Author: Benjamin Seidel
Last saved by: Wong, Eric

Section 236500
Cooling Towers – For nexus units ordered or manufactured after oct 2026
	PART 1 GENERAL
1.01	SECTION INCLUDES
A.	Closed circuit, forced draft, counterflow cooling towers with hybrid operation.
1.02	REFERENCE STANDARDS
A.	ASHRAE 90.1-2019 – Energy Standard for Buildings Except Low-Rise Residential Buildings.
B.	ASME B31.5 - Refrigeration Piping and Heat Transfer Components 2016.
C.	ASTM B117 - Standard Practice for Operating Salt Spray (Fog) Apparatus 2018.
D.	ASTM D2794 - Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact) 1993 (Reapproved 2010).
E.	CTI STD-201 OM - Operations Manual for Thermal Performance Certification of Evaporative Heat Rejection Equipment 2017.
F.	CTI STD-201 RS - Performance Rating of Evaporative Heat Rejection Equipment 2017.
G.	ISO 9001 - Quality management systems -- Requirements 2015.
H.	NEMA MG 1 - Motors and Generators 2017.
1.03	SUBMITTALS
A.	Product Data: Provide rated capacities, dimensions, weights and point loadings, accessories, electrical requirements and wiring diagrams, and location and size of field connections. 
B.	Shop Drawings: Indicate suggested structural steel supports including dimensions, sizes, and locations for mounting bolt holes.
C.	Manufacturer's Certificate: Certify that cooling tower performance, based on CTI STD-201 meets or exceeds specified requirements and submit performance curve plotting leaving water temperature against wet bulb temperature.
D.	Manufacturer's Instructions: Submit manufacturer's complete installation instructions.
E.	Operation and Maintenance Data: Include start-up instructions, maintenance data, parts lists, controls, and accessories.
F.	Warranty: Submit manufacturer's warranty and ensure forms have been filled out in Owner's name and registered with manufacturer.
1.04	QUALITY ASSURANCE
A.	Manufacturer Qualifications: Company specializing in manufacturing the type of products specified in this section, with minimum 20 years of documented experience and ISO 9001 certification.  
B.	Installer Qualifications: Company specializing in performing the type of work specified in this section with minimum 20 years of experience and approved by manufacturer.
C.	Product Performance: 
1.	Cooling tower must have a minimum energy rating of [_____] per ASHRAE 90.1, 189 and CA Title 24.
1.05	DELIVERY, STORAGE, AND HANDLING
A.	Equipment will be factory-assembled, including cold water basin, heat transfer section, water distribution, and fan drive system. For shipping, disassemble into as large as practical sub-assemblies so that minimum amount of field work is required for re-assembly. 
B.	Comply with manufacturer's installation instructions for rigging, unloading, and transporting units.
1.06	WARRANTY
A.	One-year warranty after start-up, or eighteen months from date of shipment, whichever occurs first. Warranty to include coverage for defects in material and workmanship.
B.	Fans, fan shafts, bearings, sheaves, gearboxes, drive shafts, couplings, and mechanical equipment support must be warranted against defects in materials and workmanship for a period of five (5) years.
	PART 2 PRODUCTS
2.01	MANUFACTURERS
A.	Closed Circuit, Forced Draft, Counterflow Cooling Towers with Hybrid Operation:
1.	Basis of Design: Baltimore Aircoil Company; Nexus Modular Hybrid Cooler: www.baltimoreaircoil.com #BAC
2.02	MANUFACTURED UNITS
A.	Provide a modular hybrid, forced draft counterflow cooler. It must be provided with a full controls package that provides modes to optimize water and energy savings and eliminate any potential for spray water system freezing in cold weather climates.  The entire unit and controls package shall be factory-wired and tested.  The controls will be integral to unit operation with single point power connection. Provide controls to allow for future system expansion. 
2.03	COMPONENTS
A.	Cold Water Basin:
1.	Provide sloped basin with drain/clean-out connection. Type 304 stainless steel panels and structural members. Basins constructed of 301 stainless steel are not acceptable. 
1.	The spray water collection basin and all of its components and accessories will be fully accessible while the unit is in operation. Proper lockout-tagout procedures must be followed when servicing electrical components. The cold-water basin is to be located at work bench height from base of unit to facilitate easy inspection and maintenance.
2.	Provide factory-installed collection basin accessories:
1.	Pan Strainer(s) will be all Type 304 Stainless Steel construction with large area removable perforated screens.
2.	Type 304 stainless steel overflow connection.
3.	Factory-wired and installed motorized large orifice drain valve.
4.	Factory-wired and installed motorized make-up control water valves and type 304 stainless steel connection.
3.	Provide a sloped collection basin that provides continuous turbulence of the water.  A factory-supplied solids separator and factory-installed basin sweeper piping system is an acceptable alternative. 
B.	Casing Panels and Framework:
1.	Casing panels: Galvanized steel protected by a thermosetting hybrid polymer. The polymer to consist of G-235 (Z700 metric) hot-dip galvanized steel prepared in a four-step (clean, pre-treat, rinse, and dry) process with an electrostatically applied, thermosetting, hybrid polymer fuse-bonded to the substrate during a thermally activated curing stage and monitored by a 23-step quality assurance program. Other coatings 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, unit to withstand 6000 hours of 5 percent salt spray per ASTM B117 without blistering, chipping, or loss of adhesion.
2.	When X-scribed to the steel substrate, unit to withstand 6000 hours of exposure to acidic (pH=4.0) and alkaline (pH=11.0) water solutions at 95 degrees F (35 degrees C) without signs of chemical attack.
3.	Unit to withstand impact of 160 in-lbs. per ASTM D2794 without fracture or delamination of the polymer layer.
4.	Unit to withstand 6000 hours of ultraviolet radiation equivalent to 120,000 hours of noontime sun exposure without loss of functional properties.
5.	Unit to withstand 200 thermal shock cycles between minus 25 degrees F and 180 degrees F (minus 32 degrees C and 82 degrees C) without loss of adhesion or other deterioration.
6.	Unit to withstand 6000 hours of exposure to 60 psi (42,184 kg/m^2) water jet without signs of wear or erosion.
7.	Type 304 stainless steel may be supplied as an equal to eliminate the need for passivation, minimize maintenance requirements, and prolong equipment life.
----- ALTERNATE for 304 Stainless Steel -----
C.	Casing panels, framework, and fasteners will be constructed of Type 304 stainless steel. Type 301 stainless steel is not an acceptable alternative.
D.	Fans: Epoxy coated aluminum, radial type, with electronically commutated direct drive motors.
1.	Fan Coating: Comply with DIN EN 485-2.
2.	Factory installed and located outside of the wet airstream in the unit.
3.	Fan(s) must be constructed of an aluminum alloy designed to meet or exceed standard DIN EN 485-2, protected with an epoxy coating.
4.	Fan(s) must be both statically and dynamically balanced to provide for vibration-free performance.
5.	Fan(s) must be provided with removable wire-mesh screens complying with OSHA regulations.
6.	Provide fan plenum design with swing-out fan base with stainless steel hinge that allows for access and easy removal. For units with fans at the top of the unit, a davit assembly is to be provided for fan and motor maintenance and removal.
7.	Balancing: Fans will have maximum residual balance as per DIN ISO 1940.
E.	Motors and Drives:
1.	Direct Drive System:
Electronically Commutated (EC) Drive system: Type F insulation with IP55 ingress protection. Full load efficiency of at least 91 percent, maintenance-free, permanently lubricated ball bearings, integrated thermal overload protection, PFC filter, and phase loss protection.
F.	Fan Guard: 304 Stainless steel wire mesh guards to prevent injury while fan is in operation.
G.	Heat Transfer System:
1.	Closed Circuit Heat Exchanger:
The heat exchanger will be constructed of a highly corrosion-resistant stainless-steel Type 316 alloy that exceeds accelerated cyclic corrosion test standard GMW14872. 
1)	No field passivation required.
2)	Maximum allowable working pressure of 150 psi and tested according to UL1995.
3)	The heat exchanger shall provide a minimum efficiency of 1.0 nominal ton per 1.5 gallons of internal working fluid volume.
4)	Internal heat exchanger volume must not exceed volume listed on equipment schedule.
H.	Distribution Section: Polyvinyl chloride piping header and branches with ABS plastic spray nozzles. When non-combustible option selected, piping header and branches are 304 stainless steel.
I.	Drift Eliminators: Three-pass design to minimize drift loss, made of PVC material. Must be easily accessible from a dedicated access panel. When non-combustible option selected, drift eliminators are 304 stainless steel.
J.	Basin Water Level Control: Touchless radar sensor.
K.	Alarm Contact: Contact that will close when unit experiences an alarm.
L.	Controls: Touchscreen intelligent and intuitive controls with ambient operating temperature up to 113 degrees F/ 45 degrees C in a NEMA 3R enclosure.
M.	Water Treatment System: A factory-supplied dual biocide advanced oxidant generator with UV light (with option to remove) will be shipped fully assembled and wired for fast installation. 
1.	The water treatment components will be housed in a 304 stainless steel enclosure. All piping will be constructed of CPVC.
2.	A 24VDC 254nm UV lamp will be housed in a stainless-steel disinfection chamber and provide at least 60mJ/cm^2 dosage to the circulating water. 
3.	Advanced oxidant generator provides continuous generation and has no liquid chemicals to run out or refill. 
4.	Circulation pump will have ceramic shaft and radial bearings, carbon axial bearing, stainless steel rotor can and bearing plate, corrosion-resistant impeller, composite, PES and stainless-steel pump housing. 
5.	System must be able to be completely drained. An automatic solenoid drain valve must connect to factory-supplied controls to drain the water treatment system to avoid freezing or debris accumulation. 
6.	Sensors must monitor for pump failure, low UV intensity, and loss of UV light. Alarm on water treatment panel will alert user of any sensors reporting abnormal values.  
7.	Factory-wired and installed water conductivity sensor to optimize drain cycle.
8.	Water treatment control panel enclosure will be constructed of fiberglass reinforced polyester with at least a NEMA 3R/4X rating. 
N.	Hardware: Stainless steel nuts, bolts, washers, and tappers; assembled with phenolic epoxy coated, corrosion resistant washer head fasteners.
2.04	ACCESSORIES
A.	(Optional) Electric Immersion Heaters: In pan suitable to maintain temperature of water in pan at 40 degrees F (4.4 degrees C) when outside temperature is 0 degrees F (-17.7 degrees C) [OR -20 degrees F (-28.9 degrees C)] and wind velocity is 15 mph (25 kph); immersion thermostat and float control operate heaters on low temperature when the pan is filled. Heaters will be constructed of copper.
B.	Access Packages: See submittal documents for access package requirements. Platforms and ladders must ship assembled from cooling tower manufacturer.
1.	The cold-water collection basin and all of its components and accessories will be fully accessible while the unit is in operation. Proper lockout-tagout procedures must be followed when servicing electrical components. The cold-water basin is to be located at work bench height from base of unit to facilitate easy inspection and maintenance.
2.	Drift eliminators will be accessible and removable from the side of the unit and will not require any fixed access platforms or ladders from the base of the unit.  Units that require drift eliminators to be removed from the top of the unit shall include access platforms, handrails, and ladders to facilitate maintenance of the drift eliminators.
	PART 3 EXECUTION
3.01	INSTALLATION
A.	Install in accordance with manufacturer's instructions.
B.	Provide the services of the manufacturer's field representative to supervise rigging, hoisting, and installation, allowing for minimum of one eight-hour day per tower.
C.	Install tower on structural steel beams as instructed by manufacturer.
D.	Connect condenser water piping to tower. Pitch condenser water supply to tower and condenser water suction away from tower. 
E.	Connect make-up water piping to tower. Pitch to tower. 
F.	Connect overflow and drain to acceptable discharge point as required by jurisdiction.
3.02	FIELD QUALITY CONTROL
A.	See Quality Requirements, for additional requirements.
B.	Provide the services of the manufacturer's field representative to inspect tower after installation and submit report prior to start-up, verifying installation is in accordance with specifications and manufacturer's recommendations.
3.03	SYSTEM START-UP
A.	Start-up tower in presence of and instruct Owner 's operating personnel.
3.04	SCHEDULES
A.	Cooling Towers
1.	Drawing Code:
2.	Location:
3.	Manufacturer:
4.	Model Number:
5.	Cooling Capacity
1.	Water Flow Rate:
2.	Entering Water Temperature:
3.	Leaving Water Temperature:
6.	Entering Air WB Temperature:
7.	Entering Air DB Temperature Switch point: 
8.	External Static Pressure (For indoor applications):
9.	Number of Fan Motors:
10.	Motor Size:
11.	Fan Motor Electrical Characteristics: [_____] Volts, Three-Phase, 60 Hz.
12.	Pump Motor Electrical Characteristics: [_____] Volts, Three-Phase, 60 Hz.
13.	Basin Heaters No. and Type:
a.	END OF SECTION

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