Cooling Towers: FXT

Engineering Specifications for FXT Cooling Towers

Detailed FXT Specification formatted for word processor use

1.0 Cooling Tower

1.1 General: Furnish and install ___ factory-assembled, forced-draft, crossflow cooling tower(s). The tower(s) shall have air entry on one side only. The tower(s) shall have the fan and all moving parts located in the dry entering airstream to provide greater reliability and long life. Overall dimensions shall not exceed approximately ____ft (mm) long x ____ft (mm) wide, with an overall height not exceeding ____ft (mm). The total connected fan horsepower shall not exceed ___ HP (kW). The cooling tower shall be Baltimore Aircoil Company Model FXT _____.

1.2 Thermal Capacity: The cooling tower(s) shall be warranted by the manufacturer to cool _____ USGPM (l/s) of water from ___ºF (ºC) to ___ºF (ºC) at ___ºF (ºC) entering wet-bulb temperature. Additionally, the performance shall be certified by the Cooling Technology Institute in accordance with CTI Certification Standard STD-201. Lacking such certification, a field acceptance test shall be conducted within the warranty period in accordance with CTI Acceptance Test Code ATC-105, by the Cooling Technology Institute or other CTI-accredited independent testing agency. The cooling tower(s) shall comply with the energy efficiency requirements of ASHRAE Standard 90.1.

1.3 Corrosion Resistant Construction: Unless otherwise noted in this specification, all steel panels and structural members shall be constructed of heavy-gauge, G-235 (Z700 metric) hot-dip galvanized steel with all cut edges given a protective coating of zinc-rich compound.

(Alternate) 1.3 Corrosion Resistant Construction: Unless otherwise noted in this specification, all steel panels and structural members shall be protected with the BALTIBOND® Corrosion Protection System. The system shall consist of G-235 (Z700 metric) hot-dip galvanized steel prepared in a four-step (clean, pre-treat, rinse, dry) process with an electrostatically sprayed, thermosetting, hybrid polymer fuse-bonded to the substrate during a thermally activated curing stage and monitored by a 23-step quality assurance program. Coatings other than the BALTIBOND® Corrosion Protection System must be submitted to the engineer for pre-approval. Approved equals must have undergone testing, resulting in the following results as a minimum:

1. When X-scribed to the steel substrate it shall be able to withstand 6000 hours of 5% salt spray per ASTM B117 without blistering, chipping, or loss of adhesion;

2. When X-scribed to the steel substrate it shall be able to withstand 6000 hours of exposure to acidic (pH=4.0) and alkaline (pH=11.0) water solutions at 95ºF (35ºC) without signs of chemical attack;

3. Shall withstand impact of 160 in-lbs per ASTM D2794 without fracture or delamination of the polymer layer;

4. Shall withstand 6000 hours of ultraviolet radiation equivalent to 120,000 hours of noontime sun exposure without loss of functional properties;

5. Shall withstand 200 thermal shock cycles between - 25ºF (-32ºC) and +180ºF (82ºC) without loss of adhesion or other deterioration;

6. Shall withstand 6000 hours of exposure to 60 psi (42,184.5 kg/m2) water jet without signs of wear or erosion.

(Alternate) 1.3 Stainless Steel Construction: Unless otherwise noted in this specification, all steel panels and structural members shall be constructed of type 304 stainless steel and assembled with type 304 stainless steel nut and bolt fasteners.

1.4 Quality Assurance: The cooling tower manufacturer shall have a Management System certified by an accredited registrar as complying with the requirements of ISO-9001:2000 to ensure consistent quality of products and services.

2.0 Construction Details

2.1 Cold Water Basin: The cold water basin shall be constructed of heavy-gauge, hot-dip galvanized steel. Standard accessories shall include circular access doors, large-area, lift-out hot-dip galvanized steel strainers with perforated openings sized smaller than water distribution nozzle orifices, an integral anti-vortexing hood to prevent air entrainment, and a bronze make-up valve with large diameter plastic float, arranged for easy adjustment.

(Alternate) 2.1 Stainless Steel Cold Water Basin: All steel components in the cold water basin below the overflow level and in contact with the basin water shall be made of type 304 stainless steel. All other steel panels and structural elements shall be made from heavy-gauge G-235 (Z700 metric) hot-dip galvanized steel, with cut edges given a protective coating of zinc-rich compound.

2.2 Water Distribution System: Hot water distribution basin shall be open gravity type and constructed of heavy gauge, G-235 (Z700 metric) hot-dip galvanized steel. Basin weirs and plastic metering orifices shall be provided to assure even distribution of water over the fill surface. Lift-off distribution covers shall be constructed of heavy gauge, G-235 (Z700 metric) hot-dip galvanized steel.

3.0 Mechanical Equipment

3.1 Fan(s): Fan(s) shall be heavy-duty, axial flow type. Air shall be forced into the tower through a fan cylinder designed for streamlined air entry and minimum fan blade tip clearance for maximum fan efficiency.

3.2 Bearings: Fan(s) shall be mounted directly on the motor shaft or mounted on a horizontal solid steel shaft supported by two heavy-duty, self-aligning, relubricatable ball bearings with cast iron housings and designed for minimum L10 life of 40,000 hours (280,000 Hr. Avg. Life). Extended lubrication lines are provided for ease of maintenance.

3.3 Fan Drive: Fan(s) shall be direct driven or driven by V-belts designed for not less than 150% of motor nameplate horsepower. Drives and all moving parts shall be protected by removable steel screens that shall ship installed on the unit.

3.4 Fan Motor(s): Fan motor(s) shall be totally enclosed fan cooled (TEFC), reversible, squirrel cage, ball bearing type, designed specifically for cooling tower service. The motor shall be furnished with special moisture protection on winding, shafts and bearings and labeled specifically for “Cooling Tower Duty.”

(Alternate) 3.4 Fan Motor(s): Fan motor(s) shall be totally enclosed fan cooled (TEFC), reversible, squirrel cage, ball bearing type, designed specifically for cooling tower service. The motor shall be furnished with special moisture protection on winding, shafts and bearings and labeled specifically for “Cooling Tower Duty.” Fan motors shall be inverter duty type designed per NEMA Standard MG1, Section IV, Part 31.

3.5 Mechanical Equipment Warranty: The fan(s), fan shaft(s), bearings, mechanical equipment support and fan motor shall be warranted against defects in materials and workmanship for a period of five (5) years from date of shipment.

4.0 Fill and Drift Eliminators

4.1 Fill and Drift Eliminators: The fill and integral drift eliminators shall be formed from self-extinguishing polyvinyl chloride (PVC) having a flame spread rating of 5 per ASTM E84 and shall be impervious to rot, decay, and fungus or biological attack. The fill shall be suitable for entering water temperatures up to and including 125°F (51.7°C). The fill shall be manufactured and performance tested by the cooling tower manufacturer to provide single source responsibility and assure control of the final product.

(Alternate) 4.1 Fill and Drift Eliminators: The fill and integral drift eliminators shall be formed from self-extinguishing polyvinyl chloride (PVC) having a flame spread rating of 5 per ASTM E84 and shall be impervious to rot, decay, and fungus or biological attack. The high temperature fill shall be suitable for entering water temperatures up to and including 140°F (60.0°C). The fill shall be manufactured and performance tested by the cooling tower manufacturer to provide single source responsibility and assure control of the final product.

5.0 Accessories

5.1 Basin Heater(s): The cooling tower cold water basin shall be provided with electric heater(s) to prevent freezing in low ambient conditions. The heater(s) shall be selected to maintain 40°F (4.4°C) basin water temperatures at _____°F (°C) ambient. The heater(s) shall be ______V/____phase/___Hz electric and shall be provided with low water cutout and thermostat.

5.2 Basin Water Level Control: The cooling tower manufacturer shall provide an electric water level control (EWLC) system. The system shall consist of water level sensing and control units in quantities and locations as indicated on the drawings. Each water level sensing and control unit shall consist of the following: NEMA 4 enclosure with gasketed access cover; solid state controls including all necessary relays and contacts to achieve the specified sequence of operation; stainless steel water level sensing electrodes with bronze holder; Schedule 40 PVC standpipe assembly with vent holes, and all necessary stainless steel mounting hardware. Provide PVC union directly below the control enclosure to facilitate the removal and access of electrodes and control enclosure.

The number and position of water level sensing electrodes shall be provided to sense the following: high water level, low water level, high water alarm level, low water alarm level, and heater safety cutout.

5.3 Vibration Cutout Switch: Provide a mechanical local reset vibration switch. The mechanical vibration cutout switch shall be guaranteed to trip at a point so as not to cause damage to the cooling tower. To ensure this, the trip point will be set in a frequency range of 0 to 3,600 RPM and a trip point of 0.2 to 2.0 g’s.

(Alternate) 5.4 Vibration Cutout Switch: Provide an electronic remote reset vibration switch with contact for BAS monitoring. Wiring shall be by the installing contractor. The electronic vibration cutout switch shall be
set to trip at a point so as not to cause damage to the cooling tower. To ensure this, the trip point will be set in a frequency range of 2 to 1000 Hertz and a trip point of 0.45 in/sec (0.0114 m/sec).

5.4 Variable Frequency Drive(s): A variable frequency drive (VFD) specifically configured shall be provided for each fan motor. The supplier of the VFD shall be the manufacturer of the evaporative cooling equipment. The VFD shall have a 3-contactor bypass, 3% input line reactor, a removable keypad, an RS232 terminal for PC connection, and a circuit breaker disconnect. Fuse protection will not be accepted. Control voltage shall be 24V to minimize the size of the enclosure which should not exceed _____ ft (mm) x _____ ft (mm) x ____ ft (mm) and the weight should not exceed ____ lbs. VFD shall be provided in a NEMA (1)(3R)(12) enclosure. The VFD shall be compatible with a (ModBus) (LonWorks) (Johnson N2) Building Automation System.

OR

5.4 Enclosed Controls: An enclosed control panel shall be provided for each cell of the evaporative cooling equipment. The panel shall include full voltage, non-reversing (FVNR) fan motor and pump motor (if applicable) starters in a common enclosure. The panel shall be provided with a main circuit breaker disconnect and a separate circuit breaker for each motor or speed. Fuse protection will not be accepted. Panels containing basin heaters shall have an Earth Leakage Breaker containing ground fault protection. Starters above 25 A shall be NEMA rated. IEC starters will be accepted for motors below 25 A. Panel shall include a 120V/60Hz control power transformer, Hand-Off-Auto switches for each starter or contactor, and pilot lights for each component. Enclosed controls shall be provided in a NEMA (1) (3R) (4) (4X) (12) Enclosure.

Optional enclosed control features: (A temperature sensor shall be provided with the enclosed controls.)(A temperature controller shall be provided with the enclosed controls.) (A basin heater contactor with circuit breaker shall be provided.)(A vibration cutout switch input shall be provided.)

5.5 Safety Switch (es ): A heavy-duty, non-fusible safety disconnect switch shall be provided by the manufacturer of the evaporative cooling equipment. Switch shall be single throw, 3-pole design, rated up to 600 VAC. Switch shall have triple padlocking capability, a visible double break rotary blade mechanism, a clearly visible On/Off handle, an interlocking mechanism to prevent door opening with handle in On position, and a clear line shield. Safety switch shall be provided in a NEMA (1) (3R) (12) enclosure.