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Marley
/
Sigma 1000/1200 Cooling Tower
/
Specifications: Base
15
2.0 Thermal Performance:
2.1 The tower shall be capable of cooling
_____ GPM of water from ____ °F to
_____ °F at a design entering air wet-
bulb temperature of _____ °F. The cool-
ing tower manufacturer shall guarantee
that the tower supplied will meet
the specified performance conditions
when the tower is installed according
to plans.
2.2 The purchaser will arrange for an
on-site thermal performance test, to
be conducted in the presence of the
manufacturer and owner, and under
the supervision of a qualified, disinter-
ested third party in accordance with
CTI (Cooling Technology Institute) ATC-
105 standards during the first full year
of operation. If the tower fails to per-
form within the limits of test tolerance,
then the cooling tower manufacturer
will install additional cells and/or make
such corrections as are agreeable to
the owner and shall pay for the cost of
a retest. If the tower still fails to per-
form as specified, then the manufac-
turer shall make such reimbursements
as are appropriate and agreeable to the
owner to compensate for the perfor-
mance deficiency.
■ Your reason for purchasing a cooling tower is to obtain a con-
tinuing flow of cooled water as defined in the first paragraph at
left. If the tower that you purchase is incapable of performing
as specified, then you will not have received full value for your
money.
Bear in mind that the size—and cost—of a cooling tower var-
ies directly with its true thermal capability. This paragraph is
intended to protect you against either intentional or inadvertent
under sizing of the tower by the manufacturer. Judging the level
of performance of a cooling tower on critical processes is never
easy, and the potential risk of a non-performing cooling tower
usually causes the requirement for a mandatory acceptance test
to be very desirable.
Your contract with the successful bidder should establish the
acceptable remedies for missed performance, which might
include:
• The addition of one or more cells of tower, as necessary, to
bring the cooling tower to the specified level of performance.
This is usually limited to the scope of work as defined in the
specs, which means that you (the owner) will have to pay for
the additional basin, wiring, starters, piping, etc.
• The reimbursement of a portion of the total contract price equal
to the percentage deficiency in performance.
Under no circumstances should you allow the manufacturer to
re-pitch the fans to increase motor brake horsepower above that
shown in the proposal. That creates additional operating costs
that will continue for the life of the tower—and imposes no pen-
alty on the manufacturer.
Typical cooling tower performance curve.
55°
50° 55° 60° 65° 70° 75° 80°
5°F RANGE
10°F RANGE
15°F RANGE
60°
65°
70°
75°
COLD WATER TEMP. (°F)
WET BULB TEMP. (°F)
80°
85°
90°
95°