installed three conductor rubber sheathed flexible cord with the third wire
being the grounding conductor. Water pump shall be provided with a filter
screen constructed of plastic or bronze which shall project 25 mm 1 inch
above the high water level of the water tank.
2.10.3.2
Water Handling Equipment for Slinger Coolers
Water distribution to the evaporative pad shall be accomplished by a motor
driven water slinger to uniformly distribute water to the pad.
2.10.3.3
Water Blowdown Equipment
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NOTE: Water shall be discharged as specified in the
National Standard Plumbing Code.
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Water shall be periodically dumped (approximately every six to twelve
hours). This shall be done by either the use of a mechanical timer or by
measuring the conductivity and dumping the water when the conductivity
reaches 1500-2000 micro mhos.
2.10.4
Indirect Cooler Section
The indirect cooler shall consist of a [frame and plate counter flow]
[finned tube water-to-air] heat exchanger, [evaporative media] water
distribution header, scavenger fan and motor, and recirculating water pump,
[cooling coil,] drain, overflow and makeup water.
2.10.4.1
Heat Exchanger
The unit shall be constructed of stainless steel, polymeric material, or
aluminum with the surface exposed to water being fully protected against
corrosion by an epoxy coating. The plates shall be constructed in such a
way as to withstand a 250 Pa (1 inch water gauge) 1 inch water gauge
differential pressure without collapsing the plates. Units having
horizontal air discharge shall be provided with discharge baffle to direct
air upward, constructed of the same material and thickness as the casing.
The unit must be at least 80 percent efficient. For cleaning purposes
coils on finned tube water-to-air heat exchangers shall be plugged at the
return bins.
2.10.4.2
Water Distribution Header
The water distribution header shall be a nonwettable, nondrip type. Water
shall be distributed by means of copper spray headers with brass nozzles,
or PVC header and nozzles, which shall impart a fine water mist into the
scavenger air side of the heat exchanger.
2.10.4.3
Scavenger Fan
The fan shall be the centrifugal or axial type and shall be complete with
motor, drive equipment, and vibration-isolation supports between motor and
fan housing on single-phase motors. The fan motor shall be [synchronized
to start and stop with the indoor fan unit] [controlled by the HVAC system
controls]. Water distributor motor shall be synchronized to start and stop
with the scavenger fan unit. Manual or automatic reset type thermal
overload protection shall be provided in the starter or shall be integral
with the motor. Motor starters shall be [manual] [magnetic]
SECTION 15690A
Page 13
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