373.04 with a service factor of 2 for cooling tower service. Gear reducers
shall be spiral-bevel type for single reduction and spiral-bevel and
helical with parallel shaft for double reduction. Drive shafts shall be of
stainless steel and full-floating type, fitted at each end with
stainless-steel-plate type flexible couplings.
2.7.5.24
Fan Motors
[Single speed] [Two speed], totally enclosed, insulation Class B, NEMA
Design B, 1.0 service factor, continuous-rated, and conforming to NEMA MG 1.
[Two-speed motors shall have a single winding with variable torque
characteristics.]
2.7.5.25
Motor Starters
Reduced voltage with low voltage protection and thermal-overload manual
reset relays. Starters shall conform to NEMA ICS 1 and NEMA ICS 2and shall
have a NEMA Type [1] [3R] enclosure and a MAN-OFF-AUTO selector switch.
[Two-speed motor starters shall be provided with a speed selecting switch
as part of the starter.]
2.7.5.26
Vibration Cutout Switches
Provide for each fan and interlock with motor wiring to stop motor under
excessive fan vibration.
2.7.6
Tile Filled Towers
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NOTE: Where tile filled towers are to be used in
base bid or as an alternate, drawings must be
coordinated to assure that structural loading has
been incorporated in the design and that all
construction details have been reflected on
drawings. Indicate whether fan deck is to be
furnished by tower manufacturer or under general
construction.
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Provide counterflow, induced-draft type with capacity as indicated.
2.7.6.1
Basins
Construct concrete basins using a continuous pour containing a waterproof
additive in conformance with Section 03300N CAST-IN-PLACE CONCRETE. Provide
each basin with one or more steel, cast-iron, or concrete outlet sumps
sized to prevent cavitation and air entrainment under operating conditions.
If a single outlet is indicated, and the Contractor elects to furnish two
or more sumps, additional header piping of same size as outlet pipe shown
shall be provided. Provide each outlet with a removable screen. Screens
shall consist of 15 mm 1/2 inch mesh, zinc-coated steel wire fastened to 32
by 32 by 4.76 mm 1.25 by 1.25 by 3/16 inchzinc-coated steel angle frames
conforming to [ASTM A 123/A 123M] [ASTM A 653/A 653M]. Total screen area
below operating water line shall be not less than 0.0929 square meter one
square foot for each 25.24 L/s 400 gpm of specified tower capacity.
Individual section of screens shall not weigh over 45.40 kg 100 pounds.
Provide each basin with an overflow and a valved drain connection. Pipe
overflow and drain connections to nearest sewer drain. Provide each basin
with a float-controlled makeup water valve, located to discharge not less
SECTION 15601N
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