EVAPCO USS INDUCED DRAFT COUNTERFLOW COOLING TOWER
Part 1 General
1.1
Cooling Tower
Furnish and install as indicated on drawings and schedules, and by requirements
of this section, (1) packaged induced draft, counterflow cooling tower. Crossflow
type towers shall not be acceptable.
1.2
Codes and Standards
A.
CTI Compliance: Provide capacity ratings for cooling tower in accordance with
CTI Certification Standard CTI-201.
B.
UL and NEMA Compliance: Provide electrical motors and electrical components
required as part of the cooling tower, which have been listed and labeled by UL,
and comply with NEMA standards.
C.
NEC Compliance: Install cooling towers in accordance with NFPA 70.
1.3
Warranty
The entire structure shall be covered by a five year manufacturer's warranty
including fan(s), belt(s), bearing(s), fan shaft(s), drive sheave(s), gear box,
flexible coupling(s), driveshaft(s), and fan motor(s).
Part 2 Product
2.1
Acceptable Manufacturers
Evapco USS or approved equal.
2.2
Manufactured Units
Tower shall be CTI certified to cool a total of _____ GPM of water from 95ºF to
85ºF at 80ºF EWB.
Provide units for outdoor use, factory assembled, sectional, counterflow or
crossflow, industrial duty cooling tower, with sump, fan, surface sections, drift
eliminators, and motor situated as shown in plans. Maximum footprint shall not
exceed ___ L x ___ W x ____ H. Operating weight shall not exceed ______ lbs.
2.3
A.
Mechanical Equipment
Fan Motor
Totally enclosed air over (TEAO) or totally enclosedfan cooled (TEFC), 460 volt,
3 phase, 60 cycle ball bearing fan motors with 1.15 service factor shall be
furnished suitable for cooling tower service. Motors shall be mounted outside of
the unit. Maximum horsepower per cell shall not exceed ___HP.
B.
Axial Propeller Fans
Fans shall be heavy duty axial propeller type statically balanced. The fans shall
be fabricated by the cooling tower manufacturer for single source responsibility
and reliability. The fans shall be constructed of extruded aluminum alloy blades,
installed in a closely fitted cowl with venturi air inlet for maximum fan efficiency.
Each fan blade shall be individually adjustable. Fan cowl shall be covered with a
heavy gauge hot dip galvanized wire fan guard.
Optional Super Low Sound Fan
Units shall be provided with Low Sound Fan in order to assure a maximum
sound pressure level of ___ dB measured at 5ft above the fan discharge cylinder
during full speed operation. Fans shall be high efficiency axial propeller type
with aluminum wide chord blade construction. Each fan shall be statically
balanced and installed in a closely fitted cowl with venture air inlet for maximum
fan efficiency. The fan cowl shall be covered with a heavy gauge hot dipped
galvanized steel fan guard. There shall be no performance derate when utilizing
the Low Sound Fan.
C.
Fan Shaft Bearings
Fan shaft bearings shall be heavy duty self-aligning ball type with grease fittings
extended to the outside of the unit. Bearings shall be designed for a minimum L10 life of 75,000 hours.
D.
Drive
The fan drive shall either be belt or gear driven. Belt driven units shall be a
multigroove, solid back V-belt type with taper lock sheaves designed for 150% of
the motor nameplate horsepower.
The belt material shall be neoprene
reinforced with polyester cord and specifically designed for cooling tower service.
Fan sheave(s) shall be aluminum alloy construction. The fans and fan sheaves
shall be mounted on the shaft with a specially plated bushing to provide
maximum corrosion protection. Belt adjustment shall be accomplished from the
exterior of the unit. Bearing lube lines shall be extended to the exterior of the
unit for easy maintenance. All sheaves located in the airstream shall be
constructed of aluminum alloy, vented guards shall be not acceptable. If internal
belt adjustment is necessary, an internal working platform and ladder is required
to access the drive system.
Gear reducers shall be an industrial grade, single-reduction right-angle gear
reducer with a minimum 2.0 service factor. The gear housing shall be a single
piece design to eliminate split line seals and assure permanent alignment of
bearings and gears. All gears shall be precision machined from nickel alloy
steel, case hardened, and finish ground to class 10 tolerances. Continuous oil
circulation is assured in either directions of operation or at half speed through the
location of channels and baffles within the gear casing and the use of an
oversized slinger on the input shaft. Gear design shall meet or exceed minimum
applicable AGMA and CTI standards. A gear breather vent is piped to external
ambient air. The oil fill and drain connections will be extended from the side of
the gear to the outside of the unit. The coupling between the gear reducer and
fan motor shall utilize a flexible polyester reinforced neoprene connector with
cadmium plated steel hardware.
2.4
A.
Fill, Louvers and Drift Eliminators
Fill
The cooling tower fill shall be PVC (Polyvinyl Chloride) of crossfluted design for
optimum heat transfer and efficiency. The crossfluted sheets shall be bonded
together for strength and durability. The fill shall be fabricated, formed, and
installed by the cooling tower manufacturer and shall be elevated a minimum of
6" above the floor of the cold water basin to facilitate cleaning. The fill shall be
suitable for use as a working platform. The PVC fill shall be self-extinguishing
for fire resistance with a flame spread rating of 5 per ASTM E84-81a. It shall
also be resistant to rot, decay, or biological attack. The fill shall be able to
withstand a water temperature of 130ºF.
B.
Air Inlet Louver Screens
The air inlet louver screens shall be constructed from polyvinyl chloride (PVC)
and mounted in easily removable Stainless Steel frames on all four sides of the
cooling tower for access to the entire basin area for maintenance. The
removable louvers shall have a minimum of two changes in air direction to
prevent splashout, block direct sunlight from entering the basin, and shall have
either a maximum 3/4" opening or stainless steel inlet screens to prevent debris
from entering the basin.
C.
Drift Eliminators
The eliminators shall be constructed entirely of inert polyvinyl chloride (PVC) in
easily handled sections and be completely separate from the fill section for
maximum efficiency. The eliminator design shall incorporate three changes in
air direction to assure complete removal of all entrained moisture from the
discharge air stream. Maximum drift rate shall be less than 0.001% of the
circulating water rate.
2.5
Cold Water Basin
The basin shall be constructed of Type 316 Stainless Steel for long life and
durability. The basin area shall include all steel components from the base of
the unit to the top of the air inlet louver screens. Standard basin accessories
shall include overflow, drain, anti-vortexing hood, stainless steel strainers, and
electronic water level control. The entire basin area shall incorporate a stepped
configuration for reduced water volume, lower operating weight and easier basin
maintenance. Depressed side outlet sumps which are not an integral part of the
basin shall not be acceptable. Fiberglass basin liners and epoxy coated
galvanized support structures will not be acceptable.
2.6
Casing
The casing shall be constructed of either 304 or 316 stainless steel. The casing
panels shall totally encase the sides of the fill section to protect the surface from
direct atmospheric contact. The casing shall not be constructed of flammable
materials such as fiberglass.
2.7
Non-Corrosive Water Distribution System
Each cell of the cooling tower shall have one (1) hot water return inlet connected
to a main spray header. The spray header and branches shall be constructed of
Schedule 40 polyvinyl chloride (PVC) pipe for corrosion resistance. The
connection to attach the external piping shall be stainless steel. The spray
header and branches shall be removable for cleaning purposes. The water shall
be distributed over the fill by precision molded ABS spray nozzles with large 3/8
by 1 inch orifice openings and integral sludge ring to eliminate clogging. The
nozzles shall be threaded into the water distribution piping to assure positive
positioning.
If open type gravity distribution systems are used, they shall be constructed of
316 stainless steel with stainless pan covers. If two (2) gravity distribution pans
are required, pipework to convert to a single inlet per cell must be included and
top perimeter handrailing with ladder to the top of the tower must also be
provided for servicing of pans, per OSHA standards.
2.8
A.
Accessories
Electric Pan Heaters
Electric pan heater package consists of electric immersion heaters, heater
thermostat and low water cutout, all installed in pan. The heaters are sized to
maintain +40°F pan water temperature with the fans off. Heaters are controlled
by the thermostat, and the low water cutout prevents the heaters from cycling on
unless they are completely submerged. Contractor shall provide and field install
heater contactor, transformer, circuit breaker, disconnect and wiring in conduit
for complete installation as per manufacturer’s recommendations.
B.
External Service Platform with Access Ladder
Cooling towers will be provided with an external service platform with sloped
aluminum vertical ladder extending to the base of the tower. The platform and
ladder will allow servicing of the electric motor, fan drive, mechanical equipment
and water distribution systems.
On units with gravity type hot water basins, the top of the tower shall also be
equipped with a sturdy handrail, complete with kneerail and toeboard, designed
according to OSHA guidelines. An aluminum ladder shall extend from the
mechanical platform to the top of the perimeter handrail.
C.
Control Panel
Each cell shall include a UL listed control panel complete with NEMA 4X
fiberglass enclosure, single speed fan motor starters, temperature control,
control voltage transformer, H-O-A switches, and door mounted disconnect
switch. Panel is to ship loose for field installation by installing contractor.
D.
Non-Chemical Water Treatment System
Each cooling tower shall include a non-chemical water treatment system as
manufactured by Clearwater Systems Model 2114-PVC. The Clearwater System
is to include a 14” coil pipe assembly and transformer panel mounted in NEMA
3R panel (240V). The panel shall include a Form C dry contact for remote
monitoring. Panel to be field interlocked with condenser water pump. System to
ship loose for field installation by others.
E.
Cold Water Basin Sand Filter System
Each cell shall include sump sweeper piping factory mounted by cooling tower
manufacturer. Skid mounted filter system to ship loose for field installation and
connection to factory sump sweeper piping. Skid mounted system shall include
the following: fiberglass vessel, automatic air relief valve, (2) bronze 3-way
control valves, close coupled pump with integral pre-strainer, automatic controls
with NEMA 3R panel with door disconnect, backwash timer, 24 hour backwash
clock, differential pressure switch, and electric valve actuator. Filter shall have
single electrical hook-up point.
F.
Sentinal Monitoring System
Cooling tower shall be supplied with Sentinal Monitoring System capable of
monitoring the following: pan water temperature, water pressure across the
spray header, pan water conductivity, pan water PH, pan water level, vibration of
the drive system, fan motor current, and fan motor run time. The monitor and
alarm panel shall have the following features and capabilities: integrated LCD
for display of the current status and alarms, front panel LED alarm indicators,
programmable alarm limits for each measured value, logging of all measured
values, logging of all alarms, interface to BMS via BACnet MSTP or Modbus
RTU.
G.
Motor Davit
Each cell shall include a motor/gear davit to facilitate in removal and service of
the fan motor and/or gear drive.
Part 3 Execution
3.1
A.
Installation
General
Install cooling tower where indicated in the plans, in accordance with equipment
manufacturer’s written instructions.