, mechanical binding or corrosion. Dampers shall be
fitted with a non-lubricated damper shaft bearings; corrosion resistant
damper shaft journals and pivots; pre-lubricated, antifriction, ball type
adjustable linkage; [NEMA Type 4 limit switches;] [waterproof electric
operator torque shall be not less than 2.0 times required torque;] and
temperature sensing control system with output controlling damper position.
SECTION 15602N
Page 19
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