Thermostats shall be furnished by the unit manufacturer. Provide
relays, transformers, contractors, and control wiring between
thermostats and unit. Thermostats shall read out in degrees C and
degrees F.
[2.1.3
Closed Circuit Coolers
a.
Fan and Casing: Construct the fan section (up to top of intake
louvers) of heavy gage stainless steel and construct casing of
hot-dip galvanized steel. Standard pan accessories shall include
louver access, overflow, drain, Type 304 stainless steel
strainers, and brass make-up valve with plastic float.
b.
Axial Propeller Fans: Fans shall be heavy duty axial propeller
type statically balanced. Construct fans with aluminum alloy
blades, and install in a closed fitted cowl with venturi air inlet.
c.
Fan Motors: Motors shall be totally enclosed, ball bearing type,
and suitable for outdoor service.
d.
Drive: Fan drive shall be multi-groove, solid V-belt type with
taper lock sheaves designed for 150 percent of nameplate kWHP.
Fan and motor sheave shall be aluminum alloy construction. Belt
adjustment shall be accomplished from exterior of unit.
e.
Heat Transfer Coil: The coil shall be steel, encased in steel
framework with the entire assembly hot-dip galvanized after
fabrication. Arrange tubes in a self-spacing, staggered pattern
in the direction of airflow for maximum heat transfer efficiency
and minimum pressure drop, without the use of additional spacers
between the coil tubes. Design coil with sloping tubes for free
drainage of liquid and test to 2413 kPa 350 psi air pressure under
water.
f.
Water Distribution System: The system shall provide a water flow
rate of not less than .3846 l/sec 6 gpm over each square foot of
unit face area to ensure proper flooding of the coil. Construct
spray header of Schedule 40 polyvinyl chloride (PVC) pipe for
corrosion resistance. Spray branches shall be removable for
cleaning. Distribute water over the entire coil surface by spray
nozzles (381 by 8 mm15 by 5/16 inch orifice) with internal sludge
ring to eliminate clogging. Thread nozzles into spray header to
provide easy removal for maintenance.
g.
Water Recirculation Pump: The pump shall be close-coupled,
centrifugal type with mechanical seal, installed vertically at the
factory to allow free drainage at shutdown.
h.
Eliminators: Construct eliminators of inert PVC in easily handled
sections. The eliminator design shall incorporate three changes
in air direction to ensure complete removal of entrained moisture
from the discharge airstream. Maximum drift rate shall be less
than 0.001 percent of the circulating water rate.
i.
Construct Louvers From PVC: Mount louvers in removable frames for
maintenance access to the pan. Louvers shall have a minimum of
two changes in air direction to prevent splash out and block
direct sunlight.
SECTION 15741N
Page 18
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