than 50 mm 2 inches or two pipe diameters, whichever is greater, above top
of basin. Install a hose bibb of 20 mm 3/4 inch nominal size near tower
casing. Connect makeup and hose bibb to water supply as indicated.
2.7.6.2
Walls
Construct with mortar having a waterproof additive in conformance with
Section 03300N CAST-IN-PLACE CONCRETE. Cover built-up masonry interior
walls of each cell completely with a membrane of fiberglass sheets of
commercial, first-quality, polyester-resin reinforced with fiberglass mat,
and secure to walls from top to bottom. Secure fiberglass sheets to walls
with cadmium-plated nails spaced not less than 610 mm 24 inches on center
in any direction. Seal nail heads and joints with
polyester-resin-reinforced fiberglass stripping rolled into place. Apply
finish coat of polyester resin, not less than 2 mm 1/32 inch, over entire
membrane after completion of hanging and stripping.
2.7.6.3
Fan Decks and Stacks
Construct fan decks of precast, reinforced lightweight concrete, in
multiple sections, forming a complete, vibration-free base for mounting
fan, speed reducer, drive shaft, motor, and fan stacks. Construct fan
stacks of precast, reinforced lightweight concrete in multiple sections,
constrained with bands of zinc-coated steel conforming to [ASTM A 123/A 123M
] [ASTM A 653/A 653M], not less than 3 by 76 mm 1/8 by 3 inches, and bolted
to form a compressive load on stack perimeter. Secure stack in place on
fan deck with Class A mortar.
2.7.6.4
Fill
Tile fill shall be multicellular design, set without mortar in a pattern of
sufficient height to meet indicated performance. Tile shall be dense and
vitreous, with a water absorption not to exceed 2 percent in a one-hour
boil test. Tile shall have minimum crushing strength of 2758 kPa 400 psi
over gross area of tile, when load is applied parallel to cells. Testing
shall be in accordance with ASTM C 67. Support tile fill by cast-iron tee
section lintels conforming to ASTM A 48/A 48M, Class 25, for gray iron
castings designed with a safety factor of three, plus 3 mm 1/8 inch
additional thickness for corrosion.
2.7.6.5
Water Distribution Systems
Provide each tower cell with a water distribution system and separate
regulation and stop valves for complete balancing and shut-off of each
cell. Distribution system for each cell shall consist of a centrally
located header complete with junction boxes and side laterals, fittings,
and nozzles. Piping 80 mm 3 inches and larger on the tower side of the
shut-off valve, junction boxes, and fittings shall be cast iron. Nozzles
shall be brass conforming to ASTM B 62. Piping smaller than 80 mm 3 inches
shall be [standard weight galvanized-steel pipe with threads epoxy coated]
[fiberglass-reinforced plastic pipe]. Cast-iron pipe shall be
centrifugally cast and shall conform to specifications of the American
Water Works Association (AWWA) or American National Standards Institute
(ANSI) for the required class. Cast-iron flanged and screwed fittings
shall conform to ASME B16.1 and ASME B16.4, respectively.
2.7.6.6
Inlet Pipe
Provide to each cell with a bleed connection having a regrinding type globe
SECTION 15601N
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