Sound Power
Level in dB
[_____] [_____] [_____] [_____] [_____] [_____] [_____]
[_____]]
[ Sound level criteria shall conform to Section 15070N MECHANICAL SOUND
VIBRATION AND SEISMIC CONTROL.]
2.7.5.2
Design
Notching structural members is permissible only if the members are
increased proportionately in size to provide equivalent strength. Towers
shall be designed and constructed to withstand a wind pressure of not less
than 1437 Pa 30 pound force per square foot (psf) on external surfaces.
Fan decks shall be designed to withstand a live load of not less than 2874
Pa 60 psf in addition to the concentrated or distributed loads of equipment
mounted on the fan decks. [A 15-percent increased loading shall be
included for ice or snow load.] Design data for wood towers shall conform
to applicable requirements of the CTI Std-103, CTI Std-114, USDA AH 72 and
DOA Bulletin 865.
2.7.5.3
Identification Markings
Identification shall be permanently and legibly marked directly on the
tower or on a corrosion-resisting metal plate securely attached to the
tower at the source of manufacture. Identification shall include the
manufacturer's model and serial number, name, and trademark and be readily
identifiable to the manufacturer.
2.7.5.4
Woods
Redwood shall conform to RIS Grade Use. Red cypress shall conform to SCMA
Spec. Douglas fir and hemlock shall conform to WCLIB 17. Wood grades
shall conform to WWPA G-5. Redwood and red cypress shall be clear of all
heart grade, except for structural framing members and inner casings of
double-cased towers, which may be select heart grade. Douglas fir and
hemlock grades shall be similar to redwood and red cypress grades. Plywood
shall be in accordance with Douglas Fir Plywood Association Standards or
CTI Standards and shall be marine type, pressure treated, with B-grade face
and back and C-grade inner plies. Protect cut edges.
2.7.5.5
Wood Treatment
Douglas fir and west coast hemlock used in the construction cooling towers
shall have a preservative treatment in accordance with CTI Std-112. Wood
exposed as the result of notching, cutting, or drilling shall be saturated
with the preservative.
2.7.5.6
Fiberglass-Reinforced Plastics
Provide corrosion-proof, fire-retardant plastics in tower construction.
Plastics shall be manufacturer's standard commercial material and shall
meet conditions specified herein. Components manufactured of polystyrene
will not be permitted.
2.7.5.7
Hardware
Cadmium-plated, stainless steel (Type 304), or zinc-coated steel. Angle
brackets and similar parts shall be cast iron or zinc-coated steel. Zinc
SECTION 15601N
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