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The 4" x" 4 tower diagonals carry loads to heavy-
duty hot-dip galvanized steel anchor plates or hot-dip
galvanized anchor weldments. The system of longitudinal
and transverse diagonal bracing provides stability in a true
tension-compression design.
the mechanical equipment. The taller fan cylinders used on
Series 1200 models effectively keep personnel away from
the fan, eliminating the need for guards.
All mechanical equipment is accessible both from the
interior of the tower and through the fan cylinder.
Every component of every tower is removable and
replaceable.
Casing
Tower endwalls are cased with gray 8 oz/sq ft rib-type,
fiber reinforced polyester sheets. Water and corrosion-proof,
All structural framing connections use 1/2" dia.
galvanized machine bolts with either fiber-reinforced nylon
shear connectors or FRP connector straps.
The fan deck is pressure treated exterior grade fir
plywood designed for a uniform live load of 60 psf.
Access and Safety
The Sigma tower is designed to meet all OSHA
requirements. A 3'-6" high guardrail system, complete with
toprails, intermediate rails and toeboards, surrounds the
entire top perimeter of the tower.
Aluminum ladders attached to the tower endwalls
provide access to the fan deck level. Ladders begin at the
cold water basin level and end at the top of the guarddrail.
Each tower normally includes two ladders—one at each
endwall.
Hinged doors through the endwall casing permit access
to the interior of the tower at the basin level. Single-cell
towers have one door. Multicell towers have doors in both
endwalls, plus accessways through any and all partition
walls.
Removable fan guards on Series 1000 models keep
personnel away from operating fans. The galvanized,
heavy-gauge welded rod guards lift off for easy access to
FRP is immune to biological deterioration and requires no
maintenance.
Casing ribs run vertically. Vertical joints between sheets
are overlapped one rib and are sealed in the fill areas.
Casing attaches to the structural members with stainless
steel fasteners and neoprene bonded washers. Corner trim
pieces are 12 oz/sq ft molded FRP.
/ Construction and Components /
Cold Water Collection Basin
Most Sigma owners install their towers over concrete
cold water basins provided by others. However, you can
choose a Marley wood collection basin as an optional
accessory. (See page 11).
Consult your Marley sales representative for detailed
dimensioned drawings and load schedules to help you with
your basin design.