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Specification Value
Marley
/
Sigma 1000/1200 Cooling Tower
/
Specifications: Base
16
3.0 Construction:
3.1 The tower shall be capable of with-
standing water having a pH of 6.5 to
8.0; a chloride content (NaCl) up to 750
ppm; a sulfate content (SO
4
) up to
1200 ppm; a sodium bicarbonate con-
tent (NaHCO
3
) up to 200 ppm; a cal-
cium content (CaCO
3
) up to 800 ppm;
silica (SiO
2
) up to 150 ppm; and design
hot water temperatures up to 120°F.
The circulating water will contain no
oil, grease, fatty acids, or organic sol-
vents.
3.2 The structural framework of the tower
shall be Douglas Fir, designed in accor-
dance with CTI STD-114. Nylon shear
plates shall be utilized to transmit loads
at critical joints, and all fasteners shall
be in accordance with CTI STD-119.
Basic design criteria shall be 30 psf
wind load and 5%g seismic load.
3.3 All wood components shall be treated
after fabrication with chromated cop-
per arsenate (CCA) by the full-cell
process to a chemical retention of 0.4
lbs/ft
3
.
3.4 Structural columns and diagonals shall
be 4"x4". Framing girts may be 2"x4",
except for those supporting the hot
water basins and fill. Those girts shall
be 2"x6" minimum, located both sides
of the support columns.
3.5 Multicell towers shall include treated
Douglas Fir plywood partitions
between cells in the plenum area.
Partitions shall extend the full height of
the tower from the base of fill to the
underneath side of the fan deck.
3.6 Column lines shall be on no greater
than 4'-0" longitudinal centers, and
the base of all perimeter columns
shall be firmly anchored to galvanized
steel base plates. Framing joints shall
be made with 1/2" diameter or larger
series 300 stainless steel machine
bolts, nuts and washers.
■ The limiting water quality values indicated are those which are
acceptable for the normal materials of construction specified. If
water of more aggressive quality is anticipated please change
hardware material requirement to 300 Series stainless steel, as
indicated below and following.
Cooling Technology Institute standards take into account the hot,
humid environment in which a cooling tower normally operates.
This environment can render the limits of customary construction
standards inadequate for cooling tower design.
The importance of shear plates is discussed at length in
Marley Difference, “Item S-3”. Ask your Marley representative for
a copy.
See notes on page 27 regarding the use and availability of red-
wood.
Specification of minimum member sizes assures that all offerings
will conform to an industrial level of construction.
Multicell towers must have plenum partitions between cells.
Otherwise, air will be induced downward through an inoperative
fan, bypassing the fill entirely. Without these partitions, part-load
or off-season operation of the tower would be completely unsat-
isfactory.