coatings shall conform to ASTM A 153/A 153M and [ASTM A 123/A 123M] [ASTM A
653/A 653M], as applicable, and shall have an extra heavy coating of not
less than 0.76 kg per square meter 2.5 ounces per square foot of surface.
Nails shall be silicon bronze, commercial bronze, or stainless steel.
Subject hardware to a salt-spray fog test in accordance with ASTM B 117.
No signs of corrosion shall be evident after 1,000 hours continuous
exposure to a 5 percent salt spray.
2.7.5.8
Basins
[Wood] [Concrete] construction and have capacity so that air will not be
entrained in outlets when operating, and no water will overflow on
shutdown. Basin may be rectangular, flat-bottom type, V-bottom type, or
shallow-pan type with deep storage sump. Provide each flat-bottom basin
with one or more steel, cast-iron, or concrete outlet sumps of such size
and depth as to prevent cavitation and air entrainment under operating
conditions. If a single outlet is indicated, and the Contractor elects to
provide two or more sumps, additional header piping of same size as outlet
pipe shown shall be provided. Provide outlets with removable screens.
Screens shall consist of 13 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 inchangle frames of
zinc-coated steel. 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 sections of screens shall not
weigh over 45.40 kg 100 pounds. Provide each basin with an overflow to
carry off excess flow due to incorrect adjustment of float, and a valved
drain connection. Pipe overflow and drain connections to nearest sewer
drain. Provide basins with a float-controlled, makeup water valve, located
so as to discharge not less than 50 mm 2 inches or two pipe diameters,
whichever is greater, above top of basin. Hose bibb of 20 mm 3/4 inch
nominal size shall be provided near tower casing. Connect makeup valve and
hose bibb as indicated.
2.7.5.9
Wood Basins
Fabricate wood basins of 40 mm 1.5 inch tongue and groove wood, caulked
with cotton wicking and mastic, or 20 mm 3/4 inch or heavier plywood with
plywood battens. Sides shall be through bolted to bottom whenever feasible
and to battens at joints and corners. Sides may be same material as
bottoms or of two layers of 10 mm 3/8 inchplywood.
2.7.5.10
Concrete Basins
Concrete shall be 20 MPa 2,500 psi class in accordance with Section 03300N
CAST-IN-PLACE CONCRETE, reinforced as indicated.
2.7.5.11
Casings
Fabricate from double-sheathed wood, or fiberglass-reinforced plastic. Wood
sheathing shall be not less than 15 mm 1/2 inch tongue and groove.
Partitions between cells shall be single-sheathed wood and shall extend
from fan deck to bottom of fill except for down flow towers, which shall
extend to top of fill.
2.7.5.12
Fan Decks
Fabricate from plywood a minimum of 29 mm 1.125 inches thick.
Fan decks
shall be designed to support a 293 kg/m2 60 psf live load.
SECTION 15601N
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