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Marley
/
NC Class Stainless Cooling Tower
/
Specifications: Options
15
Vibration Limit Switch:
6.5 Add the following paragraph in the
Mechanical Equipment section: A
single-pole, double-throw vibration
limit switch in a IP56 housing shall be
installed on the mechanical equipment
support for wiring into the fan motor
shutdown circuit. The purpose of this
switch will be to interrupt power to the
motor in the event of excessive vibra-
tion. It shall be adjustable for sensitiv-
ity, and shall require manual reset.
Basin Heater:
11.2 Add the following paragraph in the
Cold Water Basin section: Provide a
system of electric immersion heaters
and controls for each cell of the tower
to prevent freezing of water in the
collection basin during periods of shut-
down. The system shall consist of one
or more stainless steel electric immer-
sion heaters installed in threaded cou-
plings provided in the side of the basin.
A IP56 enclosure shall house a mag-
netic contactor to energize heaters; a
transformer to provide 24-volt control
circuit power; and a solid-state circuit
board for temperature and low water
cut-off. A control probe shall be located
in the basin to monitor water level
and temperature. The system shall be
capable of maintaining 5°C water tem-
perature at an ambient air temperature
of _____ °C.
Electric Water Level Control:
11.1 Replace this paragraph with the fol-
lowing: The collection basin shall be
heavy-gauge series 300 stainless steel
and shall include the number and type
of suction connections required to
accommodate the out-flow piping sys-
tem shown on the plans. Suction con-
nections shall be equipped with stain-
less steel debris screens. A solid-state
water level control system to monitor
the water level with a multi-relay con-
trol panel pre-wired and mounted in
a IP56 nonmetallic enclosure shall be
provided. The system shall consist of
water level sensing and control units
■ Unless specified otherwise, a
Metrix switch will be provided.
A double-pole, double-throw
model is also available. If
purchased in conjunction with
the Control System, it is also
factory-wired. The requirement
for manual reset assures that
the cooling tower will be vis-
ited to determine the cause of
excess vibration.
■ The Marley basin heater components described at left represent our rec-
ommendation for a reliable automatic system for the prevention of basin
freezing. They are normally shipped separately for installation at the job-
site by the installing contractor. When purchased in conjunction with the
enhanced Control System option, however, they are customarily factory-
mounted and tested.
Submerged in basin water,
in which zinc ions are pres-
ent, copper immersion heat-
ers must not be used. Insist
upon stainless steel.
The ambient air temperature
that you insert in the specifi-
cations should be the lowest
1% level of winter tempera-
ture prevalent at site.
■ Solid-state liquid level controls provide you with state of the art sys-
tems to control and monitor the water level in your cooling tower col-
lection basin. Relays operating in conjunction with suspended stainless
steel electrode probes monitor basin water levels, providing simple
solenoid-valve water makeup or discrete on/off signals to more sophis-
ticated automation controls. Optional configurations might include
makeup along with high and low water level alarm and cutoff, or pump
cutoff. Packaged systems including any of these variations are available.
Consult you Marley sales representative or download a copy of ACC-
NC-9D from spxcooling.com for additional information.
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