Specifications
Vibration Limit Switch:
6.5Add 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:
11.2Add 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:
11.1Replace 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
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Specification Value
■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.
