SPX Cooling Technologies Marley Sigma Wood CoolingTower 1200 - Manual (Page 6)

6
Water Distribution System
The gravity-flow water distribution system designed into
the Sigma tower essentially reduces pump head to its most
basic component – static lift – saving you money on pump
power. You won’t have to force water through internal piping
and pressure spray nozzles, as you would in a counterflow
tower.
Warm water enters the system through the Sigma
galvanized crossover pipe. Inlet connections for your piping
are standard 125# flanges. Marley flow-control valves balance
the flow to both distribution basins of each cell. Water flows
projected area and the design meets 5%g seismic loading,
based on a maximum water temperature of 120°F.
Pressure-treated Douglas Fir is the standard material
for structural members in Sigma towers because it offers
predictably consistent structural strength and provides long
service life in cooling towers. Treated redwood structure
from each valve through a splash-suppression chamber into
the treated fir plywood distribution basin.
Polypropylene patented “Spiral Target” nozzles in the
basin floor then distribute the water uniformly over the fill.
All materials in the water distribution system offer long life
and minimal maintenance. Valves consist of cast iron bodies
and grease-lubricated stainless steel operating stems. All
plywood is treated exterior grade. The nozzles are chemically
and biologically inert, so they’ll last indefinitely.
Structure and Materials
Sigma tower design conforms to the latest edition of the
National Design Specification for Wood Construction (NDS)
published by the National Forest Products Association.
Wind load criterion is normally 30 pounds per square foot of
is available as an option. However, you will benefit in the
long run from specifying redwood very selectively and very
carefully.
Unless otherwise specified, all lumber – regardless
of species – is pressure treated after fabrication. Lumber
treatment is CCA, infused into the wood by the full-cell
process to 0.40 lb/ft
3 retention.
The primary structural elements of all Sigma towers
are the 4" x 4" columns. Column bent lines occur on 4'-0"
longitudinal centers.
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