23 65 00 Cooling Towers ADD1.pdf

BID PACKAGE E – ADDENDUM 1 CENTRAL UTILITY PLANT

DATE: 04 DEC 2020 VANTHCS, DALLAS, TX

PROJECT 549-820E

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SECTION 23 65 00

COOLING TOWERS

PART 1 - GENERAL

1.1 DESCRIPTION

A. Packaged, induced draft complete with fill, fan, inlet louvers internal access ladders and walkways, external access ladders and walkways and associated accessories and equipment.

B. Packaged basin cleaning system complete with pump, centrifugal separator, piping and controls.

1.2 RELATED WORK

A. Section 03 30 00, CAST IN PLACE CONCRETE: Requirements for concrete inertia bases.

B. Section 23 05 11, COMMON WORK RESULTS FOR HVAC and STEAM GENERATION:

General mechanical requirements and items, which are common to more than one item.

C. Section 23 05 12, GENERAL MOTOR REQUIREMENTS FOR HVAC and STEAM

GENERATION EQUIPMENT.

D. Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and

EQUIPMENT: Requirements for vibration isolation.

E. Section 23 21 13, HYDRONIC PIPING: Requirements for water piping and fittings.

F. Section 23 25 00, HVAC WATER TREATMENT: Requirements for condenser water treatment.

G. Section 23 31 00, HVAC DUCTS and CASINGS: Requirements for sheet metal ductwork.

H. Section 26 29 11, MOTOR STARTERS.

1.3 QUALITY ASSURANCE

A. Refer to Article, QUALITY ASSURANCE, in specification Section 23 05 11, COMMON WORK RESULTS FOR HVAC and STEAM GENERATION.

B. Design Criteria:

1. Design to withstand 30 psf wind load.

2. Free water drift loss shall not be greater than five hundredths of one percent (0.005) of the water circulated to tower.

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3. Sound levels at 1.5 meters (5 feet) and 17 meters (55 feet) in any direction from the tower shall not exceed 84dB (A) and 71 dB (A), respectively. Select “low Noise” model cooling towers, where available. Provide sound attenuators if necessary to meet the noise criteria.

C. Performance Criteria:

1. Manufacturer shall certify that performance of cooling towers will meet contract requirements, stating entering air wet bulb temperature, entering and leaving condenser water temperatures, water flow rates, fan kW (horsepower) and pump head at base of tower.

Certification shall be made at the time of submittal.

2. Cooling Technology Institute (CTI) Certified Towers: These towers shall have been tested, rated, and certified in accordance with

Cooling Technology Institute (CTI) Standard 201, and shall bear the

CTI certification label, and shall be listed in the CTI directory of certified cooling towers.

3. The alignment and balancing of the fans and motors as installed shall operate within the vibration tolerance specified in specification

Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and

EQUIPMENT.

1.4 SUBMITTALS

A. Submit in accordance with specification Section 01 33 23, SHOP DRAWINGS, PRODUCT DATA, and SAMPLES.

B. Shop Drawings

1. Sufficient information, clearly presented, shall be included to determine compliance with drawings and specifications.

2. Include rated capacities, pressure drop, fan performance and rating curves, dimensions, weights, mounting details, front view, side view, equipment and device arrangement.

3. Include electrical rating, detail wiring for power, signals and controls.

4. Sound curves and characteristics of sound attenuators if required to meet the noise criteria.

C. Certification:

1. Submit four copies of performance curves, for CTI certified cooling towers, showing compliance with actual conditions specified, to the

Resident Engineer two weeks prior to delivery of the equipment.

2. Two weeks prior to final inspection, submit four copies of the following to the Resident Engineer:

a. Certification by the manufacturer that the cooling towers conform to the requirements of the drawings and specifications.

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b. Certification by the Contractor that the cooling towers have been installed, adjusted, and tested.

1.5 APPLICABLE PUBLICATIONS

A. The publications listed below form a part of this specification to the extent referenced. The publications are referenced in the text by the basic designation only.

B. American National Standard Institute (ANSI/ASSE)

A10.18-2007.............Safety Requirements for Temporary Floors, Holes, Wall Openings, Stairways and Other Unprotected

Edges in Construction and Demolition Operations

C. American Society of Mechanical Engineers (ASME):

PTC 23-03...............Performance Test Codes on Atmospheric Water

Cooling Equipment

D. American Society for Testing Materials (ASTM):

A385-08.................Standard Practice for Providing High-Quality

Zinc Coatings (Hot-Dip)

B117-07a................Standard Practice for Operating Salt Spray (Fog)

Apparatus

B209-07.................Standard Specification for Aluminum and

Aluminum-Alloy Sheet and Plate

E84-08a.................Standard Test Method for Surface Burning

Characteristics of Building Materials

E. Cooling Technology Institute (CTI):

ATC-105-00..............Acceptance Test Code for Water-Cooling Towers

(CTI Code Tower Standard Specifications)

ATC-105S-Rev. July 2004.Acceptance Test Code for Closed Circuit Cooling

Towers (CTI Code Tower Standard Specifications)

201-02 (Rev. 04)........Standard for Certification of Water Cooling

Tower Thermal Performance (CTI Code Tower

Standard Specifications)

F. National Electrical Manufacturers Association (NEMA):

MG 1-2006 Includes......Motors and Generators (ANSI)

250-03..................Enclosures for Electrical Equipment (1000 Volts

Maximum)

G. National Fire Protection Association (NFPA):

70-08...................National Electrical Code

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PART 2 - PRODUCTS

2.1 INDUCED DRAFT OPEN CIRCUIT COOLING TOWER:

A. Cooling tower shall be a factory assembled, induced draft, cross-flow type, vertical discharge configuration. Towers shall be basin less for mounting on concrete cold water basin.

B. Casing Panels: Casing panels shall be constructed of corrosion and

UV-resistant fiberglass reinforced polyester (FRP) to minimize maintenance requirements and prolong equipment life. Casing panels shall not provide structural support, since the sturdy, structural frame of the tower accurately transfers all loads to the equipment anchorage. Heavy gage (minimum 16 gage) ASTM A666 304 Stainless

Steel may be used in lieu of FRP panels.

1. Fasteners: Use stainless steel nuts and bolts or self tapping screws and washers with neoprene backing where required for preventing leaks.

2. Joints and Seams: Sealed watertight.

3. Welded connections: Continuous and watertight.

C. Framing: Rolled or formed structural stainless steel conforming to ASTM

A666, Type 304.

D. Louvers:

1. Inlet louvers shall be separate from the fill and removable to provide easy access for inspection of the air/water interface at the louver face. Louvers shall prevent water splash out during fan cycling and be constructed of maintenance free, corrosion and UV resistant, fiberglass reinforced polyester (FRP). Louvers which are integral with the fill material will not be acceptable.

E. Fill:

1. Fill and Drift Eliminators: The fill and integral drift eliminators shall be formed from self-extinguishing (per ASTM-568) polyvinyl chloride (PVC) having a flame spread rating of 5 per ASTM E84 and shall be impervious to rot, decay, fungus and biological attack. The fill shall be suitable for entering water temperatures up to and including 130°F (54.4°C). The fill shall be manufactured, tested and rated by the cooling tower manufacturer and shall be elevated above the cold water floor to facilitate cleaning. Spacing between fill sheets shall be a minimum of 3/4 inches (19.1 mm) to reduce the tendency for fouling and scaling, and to ensure proper airflow for maximum cooling capacity.

F. Drift Eliminators: Same as fill material. Effectively trap water droplets entrained in discharge air stream and limit drift loss to less

23 65 00-5 than 0.005 percent of the total water circulated. Sections shall be assembled into easily removable racks of the same material as the casing. Eliminators can be PVC neoprene honeycomb type.

G. Hot Water Distribution System: Open basin, flume and troughs with nozzles spaced for even distribution of water over fill material.

Provide low flow dams to prevent channeling with low flow conditions.

Provide access door. System shall be self-draining and non-clogging.

Provide manufacturer's standard pre-strainer assembly and butterfly or globe valve, for cross flow tower, to balance the water flow to each basin.

H. Cold Water Collection Basin: The cooling tower shall be basin-less for installation on a concrete basin as indicated on the plans. Towers with basins shall not be considered due to inability to access and clean the concrete basin below. Opening through bottom of tower shall be at least

42” by 167” to allow access to concrete basin for cleaning and maintenance. Provide Stainless steel mini-basin immediately below the fill deep enough to prevent air bypass below the fill. The water shall discharge directly into the concrete basin.

I. Collection Basin Water Level Control: Provide in each pump basin, an electronic operated slow closing 120V solenoid valve and NEMA MG 1, Type

4x enclosure. Electronic Solid state controls shall have stainless steel electrode probes and relays factory wired to a terminal strip to provide control of a new makeup valves, low and high level alarms and output for interface with the BAS. Provide a 3’ wide sluice gate between each cooling tower basin as shown on the plans for water equalization.

Provide a removable dam at each sluice gate for basin isolation.

J. Fans: Heavy duty axial flow type geardirectly driven and balanced at the factory after assembly, with aluminum alloy blades. Fans shall be driven by direct drive TEAO motor(s) with an IP66 NEMA enclosurevariable speed drive. The gear shall be a right angle, industrial duty, oil-lubricated, geared speed reducer. Spiral bevel or spiral bevel/helical gears are designed in accordance with the Cooling Technology Institute STD-111, "Gear Speed Reducers". All gears have a minimum service factor of 2.0 based on design fan horsepower and shall be suitable for both forward and reverse operation. An oil level fill port and sight glass shall be located on the gear drive to facilitate routine inspection and maintenance. The gear shall be doweled in position after alignment of the mechanical equipment. Drives shall have non-reversing ratchet. Fan system shall be capable of operating at any speed with no minimum requirement. Motor insulation type shall be Class H and shall be rated at 1850 volts peak. Bearings shall be designed for a minimum L10 life of

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100,000 hours. Motor paint shall be capable of passing a 1000 hour salt fog test. Motor shall be provided with normally closed thermostats.

Space heater shall be included if drive system does not include automatic protection for motor windings. If oil is required, an extended oil fill line, electric oil heater, low level oil switch, and oil level sight glass shall be included. Variable frequency drive shall be provided by the manufacturer and designed specifically for the cooling tower motor(s); refer to VFD specification for details. The drive enclosure shall be provided in NEMA 3R rated enclosure(s). Provide access doors for inspection and cleaning. Fan shaft bearings of the self-aligning, grease-lubricated ball or roller bearings with moisture proof seals and premium, moisture-resistant grease suitable for temperatures between minus 29 and 149 degrees C (minus 20 and plus 300 degrees F). Bearings designed for an L-10 life of 50,000 hours and with extended lubrication lines to an easily accessible location outside of the wet air stream. Provide access doors for inspection and cleaning.

L. Motors and drives:

1. The alignment and balancing of the fans and motors as installed shall operate within the vibration limits specified in specification

Section 23 05 41, NOISE and VIBRATION CONTROL FOR HVAC PIPING and

EQUIPMENT.

2. In addition to the requirements of specification Section 23 05 11, COMMON WORK RESULTS FOR HVAC and STEAM GENERATION, the following shall apply:

a. Motors: Totally enclosed air over (TEAO) or epoxy encapsulated

NEMA MG 1. Protect fan, bearings, and appurtenances from damage by weather, corrosion, water spray and grit. Provide motors with severe duty rating with the rotor and stator protected with corrosion-inhibiting epoxy resin, double shielded, vacuum-degassed bearings lubricated with premium moisture-resistant grease suitable for temperatures between minus 29 and plus 149 degrees C

(minus 20 and plus 300 degrees F), and an internal heater automatically energized when motor is de-energized. Provide an adjustable motor base or other suitable provision for adjusting belt tension.

b. Motor Controllers: Provide variable speed motors and controllers, if shown on drawings for cooling tower fans. See specification

Section 23 05 11, COMMON WORK RESULTS FOR HVAC and STEAM

GENERATION.

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c. Lubrication fittings shall be readily accessible outside the wet air stream. Provide access doors for inspection and cleaning.

d. The alignment and balancing of the fans and motors as installed shall operate within the vibration tolerance specified in specification Section 23-05-41, NOISE and VIBRATION CONTROL FOR

HVAC PIPING and EQUIPMENT.

M. Fans over 1500 mm (60 inches) in diameter include a vibration cutout switch located in a protected position to effectively monitor fan vibration. Vibration switch shall be solid-state with adjustable time excessive fan vibration. Interface the vibration cut-out switch with the DDC control system to provide an alarm in the event the fans stop due to excessive vibration.

N. Safety: Provide velocity recovery stacks, ladders, handrails and platform in conformance with the ANSI A10.18 as follows:

1. Fan Deck Extension: Provide a fan deck platform extension with 1-

1/4” galvanized steel pipe safety railing complying with OSHA standards and regulations to provide a means of safe and convenient access to the fan deck for maintenance of the water distribution system. The supports for the fan deck platform are constructed of G-

235 galvanized steel. The fan deck extension shall be field assembled.

2. Internal Walkway: Provide an internal aluminum ladder and an internal walkway in the plenum section for inspection and maintenance.

All working surfaces shall be able to withstand 50 psf (244 kg/m2) live load or 200 pound (90.7 kg) concentrated load. Other components of the cooling tower, i.e. basin and fill/drift eliminators, shall not be considered an internal working surface. Cooling tower manufacturers that promote these surfaces to be used as a working platform shall provide a two-year extended warranty to the Owner to repair any damage to these surfaces caused during routine maintenance.

3. Internal Platform: An internal platform shall be provided in the plenum section to provide for inspection and maintenance. All working surfaces shall be able to withstand 50 psf live load or 200 pound concentrated load. Other components of the cooling tower, i.e. basin floor and fill/drift eliminators, shall not be considered an internal working surface. Cooling tower manufacturers that promote these surfaces to be used as a working platform shall provide a two-year extended warranty to the Owner to repair any damage to these surfaces caused during routine maintenance.

4. Cooling tower may incorporate the use of a velocity recovery stack.

The velocity recovery stack shall consist of multiple panels which form a tapered 60” tall stack. It shall be constructed of Type 304

23 65 00-8 stainless steel. Fiberglass or FRP constructed fan stacks are unacceptable. Due to height of stack, a fan guard is not required.

5. Ladders: Vertical hot-dip galvanized steel or aluminum ladder for the south end tower. The existing North tower has and existing stair for access at the north end. Ladders higher than 3.6 meters (12 feet) shall have safety cage. Ladders shall extend to within 300 mm (one foot) of the grade or the roof deck surface.

6. Hand Railing: Steel or aluminum hand railings not less than 1070 mm

(42 inches) high around perimeter of each fan-deck, or working surface 3.6 meters (12 feet) or more above ground, roof or other supporting construction. Handrails shall meet OSHA Standards.

7. Platform: Galvanized steel with a bar grating floor. Provide extended fan deck platform between towers for access to all towers. Coordinate with tower spacing requirements.

O. Electric Heat Tracing: Provide in specification Section 23 21 13, HYDRONIC PIPING.

2.2 PACKAGED BASIN CLEANING SYSTEM

A. Supply a packaged basin cleaning system complete with separator, pump, piping, and controls completely factory assembled. The packaged system shall include a centrifugal vortex type separator, integral pump and schedule 80 PVC interconnecting piping. The complete system shall be mounted on an epoxy coated steel skid.

B. The separator shall be a dumbbell type design with a true tangential entry to ensure proper helical flow. The separator shall have an expected solids performance rating of 98% efficient at 74 microns and larger (with a specific gravity of 2.6 or greater) on a single pass.

The unit shall be equipped with inlet/outlet gauges to monitor pressure drop and a manual air relief valve shall be provided at the top of the vessel.

C. The separator shall be fabricated of carbon steel, rated at 150 psi working pressure (temperature dependent). The separator vessel shall be hydro tested at 1.5 times the design pressure and finished with a fusion bonded epoxy coating.

D. The system pump shall be a cast iron bronze fitted close couple, end suction type, sized for the proper flow rate of the package. The pump shall be of cast iron construction and include a cast iron pre-strainer with a perforated stainless steel basket. The pump shall be provided with a standard efficiency, TEFC motor.

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E. Purging of the accumulation chamber shall be accomplished without interrupting flow or excessive loss of system fluid.

F. The basin cleaning system shall be equipped with automatic controls consisting of an electrically actuated two-way brass ball valve with a HOA switch and solid state purge timer mounted in the control panel. The system shall be equipped with automatic controls consisting of a motor start/stop device with overload short circuit protection, pump HOA selector switch, mounted in a NEMA 4X fiberglass enclosure. The unit shall have a single electrical hook-up point.

G. The system shall be complete with schedule 80 CPVC distribution piping with spray nozzles to sweep the entire concrete basin floor.

PART 3 - EXECUTION

3.1 STARTUP AND TESTING

A. Provide the services of a factory-authorized and qualified representative to perform start up service.

B. Clean entire unit including basin.

C. Inspect field-assembled components and equipment installation, including piping and electrical connections.

D. Verify that accessories are properly installed.

E. Obtain and review performance curves and tables.

F. Perform startup checks, according to manufacturer's written instructions, and as noted below:

1. Check clearances for airflow and tower servicing.

2. Check for vibration isolation and structural support.

3. Verify fan rotation for correct direction and for vibration or binding and correct problems.

4. Adjust belts to proper alignment and tension.

5. Lubricate rotating parts and bearings.

6. Operate variable-speed fans through entire operating range and check for harmonic vibration imbalance. Set motor controller to skip speeds resulting in abnormal vibration.

7. Check vibration switch setting. Verify operation.

8. Verify operation of basin heater and control.

9. Operate equipment controls and safeties.

10. Verify that tower discharge is high enough and it does not recirculate into HVAC air intakes. Recommend corrective action.

G. Adjust water level for operating level and balance condenser water flow to each tower inlet.

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H. Check water treatment water system, including blow down for proper operation of the tower. Check makeup water-level control and valve.

I. Start cooling tower, including condenser water pumps and verify the tower operation.

J. Prepare and submit a written report of startup and inspection service to the Resident Engineer.

K Replace defective and malfunctioning units.

3.2 TRAINING:

A. Furnish the services of a competent, factory-trained engineer or technician for a 2-hour period for instructing VA personnel in operation and maintenance of the equipment, including review of the operation and maintenance manual, on a date requested by the Resident Engineer.

Coordinate this training with that of the chiller, if furnished together.

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