across-the-line type with [general purpose] [weather resistant] enclosure.
[Remote manual switch with pilot indicating light shall be provided where
indicated.] Fan scroll and wheel shall be constructed of galvanized steel,
aluminum, stainless steel or polymeric material with stainless steel,
hot-dip zinc coated steel or cadmium coated steel shaft. Fan scroll may be
made of a different material than the wheel. Fans shall have an air
delivery rating based on AMCA 210 tests by an AMCA approved laboratory.
2.10.4.4
Water Pump
The water pump shall be a self-priming centrifugal type with capacity and
head characteristics for the specified operation of the unit. The motor
shaft shall be constructed of stainless steel, cadmium coated steel or
hot-dip zinc galvanized steel. The impeller shall be constructed of
stainless steel or polymeric material conforming to UL 746C. Pump housing
shall be constructed of factory [painted] [hot-dip zinc coated] steel or
polymeric material conforming to UL 746C. Pump housing bottom shall be
removable for impeller cleaning and shall not permit galvanic action with
cooler bottom. Pump shall have permanently sealed and lubricated bearings
and fan cooled motor with moisture proof winding. Pump motor shall be
provided with a factory 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 which shall project
25 mm 1 inch above the high water level of the water tank.
2.10.5
Cooling Coil
Supplemental water cooling coil shall be located [upstream from the direct
stage] [between stages] [downstream from the second stage]. The coil shall
be fin-and-tube type constructed of seamless copper tubes and copper or
aluminum fins mechanically bonded or soldered to tubes. Headers shall be
constructed of cast iron, welded steel or copper. Casing and tube support
sheets shall be 1.6 mm (16 gauge) 16 gauge galvanized steel, formed to
provide structural strength. Tubes shall be correctly circuited for proper
water velocity without excessive pressure drop and they shall be drainable
where required or indicated. Each coil shall be factory tested at not less
than 1720 kPa (250 psi) 250 psi air pressure and shall be suitable for 1380
kPa (200 psi) 200 psi working pressure. Drainable coils shall be installed
in the units with a pitch of not less than 10 mm per m 1/8 inch per foot of
tube length toward the drain end. [Coils shall conform to the provisions
of ARI 410.]
2.11
AIR WASHERS
Air washers shall be furnished as a factory package unit, complete with fan
unit, spray pump, nozzles, piping, evaporative cells, washdown cycle and
eliminators. Air washers shall be spray type [or sprayed cell type]. A
guillotine type manual winterizing damper complete with holding rack shall
be provided on the discharge side of each unit. Holding rack shall retain
damper during operating season.
2.11.1
Fan Unit
The unit shall be the centrifugal type and shall be complete with motor,
drive equipment, and vibration-isolation supports between motor and fan
housing. Spray pump shall be synchronized to start and stop with fan unit
or on a timed cycle which allows the evaporative cells to be wetted prior
to fan start. Manual reset type thermal overload protection shall be
provided in the starter or shall be integral with the motor. The motor
SECTION 15690A
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